NFS: Remove the nfs4_label argument from nfs_setsecurity

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

NFS: Remove the nfs4_label argument from nfs_fhget()

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

NFS: Create a new nfs_alloc_fattr_with_label() function

For creating fattrs with the label field already allocated for us. I
also update nfs_free_fattr() to free the label in the end.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

nfs: update has_sec_mnt_opts after cloning lsm options from parent

After calling security_sb_clone_mnt_opts() in nfs_get_root(), it's
necessary to copy the value of has_sec_mnt_opts from the cloned
super_block's nfs_server. Otherwise, calls to nfs_compare_super()
using this super_block may not return the correct result, leading to
mount failures.

For example, mounting an nfs server with the following in /etc/exports:
/export *(rw,insecure,crossmnt,no_root_squash,security_label)
and having /export/scratch on a separate block device.

mount -o v4.2,context=system_u:object_r:root_t:s0 server:/export/test /mnt/test
mount -o v4.2,context=system_u:object_r:swapfile_t:s0 server:/export/scratch /mnt/scratch

The second mount would fail with "mount.nfs: /mnt/scratch is busy or
already mounted or sharecache fail" and "SELinux: mount invalid. Same
superblock, different security settings for..." would appear in the
syslog.

Also while we're in there, replace several instances of "NFS_SB(s)"
with "server", which was already declared at the top of the
nfs_get_root().

Fixes: ec1ade6a0448 ("nfs: account for selinux security context when deciding to share superblock")
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

NFS: Ensure security label is set for root inode

When using NFSv4.2, the security label for the root inode should be set
via a call to nfs_setsecurity() during the mount process, otherwise the
inode will appear as unlabeled for up to acdirmin seconds. Currently
the label for the root inode is allocated, retrieved, and freed entirely
witin nfs4_proc_get_root().

Add a field for the label to the nfs_fattr struct, and allocate & free
the label in nfs_get_root(), where we also add a call to
nfs_setsecurity(). Note that for the call to nfs_setsecurity() to
succeed, it's necessary to also move the logic calling
security_sb_{set,clone}_security() from nfs_get_tree_common() down into
nfs_get_root()... otherwise the SBLABEL_MNT flag will not be set in the
super_block's security flags and nfs_setsecurity() will silently fail.

Reported-by: Richard Haines <richard_c_haines@btinternet.com>
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Tested-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: fixed 80-char line width problems]
Signed-off-by: Paul Moore <paul@paul-moore.com>

NFS: Attach supplementary error information to fs_context.

Split out from commit "NFS: Add fs_context support."

Add wrappers nfs_errorf(), nfs_invalf(), and nfs_warnf() which log error
information to the fs_context. Convert some printk's to use these new
wrappers instead.

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

NFS: Additional refactoring for fs_context conversion

Split out from commit "NFS: Add fs_context support."

This patch adds additional refactoring for the conversion of NFS to use
fs_context, namely:

(*) Merge nfs_mount_info and nfs_clone_mount into nfs_fs_context.
nfs_clone_mount has had several fields removed, and nfs_mount_info
has been removed altogether.
(*) Various functions now take an fs_context as an argument instead
of nfs_mount_info, nfs_fs_context, etc.

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Replace <asm/uaccess.h> with <linux/uaccess.h> globally

This was entirely automated, using the script by Al:

PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
$(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)

to do the replacement at the end of the merge window.

Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

VFS: normal filesystems (and lustre): d_inode() annotations

that's the bulk of filesystem drivers dealing with inodes of their own

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

switch d_materialise_unique() users to d_splice_alias()

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

move d_rcu from overlapping d_child to overlapping d_alias

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

dcache: d_obtain_alias callers don't all want DISCONNECTED

There are a few d_obtain_alias callers that are using it to get the
root of a filesystem which may already have an alias somewhere else.

This is not the same as the filehandle-lookup case, and none of them
actually need DCACHE_DISCONNECTED set.

It isn't really a serious problem, but it would really be clearer if we
reserved DCACHE_DISCONNECTED for those cases where it's actually needed.

In the btrfs case this was causing a spurious printk from
nfsd/nfsfh.c:fh_verify when it found an unexpected DCACHE_DISCONNECTED
dentry. Josef worked around this by unsetting DCACHE_DISCONNECTED
manually in 3a0dfa6a12e "Btrfs: unset DCACHE_DISCONNECTED when mounting
default subvol", and this replaces that workaround.

Cc: Josef Bacik <jbacik@fb.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

NFS: Fix memroy leak for double mounts

When double mounting same nfs filesystem, the devname saved in d_fsdata
will be lost.The second mount should not change the devname that
be saved in d_fsdata.

Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

NFS:Add labels to client function prototypes

After looking at all of the nfsv4 operations the label structure has been added
to the prototypes of the functions which can transmit label data.

