fsnotify: Fix misspelling of "writable"

Several file system notification system headers have "writable"
misspelled as "writtable" in the comments. This patch fixes it in the
fsnotify header.

Signed-off-by: Vicki Pfau <vi@endrift.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20240306020831.1404033-2-vi@endrift.com>

fanotify: allow "weak" fsid when watching a single filesystem

So far, fanotify returns -ENODEV or -EXDEV when trying to set a mark
on a filesystem with a "weak" fsid, namely, zero fsid (e.g. fuse), or
non-uniform fsid (e.g. btrfs non-root subvol).

When group is watching inodes all from the same filesystem (or subvol),
allow adding inode marks with "weak" fsid, because there is no ambiguity
regarding which filesystem reports the event.

The first mark added to a group determines if this group is single or
multi filesystem, depending on the fsid at the path of the added mark.

If the first mark added has a "strong" fsid, marks with "weak" fsid
cannot be added and vice versa.

If the first mark added has a "weak" fsid, following marks must have
the same "weak" fsid and the same sb as the first mark.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20231130165619.3386452-3-amir73il@gmail.com>

fanotify: store fsid in mark instead of in connector

Some filesystems like fuse and nfs have zero or non-unique fsid.
We would like to avoid reporting ambiguous fsid in events, so we need
to avoid marking objects with same fsid and different sb.

To make this easier to enforce, store the fsid in the marks of the group
instead of in the shared conenctor.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20231130165619.3386452-2-amir73il@gmail.com>

fanotify: Remove unused extern declaration fsnotify_get_conn_fsid()

This is never used, so can remove it.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20230725135528.25996-1-yuehaibing@huawei.com>

fanotify: prepare for setting event flags in ignore mask

Setting flags FAN_ONDIR FAN_EVENT_ON_CHILD in ignore mask has no effect.
The FAN_EVENT_ON_CHILD flag in mask implicitly applies to ignore mask and
ignore mask is always implicitly applied to events on directories.

Define a mark flag that replaces this legacy behavior with logic of
applying the ignore mask according to event flags in ignore mask.

Implement the new logic to prepare for supporting an ignore mask that
ignores events on children and ignore mask that does not ignore events
on directories.

To emphasize the change in terminology, also rename ignored_mask mark
member to ignore_mask and use accessors to get only the effective
ignored events or the ignored events and flags.

This change in terminology finally aligns with the "ignore mask"
language in man pages and in most of the comments.

Link: https://lore.kernel.org/r/20220629144210.2983229-2-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: introduce mark type iterator

fsnotify_foreach_iter_mark_type() is used to reduce boilerplate code
of iterating all marks of a specific group interested in an event
by consulting the iterator report_mask.

Use an open coded version of that iterator in fsnotify_iter_next()
that collects all marks of the current iteration group without
consulting the iterator report_mask.

At the moment, the two iterator variants are the same, but this
decoupling will allow us to exclude some of the group's marks from
reporting the event, for example for event on child and inode marks
on parent did not request to watch events on children.

Fixes: 2f02fd3fa13e ("fanotify: fix ignore mask logic for events on child and on dir")
Reported-by: Jan Kara <jack@suse.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220511190213.831646-2-amir73il@gmail.com

fsnotify: allow adding an inode mark without pinning inode

fsnotify_add_mark() and variants implicitly take a reference on inode
when attaching a mark to an inode.

Make that behavior opt-out with the mark flag FSNOTIFY_MARK_FLAG_NO_IREF.

Instead of taking the inode reference when attaching connector to inode
and dropping the inode reference when detaching connector from inode,
take the inode reference on attach of the first mark that wants to hold
an inode reference and drop the inode reference on detach of the last
mark that wants to hold an inode reference.

Backends can "upgrade" an existing mark to take an inode reference, but
cannot "downgrade" a mark with inode reference to release the refernce.

This leaves the choice to the backend whether or not to pin the inode
when adding an inode mark.

This is intended to be used when adding a mark with ignored mask that is
used for optimization in cases where group can afford getting unneeded
events and reinstate the mark with ignored mask when inode is accessed
again after being evicted.

Link: https://lore.kernel.org/r/20220422120327.3459282-12-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: create helpers for group mark_mutex lock

Create helpers to take and release the group mark_mutex lock.

Define a flag FSNOTIFY_GROUP_NOFS in fsnotify_group that determines
if the mark_mutex lock is fs reclaim safe or not. If not safe, the
lock helpers take the lock and disable direct fs reclaim.

In that case we annotate the mutex with a different lockdep class to
express to lockdep that an allocation of mark of an fs reclaim safe group
may take the group lock of another "NOFS" group to evict inodes.

For now, converted only the callers in common code and no backend
defines the NOFS flag. It is intended to be set by fanotify for
evictable marks support.

Link: https://lore.kernel.org/r/20220422120327.3459282-7-amir73il@gmail.com
Suggested-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220321112310.vpr7oxro2xkz5llh@quack3.lan/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: make allow_dups a property of the group

Instead of passing the allow_dups argument to fsnotify_add_mark()
as an argument, define the group flag FSNOTIFY_GROUP_DUPS to express
the allow_dups behavior and set this behavior at group creation time
for all calls of fsnotify_add_mark().

Rename the allow_dups argument to generic add_flags argument for future
use.

Link: https://lore.kernel.org/r/20220422120327.3459282-6-amir73il@gmail.com
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: pass flags argument to fsnotify_alloc_group()

Add flags argument to fsnotify_alloc_group(), define and use the flag
FSNOTIFY_GROUP_USER in inotify and fanotify instead of the helper
fsnotify_alloc_user_group() to indicate user allocation.

Although the flag FSNOTIFY_GROUP_USER is currently not used after group
allocation, we store the flags argument in the group struct for future
use of other group flags.

Link: https://lore.kernel.org/r/20220422120327.3459282-5-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

inotify: move control flags from mask to mark flags

The inotify control flags in the mark mask (e.g. FS_IN_ONE_SHOT) are not
relevant to object interest mask, so move them to the mark flags.

This frees up some bits in the object interest mask.

Link: https://lore.kernel.org/r/20220422120327.3459282-3-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: optimize FS_MODIFY events with no ignored masks

fsnotify() treats FS_MODIFY events specially - it does not skip them
even if the FS_MODIFY event does not apear in the object's fsnotify
mask. This is because send_to_group() checks if FS_MODIFY needs to
clear ignored mask of marks.

The common case is that an object does not have any mark with ignored
mask and in particular, that it does not have a mark with ignored mask
and without the FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY flag.

Set FS_MODIFY in object's fsnotify mask during fsnotify_recalc_mask()
if object has a mark with an ignored mask and without the
FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY flag and remove the special
treatment of FS_MODIFY in fsnotify(), so that FS_MODIFY events could
be optimized in the common case.

Call fsnotify_recalc_mask() from fanotify after adding or removing an
ignored mask from a mark without FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY
or when adding the FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY flag to a mark
with ignored mask (the flag cannot be removed by fanotify uapi).

Performance results for doing 10000000 write(2)s to tmpfs:

vanilla patched
without notification mark 25.486+-1.054 24.965+-0.244
with notification mark 30.111+-0.139 26.891+-1.355

So we can see the overhead of notification subsystem has been
drastically reduced.

Link: https://lore.kernel.org/r/20220223151438.790268-3-amir73il@gmail.com
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: fix merge with parent's ignored mask

fsnotify_parent() does not consider the parent's mark at all unless
the parent inode shows interest in events on children and in the
specific event.

So unless parent added an event to both its mark mask and ignored mask,
the event will not be ignored.

Fix this by declaring the interest of an object in an event when the
event is in either a mark mask or ignored mask.

Link: https://lore.kernel.org/r/20220223151438.790268-2-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: generate FS_RENAME event with rich information

The dnotify FS_DN_RENAME event is used to request notification about
a move within the same parent directory and was always coupled with
the FS_MOVED_FROM event.

Rename the FS_DN_RENAME event flag to FS_RENAME, decouple it from
FS_MOVED_FROM and report it with the moved dentry instead of the moved
inode, so it has the information about both old and new parent and name.

Generate the FS_RENAME event regardless of same parent dir and apply
the "same parent" rule in the generic fsnotify_handle_event() helper
that is used to call backends with ->handle_inode_event() method
(i.e. dnotify). The ->handle_inode_event() method is not rich enough to
report both old and new parent and name anyway.

The enriched event is reported to fanotify over the ->handle_event()
method with the old and new dir inode marks in marks array slots for
ITER_TYPE_INODE and a new iter type slot ITER_TYPE_INODE2.

The enriched event will be used for reporting old and new parent+name to
fanotify groups with FAN_RENAME events.

Link: https://lore.kernel.org/r/20211129201537.1932819-5-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: separate mark iterator type from object type enum

They are two different types that use the same enum, so this confusing.

Use the object type to indicate the type of object mark is attached to
and the iter type to indicate the type of watch.

A group can have two different watches of the same object type (parent
and child watches) that match the same event.

Link: https://lore.kernel.org/r/20211129201537.1932819-3-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: clarify object type argument

In preparation for separating object type from iterator type, rename
some 'type' arguments in functions to 'obj_type' and remove the unused
interface to clear marks by object type mask.

Link: https://lore.kernel.org/r/20211129201537.1932819-2-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: Pre-allocate pool of error events

Pre-allocate slots for file system errors to have greater chances of
succeeding, since error events can happen in GFP_NOFS context. This
patch introduces a group-wide mempool of error events, shared by all
FAN_FS_ERROR marks in this group.

Link: https://lore.kernel.org/r/20211025192746.66445-20-krisman@collabora.com
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Support FS_ERROR event type

Expose a new type of fsnotify event for filesystems to report errors for
userspace monitoring tools. fanotify will send this type of
notification for FAN_FS_ERROR events. This also introduce a helper for
generating the new event.

Link: https://lore.kernel.org/r/20211025192746.66445-18-krisman@collabora.com
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Pass group argument to free_event

For group-wide mempool backed events, like FS_ERROR, the free_event
callback will need to reference the group's mempool to free the memory.
Wire that argument into the current callers.

Link: https://lore.kernel.org/r/20211025192746.66445-13-krisman@collabora.com
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Protect fsnotify_handle_inode_event from no-inode events

FAN_FS_ERROR allows events without inodes - i.e. for file system-wide
errors. Even though fsnotify_handle_inode_event is not currently used
by fanotify, this patch protects other backends from cases where neither
inode or dir are provided. Also document the constraints of the
interface (inode and dir cannot be both NULL).

Link: https://lore.kernel.org/r/20211025192746.66445-12-krisman@collabora.com
Suggested-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Retrieve super block from the data field

Some file system events (i.e. FS_ERROR) might not be associated with an
inode or directory. For these, we can retrieve the super block from the
data field. But, since the super_block is available in the data field
on every event type, simplify the code to always retrieve it from there,
through a new helper.

Link: https://lore.kernel.org/r/20211025192746.66445-11-krisman@collabora.com
Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Add wrapper around fsnotify_add_event

fsnotify_add_event is growing in number of parameters, which in most
case are just passed a NULL pointer. So, split out a new
fsnotify_insert_event function to clean things up for users who don't
need an insert hook.

Link: https://lore.kernel.org/r/20211025192746.66445-10-krisman@collabora.com
Suggested-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Add helper to detect overflow_event

Similarly to fanotify_is_perm_event and friends, provide a helper
predicate to say whether a mask is of an overflow event.

Link: https://lore.kernel.org/r/20211025192746.66445-9-krisman@collabora.com
Suggested-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: pass dentry instead of inode data

Define a new data type to pass for event - FSNOTIFY_EVENT_DENTRY.
Use it to pass the dentry instead of it's ->d_inode where available.

This is needed in preparation to the refactor to retrieve the super
block from the data field. In some cases (i.e. mkdir in kernfs), the
data inode comes from a negative dentry, such that no super block
information would be available. By receiving the dentry itself, instead
of the inode, fsnotify can derive the super block even on these cases.

Link: https://lore.kernel.org/r/20211025192746.66445-3-krisman@collabora.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
[Expand explanation in commit message]
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: configurable limits via sysfs

fanotify has some hardcoded limits. The only APIs to escape those limits
are FAN_UNLIMITED_QUEUE and FAN_UNLIMITED_MARKS.

