nilfs2: use div64_ul() instead of do_div()

Fixes Coccinelle/coccicheck warnings reported by do_div.cocci.

Compared to do_div(), div64_ul() does not implicitly cast the divisor and
does not unnecessarily calculate the remainder.

Link: https://lkml.kernel.org/r/20240229210456.63234-2-thorsten.blum@toblux.com
Link: https://lkml.kernel.org/r/20240306142547.4612-1-konishi.ryusuke@gmail.com
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

nilfs2: convert cpfile to use kmap_local

Convert all remaining usages of kmap_atomic in cpfile to kmap_local.

Link: https://lkml.kernel.org/r/20240122140202.6950-16-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

nilfs2: remove nilfs_cpfile_{get,put}_checkpoint()

All calls to nilfs_cpfile_get_checkpoint() and
nilfs_cpfile_put_checkpoint() that call kmap() and kunmap() separately are
now gone, so remove these methods.

Link: https://lkml.kernel.org/r/20240122140202.6950-15-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

nilfs2: localize highmem mapping for checkpoint reading within cpfile

Move the code for reading from a checkpoint entry that is performed in
nilfs_attach_checkpoint() to the cpfile side, and make the page mapping
local and temporary. And use kmap_local instead of kmap to access the
checkpoint entry page.

In order to load the ifile inode information included in the checkpoint
entry within the inode lock section of nilfs_ifile_read(), the newly added
checkpoint reading method nilfs_cpfile_read_checkpoint() is called
indirectly via nilfs_ifile_read() instead of from
nilfs_attach_checkpoint().

Link: https://lkml.kernel.org/r/20240122140202.6950-14-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

nilfs2: localize highmem mapping for checkpoint finalization within cpfile

Move the checkpoint finalization routine to the cpfile side, and make the
page mapping local and temporary. And use kmap_local instead of kmap to
access the checkpoint entry page when finalizing a checkpoint.

In this conversion, some of the information on the checkpoint entry being
rewritten is passed through the arguments of the newly added method
nilfs_cpfile_finalize_checkpoint().

Link: https://lkml.kernel.org/r/20240122140202.6950-13-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

nilfs2: localize highmem mapping for checkpoint creation within cpfile

In order to convert kmap() used in cpfile to kmap_local, first move the
checkpoint creation routine, which is one of the places where kmap is
used, to the cpfile side and make the page mapping local and temporary.
And use kmap_local instead of kmap to access the checkpoint entry page
(and header block page) when generating a checkpoint.

Link: https://lkml.kernel.org/r/20240122140202.6950-12-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

nilfs2: cpfile: fix some kernel-doc warnings

Correct the function parameter names for nilfs_cpfile_get_info():

cpfile.c:564: warning: Function parameter or member 'cnop' not described in 'nilfs_cpfile_get_cpinfo'
cpfile.c:564: warning: Function parameter or member 'mode' not described in 'nilfs_cpfile_get_cpinfo'
cpfile.c:564: warning: Function parameter or member 'buf' not described in 'nilfs_cpfile_get_cpinfo'
cpfile.c:564: warning: Function parameter or member 'cisz' not described in 'nilfs_cpfile_get_cpinfo'
cpfile.c:564: warning: Excess function parameter 'cno' description in 'nilfs_cpfile_get_cpinfo'
cpfile.c:564: warning: Excess function parameter 'ci' description in 'nilfs_cpfile_get_cpinfo'

Also add missing descriptions of the function's specification.

[ konishi.ryusuke@gmail.com: filled in missing descriptions ]

Link: https://lkml.kernel.org/r/20231220065931.2372-1-rdunlap@infradead.org
Link: https://lkml.kernel.org/r/20231220221342.11505-1-konishi.ryusuke@gmail.com
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

nilfs2: remove filenames from file comments

Remove filenames that are not particularly useful in file comments, and
suppress checkpatch warnings

WARNING: It's generally not useful to have the filename in the file

Link: https://lkml.kernel.org/r/1635151862-11547-3-git-send-email-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: Qing Wang <wangqing@vivo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: fix typos in comments

numer -> number in fs/nilfs2/cpfile.c
Decription -> Description in fs/nilfs2/ioctl.c
isntance -> instance in fs/nilfs2/the_nilfs.c