Signed-off-by: Matthew N. Dodd <Matthew.Dodd@sparta.com>
Signed-off-by: Miguel Rodel Felipe <Rodel_FM@dsi.a-star.edu.sg>
Signed-off-by: Phua Eu Gene <PHUA_Eu_Gene@dsi.a-star.edu.sg>
Signed-off-by: Khin Mi Mi Aung <Mi_Mi_AUNG@dsi.a-star.edu.sg>
Signed-off-by: Steve Dickson <steved@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

nfs: remove kfree() redundant null checks

smatch analysis:

fs/nfs/getroot.c:130 nfs_get_root() info: redundant null
check on name calling kfree()

fs/nfs/unlink.c:272 nfs_async_unlink() info: redundant null
check on devname_garbage calling kfree()

Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: linux-nfs@vger.kernel.org
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

nfs: include internal.h in getroot.h

Sparse warning:
fs/nfs/nfs4getroot.c:11:5: warning: symbol 'nfs4_get_rootfh' was not declared.
Should it be static?

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

NFS: Move the v4 getroot code to nfs4getroot.c

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

vfs: switch i_dentry/d_alias to hlist

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

NFS: Create a single nfs_get_root()

This patch splits out the NFS v4 specific functionality of
nfs4_get_root() into its own rpc_op called by the generic client, and
leaves nfs4_proc_get_rootfh() as its own stand alone function. This
also allows me to change nfs4_remote_mount(), nfs4_xdev_mount() and
nfs4_remote_referral_mount() to use the generic client's nfs_get_root()
function. Later patches in this series will collapse these functions
into one common function, so using the same get_root() function
everywhere simplifies future changes.

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

NFS: Rename nfs4_proc_get_root()

This function is really getting the root filehandle and not the root
dentry of the filesystem. I also removed the rpc_ops lookup from
nfs4_get_rootfh() under the assumption that if we reach this function
then we already know we are using NFS v4.

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Remove all #inclusions of asm/system.h

Remove all #inclusions of asm/system.h preparatory to splitting and killing
it. Performed with the following command:

perl -p -i -e 's!^#\s*include\s*<asm/system[.]h>.*\n!!' `grep -Irl '^#\s*include\s*<asm/system[.]h>' *`

Signed-off-by: David Howells <dhowells@redhat.com>

switch open-coded instances of d_make_root() to new helper

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

nfs4: Fix NULL dereference at d_alloc_and_lookup()

d_alloc_and_lookup() calls i_op->lookup method due to
rootfh changes his fsid.

During mount i_op of NFS root inode is set to
nfs_mountpoint_inode_operations, if rpc_ops->getroot()
and rpc_ops->getattr() return different fsid.

After that nfs_follow_remote_path() raised oops:

BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [< (null)>] (null)

stack trace:

d_alloc_and_lookup+0x4c/0x74
do_lookup+0x1e3/0x280
link_path_walk+0x12e/0xab0
nfs4_remote_get_sb+0x56/0x2c0 [nfs]
path_walk+0x67/0xe0
vfs_path_lookup+0x8e/0x100
nfs_follow_remote_path+0x16f/0x3e0 [nfs]
nfs4_try_mount+0x6f/0xd0 [nfs]
nfs_get_sb+0x269/0x400 [nfs]
vfs_kern_mount+0x8a/0x1f0
do_kern_mount+0x52/0x130
do_mount+0x20a/0x260
sys_mount+0x90/0xe0
system_call_fastpath+0x16/0x1b

So just refresh fsid, as RFC3530 doesn't specify behavior
in case of rootfh changes fsid.

Signed-off-by: Vitaliy Gusev <gusev.vitaliy@nexenta.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

nfs: store devname at disconnected NFS roots

part 2: make sure that disconnected roots have corresponding mnt_devname
values stashed into them.

Have nfs*_get_root() stuff a copy of devname into ->d_fsdata of the
found root, provided that it is disconnected.

Have ->d_release() free it when dentry goes away.

Have the places where NFS uses ->d_fsdata for sillyrename (and that
can *never* happen to a disconnected root - dentry will be attached
to its parent) free old devname copies if they find those.

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

nfs: propagate devname to nfs{,4}_get_root()

step 1 of ->mnt_devname fixes: make sure we have the value of devname
available in ..._get_root().

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

switch nfs to ->s_d_op

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

fs: dcache per-inode inode alias locking

dcache_inode_lock can be replaced with per-inode locking. Use existing
inode->i_lock for this. This is slightly non-trivial because we sometimes
need to find the inode from the dentry, which requires d_inode to be
stabilised (either with refcount or d_lock).