Allow finer grained tuning of the system limits via sysfs tunables under
/proc/sys/fs/fanotify, similar to tunables under /proc/sys/fs/inotify,
with some minor differences.

- max_queued_events - global system tunable for group queue size limit.
Like the inotify tunable with the same name, it defaults to 16384 and
applies on initialization of a new group.

- max_user_marks - user ns tunable for marks limit per user.
Like the inotify tunable named max_user_watches, on a machine with
sufficient RAM and it defaults to 1048576 in init userns and can be
further limited per containing user ns.

- max_user_groups - user ns tunable for number of groups per user.
Like the inotify tunable named max_user_instances, it defaults to 128
in init userns and can be further limited per containing user ns.

The slightly different tunable names used for fanotify are derived from
the "group" and "mark" terminology used in the fanotify man pages and
throughout the code.

Considering the fact that the default value for max_user_instances was
increased in kernel v5.10 from 8192 to 1048576, leaving the legacy
fanotify limit of 8192 marks per group in addition to the max_user_marks
limit makes little sense, so the per group marks limit has been removed.

Note that when a group is initialized with FAN_UNLIMITED_MARKS, its own
marks are not accounted in the per user marks account, so in effect the
limit of max_user_marks is only for the collection of groups that are
not initialized with FAN_UNLIMITED_MARKS.

Link: https://lore.kernel.org/r/20210304112921.3996419-2-amir73il@gmail.com
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: use hash table for faster events merge

In order to improve event merge performance, hash events in a 128 size
hash table by the event merge key.

The fanotify_event size grows by two pointers, but we just reduced its
size by removing the objectid member, so overall its size is increased
by one pointer.

Permission events and overflow event are not merged so they are also
not hashed.

Link: https://lore.kernel.org/r/20210304104826.3993892-5-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: reduce event objectid to 29-bit hash

objectid is only used by fanotify backend and it is just an optimization
for event merge before comparing all fields in event.

Move the objectid member from common struct fsnotify_event into struct
fanotify_event and reduce it to 29-bit hash to cram it together with the
3-bit event type.

Events of different types are never merged, so the combination of event
type and hash form a 32-bit key for fast compare of events.

This reduces the size of events by one pointer and paves the way for
adding hashed queue support for fanotify.

Link: https://lore.kernel.org/r/20210304104826.3993892-3-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: allow fsnotify_{peek,remove}_first_event with empty queue

Current code has an assumtion that fsnotify_notify_queue_is_empty() is
called to verify that queue is not empty before trying to peek or remove
an event from queue.

Remove this assumption by moving the fsnotify_notify_queue_is_empty()
into the functions, allow them to return NULL value and check return
value by all callers.

This is a prep patch for multi event queues.

Link: https://lore.kernel.org/r/20210304104826.3993892-2-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

inotify, memcg: account inotify instances to kmemcg

Currently the fs sysctl inotify/max_user_instances is used to limit the
number of inotify instances on the system. For systems running multiple
workloads, the per-user namespace sysctl max_inotify_instances can be
used to further partition inotify instances. However there is no easy
way to set a sensible system level max limit on inotify instances and
further partition it between the workloads. It is much easier to charge
the underlying resource (i.e. memory) behind the inotify instances to
the memcg of the workload and let their memory limits limit the number
of inotify instances they can create.

With inotify instances charged to memcg, the admin can simply set
max_user_instances to INT_MAX and let the memcg limits of the jobs limit
their inotify instances.

Link: https://lore.kernel.org/r/20201220044608.1258123-1-shakeelb@google.com
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: fix events reported to watching parent and child

fsnotify_parent() used to send two separate events to backends when a
parent inode is watching children and the child inode is also watching.
In an attempt to avoid duplicate events in fanotify, we unified the two
backend callbacks to a single callback and handled the reporting of the
two separate events for the relevant backends (inotify and dnotify).
However the handling is buggy and can result in inotify and dnotify
listeners receiving events of the type they never asked for or spurious
events.

The problem is the unified event callback with two inode marks (parent and
child) is called when any of the parent and child inodes are watched and
interested in the event, but the parent inode's mark that is interested
in the event on the child is not necessarily the one we are currently
reporting to (it could belong to a different group).

So before reporting the parent or child event flavor to backend we need
to check that the mark is really interested in that event flavor.

The semantics of INODE and CHILD marks were hard to follow and made the
logic more complicated than it should have been. Replace it with INODE
and PARENT marks semantics to hopefully make the logic more clear.

Thanks to Hugh Dickins for spotting a bug in the earlier version of this
patch.

Fixes: 497b0c5a7c06 ("fsnotify: send event to parent and child with single callback")
CC: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201202120713.702387-4-amir73il@gmail.com
Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: generalize handle_inode_event()

The handle_inode_event() interface was added as (quoting comment):
"a simple variant of handle_event() for groups that only have inode
marks and don't have ignore mask".

In other words, all backends except fanotify. The inotify backend
also falls under this category, but because it required extra arguments
it was left out of the initial pass of backends conversion to the
simple interface.

This results in code duplication between the generic helper
fsnotify_handle_event() and the inotify_handle_event() callback
which also happen to be buggy code.

Generalize the handle_inode_event() arguments and add the check for
FS_EXCL_UNLINK flag to the generic helper, so inotify backend could
be converted to use the simple interface.

Link: https://lore.kernel.org/r/20201202120713.702387-2-amir73il@gmail.com
CC: stable@vger.kernel.org
Fixes: b9a1b9772509 ("fsnotify: create method handle_inode_event() in fsnotify_operations")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: create method handle_inode_event() in fsnotify_operations

The method handle_event() grew a lot of complexity due to the design of
fanotify and merging of ignore masks.

Most backends do not care about this complex functionality, so we can hide
this complexity from them.

Introduce a method handle_inode_event() that serves those backends and
passes a single inode mark and less arguments.

This change converts all backends except fanotify and inotify to use the
simplified handle_inode_event() method. In pricipal, inotify could have
also used the new method, but that would require passing more arguments
on the simple helper (data, data_type, cookie), so we leave it with the
handle_event() method.

Link: https://lore.kernel.org/r/20200722125849.17418-9-amir73il@gmail.com
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: send event with parent/name info to sb/mount/non-dir marks

Similar to events "on child" to watching directory, send event
with parent/name info if sb/mount/non-dir marks are interested in
parent/name info.

The FS_EVENT_ON_CHILD flag can be set on sb/mount/non-dir marks to specify
interest in parent/name info for events on non-directory inodes.

Events on "orphan" children (disconnected dentries) are sent without
parent/name info.

Events on directories are sent with parent/name info only if the parent
directory is watching.

After this change, even groups that do not subscribe to events on
children could get an event with mark iterator type TYPE_CHILD and
without mark iterator type TYPE_INODE if fanotify has marks on the same
objects.

dnotify and inotify event handlers can already cope with that situation.
audit does not subscribe to events that are possible on child, so won't
get to this situation. nfsd does not access the marks iterator from its
event handler at the moment, so it is not affected.

This is a bit too fragile, so we should prepare all groups to cope with
mark type TYPE_CHILD preferably using a generic helper.

Link: https://lore.kernel.org/r/20200716084230.30611-16-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: pass dir and inode arguments to fsnotify()

The arguments of fsnotify() are overloaded and mean different things
for different event types.

Replace the to_tell argument with separate arguments @dir and @inode,
because we may be sending to both dir and child. Using the @data
argument to pass the child is not enough, because dirent events pass
this argument (for audit), but we do not report to child.

Document the new fsnotify() function argumenets.

Link: https://lore.kernel.org/r/20200722125849.17418-7-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: add object type "child" to object type iterator

The object type iterator is used to collect all the marks of
a specific group that have interest in an event.

It is used by fanotify to get a single handle_event callback
when an event has a match to either of inode/sb/mount marks
of the group.

The nature of fsnotify events is that they are associated with
at most one sb at most one mount and at most one inode.

When a parent and child are both watching, two events are sent
to backend, one associated to parent inode and one associated
to the child inode.

This results in duplicate events in fanotify, which usually
get merged before user reads them, but this is sub-optimal.

It would be better if the same event is sent to backend with
an object type iterator that has both the child inode and its
parent, and let the backend decide if the event should be reported
once (fanotify) or twice (inotify).

Link: https://lore.kernel.org/r/20200716084230.30611-9-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: remove event FAN_DIR_MODIFY

It was never enabled in uapi and its functionality is about to be
superseded by events FAN_CREATE, FAN_DELETE, FAN_MOVE with group
flag FAN_REPORT_NAME.

Keep a place holder variable name_event instead of removing the
name recording code since it will be used by the new events.

Link: https://lore.kernel.org/r/20200708111156.24659-17-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: pass dir argument to handle_event() callback

The 'inode' argument to handle_event(), sometimes referred to as
'to_tell' is somewhat obsolete.
It is a remnant from the times when a group could only have an inode mark
associated with an event.

We now pass an iter_info array to the callback, with all marks associated
with an event.

Most backends ignore this argument, with two exceptions:
1. dnotify uses it for sanity check that event is on directory
2. fanotify uses it to report fid of directory on directory entry
modification events

Remove the 'inode' argument and add a 'dir' argument.
The callback function signature is deliberately changed, because
the meaning of the argument has changed and the arguments have
been documented.

The 'dir' argument is set to when 'file_name' is specified and it is
referring to the directory that the 'file_name' entry belongs to.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: return non const from fsnotify_data_inode()

Return non const inode pointer from fsnotify_data_inode().
None of the fsnotify hooks pass const inode pointer as data and
callers often need to cast to a non const pointer.

Link: https://lore.kernel.org/r/20200708111156.24659-3-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Rearrange fast path to minimise overhead when there is no watcher

The fsnotify paths are trivial to hit even when there are no watchers and
they are surprisingly expensive. For example, every successful vfs_write()
hits fsnotify_modify which calls both fsnotify_parent and fsnotify unless
FMODE_NONOTIFY is set which is an internal flag invisible to userspace.
As it stands, fsnotify_parent is a guaranteed functional call even if there
are no watchers and fsnotify() does a substantial amount of unnecessary
work before it checks if there are any watchers. A perf profile showed
that applying mnt->mnt_fsnotify_mask in fnotify() was almost half of the
total samples taken in that function during a test. This patch rearranges
the fast paths to reduce the amount of work done when there are no
watchers.

The test motivating this was "perf bench sched messaging --pipe". Despite
the fact the pipes are anonymous, fsnotify is still called a lot and
the overhead is noticeable even though it's completely pointless. It's
likely the overhead is negligible for real IO so this is an extreme
example. This is a comparison of hackbench using processes and pipes on
a 1-socket machine with 8 CPU threads without fanotify watchers.

5.7.0 5.7.0
vanilla fastfsnotify-v1r1
Amean 1 0.4837 ( 0.00%) 0.4630 * 4.27%*
Amean 3 1.5447 ( 0.00%) 1.4557 ( 5.76%)
Amean 5 2.6037 ( 0.00%) 2.4363 ( 6.43%)
Amean 7 3.5987 ( 0.00%) 3.4757 ( 3.42%)
Amean 12 5.8267 ( 0.00%) 5.6983 ( 2.20%)
Amean 18 8.4400 ( 0.00%) 8.1327 ( 3.64%)
Amean 24 11.0187 ( 0.00%) 10.0290 * 8.98%*
Amean 30 13.1013 ( 0.00%) 12.8510 ( 1.91%)
Amean 32 13.9190 ( 0.00%) 13.2410 ( 4.87%)

5.7.0 5.7.0
vanilla fastfsnotify-v1r1
Duration User 157.05 152.79
Duration System 1279.98 1219.32
Duration Elapsed 182.81 174.52

This is showing that the latencies are improved by roughly 2-9%. The
variability is not shown but some of these results are within the noise
as this workload heavily overloads the machine. That said, the system CPU
usage is reduced by quite a bit so it makes sense to avoid the overhead
even if it is a bit tricky to detect at times. A perf profile of just 1
group of tasks showed that 5.14% of samples taken were in either fsnotify()
or fsnotify_parent(). With the patch, 2.8% of samples were in fsnotify,
mostly function entry and the initial check for watchers. The check for
watchers is complicated enough that inlining it may be controversial.

