linux.git/fs/super.c, branch v2.6.18

[PATCH] add missing desctiption in super.c

2006-09-06T18:00:01+00:00

Adds kernel-doc for alloc_super() type in fs/super.c.

Signed-off-by: Henrik Kretzschmar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] lockdep: annotate sb ->s_umount

2006-07-03T22:27:09+00:00

The s_umount rwsem needs to be classified as per-superblock since it's
perfectly legit to keep multiple of those recursively in the VFS locking
rules.

Has no effect on non-lockdep kernels.

Signed-off-by: Arjan van de Ven 
Signed-off-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] lockdep: annotate ->s_lock

2006-07-03T22:27:09+00:00

Teach special (per-filesystem) locking code to the lock validator.

Minimal effect on non-lockdep kernels: one extra parameter to alloc_super().

Signed-off-by: Ingo Molnar 
Signed-off-by: Arjan van de Ven 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Remove obsolete #include

2006-06-30T17:25:36+00:00

Signed-off-by: Jörn Engel 
Signed-off-by: Adrian Bunk

Merge branch 'master' of /home/trondmy/kernel/linux-2.6/

2006-06-24T17:07:53+00:00

Conflicts:

	fs/nfs/inode.c
	fs/super.c

Fix conflicts between patch 'NFS: Split fs/nfs/inode.c' and patch
'VFS: Permit filesystem to override root dentry on mount'

[PATCH] VFS: Permit filesystem to perform statfs with a known root dentry

2006-06-23T14:42:45+00:00

Give the statfs superblock operation a dentry pointer rather than a superblock
pointer.

This complements the get_sb() patch.  That reduced the significance of
sb->s_root, allowing NFS to place a fake root there.  However, NFS does
require a dentry to use as a target for the statfs operation.  This permits
the root in the vfsmount to be used instead.

linux/mount.h has been added where necessary to make allyesconfig build
successfully.

Interest has also been expressed for use with the FUSE and XFS filesystems.

Signed-off-by: David Howells 
Acked-by: Al Viro 
Cc: Nathan Scott 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] VFS: Permit filesystem to override root dentry on mount

2006-06-23T14:42:45+00:00

Extend the get_sb() filesystem operation to take an extra argument that
permits the VFS to pass in the target vfsmount that defines the mountpoint.

The filesystem is then required to manually set the superblock and root dentry
pointers.  For most filesystems, this should be done with simple_set_mnt()
which will set the superblock pointer and then set the root dentry to the
superblock's s_root (as per the old default behaviour).

The get_sb() op now returns an integer as there's now no need to return the
superblock pointer.

This patch permits a superblock to be implicitly shared amongst several mount
points, such as can be done with NFS to avoid potential inode aliasing.  In
such a case, simple_set_mnt() would not be called, and instead the mnt_root
and mnt_sb would be set directly.

The patch also makes the following changes:

 (*) the get_sb_*() convenience functions in the core kernel now take a vfsmount
     pointer argument and return an integer, so most filesystems have to change
     very little.

 (*) If one of the convenience function is not used, then get_sb() should
     normally call simple_set_mnt() to instantiate the vfsmount. This will
     always return 0, and so can be tail-called from get_sb().

 (*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the
     dcache upon superblock destruction rather than shrink_dcache_anon().

     This is required because the superblock may now have multiple trees that
     aren't actually bound to s_root, but that still need to be cleaned up. The
     currently called functions assume that the whole tree is rooted at s_root,
     and that anonymous dentries are not the roots of trees which results in
     dentries being left unculled.

     However, with the way NFS superblock sharing are currently set to be
     implemented, these assumptions are violated: the root of the filesystem is
     simply a dummy dentry and inode (the real inode for '/' may well be
     inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries
     with child trees.

     [*] Anonymous until discovered from another tree.

 (*) The documentation has been adjusted, including the additional bit of
     changing ext2_* into foo_* in the documentation.

[akpm@osdl.org: convert ipath_fs, do other stuff]
Signed-off-by: David Howells 
Acked-by: Al Viro 
Cc: Nathan Scott 
Cc: Roland Dreier 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Fix dcache race during umount

2006-06-22T22:05:57+00:00

The race is that the shrink_dcache_memory shrinker could get called while a
filesystem is being unmounted, and could try to prune a dentry belonging to
that filesystem.

If it does, then it will call in to iput on the inode while the dentry is
no longer able to be found by the umounting process.  If iput takes a
while, generic_shutdown_super could get all the way though
shrink_dcache_parent and shrink_dcache_anon and invalidate_inodes without
ever waiting on this particular inode.

Eventually the superblock gets freed anyway and if the iput tried to touch
it (which some filesystems certainly do), it will lose.  The promised
"Self-destruct in 5 seconds" doesn't lead to a nice day.

The race is closed by holding s_umount while calling prune_one_dentry on
someone else's dentry.  As a down_read_trylock is used,
shrink_dcache_memory will no longer try to prune the dentry of a filesystem
that is being unmounted, and unmount will not be able to start until any
such active prune_one_dentry completes.

This requires that prune_dcache *knows* which filesystem (if any) it is
doing the prune on behalf of so that it can be careful of other
filesystems.  shrink_dcache_memory isn't called it on behalf of any
filesystem, and so is careful of everything.

shrink_dcache_anon is now passed a super_block rather than the s_anon list
out of the superblock, so it can get the s_anon list itself, and can pass
the superblock down to prune_dcache.

If prune_dcache finds a dentry that it cannot free, it leaves it where it
is (at the tail of the list) and exits, on the assumption that some other
thread will be removing that dentry soon.  To try to make sure that some
work gets done, a limited number of dnetries which are untouchable are
skipped over while choosing the dentry to work on.

I believe this race was first found by Kirill Korotaev.

Cc: Jan Blunck 
Acked-by: Kirill Korotaev 
Cc: Olaf Hering 
Acked-by: Balbir Singh 
Signed-off-by: Neil Brown 
Signed-off-by: Balbir Singh 
Acked-by: David Howells 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

VFS: Unexport do_kern_mount() and clean up simple_pin_fs()

2006-06-09T13:34:16+00:00

Replace all module uses with the new vfs_kern_mount() interface, and fix up
simple_pin_fs().

Signed-off-by: Trond Myklebust

VFS: Add GPL_EXPORTED function vfs_kern_mount()

2006-06-09T13:34:15+00:00

do_kern_mount() does not allow the kernel to use private mount interfaces
without exposing the same interfaces to userland. The problem is that the
filesystem is referenced by name, thus meaning that it and its mount
interface must be registered in the global filesystem list.

vfs_kern_mount() passes the struct file_system_type as an explicit
parameter in order to overcome this limitation.

Signed-off-by: Trond Myklebust