Link: https://lkml.kernel.org/r/1617942951-14631-1-git-send-email-konishi.ryusuke@gmail.com
Link: https://lore.kernel.org/r/20210409022519.176988-1-lujialin4@huawei.com
Signed-off-by: Lu Jialin <lujialin4@huawei.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: fix some kernel-doc warnings for nilfs2

Fixes the following W=1 kernel build warning(s):

fs/nilfs2/bmap.c:378: warning: Excess function parameter 'bhp' description in 'nilfs_bmap_assign'
fs/nilfs2/cpfile.c:907: warning: Excess function parameter 'status' description in 'nilfs_cpfile_change_cpmode'
fs/nilfs2/cpfile.c:946: warning: Excess function parameter 'stat' description in 'nilfs_cpfile_get_stat'
fs/nilfs2/page.c:76: warning: Excess function parameter 'inode' description in 'nilfs_forget_buffer'
fs/nilfs2/sufile.c:563: warning: Excess function parameter 'stat' description in 'nilfs_sufile_get_stat'

Signed-off-by: Wang Hai <wanghai38@huawei.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/1601386269-2423-1-git-send-email-konishi.ryusuke@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: use a more common logging style

Add macros for nilfs_<level>(sb, fmt, ...) and convert the uses of
'nilfs_msg(sb, KERN_<LEVEL>, ...)' to 'nilfs_<level>(sb, ...)' so nilfs2
uses a logging style more like the typical kernel logging style.

Miscellanea:

o Realign arguments for these uses

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1595860111-3920-4-git-send-email-konishi.ryusuke@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: convert to SPDX license tags

Remove the verbose license text from NILFS2 files and replace them with
SPDX tags. This does not change the license of any of the code.

Link: http://lkml.kernel.org/r/1535624528-5982-1-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: move ioctl interface and disk layout to uapi separately

The header file "include/linux/nilfs2_fs.h" is composed of parts for
ioctl and disk format, and both are intended to be shared with user
space programs.

This moves them to the uapi directory "include/uapi/linux" splitting the
file to "nilfs2_api.h" and "nilfs2_ondisk.h". The following minor
changes are accompanied by this migration:

- nilfs_direct_node struct in nilfs2/direct.h is converged to
nilfs2_ondisk.h because it's an on-disk structure.
- inline functions nilfs_rec_len_from_disk() and
nilfs_rec_len_to_disk() are moved to nilfs2/dir.c.

Link: http://lkml.kernel.org/r/1465825507-3407-4-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: reduce bare use of printk() with nilfs_msg()

Replace most use of printk() in nilfs2 implementation with nilfs_msg(),
and reduce the following checkpatch.pl warning:

"WARNING: Prefer [subsystem eg: netdev]_crit([subsystem]dev, ...
then dev_crit(dev, ... then pr_crit(... to printk(KERN_CRIT ..."

This patch also fixes a minor checkpatch warning "WARNING: quoted string
split across lines" that often accompanies the prior warning, and amends
message format as needed.

Link: http://lkml.kernel.org/r/1464875891-5443-5-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: fix block comments

This fixes block comments with proper formatting to eliminate the
following checkpatch.pl warnings:

"WARNING: Block comments use * on subsequent lines"
"WARNING: Block comments use a trailing */ on a separate line"

Link: http://lkml.kernel.org/r/1462886671-3521-8-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: avoid bare use of 'unsigned'

This fixes checkpatch.pl warning "WARNING: Prefer 'unsigned int' to
bare use of 'unsigned'".

Link: http://lkml.kernel.org/r/1462886671-3521-5-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: add missing line spacing

Clean up checkpatch.pl warnings "WARNING: Missing a blank line after
declarations" from nilfs2.

Link: http://lkml.kernel.org/r/1461935747-10380-11-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: clean up old e-mail addresses

E-mail addresses of osrg.net domain are no longer available. This
removes them from authorship notices and prevents reporters from being
confused.

Link: http://lkml.kernel.org/r/1461935747-10380-5-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: remove FSF mailing address from GPL notices

This removes the extra paragraph which mentions FSF address in GPL
notices from source code of nilfs2 and avoids the checkpatch.pl error
related to it.