[Amir] Slightly simplify with mnt_or_sb_mask => marks_mask

Link: https://lore.kernel.org/r/20200708111156.24659-1-amir73il@gmail.com
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: send FAN_DIR_MODIFY event flavor with dir inode and name

Dirent events are going to be supported in two flavors:

1. Directory fid info + mask that includes the specific event types
(e.g. FAN_CREATE) and an optional FAN_ONDIR flag.
2. Directory fid info + name + mask that includes only FAN_DIR_MODIFY.

To request the second event flavor, user needs to set the event type
FAN_DIR_MODIFY in the mark mask.

The first flavor is supported since kernel v5.1 for groups initialized
with flag FAN_REPORT_FID. It is intended to be used for watching
directories in "batch mode" - the watcher is notified when directory is
changed and re-scans the directory content in response. This event
flavor is stored more compactly in the event queue, so it is optimal
for workloads with frequent directory changes.

The second event flavor is intended to be used for watching large
directories, where the cost of re-scan of the directory on every change
is considered too high. The watcher getting the event with the directory
fid and entry name is expected to call fstatat(2) to query the content of
the entry after the change.

Legacy inotify events are reported with name and event mask (e.g. "foo",
FAN_CREATE | FAN_ONDIR). That can lead users to the conclusion that
there is *currently* an entry "foo" that is a sub-directory, when in fact
"foo" may be negative or non-dir by the time user gets the event.

To make it clear that the current state of the named entry is unknown,
when reporting an event with name info, fanotify obfuscates the specific
event types (e.g. create,delete,rename) and uses a common event type -
FAN_DIR_MODIFY to describe the change. This should make it harder for
users to make wrong assumptions and write buggy filesystem monitors.

At this point, name info reporting is not yet implemented, so trying to
set FAN_DIR_MODIFY in mark mask will return -EINVAL.

Link: https://lore.kernel.org/r/20200319151022.31456-12-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: replace inode pointer with an object id

The event inode field is used only for comparison in queue merges and
cannot be dereferenced after handle_event(), because it does not hold a
refcount on the inode.

Replace it with an abstract id to do the same thing.

Link: https://lore.kernel.org/r/20200319151022.31456-8-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: simplify arguments passing to fsnotify_parent()

Instead of passing both dentry and path and having to figure out which
one to use, pass data/data_type to simplify the code.

Link: https://lore.kernel.org/r/20200319151022.31456-6-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: use helpers to access data by data_type

Create helpers to access path and inode from different data types.

Link: https://lore.kernel.org/r/20200319151022.31456-5-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: tidy up FS_ and FAN_ constants

Order by value, so the free value ranges are easier to find.

Link: https://lore.kernel.org/r/20200319151022.31456-2-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

notify: export symbols for use by the knfsd file cache

The knfsd file cache will need to detect when files are unlinked, so that
it can close the associated cached files. Export a minimal set of notifier
functions to allow it to do so.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fsnotify: get rid of fsnotify_nameremove()

For all callers of fsnotify_{unlink,rmdir}(), we made sure that d_parent
and d_name are stable. Therefore, fsnotify_{unlink,rmdir}() do not need
the safety measures in fsnotify_nameremove() to stabilize parent and name.
We can now simplify those hooks and get rid of fsnotify_nameremove().

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: update connector fsid cache on add mark

When implementing connector fsid cache, we only initialized the cache
when the first mark added to object was added by FAN_REPORT_FID group.
We forgot to update conn->fsid when the second mark is added by
FAN_REPORT_FID group to an already attached connector without fsid
cache.

Reported-and-tested-by: syzbot+c277e8e2f46414645508@syzkaller.appspotmail.com
Fixes: 77115225acc6 ("fanotify: cache fsid in fsnotify_mark_connector")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: fix unlink performance regression

__fsnotify_parent() has an optimization in place to avoid unneeded
take_dentry_name_snapshot(). When fsnotify_nameremove() was changed
not to call __fsnotify_parent(), we left out the optimization.
Kernel test robot reported a 5% performance regression in concurrent
unlink() workload.

Reported-by: kernel test robot <rong.a.chen@intel.com>
Link: https://lore.kernel.org/lkml/20190505062153.GG29809@shao2-debian/
Link: https://lore.kernel.org/linux-fsdevel/20190104090357.GD22409@quack2.suse.cz/
Fixes: 5f02a8776384 ("fsnotify: annotate directory entry modification events")
CC: stable@vger.kernel.org
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: switch send_to_group() and ->handle_event to const struct qstr *

note that conditions surrounding accesses to dname in audit_watch_handle_event()
and audit_mark_handle_event() guarantee that dname won't have been NULL.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fsnotify(): switch to passing const struct qstr * for file_name

Note that in fnsotify_move() and fsnotify_link() we are guaranteed
that dentry->d_name won't change during the fsnotify() evaluation
(by having the parent directory locked exclusive), so we don't
need to fetch dentry->d_name.name in the callers. In fsnotify_dirent()
the same stability of dentry->d_name is also true, but it's a bit
more convoluted - there is one callchain (devpts_pty_new() ->
fsnotify_create() -> fsnotify_dirent()) where the parent is _not_
locked, but on devpts ->d_name of everything is unchanging; it
has neither explicit nor implicit renames.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fsnotify: Create function to remove event from notification list

Create function to remove event from the notification list. Later it will
be used from more places.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: cache fsid in fsnotify_mark_connector

For FAN_REPORT_FID, we need to encode fid with fsid of the filesystem on
every event. To avoid having to call vfs_statfs() on every event to get
fsid, we store the fsid in fsnotify_mark_connector on the first time we
add a mark and on handle event we use the cached fsid.

Subsequent calls to add mark on the same object are expected to pass the
same fsid, so the call will fail on cached fsid mismatch.

If an event is reported on several mark types (inode, mount, filesystem),
all connectors should already have the same fsid, so we use the cached
fsid from the first connector.

[JK: Simplify code flow around fanotify_get_fid()
make fsid argument of fsnotify_add_mark_locked() unconditional]

Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: move mask out of struct fsnotify_event

Common fsnotify_event helpers have no need for the mask field.
It is only used by backend code, so move the field out of the
abstract fsnotify_event struct and into the concrete backend
event structs.

This change packs struct inotify_event_info better on 64bit
machine and will allow us to cram some more fields into
struct fanotify_event_info.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: remove dirent events from FS_EVENTS_POSS_ON_CHILD mask

"dirent" events are referring to events that modify directory entries,
such as create,delete,rename. Those events are always be reported
on a watched directory, regardless if FS_EVENT_ON_CHILD is set
on the watch mask.

ALL_FSNOTIFY_DIRENT_EVENTS defines all the dirent event types and
those event types are removed from FS_EVENTS_POSS_ON_CHILD.

That means for a directory with an inotify watch and only dirent
events in the mask (i.e. create,delete,move), all children dentries
will no longer have the DCACHE_FSNOTIFY_PARENT_WATCHED flag set.
This will allow all events that happen on children to be optimized
away in __fsnotify_parent() without the need to dereference
child->d_parent->d_inode->i_fsnotify_mask.

Since the dirent events are never repoted via __fsnotify_parent(),
this results in no change of logic, but only an optimization.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: introduce new event mask FAN_OPEN_EXEC_PERM

A new event mask FAN_OPEN_EXEC_PERM has been defined. This allows users
to receive events and grant access to files that are intending to be
opened for execution. Events of FAN_OPEN_EXEC_PERM type will be
generated when a file has been opened by using either execve(),
execveat() or uselib() system calls.

This acts in the same manner as previous permission event mask, meaning
that an access response is required from the user application in order
to permit any further operations on the file.

Signed-off-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: introduce new event mask FAN_OPEN_EXEC

A new event mask FAN_OPEN_EXEC has been defined so that users have the
ability to receive events specifically when a file has been opened with
the intent to be executed. Events of FAN_OPEN_EXEC type will be
generated when a file has been opened using either execve(), execveat()
or uselib() system calls.

The feature is implemented within fsnotify_open() by generating the
FAN_OPEN_EXEC event type if __FMODE_EXEC is set within file->f_flags.

Signed-off-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: generalize handling of extra event flags

FS_EVENT_ON_CHILD gets a special treatment in fsnotify() because it is
not a flag specifying an event type, but rather an extra flags that may
be reported along with another event and control the handling of the
event by the backend.

FS_ISDIR is also an "extra flag" and not an "event type" and therefore
desrves the same treatment. With inotify/dnotify backends it was never
possible to set FS_ISDIR in mark masks, so it did not matter.
With fanotify backend, mark adding code jumps through hoops to avoid
setting the FS_ISDIR in the commulative object mask.

Separate the constant ALL_FSNOTIFY_EVENTS to ALL_FSNOTIFY_FLAGS and
ALL_FSNOTIFY_EVENTS, so the latter can be used to test for specific
event types.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: store fanotify_init() flags in group's fanotify_data

This averts the need to re-generate flags in fanotify_show_fdinfo()
and sets the scene for addition of more upcoming flags without growing
new members to the fanotify_data struct.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: add super block object type

Add the infrastructure to attach a mark to a super_block struct
and detach all attached marks when super block is destroyed.

This is going to be used by fanotify backend to setup super block
marks.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs: fsnotify: account fsnotify metadata to kmemcg

Patch series "Directed kmem charging", v8.

The Linux kernel's memory cgroup allows limiting the memory usage of the
jobs running on the system to provide isolation between the jobs. All
the kernel memory allocated in the context of the job and marked with
__GFP_ACCOUNT will also be included in the memory usage and be limited
by the job's limit.

The kernel memory can only be charged to the memcg of the process in
whose context kernel memory was allocated. However there are cases
where the allocated kernel memory should be charged to the memcg
different from the current processes's memcg. This patch series
contains two such concrete use-cases i.e. fsnotify and buffer_head.

The fsnotify event objects can consume a lot of system memory for large
or unlimited queues if there is either no or slow listener. The events
are allocated in the context of the event producer. However they should
be charged to the event consumer. Similarly the buffer_head objects can
be allocated in a memcg different from the memcg of the page for which
buffer_head objects are being allocated.

To solve this issue, this patch series introduces mechanism to charge
kernel memory to a given memcg. In case of fsnotify events, the memcg
of the consumer can be used for charging and for buffer_head, the memcg
of the page can be charged. For directed charging, the caller can use
the scope API memalloc_[un]use_memcg() to specify the memcg to charge
for all the __GFP_ACCOUNT allocations within the scope.

This patch (of 2):

A lot of memory can be consumed by the events generated for the huge or
unlimited queues if there is either no or slow listener. This can cause
system level memory pressure or OOMs. So, it's better to account the
fsnotify kmem caches to the memcg of the listener.

However the listener can be in a different memcg than the memcg of the
producer and these allocations happen in the context of the event
producer. This patch introduces remote memcg charging API which the
producer can use to charge the allocations to the memcg of the listener.

There are seven fsnotify kmem caches and among them allocations from
dnotify_struct_cache, dnotify_mark_cache, fanotify_mark_cache and
inotify_inode_mark_cachep happens in the context of syscall from the
listener. So, SLAB_ACCOUNT is enough for these caches.

The objects from fsnotify_mark_connector_cachep are not accounted as
they are small compared to the notification mark or events and it is
unclear whom to account connector to since it is shared by all events
attached to the inode.

The allocations from the event caches happen in the context of the event
producer. For such caches we will need to remote charge the allocations
to the listener's memcg. Thus we save the memcg reference in the
fsnotify_group structure of the listener.

This patch has also moved the members of fsnotify_group to keep the size
same, at least for 64 bit build, even with additional member by filling
the holes.

[shakeelb@google.com: use GFP_KERNEL_ACCOUNT rather than open-coding it]
Link: http://lkml.kernel.org/r/20180702215439.211597-1-shakeelb@google.com
Link: http://lkml.kernel.org/r/20180627191250.209150-2-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fsnotify: add helper to get mask from connector

Use a helper to get the mask from the object (i.e. i_fsnotify_mask)
to generalize code of add/remove inode/vfsmount mark.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: let connector point to an abstract object

Make the code to attach/detach a connector to object more generic
by letting the fsnotify connector point to an abstract fsnotify_connp_t.
Code that needs to dereference an inode or mount object now uses the
helpers fsnotify_conn_{inode,mount}.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: pass connp and object type to fsnotify_add_mark()

Instead of passing inode and vfsmount arguments to fsnotify_add_mark()
and its _locked variant, pass an abstract object pointer and the object
type.

