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Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

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Pull vfs fixes from Al Viro:
 "A couple of fixes; one for automount/lazy umount race, another a
  classic "we don't protect the refcount transition to zero with the
  lock that protects looking for object in hash" kind of crap in lockd."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  close the race in nlmsvc_free_block()
  do_add_mount()/umount -l races
This commit is contained in:
Linus Torvalds 2012-09-28 10:02:53 -07:00
commit 7596824e66
2 changed files with 9 additions and 4 deletions
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3
fs/lockd/svclock.c
View File

@ -289,7 +289,6 @@ static void nlmsvc_free_block(struct kref *kref)
dprintk("lockd: freeing block %p...\n", block);
/* Remove block from file's list of blocks */
mutex_lock(&file->f_mutex);
list_del_init(&block->b_flist);
mutex_unlock(&file->f_mutex);
@ -303,7 +302,7 @@ static void nlmsvc_free_block(struct kref *kref)
static void nlmsvc_release_block(struct nlm_block *block)
{
if (block != NULL)
kref_put(&block->b_count, nlmsvc_free_block);
kref_put_mutex(&block->b_count, nlmsvc_free_block, &block->b_file->f_mutex);
}
/*

10
fs/namespace.c
View File

@ -1886,8 +1886,14 @@ static int do_add_mount(struct mount *newmnt, struct path *path, int mnt_flags)
return err;
err = -EINVAL;
if (!(mnt_flags & MNT_SHRINKABLE) && !check_mnt(real_mount(path->mnt)))
goto unlock;
if (unlikely(!check_mnt(real_mount(path->mnt)))) {
/* that's acceptable only for automounts done in private ns */
if (!(mnt_flags & MNT_SHRINKABLE))
goto unlock;
/* ... and for those we'd better have mountpoint still alive */
if (!real_mount(path->mnt)->mnt_ns)
goto unlock;
}
/* Refuse the same filesystem on the same mount point */
err = -EBUSY;