Link: http://lkml.kernel.org/r/1461935747-10380-4-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: improve execution time of NILFS_IOCTL_GET_CPINFO ioctl

The older a filesystem gets, the slower lscp command becomes. This is
because nilfs_cpfile_do_get_cpinfo() function meets more hole blocks
as the start offset of valid checkpoint numbers gets bigger.

This reduces the overhead by skipping hole blocks efficiently with
nilfs_mdt_find_block() helper.

A measurement result of this patch is as follows:

Before:
$ time lscp
CNO DATE TIME MODE FLG BLKCNT ICNT
5769303 2015-02-22 19:31:33 cp - 108 1
5769304 2015-02-22 19:38:54 cp - 108 1

real 0m0.182s
user 0m0.003s
sys 0m0.180s

After:
$ time lscp
CNO DATE TIME MODE FLG BLKCNT ICNT
5769303 2015-02-22 19:31:33 cp - 108 1
5769304 2015-02-22 19:38:54 cp - 108 1

real 0m0.003s
user 0m0.001s
sys 0m0.002s

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: verify metadata sizes read from disk

Add code to check sizes of on-disk data of metadata files such as inode
size, segment usage size, DAT entry size, and checkpoint size. Although
these sizes are read from disk, the current implementation doesn't check
them.

If these sizes are not sane on disk, it can cause out-of-range access to
metadata or memory access overrun on metadata block buffers due to
overflow in sundry calculations.

Both lower limit and upper limit of metadata sizes are verified to
prevent these issues.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Andreas Rohner <andreas.rohner@gmx.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: fix timing issue between rmcp and chcp ioctls

The checkpoint deletion ioctl (rmcp ioctl) has potential for breaking
snapshot because it is not fully exclusive with checkpoint mode change
ioctl (chcp ioctl).

The rmcp ioctl first tests if the specified checkpoint is a snapshot or
not within nilfs_cpfile_delete_checkpoint function, and then calls
nilfs_cpfile_delete_checkpoints function to actually invalidate the
checkpoint only if it's not a snapshot. However, the checkpoint can be
changed into a snapshot by the chcp ioctl between these two operations.
In that case, calling nilfs_cpfile_delete_checkpoints() wrongly
invalidates the snapshot, which leads to snapshot list corruption and
snapshot count mismatch.

This fixes the issue by changing nilfs_cpfile_delete_checkpoints() so
that it reconfirms the target checkpoints are snapshot or not.

This second check is exclusive with the chcp operation since it is
protected by an existing semaphore.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: remove the second argument of k[un]map_atomic()

Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Cong Wang <amwang@redhat.com>

nilfs2: use mark_buffer_dirty to mark btnode or meta data dirty

This replaces nilfs_mdt_mark_buffer_dirty and nilfs_btnode_mark_dirty
macros with mark_buffer_dirty and gets rid of nilfs_mark_buffer_dirty,
an own mark buffer dirty function.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: see state of root dentry for mount check of snapshots

After applied the patch that unified sb instances, root dentry of
snapshots can be left in dcache even after their trees are unmounted.

The orphan root dentry/inode keeps a root object, and this causes
false positive of nilfs_checkpoint_is_mounted function.

This resolves the issue by having nilfs_checkpoint_is_mounted test
whether the root dentry is busy or not.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: use iget for all metadata files

This makes use of iget5_locked to allocate or get inode for metadata
files to stop using own inode allocator.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: trivial coding style fix

This is a trivial style fix patch to mend errors/warnings
reported by "checkpatch.pl --file".

Signed-off-by: Jiro SEKIBA <jir@unicus.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: separate read method of meta data files on super root block

Will displace nilfs_mdt_read_inode_direct function with an individual
read method: nilfs_dat_read, nilfs_sufile_read, nilfs_cpfile_read.

This provides the opportunity to initialize local variables of each
metadata file after reading the inode.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: separate constructor of metadata files

This will displace nilfs_mdt_new() constructor with individual
metadata file constructors like nilfs_dat_new(), new_sufile_new(),
nilfs_cpfile_new(), and nilfs_ifile_new().