The helpers fsnotify_obj_{inode,mount} are added to get the concrete
object pointer from abstract object pointer.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: use typedef fsnotify_connp_t for brevity

The object marks manipulation functions fsnotify_destroy_marks()
fsnotify_find_mark() and their helpers take an argument of type
struct fsnotify_mark_connector __rcu ** to dereference the connector
pointer. use a typedef to describe this type for brevity.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: add fsnotify_add_inode_mark() wrappers

Before changing the arguments of the functions fsnotify_add_mark()
and fsnotify_add_mark_locked(), convert most callers to use a wrapper.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: generalize iteration of marks by object type

Make some code that handles marks of object types inode and vfsmount
generic, so it can handle other object types.

Introduce fsnotify_foreach_obj_type macro to iterate marks by object type
and fsnotify_iter_{should|set}_report_type macros to set/test report_mask.

This is going to be used for adding mark of another object type
(super block mark).

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: remove redundant arguments to handle_event()

inode_mark and vfsmount_mark arguments are passed to handle_event()
operation as function arguments as well as on iter_info struct.
The difference is that iter_info struct may contain marks that should
not be handled and are represented as NULL arguments to inode_mark or
vfsmount_mark.

Instead of passing the inode_mark and vfsmount_mark arguments, add
a report_mask member to iter_info struct to indicate which marks should
be handled, versus marks that should only be kept alive during user
wait.

This change is going to be used for passing more mark types
with handle_event() (i.e. super block marks).

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: use type id to identify connector object type

An fsnotify_mark_connector is referencing a single type of object
(either inode or vfsmount). Instead of storing a type mask in
connector->flags, store a single type id in connector->type to
identify the type of object.

When a connector object is detached from the object, its type is set
to FSNOTIFY_OBJ_TYPE_DETACHED and this object is not going to be
reused.

The function fsnotify_clear_marks_by_group() is the only place where
type mask was used, so use type flags instead of type id to this
function.

This change is going to be more convenient when adding a new object
type (super block).

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Fix fsnotify_mark_connector race

fsnotify() acquires a reference to a fsnotify_mark_connector through
the SRCU-protected pointer to_tell->i_fsnotify_marks. However, it
appears that no precautions are taken in fsnotify_put_mark() to
ensure that fsnotify() drops its reference to this
fsnotify_mark_connector before assigning a value to its 'destroy_next'
field. This can result in fsnotify_put_mark() assigning a value
to a connector's 'destroy_next' field right before fsnotify() tries to
traverse the linked list referenced by the connector's 'list' field.
Since these two fields are members of the same union, this behavior
results in a kernel panic.

This issue is resolved by moving the connector's 'destroy_next' field
into the object pointer union. This should work since the object pointer
access is protected by both a spinlock and the value of the 'flags'
field, and the 'flags' field is cleared while holding the spinlock in
fsnotify_put_mark() before 'destroy_next' is updated. It shouldn't be
possible for another thread to accidentally read from the object pointer
after the 'destroy_next' field is updated.

The offending behavior here is extremely unlikely; since
fsnotify_put_mark() removes references to a connector (specifically,
it ensures that the connector is unreachable from the inode it was
formerly attached to) before updating its 'destroy_next' field, a
sizeable chunk of code in fsnotify_put_mark() has to execute in the
short window between when fsnotify() acquires the connector reference
and saves the value of its 'list' field. On the HEAD kernel, I've only
been able to reproduce this by inserting a udelay(1) in fsnotify().
However, I've been able to reproduce this issue without inserting a
udelay(1) anywhere on older unmodified release kernels, so I believe
it's worth fixing at HEAD.

References: https://bugzilla.kernel.org/show_bug.cgi?id=199437
Fixes: 08991e83b7286635167bab40927665a90fb00d81
CC: stable@vger.kernel.org
Signed-off-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: fix typo in a comment about mark->g_list

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Let userspace know about lost events due to ENOMEM

Currently if notification event is lost due to event allocation failing
we ENOMEM, we just silently continue (except for fanotify permission
events where we deny the access). This is undesirable as userspace has
no way of knowing whether the notifications it got are complete or not.
Treat lost events due to ENOMEM the same way as lost events due to queue
overflow so that userspace knows something bad happened and it likely
needs to rescan the filesystem.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fsnotify: convert fsnotify_mark.refcnt from atomic_t to refcount_t

atomic_t variables are currently used to implement reference
counters with the following properties:
- counter is initialized to 1 using atomic_set()
- a resource is freed upon counter reaching zero
- once counter reaches zero, its further
increments aren't allowed
- counter schema uses basic atomic operations
(set, inc, inc_not_zero, dec_and_test, etc.)

Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.

The variable fsnotify_mark.refcnt is used as pure reference counter.
Convert it to refcount_t and fix up the operations.

Suggested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fanotify: clean up CONFIG_FANOTIFY_ACCESS_PERMISSIONS ifdefs

The only negative from this patch should be an addition of 32bytes to
'struct fsnotify_group' if CONFIG_FANOTIFY_ACCESS_PERMISSIONS is not
defined.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: convert fsnotify_group.refcnt from atomic_t to refcount_t

atomic_t variables are currently used to implement reference
counters with the following properties:
- counter is initialized to 1 using atomic_set()
- a resource is freed upon counter reaching zero
- once counter reaches zero, its further
increments aren't allowed
- counter schema uses basic atomic operations
(set, inc, inc_not_zero, dec_and_test, etc.)

Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.

The variable fsnotify_group.refcnt is used as pure reference counter.
Convert it to refcount_t and fix up the operations.

Suggested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>

audit: Record fanotify access control decisions

The fanotify interface allows user space daemons to make access
control decisions. Under common criteria requirements, we need to
optionally record decisions based on policy. This patch adds a bit mask,
FAN_AUDIT, that a user space daemon can 'or' into the response decision
which will tell the kernel that it made a decision and record it.

It would be used something like this in user space code:

response.response = FAN_DENY | FAN_AUDIT;
write(fd, &response, sizeof(struct fanotify_response));

When the syscall ends, the audit system will record the decision as a
AUDIT_FANOTIFY auxiliary record to denote that the reason this event
occurred is the result of an access control decision from fanotify
rather than DAC or MAC policy.

A sample event looks like this:

type=PATH msg=audit(1504310584.332:290): item=0 name="./evil-ls"
inode=1319561 dev=fc:03 mode=0100755 ouid=1000 ogid=1000 rdev=00:00
obj=unconfined_u:object_r:user_home_t:s0 nametype=NORMAL
type=CWD msg=audit(1504310584.332:290): cwd="/home/sgrubb"
type=SYSCALL msg=audit(1504310584.332:290): arch=c000003e syscall=2
success=no exit=-1 a0=32cb3fca90 a1=0 a2=43 a3=8 items=1 ppid=901
pid=959 auid=1000 uid=1000 gid=1000 euid=1000 suid=1000
fsuid=1000 egid=1000 sgid=1000 fsgid=1000 tty=pts1 ses=3 comm="bash"
exe="/usr/bin/bash" subj=unconfined_u:unconfined_r:unconfined_t:
s0-s0:c0.c1023 key=(null)
type=FANOTIFY msg=audit(1504310584.332:290): resp=2

Prior to using the audit flag, the developer needs to call
fanotify_init or'ing in FAN_ENABLE_AUDIT to ensure that the kernel
supports auditing. The calling process must also have the CAP_AUDIT_WRITE
capability.

Signed-off-by: sgrubb <sgrubb@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Move ->free_mark callback to fsnotify_ops

Pointer to ->free_mark callback unnecessarily occupies one long in each
fsnotify_mark although they are the same for all marks from one
notification group. Move the callback pointer to fsnotify_ops.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Add group pointer in fsnotify_init_mark()

Currently we initialize mark->group only in fsnotify_add_mark_lock().
However we will need to access fsnotify_ops of corresponding group from
fsnotify_put_mark() so we need mark->group initialized earlier. Do that
in fsnotify_init_mark() which has a consequence that once
fsnotify_init_mark() is called on a mark, the mark has to be destroyed
by fsnotify_put_mark().

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Remove fsnotify_find_{inode|vfsmount}_mark()

These are very thin wrappers, just remove them. Drop
fs/notify/vfsmount_mark.c as it is empty now.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Remove fsnotify_detach_group_marks()

The function is already mostly contained in what
fsnotify_clear_marks_by_group() does. Just update that function to not
select marks when all of them should be destroyed and remove
fsnotify_detach_group_marks().

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Rename fsnotify_clear_marks_by_group_flags()

The _flags() suffix in the function name was more confusing than
explaining so just remove it. Also rename the argument from 'flags' to
'type' to better explain what the function expects.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Suggested-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Inline fsnotify_clear_{inode|vfsmount}_mark_group()

Inline these helpers as they are very thin. We still keep them as we
don't want to expose details about how list type is determined.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Remove fsnotify_recalc_{inode|vfsmount}_mask()

These helpers are just very thin wrappers now. Remove them.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Remove fsnotify_set_mark_{,ignored_}mask_locked()

These helpers are now only a simple assignment and just obfuscate
what is going on. Remove them.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Pass fsnotify_iter_info into handle_event handler

Pass fsnotify_iter_info into ->handle_event() handler so that it can
release and reacquire SRCU lock via fsnotify_prepare_user_wait() and
fsnotify_finish_user_wait() functions. These functions also make sure
current marks are appropriately pinned so that iteration protected by
srcu in fsnotify() stays safe.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Provide framework for dropping SRCU lock in ->handle_event

fanotify wants to drop fsnotify_mark_srcu lock when waiting for response
from userspace so that the whole notification subsystem is not blocked
during that time. This patch provides a framework for safely getting
mark reference for a mark found in the object list which pins the mark
in that list. We can then drop fsnotify_mark_srcu, wait for userspace
response and then safely continue iteration of the object list once we
reaquire fsnotify_mark_srcu.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Detach mark from object list when last reference is dropped

Instead of removing mark from object list from fsnotify_detach_mark(),
remove the mark when last reference to the mark is dropped. This will
allow fanotify to wait for userspace response to event without having to
hold onto fsnotify_mark_srcu.

To avoid pinning inodes by elevated refcount (and thus e.g. delaying
file deletion) while someone holds mark reference, we detach connector
from the object also from fsnotify_destroy_marks() and not only after
removing last mark from the list as it was now.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Free fsnotify_mark_connector when there is no mark attached

Currently we free fsnotify_mark_connector structure only when inode /
vfsmount is getting freed. This can however impose noticeable memory
overhead when marks get attached to inodes only temporarily. So free the
connector structure once the last mark is detached from the object.
Since notification infrastructure can be working with the connector
under the protection of fsnotify_mark_srcu, we have to be careful and
free the fsnotify_mark_connector only after SRCU period passes.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Lock object list with connector lock

So far list of marks attached to an object (inode / vfsmount) was
protected by i_lock or mnt_root->d_lock. This dictates that the list
must be empty before the object can be destroyed although the list is
now anchored in the fsnotify_mark_connector structure. Protect the list
by a spinlock in the fsnotify_mark_connector structure to decouple
lifetime of a list of marks from a lifetime of the object. This also
simplifies the code quite a bit since we don't have to differentiate
between inode and vfsmount lists in quite a few places anymore.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Move locking into fsnotify_recalc_mask()

Move locking of locks protecting a list of marks into
fsnotify_recalc_mask(). This reduces code churn in the following patch
which changes the lock protecting the list of marks.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Make fsnotify_mark_connector hold inode reference

Currently inode reference is held by fsnotify marks. Change the rules so
that inode reference is held by fsnotify_mark_connector structure
whenever the list is non-empty. This simplifies the code and is more
logical.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Move object pointer to fsnotify_mark_connector

Move pointer to inode / vfsmount from mark itself to the
fsnotify_mark_connector structure. This is another step on the path
towards decoupling inode / vfsmount lifetime from notification mark
lifetime.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Move mark list head from object into dedicated structure

Currently notification marks are attached to object (inode or vfsmnt) by
a hlist_head in the object. The list is also protected by a spinlock in
the object. So while there is any mark attached to the list of marks,
the object must be pinned in memory (and thus e.g. last iput() deleting
inode cannot happen). Also for list iteration in fsnotify() to work, we
must hold fsnotify_mark_srcu lock so that mark itself and
mark->obj_list.next cannot get freed. Thus we are required to wait for
response to fanotify events from userspace process with
fsnotify_mark_srcu lock held. That causes issues when userspace process
is buggy and does not reply to some event - basically the whole
notification subsystem gets eventually stuck.