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

fs: dcache reduce branches in lookup path

Reduce some branches and memory accesses in dcache lookup by adding dentry
flags to indicate common d_ops are set, rather than having to check them.
This saves a pointer memory access (dentry->d_op) in common path lookup
situations, and saves another pointer load and branch in cases where we
have d_op but not the particular operation.

Patched with:

git grep -E '[.>]([[:space:]])*d_op([[:space:]])*=' | xargs sed -e 's/\([^\t ]*\)->d_op = \(.*\);/d_set_d_op(\1, \2);/' -e 's/\([^\t ]*\)\.d_op = \(.*\);/d_set_d_op(\&\1, \2);/' -i

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

fs: dcache remove dcache_lock

dcache_lock no longer protects anything. remove it.

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

fs: scale inode alias list

Add a new lock, dcache_inode_lock, to protect the inode's i_dentry list
from concurrent modification. d_alias is also protected by d_lock.

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

new helper: ihold()

Clones an existing reference to inode; caller must already hold one.

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

nfs4 use mandatory attribute file type in nfs4_get_root

S_ISDIR(fsinfo.fattr->mode) checks the file type rather than the mode bits,
so we should be checking for the NFS_ATTR_FATTR_TYPE fattr property.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@kernel.org

NFSv4: Reduce stack footprint of nfs4_get_root()

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

NFSv4: Eliminate nfs4_path_walk()

All we really want is the ability to retrieve the root file handle. We no
longer need the ability to walk down the path, since that is now done in
nfs_follow_remote_path().

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

headers: mnt_namespace.h redux

Fix various silly problems wrt mnt_namespace.h:

- exit_mnt_ns() isn't used, remove it
- done that, sched.h and nsproxy.h inclusions aren't needed
- mount.h inclusion was need for vfsmount_lock, but no longer
- remove mnt_namespace.h inclusion from files which don't use anything
from mnt_namespace.h

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

NFS: Fix the type of struct nfs_fattr->mode

There is no point in using anything other than umode_t, since we copy the
content pretty much directly into inode->i_mode.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

[PATCH] switch all filesystems over to d_obtain_alias

Switch all users of d_alloc_anon to d_obtain_alias.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Convert ERR_PTR(PTR_ERR(p)) instances to ERR_CAST(p)

Convert instances of ERR_PTR(PTR_ERR(p)) to ERR_CAST(p) using:

perl -spi -e 's/ERR_PTR[(]PTR_ERR[(](.*)[)][)]/ERR_CAST(\1)/' `grep -rl 'ERR_PTR[(]*PTR_ERR' fs crypto net security`

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

NFS: Fix an Oops in NFS unmount

Ensure that the dummy 'root dentry' is invisible to d_find_alias(). If not,
then it may be spliced into the tree if a parent directory from the same
filesystem gets mounted at a later time.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

NFS: Fix the ustat() regression

Since 2.6.18, the superblock sb->s_root has been a dummy dentry with a
dummy inode. This breaks ustat(), which actually uses sb->s_root in a
vfstat() call.

Fix this by making the s_root a dummy alias to the directory inode that was
used when creating the superblock.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

NFS: Fix an Oops in encode_lookup()

It doesn't look as if the NFS file name limit is being initialised correctly
in the struct nfs_server. Make sure that we limit whatever is being set in
nfs_probe_fsinfo() and nfs_init_server().

Also ensure that readdirplus and nfs4_path_walk respect our file name
limits.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

NFS: Kill the obsolete NFS_PARANOIA

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

header cleaning: don't include smp_lock.h when not used

Remove includes of <linux/smp_lock.h> where it is not used/needed.
Suggested by Al Viro.

Builds cleanly on x86_64, i386, alpha, ia64, powerpc, sparc,
sparc64, and arm (all 59 defconfigs).

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

NFSv4: Don't require that NFSv4 mount paths begin with '/'

Addresses the regression noted in
http://bugzilla.linux-nfs.org/show_bug.cgi?id=134

Also mark a couple of other regressions as requiring fixing.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

[PATCH] rename struct namespace to struct mnt_namespace

Rename 'struct namespace' to 'struct mnt_namespace' to avoid confusion with
other namespaces being developped for the containers : pid, uts, ipc, etc.
'namespace' variables and attributes are also renamed to 'mnt_ns'

Signed-off-by: Kirill Korotaev <dev@sw.ru>
Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Remove all inclusions of <linux/config.h>
kbuild explicitly includes this at build time.

Signed-off-by: Dave Jones <davej@redhat.com>

NFS: Secure the roots of the NFS subtrees in a shared superblock

Invoke security_d_instantiate() on root dentries after allocating them with
dentry_alloc_anon(). Normally dentry_alloc_root() would do that, but we don't
call that as we don't want to assign a name to the root dentry at this point
(we may discover the real name later).

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

NFS: Share NFS superblocks per-protocol per-server per-FSID

The attached patch makes NFS share superblocks between mounts from the same
server and FSID over the same protocol.