This makes it possible for each metadata file to have own
intialization code.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: fix lock order reversal in chcp operation

Will fix the following lock order reversal lockdep detected:

=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.32-rc6 #7
-------------------------------------------------------
chcp/30157 is trying to acquire lock:
(&nilfs->ns_mount_mutex){+.+.+.}, at: [<fed7cfcc>] nilfs_cpfile_change_cpmode+0x46/0x752 [nilfs2]

but task is already holding lock:
(&nilfs->ns_segctor_sem){++++.+}, at: [<fed7ca32>] nilfs_transaction_begin+0xba/0x110 [nilfs2]

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (&nilfs->ns_segctor_sem){++++.+}:
[<c105799c>] __lock_acquire+0x109c/0x139d
[<c1057d26>] lock_acquire+0x89/0xa0
[<c14151e2>] down_read+0x31/0x45
[<fed6d77b>] nilfs_attach_checkpoint+0x8f/0x16b [nilfs2]
[<fed6e393>] nilfs_get_sb+0x3e7/0x653 [nilfs2]
[<c10c0ccb>] vfs_kern_mount+0x8b/0x124
[<c10c0db2>] do_kern_mount+0x37/0xc3
[<c10d7517>] do_mount+0x64d/0x69d
[<c10d75cd>] sys_mount+0x66/0x95
[<c1002a14>] sysenter_do_call+0x12/0x32

-> #1 (&type->s_umount_key#31/1){+.+.+.}:
[<c105799c>] __lock_acquire+0x109c/0x139d
[<c1057d26>] lock_acquire+0x89/0xa0
[<c104c0f3>] down_write_nested+0x34/0x52
[<c10c08fe>] sget+0x22e/0x389
[<fed6e133>] nilfs_get_sb+0x187/0x653 [nilfs2]
[<c10c0ccb>] vfs_kern_mount+0x8b/0x124
[<c10c0db2>] do_kern_mount+0x37/0xc3
[<c10d7517>] do_mount+0x64d/0x69d
[<c10d75cd>] sys_mount+0x66/0x95
[<c1002a14>] sysenter_do_call+0x12/0x32

-> #0 (&nilfs->ns_mount_mutex){+.+.+.}:
[<c1057727>] __lock_acquire+0xe27/0x139d
[<c1057d26>] lock_acquire+0x89/0xa0
[<c1414d63>] mutex_lock_nested+0x41/0x23e
[<fed7cfcc>] nilfs_cpfile_change_cpmode+0x46/0x752 [nilfs2]
[<fed801b2>] nilfs_ioctl+0x11a/0x7da [nilfs2]
[<c10cca12>] vfs_ioctl+0x27/0x6e
[<c10ccf93>] do_vfs_ioctl+0x491/0x4db
[<c10cd022>] sys_ioctl+0x45/0x5f
[<c1002a14>] sysenter_do_call+0x12/0x32

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: add more check routines in mount process

nilfs2: Add more safeguard routines and protections in mount process,
which also makes nilfs2 report consistency error messages when
checkpoint number is invalid.

Signed-off-by: Zhu Yanhai <zhu.yanhai@gmail.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: fix disorder in cp count on error during deleting checkpoints

This fixes a bug that checkpoint count gets wrong on errors when
deleting a series of checkpoints.

The count error is persistent since the checkpoint count is stored on
disk. Some userland programs refer to the count via ioctl, and this
bugfix is needed to prevent malfunction of such programs.

Signed-off-by: Jiro SEKIBA <jir@unicus.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: stable@kernel.org

nilfs2: get rid of bd_mount_sem use from nilfs

This will remove every bd_mount_sem use in nilfs.

The intended exclusion control was replaced by the previous patch
("nilfs2: correct exclusion control in nilfs_remount function") for
nilfs_remount(), and this patch will replace remains with a new mutex
that this inserts in nilfs object.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

nilfs2: return EBUSY against delete request on snapshot

This helps userland programs like the rmcp command to distinguish
error codes returned against a checkpoint removal request.

Previously -EPERM was returned, and not discriminable from real
permission errors. This also allows removal of the latest checkpoint
because the deletion leads to create a new checkpoint, and thus it's
harmless for the filesystem.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: allow future expansion of metadata read out via get info ioctl

Nilfs has some ioctl commands to read out metadata from meta data
files:

- NILFS_IOCTL_GET_CPINFO for checkpoint file,
- NILFS_IOCTL_GET_SUINFO for segment usage file, and
- NILFS_IOCTL_GET_VINFO for Disk Address Transalation (DAT) file,
respectively.