So to be able to drop fsnotify_mark_srcu lock while waiting for
response, we have to pin the mark in memory and make sure it stays in
the object list (as removing the mark waiting for response could lead to
lost notification events for groups later in the list). However we don't
want inode reclaim to block on such mark as that would lead to system
just locking up elsewhere.

This commit is the first in the series that paves way towards solving
these conflicting lifetime needs. Instead of anchoring the list of marks
directly in the object, we anchor it in a dedicated structure
(fsnotify_mark_connector) and just point to that structure from the
object. The following commits will also add spinlock protecting the list
and object pointer to the structure.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

inotify: Convert to using per-namespace limits

This patchset converts inotify to using the newly introduced
per-userns sysctl infrastructure.

Currently the inotify instances/watches are being accounted in the
user_struct structure. This means that in setups where multiple
users in unprivileged containers map to the same underlying
real user (i.e. pointing to the same user_struct) the inotify limits
are going to be shared as well, allowing one user(or application) to exhaust
all others limits.

Fix this by switching the inotify sysctls to using the
per-namespace/per-user limits. This will allow the server admin to
set sensible global limits, which can further be tuned inside every
individual user namespace. Additionally, in order to preserve the
sysctl ABI make the existing inotify instances/watches sysctls
modify the values of the initial user namespace.

Signed-off-by: Nikolay Borisov <n.borisov.lkml@gmail.com>
Acked-by: Jan Kara <jack@suse.cz>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

fsnotify: Remove fsnotify_duplicate_mark()

There are only two calls sites of fsnotify_duplicate_mark(). Those are
in kernel/audit_tree.c and both are bogus. Vfsmount pointer is unused
for audit tree, inode pointer and group gets set in
fsnotify_add_mark_locked() later anyway, mask and free_mark are already
set in alloc_chunk(). In fact, calling fsnotify_duplicate_mark() is
actively harmful because following fsnotify_add_mark_locked() will leak
group reference by overwriting the group pointer. So just remove the two
calls to fsnotify_duplicate_mark() and the function.

Signed-off-by: Jan Kara <jack@suse.cz>
[PM: line wrapping to fit in 80 chars]
Signed-off-by: Paul Moore <paul@paul-moore.com>

constify fsnotify_parent()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fsnotify(): constify 'data'

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fsnotify: constify 'data' passed to ->handle_event()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fanotify: use notification_lock instead of access_lock

Fanotify code has its own lock (access_lock) to protect a list of events
waiting for a response from userspace.

However this is somewhat awkward as the same list_head in the event is
protected by notification_lock if it is part of the notification queue
and by access_lock if it is part of the fanotify private queue which
makes it difficult for any reliable checks in the generic code. So make
fanotify use the same lock - notification_lock - for protecting its
private event list.

Link: http://lkml.kernel.org/r/1473797711-14111-6-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fsnotify: convert notification_mutex to a spinlock

notification_mutex is used to protect the list of pending events. As such
there's no reason to use a sleeping lock for it. Convert it to a
spinlock.

[jack@suse.cz: fixed version]
Link: http://lkml.kernel.org/r/1474031567-1831-1-git-send-email-jack@suse.cz
Link: http://lkml.kernel.org/r/1473797711-14111-5-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fanotify: fix list corruption in fanotify_get_response()

fanotify_get_response() calls fsnotify_remove_event() when it finds that
group is being released from fanotify_release() (bypass_perm is set).

However the event it removes need not be only in the group's notification
queue but it can have already moved to access_list (userspace read the
event before closing the fanotify instance fd) which is protected by a
different lock. Thus when fsnotify_remove_event() races with
fanotify_release() operating on access_list, the list can get corrupted.

Fix the problem by moving all the logic removing permission events from
the lists to one place - fanotify_release().

Fixes: 5838d4442bd5 ("fanotify: fix double free of pending permission events")
Link: http://lkml.kernel.org/r/1473797711-14111-3-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reported-by: Miklos Szeredi <mszeredi@redhat.com>
Tested-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fsnotify: add a way to stop queueing events on group shutdown

Implement a function that can be called when a group is being shutdown
to stop queueing new events to the group. Fanotify will use this.

Fixes: 5838d4442bd5 ("fanotify: fix double free of pending permission events")
Link: http://lkml.kernel.org/r/1473797711-14111-2-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

trim fsnotify hooks a bit

fsnotify_d_move()/__fsnotify_d_instantiate()/__fsnotify_update_dcache_flags()
are identical to each other, regardless of the config.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

undo "fs: allow d_instantiate to be called with negative parent dentry"

Background: spufs used to mangle the order in which it had been building
dentry trees. It was broken in a lot of ways, but most of them required
the right timing to trigger until an fsnotify change had added one more
- the one that was always triggered.

Unfortunately, insteading of fixing their long-standing bug the spufs
folks had chosen to paper over the fsnotify trigger. Eventually said
bug had been spotted and killed off, but the pointless check in
fsnotify has remained, complete with the implication that one *could*
do that kind of crap.

Again, a parent of any dentry should always be positive. Any code
can rely upon that and anything violating that assert is a bug,
*not* something to be accomodated.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fsnotify: avoid spurious EMFILE errors from inotify_init()

Inotify instance is destroyed when all references to it are dropped.
That not only means that the corresponding file descriptor needs to be
closed but also that all corresponding instance marks are freed (as each
mark holds a reference to the inotify instance). However marks are
freed only after SRCU period ends which can take some time and thus if
user rapidly creates and frees inotify instances, number of existing
inotify instances can exceed max_user_instances limit although from user
point of view there is always at most one existing instance. Thus
inotify_init() returns EMFILE error which is hard to justify from user
point of view. This problem is exposed by LTP inotify06 testcase on
some machines.

We fix the problem by making sure all group marks are properly freed
while destroying inotify instance. We wait for SRCU period to end in
that path anyway since we have to make sure there is no event being
added to the instance while we are tearing down the instance. So it
takes only some plumbing to allow for marks to be destroyed in that path
as well and not from a dedicated work item.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Jan Kara <jack@suse.cz>
Reported-by: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com>
Tested-by: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

untangle fsnotify_d_instantiate() a bit

First of all, don't bother calling it if inode is NULL -
that makes inode argument unused. Moreover, do it *before*
dropping ->d_lock, not right after that (and don't bother
grabbing ->d_lock in it, of course).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Revert "fsnotify: destroy marks with call_srcu instead of dedicated thread"

This reverts commit c510eff6beba ("fsnotify: destroy marks with
call_srcu instead of dedicated thread").

Eryu reported that he was seeing some OOM kills kick in when running a
testcase that adds and removes inotify marks on a file in a tight loop.

The above commit changed the code to use call_srcu to clean up the
marks. While that does (in principle) work, the srcu callback job is
limited to cleaning up entries in small batches and only once per jiffy.
It's easily possible to overwhelm that machinery with too many call_srcu
callbacks, and Eryu's reproduer did just that.

There's also another potential problem with using call_srcu here. While
you can obviously sleep while holding the srcu_read_lock, the callbacks
run under local_bh_disable, so you can't sleep there.

It's possible when putting the last reference to the fsnotify_mark that
we'll end up putting a chain of references including the fsnotify_group,
uid, and associated keys. While I don't see any obvious ways that that
could occurs, it's probably still best to avoid using call_srcu here
after all.

This patch reverts the above patch. A later patch will take a different
approach to eliminated the dedicated thread here.

Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Reported-by: Eryu Guan <guaneryu@gmail.com>
Tested-by: Eryu Guan <guaneryu@gmail.com>
Cc: Jan Kara <jack@suse.com>
Cc: Eric Paris <eparis@parisplace.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fsnotify: destroy marks with call_srcu instead of dedicated thread

At the time that this code was originally written, call_srcu didn't
exist, so this thread was required to ensure that we waited for that
SRCU grace period to settle before finally freeing the object.

It does exist now however and we can much more efficiently use call_srcu
to handle this. That also allows us to potentially use srcu_barrier to
ensure that they are all of the callbacks have run before proceeding.
In order to conserve space, we union the rcu_head with the g_list.

This will be necessary for nfsd which will allocate marks from a
dedicated slabcache. We have to be able to ensure that all of the
objects are destroyed before destroying the cache. That's fairly

Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Cc: Eric Paris <eparis@parisplace.org>
Reviewed-by: Jan Kara <jack@suse.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fsnotify: get rid of fsnotify_destroy_mark_locked()

fsnotify_destroy_mark_locked() is subtle to use because it temporarily
releases group->mark_mutex. To avoid future problems with this
function, split it into two.

fsnotify_detach_mark() is the part that needs group->mark_mutex and
fsnotify_free_mark() is the part that must be called outside of
group->mark_mutex. This way it's much clearer what's going on and we
also avoid some pointless acquisitions of group->mark_mutex.

Signed-off-by: Jan Kara <jack@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fsnotify: remove mark->free_list

Free list is used when all marks on given inode / mount should be
destroyed when inode / mount is going away. However we can free all of
the marks without using a special list with some care.

Signed-off-by: Jan Kara <jack@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fsnotify: document mark locking

Signed-off-by: Jan Kara <jack@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

inode: convert inode_sb_list_lock to per-sb

The process of reducing contention on per-superblock inode lists
starts with moving the locking to match the per-superblock inode
list. This takes the global lock out of the picture and reduces the
contention problems to within a single filesystem. This doesn't get
rid of contention as the locks still have global CPU scope, but it
does isolate operations on different superblocks form each other.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Dave Chinner <dchinner@redhat.com>

fsnotify: remove obsolete documentation

should_send_event is no longer part of struct fsnotify_ops, so remove it.

Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fsnotify: remove destroy_list from fsnotify_mark

destroy_list is used to track marks which still need waiting for srcu
period end before they can be freed. However by the time mark is added to
destroy_list it isn't in group's list of marks anymore and thus we can
reuse fsnotify_mark->g_list for queueing into destroy_list. This saves
two pointers for each fsnotify_mark.

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Eric Paris <eparis@redhat.com>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fsnotify: unify inode and mount marks handling

There's a lot of common code in inode and mount marks handling. Factor it
out to a common helper function.

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Eric Paris <eparis@redhat.com>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fanotify: fix double free of pending permission events

Commit 85816794240b ("fanotify: Fix use after free for permission
events") introduced a double free issue for permission events which are
pending in group's notification queue while group is being destroyed.
These events are freed from fanotify_handle_event() but they are not
removed from groups notification queue and thus they get freed again
from fsnotify_flush_notify().

Fix the problem by removing permission events from notification queue
before freeing them if we skip processing access response. Also expand
comments in fanotify_release() to explain group shutdown in detail.

Fixes: 85816794240b9659e66e4d9b0df7c6e814e5f603
Signed-off-by: Jan Kara <jack@suse.cz>
Reported-by: Douglas Leeder <douglas.leeder@sophos.com>
Tested-by: Douglas Leeder <douglas.leeder@sophos.com>
Reported-by: Heinrich Schuchard <xypron.glpk@gmx.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fsnotify: rename event handling functions

Rename fsnotify_add_notify_event() to fsnotify_add_event() since the
"notify" part is duplicit. Rename fsnotify_remove_notify_event() and
fsnotify_peek_notify_event() to fsnotify_remove_first_event() and
fsnotify_peek_first_event() respectively since "notify" part is duplicit
and they really look at the first event in the queue.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fanotify: convert access_mutex to spinlock

access_mutex is used only to guard operations on access_list. There's
no need for sleeping within this lock so just make a spinlock out of it.

