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  1. 23 6月, 2006 7 次提交
    • D
      [PATCH] VFS: Permit filesystem to perform statfs with a known root dentry · 726c3342
      由 David Howells 提交于 
      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: NDavid Howells <dhowells@redhat.com>
Acked-by: NAl Viro <viro@zeniv.linux.org.uk>
Cc: Nathan Scott <nathans@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      726c3342
    • D
      [PATCH] VFS: Permit filesystem to override root dentry on mount · 454e2398
      由 David Howells 提交于 
      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: NDavid Howells <dhowells@redhat.com>
Acked-by: NAl Viro <viro@zeniv.linux.org.uk>
Cc: Nathan Scott <nathans@sgi.com>
Cc: Roland Dreier <rolandd@cisco.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      454e2398
    • A
      [PATCH] prune_one_dentry() tweaks · d702ccb3
      由 Andrew Morton 提交于 
      - Add description of d_lock handling to comments over prune_one_dentry().

- It has three callsites - uninline it, saving 200 bytes of text.

Cc: Jan Blunck <jblunck@suse.de>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: Olaf Hering <olh@suse.de>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      d702ccb3
    • N
      [PATCH] Fix dcache race during umount · 0feae5c4
      由 NeilBrown 提交于 
      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 <jblunck@suse.de>
Acked-by: NKirill Korotaev <dev@openvz.org>
Cc: Olaf Hering <olh@suse.de>
Acked-by: NBalbir Singh <balbir@in.ibm.com>
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NBalbir Singh <balbir@in.ibm.com>
Acked-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      0feae5c4
    • M
      [PATCH] remove steal_locks() · c89681ed
      由 Miklos Szeredi 提交于 
      This patch removes the steal_locks() function.

steal_locks() doesn't work correctly with any filesystem that does it's own
lock management, including NFS, CIFS, etc.

In addition it has weird semantics on local filesystems in case tasks
sharing file-descriptor tables are doing POSIX locking operations in
parallel to execve().

The steal_locks() function has an effect on applications doing:

clone(CLONE_FILES)
  /* in child */
  lock
  execve
  lock

POSIX locks acquired before execve (by "child", "parent" or any further
task sharing files_struct) will after the execve be owned exclusively by
"child".

According to Chris Wright some LSB/LTP kind of suite triggers without the
stealing behavior, but there's no known real-world application that would
also fail.

Apps using NPTL are not affected, since all other threads are killed before
execve.

Apps using LinuxThreads are only affected if they

  - have multiple threads during exec (LinuxThreads doesn't kill other
    threads, the app may do it with pthread_kill_other_threads_np())
  - rely on POSIX locks being inherited across exec

Both conditions are documented, but not their interaction.

Apps using clone() natively are affected if they

  - use clone(CLONE_FILES)
  - rely on POSIX locks being inherited across exec

The above scenarios are unlikely, but possible.

If the patch is vetoed, there's a plan B, that involves mostly keeping the
weird stealing semantics, but changing the way lock ownership is handled so
that network and local filesystems work consistently.

That would add more complexity though, so this solution seems to be
preferred by most people.
Signed-off-by: NMiklos Szeredi <miklos@szeredi.hu>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Matthew Wilcox <willy@debian.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Steven French <sfrench@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      c89681ed
    • O
      [PATCH] Fix a race condition between ->i_mapping and iput() · 09d967c6
      由 OGAWA Hirofumi 提交于 
      This race became a cause of oops, and can reproduce by the following.

    while true; do
	dd if=/dev/zero of=/dev/.static/dev/hdg1 bs=512 count=1000 & sync
    done

This race condition was between __sync_single_inode() and iput().

          cpu0 (fs's inode)                 cpu1 (bdev's inode)
          -----------------                 -------------------
                                       close("/dev/hda2")
                                       [...]
__sync_single_inode()
   /* copy the bdev's ->i_mapping */
   mapping = inode->i_mapping;

                                       generic_forget_inode()
                                          bdev_clear_inode()
					     /* restre the fs's ->i_mapping */
				             inode->i_mapping = &inode->i_data;
				          /* bdev's inode was freed */
                                          destroy_inode(inode);

   if (wait) {
      /* dereference a freed bdev's mapping->host */
      filemap_fdatawait(mapping);  /* Oops */

Since __sync_single_inode() is only taking a ref-count of fs's inode, the
another process can be close() and freeing the bdev's inode while writing
fs's inode.  So, __sync_signle_inode() accesses the freed ->i_mapping,
oops.

This patch takes a ref-count on the bdev's inode for the fs's inode before
setting a ->i_mapping, and the clear_inode() of the fs's inode does iput() on
the bdev's inode.  So if the fs's inode is still living, bdev's inode
shouldn't be freed.
Signed-off-by: NOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      09d967c6
    • A
      [PATCH] NTFS: Critical bug fix (affects MIPS and possibly others) · f893afbe
      由 Anton Altaparmakov 提交于 
      Many thanks to Pauline Ng for the detailed bug report and analysis!
Signed-off-by: NAnton Altaparmakov <aia21@cantab.net>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      f893afbe
  3. 22 6月, 2006 1 次提交
  5. 20 6月, 2006 11 次提交
  7. 19 6月, 2006 7 次提交
  9. 18 6月, 2006 3 次提交
  11. 14 6月, 2006 1 次提交
  13. 13 6月, 2006 1 次提交
  15. 09 6月, 2006 9 次提交