Every routine on these metadata files is implemented so that it allows
future expansion of on-disk format. But, the above ioctl commands do
not support expansion even though nilfs_argv structure can handle
arbitrary size for data exchanged via ioctl.

This allows future expansion of the following structures which give
basic format of the "get information" ioctls:

- struct nilfs_cpinfo
- struct nilfs_suinfo
- struct nilfs_vinfo

So, this introduces forward compatility of such ioctl commands.

In this patch, a sanity check in nilfs_ioctl_get_info() function is
changed to accept larger data structure [1], and metadata read
routines are rewritten so that they become compatible for larger
structures; the routines will just ignore the remaining fields which
the current version of nilfs doesn't know.

[1] The ioctl function already has another upper limit (PAGE_SIZE
against a structure, which appears in nilfs_ioctl_wrap_copy
function), and this will not cause security problem.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: fix bh leak in nilfs_cpfile_delete_checkpoints function

The nilfs_cpfile_delete_checkpoints() wrongly skips brelse() for the
header block of checkpoint file in case of errors. This fixes the
leak bug.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: replace BUG_ON and BUG calls triggerable from ioctl

Pekka Enberg advised me:
> It would be nice if BUG(), BUG_ON(), and panic() calls would be
> converted to proper error handling using WARN_ON() calls. The BUG()
> call in nilfs_cpfile_delete_checkpoints(), for example, looks to be
> triggerable from user-space via the ioctl() system call.

This will follow the comment and keep them to a minimum.

Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: fix buggy behavior seen in enumerating checkpoints

This will fix the weird behavior of lscp command in listing continuously
created checkpoints; the output of lscp is rewinded regularly for the
recent nilfs. As a result of debugging, a defect was found in
nilfs_cpfile_do_get_cpinfo() function.

Though the function can be repeatedly called to enumerate checkpoints and
it can skip invalid checkpoint entries, the index value was not carried
between successive calls.

The bug has long been present, and came to surface after applying a bugfix
nilfs2-fix-problems-of-memory-allocation-in-ioctl.patch, which increased
frequency of calling the function. The similar bugfix was already applied
for ``snapshots'' by
nilfs2-fix-gc-failure-on-volumes-keeping-numerous-snapshots.patch.

This fixes the problem by making the index argument bidirectional on the
function.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: fix improper return values of nilfs_get_cpinfo ioctl

A few tool developers gave me requests for fixing inconvenient return
value of nilfs_get_cpinfo() ioctl; if the requested mode is NILFS_SNAPSHOT
and the specified start entry is not a snapshot, the ioctl unnaturally
returns one as the number of acquired snapshot item.

In addition, the ioctl function returns an ENOENT error for checkpoints
within blocks deleted by garbage collection.

These behaviors require corrections for programs which enumerate
snapshots. This resolves the inconvenience by changing the return values
to zero for the above cases.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: fix gc failure on volumes keeping numerous snapshots

This resolves the following failure of nilfs2 cleaner daemon:

nilfs_cleanerd[20670]: cannot clean segments: No such file or directory
nilfs_cleanerd[20670]: shutdown

When creating thousands of snapshots, the cleaner daemon had rarely died
as above due to an error returned from the kernel code.

After applying the recent patch which fixed memory allocation problems in
ioctl (Message-Id: <20081215.155840.105124170.ryusuke@osrg.net>), the
problem gets more frequent.

It turned out to be a bug of nilfs_ioctl_wrap_copy function and one of its
callback routines to read out information of snapshots; if the
nilfs_ioctl_wrap_copy function divided a large read request into multiple
requests, the second and later requests have failed since a restart
position on snapshot meta data was not properly set forward.

It's a deficiency of the callback interface that cannot pass the restart
position among multiple requests. This patch fixes the issue by allowing
nilfs_ioctl_wrap_copy and snapshot read functions to exchange a position
argument.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: segment usage file

This adds a meta data file which stores the allocation state of segments.

[konishi.ryusuke@lab.ntt.co.jp: fix wrong counting of checkpoints and dirty segments]
Signed-off-by: Koji Sato <sato.koji@lab.ntt.co.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: checkpoint file

This adds a meta data file which holds checkpoint entries in its data
blocks.

Signed-off-by: Koji Sato <sato.koji@lab.ntt.co.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>