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Eric Paris <eparis@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fsnotify: Allocate overflow events with proper type

Commit 7053aee26a35 "fsnotify: do not share events between notification
groups" used overflow event statically allocated in a group with the
size of the generic notification event. This causes problems because
some code looks at type specific parts of event structure and gets
confused by a random data it sees there and causes crashes.

Fix the problem by allocating overflow event with type corresponding to
the group type so code cannot get confused.

Signed-off-by: Jan Kara <jack@suse.cz>

inotify: Fix reporting of cookies for inotify events

My rework of handling of notification events (namely commit 7053aee26a35
"fsnotify: do not share events between notification groups") broke
sending of cookies with inotify events. We didn't propagate the value
passed to fsnotify() properly and passed 4 uninitialized bytes to
userspace instead (so it is also an information leak). Sadly I didn't
notice this during my testing because inotify cookies aren't used very
much and LTP inotify tests ignore them.

Fix the problem by passing the cookie value properly.

Fixes: 7053aee26a3548ebaba046ae2e52396ccf56ac6c
Reported-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: Do not return merged event from fsnotify_add_notify_event()

The event returned from fsnotify_add_notify_event() cannot ever be used
safely as the event may be freed by the time the function returns (after
dropping notification_mutex). So change the prototype to just return
whether the event was added or merged into some existing event.

Reported-and-tested-by: Jiri Kosina <jkosina@suse.cz>
Reported-and-tested-by: Dave Jones <davej@fedoraproject.org>
Signed-off-by: Jan Kara <jack@suse.cz>

fsnotify: remove .should_send_event callback

After removing event structure creation from the generic layer there is
no reason for separate .should_send_event and .handle_event callbacks.
So just remove the first one.

Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Eric Paris <eparis@parisplace.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fsnotify: do not share events between notification groups

Currently fsnotify framework creates one event structure for each
notification event and links this event into all interested notification
groups. This is done so that we save memory when several notification
groups are interested in the event. However the need for event
structure shared between inotify & fanotify bloats the event structure
so the result is often higher memory consumption.

Another problem is that fsnotify framework keeps path references with
outstanding events so that fanotify can return open file descriptors
with its events. This has the undesirable effect that filesystem cannot
be unmounted while there are outstanding events - a regression for
inotify compared to a situation before it was converted to fsnotify
framework. For fanotify this problem is hard to avoid and users of
fanotify should kind of expect this behavior when they ask for file
descriptors from notified files.

This patch changes fsnotify and its users to create separate event
structure for each group. This allows for much simpler code (~400 lines
removed by this patch) and also smaller event structures. For example
on 64-bit system original struct fsnotify_event consumes 120 bytes, plus
additional space for file name, additional 24 bytes for second and each
subsequent group linking the event, and additional 32 bytes for each
inotify group for private data. After the conversion inotify event
consumes 48 bytes plus space for file name which is considerably less
memory unless file names are long and there are several groups
interested in the events (both of which are uncommon). Fanotify event
fits in 56 bytes after the conversion (fanotify doesn't care about file
names so its events don't have to have it allocated). A win unless
there are four or more fanotify groups interested in the event.

The conversion also solves the problem with unmount when only inotify is
used as we don't have to grab path references for inotify events.

[hughd@google.com: fanotify: fix corruption preventing startup]
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Eric Paris <eparis@parisplace.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

inotify: convert inotify_add_to_idr() to use idr_alloc_cyclic()

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: John McCutchan <john@johnmccutchan.com>
Cc: Robert Love <rlove@rlove.org>
Cc: Eric Paris <eparis@parisplace.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fsnotify: make fasync generic for both inotify and fanotify

inotify is supposed to support async signal notification when information
is available on the inotify fd. This patch moves that support to generic
fsnotify functions so it can be used by all notification mechanisms.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: change locking order

On Mon, Aug 01, 2011 at 04:38:22PM -0400, Eric Paris wrote:
>
> I finally built and tested a v3.0 kernel with these patches (I know I'm
> SOOOOOO far behind). Not what I hoped for:
>
> > [ 150.937798] VFS: Busy inodes after unmount of tmpfs. Self-destruct in 5 seconds. Have a nice day...
> > [ 150.945290] BUG: unable to handle kernel NULL pointer dereference at 0000000000000070
> > [ 150.946012] IP: [<ffffffff810ffd58>] shmem_free_inode+0x18/0x50
> > [ 150.946012] PGD 2bf9e067 PUD 2bf9f067 PMD 0
> > [ 150.946012] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
> > [ 150.946012] CPU 0
> > [ 150.946012] Modules linked in: nfs lockd fscache auth_rpcgss nfs_acl sunrpc ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ext4 jbd2 crc16 joydev ata_piix i2c_piix4 pcspkr uinput ipv6 autofs4 usbhid [last unloaded: scsi_wait_scan]
> > [ 150.946012]
> > [ 150.946012] Pid: 2764, comm: syscall_thrash Not tainted 3.0.0+ #1 Red Hat KVM
> > [ 150.946012] RIP: 0010:[<ffffffff810ffd58>] [<ffffffff810ffd58>] shmem_free_inode+0x18/0x50
> > [ 150.946012] RSP: 0018:ffff88002c2e5df8 EFLAGS: 00010282
> > [ 150.946012] RAX: 000000004e370d9f RBX: 0000000000000000 RCX: ffff88003a029438
> > [ 150.946012] RDX: 0000000033630a5f RSI: 0000000000000000 RDI: ffff88003491c240
> > [ 150.946012] RBP: ffff88002c2e5e08 R08: 0000000000000000 R09: 0000000000000000
> > [ 150.946012] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88003a029428
> > [ 150.946012] R13: ffff88003a029428 R14: ffff88003a029428 R15: ffff88003499a610
> > [ 150.946012] FS: 00007f5a05420700(0000) GS:ffff88003f600000(0000) knlGS:0000000000000000
> > [ 150.946012] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> > [ 150.946012] CR2: 0000000000000070 CR3: 000000002a662000 CR4: 00000000000006f0
> > [ 150.946012] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > [ 150.946012] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> > [ 150.946012] Process syscall_thrash (pid: 2764, threadinfo ffff88002c2e4000, task ffff88002bfbc760)
> > [ 150.946012] Stack:
> > [ 150.946012] ffff88003a029438 ffff88003a029428 ffff88002c2e5e38 ffffffff81102f76
> > [ 150.946012] ffff88003a029438 ffff88003a029598 ffffffff8160f9c0 ffff88002c221250
> > [ 150.946012] ffff88002c2e5e68 ffffffff8115e9be ffff88002c2e5e68 ffff88003a029438
> > [ 150.946012] Call Trace:
> > [ 150.946012] [<ffffffff81102f76>] shmem_evict_inode+0x76/0x130
> > [ 150.946012] [<ffffffff8115e9be>] evict+0x7e/0x170
> > [ 150.946012] [<ffffffff8115ee40>] iput_final+0xd0/0x190
> > [ 150.946012] [<ffffffff8115ef33>] iput+0x33/0x40
> > [ 150.946012] [<ffffffff81180205>] fsnotify_destroy_mark_locked+0x145/0x160
> > [ 150.946012] [<ffffffff81180316>] fsnotify_destroy_mark+0x36/0x50
> > [ 150.946012] [<ffffffff81181937>] sys_inotify_rm_watch+0x77/0xd0
> > [ 150.946012] [<ffffffff815aca52>] system_call_fastpath+0x16/0x1b
> > [ 150.946012] Code: 67 4a 00 b8 e4 ff ff ff eb aa 66 0f 1f 84 00 00 00 00 00 55 48 89 e5 48 83 ec 10 48 89 1c 24 4c 89 64 24 08 48 8b 9f 40 05 00 00
> > [ 150.946012] 83 7b 70 00 74 1c 4c 8d a3 80 00 00 00 4c 89 e7 e8 d2 5d 4a
> > [ 150.946012] RIP [<ffffffff810ffd58>] shmem_free_inode+0x18/0x50
> > [ 150.946012] RSP <ffff88002c2e5df8>
> > [ 150.946012] CR2: 0000000000000070
>
> Looks at aweful lot like the problem from:
> http://www.spinics.net/lists/linux-fsdevel/msg46101.html
>

I tried to reproduce this bug with your test program, but without success.
However, if I understand correctly, this occurs since we dont hold any locks when
we call iput() in mark_destroy(), right?
With the patches you tested, iput() is also not called within any lock, since the
groups mark_mutex is released temporarily before iput() is called. This is, since
the original codes behaviour is similar.
However since we now have a mutex as the biggest lock, we can do what you
suggested (http://www.spinics.net/lists/linux-fsdevel/msg46107.html) and
call iput() with the mutex held to avoid the race.
The patch below implements this. It uses nested locking to avoid deadlock in case
we do the final iput() on an inode which still holds marks and thus would take
the mutex again when calling fsnotify_inode_delete() in destroy_inode().

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: dont put marks on temporary list when clearing marks by group

In clear_marks_by_group_flags() the mark list of a group is iterated and the
marks are put on a temporary list.
Since we introduced fsnotify_destroy_mark_locked() we dont need the temp list
any more and are able to remove the marks while the mark list is iterated and
the mark list mutex is held.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: introduce locked versions of fsnotify_add_mark() and fsnotify_remove_mark()

This patch introduces fsnotify_add_mark_locked() and fsnotify_remove_mark_locked()
which are essentially the same as fsnotify_add_mark() and fsnotify_remove_mark() but
assume that the caller has already taken the groups mark mutex.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: pass group to fsnotify_destroy_mark()

In fsnotify_destroy_mark() dont get the group from the passed mark anymore,
but pass the group itself as an additional parameter to the function.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: use a mutex instead of a spinlock to protect a groups mark list

Replaces the groups mark_lock spinlock with a mutex. Using a mutex instead
of a spinlock results in more flexibility (i.e it allows to sleep while the
lock is held).

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: introduce fsnotify_get_group()

Introduce fsnotify_get_group() which increments the reference counter of a group.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

inotify, fanotify: replace fsnotify_put_group() with fsnotify_destroy_group()

Currently in fsnotify_put_group() the ref count of a group is decremented and if
it becomes 0 fsnotify_destroy_group() is called. Since a groups ref count is only
at group creation set to 1 and never increased after that a call to fsnotify_put_group()
always results in a call to fsnotify_destroy_group().
With this patch fsnotify_destroy_group() is called directly.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: handle subfiles' perm events

Recently I'm working on fanotify and found the following strange
behaviors.

I wrote a program to set fanotify_mark on "/tmp/block" and FAN_DENY
all events notified.

fanotify_mask = FAN_ALL_EVENTS | FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD:
$ cd /tmp/block; cat foo
cat: foo: Operation not permitted

Operation on the file is blocked as expected.

But,

fanotify_mask = FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD:
$ cd /tmp/block; cat foo
aaa

It's not blocked anymore. This is confusing behavior. Also reading
commit "fsnotify: call fsnotify_parent in perm events", it seems like
fsnotify should handle subfiles' perm events as well as the other notify
events.

With this patch, regardless of FAN_ALL_EVENTS set or not:
$ cd /tmp/block; cat foo
cat: foo: Operation not permitted

Operation on the file is now blocked properly.

FS_OPEN_PERM and FS_ACCESS_PERM are not listed on FS_EVENTS_POSS_ON_CHILD.
Due to fsnotify_inode_watches_children() check, if you only specify only
these events as fsnotify_mask, you don't get subfiles' perm events
notified.

This patch add the events to FS_EVENTS_POSS_ON_CHILD to get them notified
even if only these events are specified to fsnotify_mask.

Signed-off-by: Naohiro Aota <naota@elisp.net>
Cc: Eric Paris <eparis@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

atomic: use <linux/atomic.h>

This allows us to move duplicated code in <asm/atomic.h>
(atomic_inc_not_zero() for now) to <linux/atomic.h>

Signed-off-by: Arun Sharma <asharma@fb.com>
Reviewed-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs: dcache remove dcache_lock

dcache_lock no longer protects anything. remove it.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

fanotify: on group destroy allow all waiters to bypass permission check

When fanotify_release() is called, there may still be processes waiting for
access permission. Currently only processes for which an event has already been
queued into the groups access list will be woken up. Processes for which no
event has been queued will continue to sleep and thus cause a deadlock when
fsnotify_put_group() is called.
Furthermore there is a race allowing further processes to be waiting on the
access wait queue after wake_up (if they arrive before clear_marks_by_group()
is called).
This patch corrects this by setting a flag to inform processes that the group
is about to be destroyed and thus not to wait for access permission.