It does this by creating each superblock with a false root and returning the
real root dentry in the vfsmount presented by get_sb(). The root dentry set
starts off as an anonymous dentry if we don't already have the dentry for its
inode, otherwise it simply returns the dentry we already have.

We may thus end up with several trees of dentries in the superblock, and if at
some later point one of anonymous tree roots is discovered by normal filesystem
activity to be located in another tree within the superblock, the anonymous
root is named and materialises attached to the second tree at the appropriate
point.

Why do it this way? Why not pass an extra argument to the mount() syscall to
indicate the subpath and then pathwalk from the server root to the desired
directory? You can't guarantee this will work for two reasons:

(1) The root and intervening nodes may not be accessible to the client.

With NFS2 and NFS3, for instance, mountd is called on the server to get
the filehandle for the tip of a path. mountd won't give us handles for
anything we don't have permission to access, and so we can't set up NFS
inodes for such nodes, and so can't easily set up dentries (we'd have to
have ghost inodes or something).

With this patch we don't actually create dentries until we get handles
from the server that we can use to set up their inodes, and we don't
actually bind them into the tree until we know for sure where they go.

(2) Inaccessible symbolic links.

If we're asked to mount two exports from the server, eg:

mount warthog:/warthog/aaa/xxx /mmm
mount warthog:/warthog/bbb/yyy /nnn

We may not be able to access anything nearer the root than xxx and yyy,
but we may find out later that /mmm/www/yyy, say, is actually the same
directory as the one mounted on /nnn. What we might then find out, for
example, is that /warthog/bbb was actually a symbolic link to
/warthog/aaa/xxx/www, but we can't actually determine that by talking to
the server until /warthog is made available by NFS.

This would lead to having constructed an errneous dentry tree which we
can't easily fix. We can end up with a dentry marked as a directory when
it should actually be a symlink, or we could end up with an apparently
hardlinked directory.

With this patch we need not make assumptions about the type of a dentry
for which we can't retrieve information, nor need we assume we know its
place in the grand scheme of things until we actually see that place.

This patch reduces the possibility of aliasing in the inode and page caches for
inodes that may be accessed by more than one NFS export. It also reduces the
number of superblocks required for NFS where there are many NFS exports being
used from a server (home directory server + autofs for example).

This in turn makes it simpler to do local caching of network filesystems, as it
can then be guaranteed that there won't be links from multiple inodes in
separate superblocks to the same cache file.

Obviously, cache aliasing between different levels of NFS protocol could still
be a problem, but at least that gives us another key to use when indexing the
cache.

This patch makes the following changes:

(1) The server record construction/destruction has been abstracted out into
its own set of functions to make things easier to get right. These have
been moved into fs/nfs/client.c.

All the code in fs/nfs/client.c has to do with the management of
connections to servers, and doesn't touch superblocks in any way; the
remaining code in fs/nfs/super.c has to do with VFS superblock management.

(2) The sequence of events undertaken by NFS mount is now reordered:

(a) A volume representation (struct nfs_server) is allocated.

(b) A server representation (struct nfs_client) is acquired. This may be
allocated or shared, and is keyed on server address, port and NFS
version.

(c) If allocated, the client representation is initialised. The state
member variable of nfs_client is used to prevent a race during
initialisation from two mounts.

(d) For NFS4 a simple pathwalk is performed, walking from FH to FH to find
the root filehandle for the mount (fs/nfs/getroot.c). For NFS2/3 we
are given the root FH in advance.

(e) The volume FSID is probed for on the root FH.

(f) The volume representation is initialised from the FSINFO record
retrieved on the root FH.

(g) sget() is called to acquire a superblock. This may be allocated or
shared, keyed on client pointer and FSID.

(h) If allocated, the superblock is initialised.

(i) If the superblock is shared, then the new nfs_server record is
discarded.

(j) The root dentry for this mount is looked up from the root FH.

(k) The root dentry for this mount is assigned to the vfsmount.

(3) nfs_readdir_lookup() creates dentries for each of the entries readdir()
returns; this function now attaches disconnected trees from alternate
roots that happen to be discovered attached to a directory being read (in
the same way nfs_lookup() is made to do for lookup ops).

The new d_materialise_unique() function is now used to do this, thus
permitting the whole thing to be done under one set of locks, and thus
avoiding any race between mount and lookup operations on the same
directory.

(4) The client management code uses a new debug facility: NFSDBG_CLIENT which
is set by echoing 1024 to /proc/net/sunrpc/nfs_debug.

(5) Clone mounts are now called xdev mounts.

(6) Use the dentry passed to the statfs() op as the handle for retrieving fs
statistics rather than the root dentry of the superblock (which is now a
dummy).

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>