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| author | Ian Kent <raven@themaw.net> | 2012-12-14 10:23:29 +0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-12-13 19:13:25 -0800 |
| commit | 0259cb02c4004d3088b0999799f8f5c8801f6b97 (patch) | |
| tree | b93489768a12a36fbb2ec33d1e04742f84238d9e | |
| parent | f55fb0c24386cee8b78f60d60186716bd0909493 (diff) | |
| download | lwn-0259cb02c4004d3088b0999799f8f5c8801f6b97.tar.gz lwn-0259cb02c4004d3088b0999799f8f5c8801f6b97.zip | |
autofs4 - use simple_empty() for empty directory check
For direct (and offset) mounts, if an automounted mount is manually
umounted the trigger mount dentry can appear non-empty causing it to
not trigger mounts. This can also happen if there is a file handle
leak in a user space automounting application.
This happens because, when a ioctl control file handle is opened
on the mount, a cursor dentry is created which causes list_empty()
to see the dentry as non-empty. Since there is a case where listing
the directory of these dentrys is needed, the use of dcache_dir_*()
functions for .open() and .release() is needed.
Consequently simple_empty() must be used instead of list_empty()
when checking for an empty directory.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/autofs4/root.c | 22 |
1 files changed, 5 insertions, 17 deletions
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c index 30a6ab66e99a..c93447604da8 100644 --- a/fs/autofs4/root.c +++ b/fs/autofs4/root.c @@ -124,13 +124,10 @@ static int autofs4_dir_open(struct inode *inode, struct file *file) * it. */ spin_lock(&sbi->lookup_lock); - spin_lock(&dentry->d_lock); - if (!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) { - spin_unlock(&dentry->d_lock); + if (!d_mountpoint(dentry) && simple_empty(dentry)) { spin_unlock(&sbi->lookup_lock); return -ENOENT; } - spin_unlock(&dentry->d_lock); spin_unlock(&sbi->lookup_lock); out: @@ -386,12 +383,8 @@ static struct vfsmount *autofs4_d_automount(struct path *path) goto done; } } else { - spin_lock(&dentry->d_lock); - if (!list_empty(&dentry->d_subdirs)) { - spin_unlock(&dentry->d_lock); + if (!simple_empty(dentry)) goto done; - } - spin_unlock(&dentry->d_lock); } ino->flags |= AUTOFS_INF_PENDING; spin_unlock(&sbi->fs_lock); @@ -610,9 +603,7 @@ static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry) spin_lock(&sbi->lookup_lock); __autofs4_add_expiring(dentry); - spin_lock(&dentry->d_lock); - __d_drop(dentry); - spin_unlock(&dentry->d_lock); + d_drop(dentry); spin_unlock(&sbi->lookup_lock); return 0; @@ -683,15 +674,12 @@ static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry) return -EACCES; spin_lock(&sbi->lookup_lock); - spin_lock(&dentry->d_lock); - if (!list_empty(&dentry->d_subdirs)) { - spin_unlock(&dentry->d_lock); + if (!simple_empty(dentry)) { spin_unlock(&sbi->lookup_lock); return -ENOTEMPTY; } __autofs4_add_expiring(dentry); - __d_drop(dentry); - spin_unlock(&dentry->d_lock); + d_drop(dentry); spin_unlock(&sbi->lookup_lock); if (sbi->version < 5) |