[additional changelog from eparis]
Lets think about the 4 relevant code paths from the PoV of the
'operator' 'listener' 'responder' and 'closer'. Where operator is the
process doing an action (like open/read) which could require permission.
Listener is the task (or in this case thread) slated with reading from
the fanotify file descriptor. The 'responder' is the thread responsible
for responding to access requests. 'Closer' is the thread attempting to
close the fanotify file descriptor.

The 'operator' is going to end up in:
fanotify_handle_event()
get_response_from_access()
(THIS BLOCKS WAITING ON USERSPACE)

The 'listener' interesting code path
fanotify_read()
copy_event_to_user()
prepare_for_access_response()
(THIS CREATES AN fanotify_response_event)

The 'responder' code path:
fanotify_write()
process_access_response()
(REMOVE A fanotify_response_event, SET RESPONSE, WAKE UP 'operator')

The 'closer':
fanotify_release()
(SUPPOSED TO CLEAN UP THE REST OF THIS MESS)

What we have today is that in the closer we remove all of the
fanotify_response_events and set a bit so no more response events are
ever created in prepare_for_access_response().

The bug is that we never wake all of the operators up and tell them to
move along. You fix that in fanotify_get_response_from_access(). You
also fix other operators which haven't gotten there yet. So I agree
that's a good fix.
[/additional changelog from eparis]

[remove additional changes to minimize patch size]
[move initialization so it was inside CONFIG_FANOTIFY_PERMISSION]

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: remove alignment padding from fsnotify_mark on 64 bit builds

Reorder struct fsnotfiy_mark to remove 8 bytes of alignment padding on 64
bit builds. Shrinks fsnotfiy_mark to 128 bytes allowing more objects per
slab in its kmem_cache and reduces the number of cachelines needed for
each structure.

Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: rename FS_IN_ISDIR to FS_ISDIR

The _IN_ in the naming is reserved for flags only used by inotify. Since I
am about to use this flag for fanotify rename it to be generic like the
rest.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: limit number of listeners per user

fanotify currently has no limit on the number of listeners a given user can
have open. This patch limits the total number of listeners per user to
128. This is the same as the inotify default limit.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: limit the number of marks in a single fanotify group

There is currently no limit on the number of marks a given fanotify group
can have. Since fanotify is gated on CAP_SYS_ADMIN this was not seen as
a serious DoS threat. This patch implements a default of 8192, the same as
inotify to work towards removing the CAP_SYS_ADMIN gating and eliminating
the default DoS'able status.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: call fsnotify_parent in perm events

fsnotify perm events do not call fsnotify parent. That means you cannot
register a perm event on a directory and enforce permissions on all inodes in
that directory. This patch fixes that situation.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: correctly handle return codes from listeners

When fsnotify groups return errors they are ignored. For permissions
events these should be passed back up the stack, but for most events these
should continue to be ignored.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: implement ordering between notifiers

fanotify needs to be able to specify that some groups get events before
others. They use this idea to make sure that a hierarchical storage
manager gets access to files before programs which actually use them. This
is purely infrastructure. Everything will have a priority of 0, but the
infrastructure will exist for it to be non-zero.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: flush outstanding perm requests on group destroy

When an fanotify listener is closing it may cause a deadlock between the
listener and the original task doing an fs operation. If the original task
is waiting for a permissions response it will be holding the srcu lock. The
listener cannot clean up and exit until after that srcu lock is syncronized.
Thus deadlock. The fix introduced here is to stop accepting new permissions
events when a listener is shutting down and to grant permission for all
outstanding events. Thus the original task will eventually release the srcu
lock and the listener can complete shutdown.

Reported-by: Andreas Gruenbacher <agruen@suse.de>
Cc: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

Revert "fsnotify: store struct file not struct path"

This reverts commit 3bcf3860a4ff9bbc522820b4b765e65e4deceb3e (and the
accompanying commit c1e5c954020e "vfs/fsnotify: fsnotify_close can delay
the final work in fput" that was a horribly ugly hack to make it work at
all).

The 'struct file' approach not only causes that disgusting hack, it
somehow breaks pulseaudio, probably due to some other subtlety with
f_count handling.

Fix up various conflicts due to later fsnotify work.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fanotify: use both marks when possible

fanotify currently, when given a vfsmount_mark will look up (if it exists)
the corresponding inode mark. This patch drops that lookup and uses the
mark provided.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: pass both the vfsmount mark and inode mark

should_send_event() and handle_event() will both need to look up the inode
event if they get a vfsmount event. Lets just pass both at the same time
since we have them both after walking the lists in lockstep.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: remove global fsnotify groups lists

The global fsnotify groups lists were invented as a way to increase the
performance of fsnotify by shortcutting events which were not interesting.
With the changes to walk the object lists rather than global groups lists
these shortcuts are not useful.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: remove group->mask

group->mask is now useless. It was originally a shortcut for fsnotify to
save on performance. These checks are now redundant, so we remove them.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: remove the global masks

Because we walk the object->fsnotify_marks list instead of the global
fsnotify groups list we don't need the fsnotify_inode_mask and
fsnotify_vfsmount_mask as these were simply shortcuts in fsnotify() for
performance. They are now extra checks, rip them out.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: send fsnotify_mark to groups in event handling functions

With the change of fsnotify to use srcu walking the marks list instead of
walking the global groups list we now know the mark in question. The code can
send the mark to the group's handling functions and the groups won't have to
find those marks themselves.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: srcu to protect read side of inode and vfsmount locks

Currently reading the inode->i_fsnotify_marks or
vfsmount->mnt_fsnotify_marks lists are protected by a spinlock on both the
read and the write side. This patch protects the read side of those lists
with a new single srcu.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: use an explicit flag to indicate fsnotify_destroy_mark has been called

Currently fsnotify check is mark->group is NULL to decide if
fsnotify_destroy_mark() has already been called or not. With the upcoming
rcu work it is a heck of a lot easier to use an explicit flag than worry
about group being set to NULL.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: store struct file not struct path

Al explains that calling dentry_open() with a mnt/dentry pair is only
garunteed to be safe if they are already used in an open struct file. To
make sure this is the case don't store and use a struct path in fsnotify,
always use a struct file.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: fsnotify_add_notify_event should return an event

Rather than the horrific void ** argument and such just to pass the
fanotify_merge event back to the caller of fsnotify_add_notify_event() have
those things return an event if it was different than the event suggusted to
be added.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: groups can specify their f_flags for new fd

Currently fanotify fds opened for thier listeners are done with f_flags
equal to O_RDONLY | O_LARGEFILE. This patch instead takes f_flags from the
fanotify_init syscall and uses those when opening files in the context of
the listener.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: check to make sure all fsnotify bits are unique

This patch adds a check to make sure that all fsnotify bits are unique and we
cannot accidentally use the same bit for 2 different fsnotify event types.

Signed-off-by: Eric Paris <eparis@redhat.com>

inotify: allow users to request not to recieve events on unlinked children

An inotify watch on a directory will send events for children even if those
children have been unlinked. This patch add a new inotify flag IN_EXCL_UNLINK
which allows a watch to specificy they don't care about unlinked children.
This should fix performance problems seen by tasks which add a watch to
/tmp and then are overrun with events when other processes are reading and
writing to unlinked files they created in /tmp.

https://bugzilla.kernel.org/show_bug.cgi?id=16296

Requested-by: Matthias Clasen <mclasen@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: drop the useless priority argument

The priority argument in fanotify is useless. Kill it.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: permissions and blocking

This is the backend work needed for fanotify to support the new
FS_OPEN_PERM and FS_ACCESS_PERM fsnotify events. This is done using the
new fsnotify secondary queue. No userspace interface is provided actually
respond to or request these events.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: new fsnotify hooks and events types for access decisions

introduce a new fsnotify hook, fsnotify_perm(), which is called from the
security code. This hook is used to allow fsnotify groups to make access
control decisions about events on the system. We also must change the
generic fsnotify function to return an error code if we intend these hooks
to be in any way useful.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: use unsigned char * for dentry->d_name.name

fsnotify was using char * when it passed around the d_name.name string
internally but it is actually an unsigned char *. This patch switches
fsnotify to use unsigned and should silence some pointer signess warnings
which have popped out of xfs. I do not add -Wpointer-sign to the fsnotify
code as there are still issues with kstrdup and strlen which would pop
out needless warnings.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: intoduce a notification merge argument

Each group can define their own notification (and secondary_q) merge
function. Inotify does tail drop, fanotify does matching and drop which
can actually allocate a completely new event. But for fanotify to properly
deal with permissions events it needs to know the new event which was
ultimately added to the notification queue. This patch just implements a
void ** argument which is passed to the merge function. fanotify can use
this field to pass the new event back to higher layers.

Signed-off-by: Eric Paris <eparis@redhat.com>
for fanotify to properly deal with permissions events

fsnotify: add group priorities

This introduces an ordering to fsnotify groups. With purely asynchronous
notification based "things" implementing fsnotify (inotify, dnotify) ordering
isn't particularly important. But if people want to use fsnotify for the
basis of sycronous notification or blocking notification ordering becomes
important.

eg. A Hierarchical Storage Management listener would need to get its event
before an AV scanner could get its event (since the HSM would need to
bring the data in for the AV scanner to scan.) Typically asynchronous notification
would want to run after the AV scanner made any relevant access decisions
so as to not send notification about an event that was denied.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: clear all fanotify marks

fanotify listeners may want to clear all marks. They may want to do this
to destroy all of their inode marks which have nothing but ignores.
Realistically this is useful for av vendors who update policy and want to
clear all of their cached allows.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: allow ignored_mask to survive modification

Some inodes a group may want to never hear about a set of events even if
the inode is modified. We add a new mark flag which indicates that these
marks should not have their ignored_mask cleared on modification.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: ignored_mask - excluding notification

The ignored_mask is a new mask which is part of fsnotify marks. A group's
should_send_event() function can use the ignored mask to determine that
certain events are not of interest. In particular if a group registers a
mask including FS_OPEN on a vfsmount they could add FS_OPEN to the
ignored_mask for individual inodes and not send open events for those
inodes.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: allow marks to not pin inodes in core

inotify marks must pin inodes in core. dnotify doesn't technically need to
since they are closed when the directory is closed. fanotify also need to
pin inodes in core as it works today. But the next step is to introduce
the concept of 'ignored masks' which is actually a mask of events for an
inode of no interest. I claim that these should be liberally sent to the
kernel and should not pin the inode in core. If the inode is brought back
in the listener will get an event it may have thought excluded, but this is
not a serious situation and one any listener should deal with.

This patch lays the ground work for non-pinning inode marks by using lazy
inode pinning. We do not pin a mark until it has a non-zero mask entry. If a
listener new sets a mask we never pin the inode.

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: should_send_event needs to handle vfsmounts

currently should_send_event in fanotify only cares about marks on inodes.
This patch extends that interface to indicate that it cares about events
that happened on vfsmounts.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: Infrastructure for per-mount watches

Per-mount watches allow groups to listen to fsnotify events on an entire
mount. This patch simply adds and initializes the fields needed in the
vfsmount struct to make this happen.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: vfsmount marks generic functions

Much like inode-mark.c has all of the code dealing with marks on inodes
this patch adds a vfsmount-mark.c which has similar code but is intended
for marks on vfsmounts.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: split generic and inode specific mark code

currently all marking is done by functions in inode-mark.c. Some of this
is pretty generic and should be instead done in a generic function and we
should only put the inode specific code in inode-mark.c

Signed-off-by: Eric Paris <eparis@redhat.com>

fanotify: Add pids to events

Pass the process identifiers of the triggering processes to fanotify
listeners: this information is useful for event filtering and logging.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: rename mark_entry to just mark

previously I used mark_entry when talking about marks on inodes. The
_entry is pretty useless. Just use "mark" instead.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: rename fsnotify_find_mark_entry to fsnotify_find_mark

the _entry portion of fsnotify functions is useless. Drop it.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: rename fsnotify_mark_entry to just fsnotify_mark

The name is long and it serves no real purpose. So rename
fsnotify_mark_entry to just fsnotify_mark.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: kill FSNOTIFY_EVENT_FILE

Some fsnotify operations send a struct file. This is more information than
we technically need. We instead send a struct path in all cases instead of
sometimes a path and sometimes a file.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: add flags to fsnotify_mark_entries

To differentiate between inode and vfsmount (or other future) types of
marks we add a flags field and set the inode bit on inode marks (the only
currently supported type of mark)

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: add vfsmount specific fields to the fsnotify_mark_entry union

vfsmount marks need mostly the same data as inode specific fields, but for
consistency and understandability we put that data in a vfsmount specific
struct inside a union with inode specific data.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: put inode specific fields in an fsnotify_mark in a union

The addition of marks on vfs mounts will be simplified if the inode
specific parts of a mark and the vfsmnt specific parts of a mark are
actually in a union so naming can be easy. This patch just implements the
inode struct and the union.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: include vfsmount in should_send_event when appropriate

To ensure that a group will not duplicate events when it receives it based
on the vfsmount and the inode should_send_event test we should distinguish
those two cases. We pass a vfsmount to this function so groups can make
their own determinations.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: mount point listeners list and global mask

currently all of the notification systems implemented select which inodes
they care about and receive messages only about those inodes (or the
children of those inodes.) This patch begins to flesh out fsnotify support
for the concept of listeners that want to hear notification for an inode
accessed below a given monut point. This patch implements a second list
of fsnotify groups to hold these types of groups and a second global mask
to hold the events of interest for this type of group.

The reason we want a second group list and mask is because the inode based
notification should_send_event support which makes each group look for a mark
on the given inode. With one nfsmount listener that means that every group would
have to take the inode->i_lock, look for their mark, not find one, and return
for every operation. By seperating vfsmount from inode listeners only when
there is a inode listener will the inode groups have to look for their
mark and take the inode lock. vfsmount listeners will have to grab the lock and
look for a mark but there should be fewer of them, and one vfsmount listener
won't cause the i_lock to be grabbed and released for every fsnotify group
on every io operation.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: rename fsnotify_groups to fsnotify_inode_groups

Simple renaming patch. fsnotify is about to support mount point listeners
so I am renaming fsnotify_groups and fsnotify_mask to indicate these are lists
used only for groups which have watches on inodes.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: drop mask argument from fsnotify_alloc_group

Nothing uses the mask argument to fsnotify_alloc_group. This patch drops
that argument.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: fsnotify_obtain_group should be fsnotify_alloc_group

fsnotify_obtain_group was intended to be able to find an already existing
group. Nothing uses that functionality. This just renames it to
fsnotify_alloc_group so it is clear what it is doing.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: remove group_num altogether

The original fsnotify interface has a group-num which was intended to be
able to find a group after it was added. I no longer think this is a
necessary thing to do and so we remove the group_num.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: replace an event on a list

fanotify would like to clone events already on its notification list, make
changes to the new event, and then replace the old event on the list with
the new event. This patch implements the replace functionality of that
process.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: clone existing events

fsnotify_clone_event will take an event, clone it, and return the cloned
event to the caller. Since events may be in use by multiple fsnotify
groups simultaneously certain event entries (such as the mask) cannot be
changed after the event was created. Since fanotify would like to merge
events happening on the same file it needs a new clean event to work with
so it can change any fields it wishes.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: per group notification queue merge types

inotify only wishes to merge a new event with the last event on the
notification fifo. fanotify is willing to merge any events including by
means of bitwise OR masks of multiple events together. This patch moves
the inotify event merging logic out of the generic fsnotify notification.c
and into the inotify code. This allows each use of fsnotify to provide
their own merge functionality.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: send struct file when sending events to parents when possible

fanotify needs a path in order to open an fd to the object which changed.
Currently notifications to inode's parents are done using only the inode.
For some parental notification we have the entire file, send that so
fanotify can use it.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: include data in should_send calls

fanotify is going to need to look at file->private_data to know if an event
should be sent or not. This passes the data (which might be a file,
dentry, inode, or none) to the should_send function calls so fanotify can
get that information when available

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: provide the data type to should_send_event

fanotify is only interested in event types which contain enough information
to open the original file in the context of the fanotify listener. Since
fanotify may not want to send events if that data isn't present we pass
the data type to the should_send_event function call so fanotify can express
its lack of interest.

Signed-off-by: Eric Paris <eparis@redhat.com>

audit: reimplement audit_trees using fsnotify rather than inotify

Simply switch audit_trees from using inotify to using fsnotify for it's
inode pinning and disappearing act information.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: allow addition of duplicate fsnotify marks

This patch allows a task to add a second fsnotify mark to an inode for the
same group. This mark will be added to the end of the inode's list and
this will never be found by the stand fsnotify_find_mark() function. This
is useful if a user wants to add a new mark before removing the old one.

Signed-off-by: Eric Paris <eparis@redhat.com>

fsnotify: duplicate fsnotify_mark_entry data between 2 marks

Simple copy fsnotify information from one mark to another in preparation
for the second mark to replace the first.

Signed-off-by: Eric Paris <eparis@redhat.com>

audit: convert audit watches to use fsnotify instead of inotify

Audit currently uses inotify to pin inodes in core and to detect when
watched inodes are deleted or unmounted. This patch uses fsnotify instead
of inotify.

Signed-off-by: Eric Paris <eparis@redhat.com>

inotify: use GFP_NOFS under potential memory pressure

inotify can have a watchs removed under filesystem reclaim.

=================================
[ INFO: inconsistent lock state ]
2.6.31-rc2 #16
---------------------------------
inconsistent {IN-RECLAIM_FS-W} -> {RECLAIM_FS-ON-W} usage.
khubd/217 [HC0[0]:SC0[0]:HE1:SE1] takes:
(iprune_mutex){+.+.?.}, at: [<c10ba899>] invalidate_inodes+0x20/0xe3
{IN-RECLAIM_FS-W} state was registered at:
[<c10536ab>] __lock_acquire+0x2c9/0xac4
[<c1053f45>] lock_acquire+0x9f/0xc2
[<c1308872>] __mutex_lock_common+0x2d/0x323
[<c1308c00>] mutex_lock_nested+0x2e/0x36
[<c10ba6ff>] shrink_icache_memory+0x38/0x1b2
[<c108bfb6>] shrink_slab+0xe2/0x13c
[<c108c3e1>] kswapd+0x3d1/0x55d
[<c10449b5>] kthread+0x66/0x6b
[<c1003fdf>] kernel_thread_helper+0x7/0x10
[<ffffffff>] 0xffffffff

Two things are needed to fix this. First we need a method to tell
fsnotify_create_event() to use GFP_NOFS and second we need to stop using
one global IN_IGNORED event and allocate them one at a time. This solves
current issues with multiple IN_IGNORED on a queue having tail drop
problems and simplifies the allocations since we don't have to worry about
two tasks opperating on the IGNORED event concurrently.

Signed-off-by: Eric Paris <eparis@redhat.com>

fs: allow d_instantiate to be called with negative parent dentry

The new fsnotify infrastructure (starting at 90586523) causes an oops in
spufs, where we populate a directory with files before instantiating the
directory itself. The new changes seem to have introduced an assumption
that a dentry's parent will be positive when instantiating.

This change makes it once again possible to d_instantiate a dentry
with a negative parent, and brings __fsnotify_d_instantiate() into
line with inotify_d_instantiate(), which already has this NULL check.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Eric Paris <eparis@redhat.com>

inotify: reimplement inotify using fsnotify

Reimplement inotify_user using fsnotify. This should be feature for feature
exactly the same as the original inotify_user. This does not make any changes
to the in kernel inotify feature used by audit. Those patches (and the eventual
removal of in kernel inotify) will come after the new inotify_user proves to be
working correctly.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>

fsnotify: handle filesystem unmounts with fsnotify marks

When an fs is unmounted with an fsnotify mark entry attached to one of its
inodes we need to destroy that mark entry and we also (like inotify) send
an unmount event.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>

fsnotify: allow groups to add private data to events

inotify needs per group information attached to events. This patch allows
groups to attach private information and implements a callback so that
information can be freed when an event is being destroyed.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>

fsnotify: add correlations between events

As part of the standard inotify events it includes a correlation cookie
between two dentry move operations. This patch includes the same behaviour
in fsnotify events. It is needed so that inotify userspace can be
implemented on top of fsnotify.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>

fsnotify: include pathnames with entries when possible

When inotify wants to send events to a directory about a child it includes
the name of the original file. This patch collects that filename and makes
it available for notification.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>

fsnotify: generic notification queue and waitq

inotify needs to do asyc notification in which event information is stored
on a queue until the listener is ready to receive it. This patch
implements a generic notification queue for inotify (and later fanotify) to
store events to be sent at a later time.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>

dnotify: reimplement dnotify using fsnotify

Reimplement dnotify using fsnotify.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>

fsnotify: parent event notification

inotify and dnotify both use a similar parent notification mechanism. We
add a generic parent notification mechanism to fsnotify for both of these
to use. This new machanism also adds the dentry flag optimization which
exists for inotify to dnotify.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>

fsnotify: add marks to inodes so groups can interpret how to handle those inodes

This patch creates a way for fsnotify groups to attach marks to inodes.
These marks have little meaning to the generic fsnotify infrastructure
and thus their meaning should be interpreted by the group that attached
them to the inode's list.

dnotify and inotify will make use of these markings to indicate which
inodes are of interest to their respective groups. But this implementation
has the useful property that in the future other listeners could actually
use the marks for the exact opposite reason, aka to indicate which inodes
it had NO interest in.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>

fsnotify: unified filesystem notification backend

fsnotify is a backend for filesystem notification. fsnotify does
not provide any userspace interface but does provide the basis
needed for other notification schemes such as dnotify. fsnotify
can be extended to be the backend for inotify or the upcoming
fanotify. fsnotify provides a mechanism for "groups" to register for
some set of filesystem events and to then deliver those events to
those groups for processing.

fsnotify has a number of benefits, the first being actually shrinking the size
of an inode. Before fsnotify to support both dnotify and inotify an inode had

unsigned long i_dnotify_mask; /* Directory notify events */
struct dnotify_struct *i_dnotify; /* for directory notifications */
struct list_head inotify_watches; /* watches on this inode */
struct mutex inotify_mutex; /* protects the watches list

But with fsnotify this same functionallity (and more) is done with just

__u32 i_fsnotify_mask; /* all events for this inode */
struct hlist_head i_fsnotify_mark_entries; /* marks on this inode */

That's right, inotify, dnotify, and fanotify all in 64 bits. We used that
much space just in inotify_watches alone, before this patch set.

fsnotify object lifetime and locking is MUCH better than what we have today.
inotify locking is incredibly complex. See 8f7b0ba1c8539 as an example of
what's been busted since inception. inotify needs to know internal semantics
of superblock destruction and unmounting to function. The inode pinning and
vfs contortions are horrible.

no fsnotify implementers do allocation under locks. This means things like
f04b30de3 which (due to an overabundance of caution) changes GFP_KERNEL to
GFP_NOFS can be reverted. There are no longer any allocation rules when using
or implementing your own fsnotify listener.

fsnotify paves the way for fanotify. In brief fanotify is a notification
mechanism that delivers the lisener both an 'event' and an open file descriptor
to the object in question. This means that fanotify is pathname agnostic.
Some on lkml may not care for the original companies or users that pushed for
TALPA, but fanotify was designed with flexibility and input for other users in
mind. The readahead group expressed interest in fanotify as it could be used
to profile disk access on boot without breaking the audit system. The desktop
search groups have also expressed interest in fanotify as it solves a number
of the race conditions and problems present with managing inotify when more
than a limited number of specific files are of interest. fanotify can provide
for a userspace access control system which makes it a clean interface for AV
vendors to hook without trying to do binary patching on the syscall table,
LSM, and everywhere else they do their things today. With this patch series
fanotify can be implemented in less than 1200 lines of easy to review code.
Almost all of which is the socket based user interface.

This patch series builds fsnotify to the point that it can implement
dnotify and inotify_user. Patches exist and will be sent soon after
acceptance to finish the in kernel inotify conversion (audit) and implement
fanotify.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>