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authorIan Kent <raven@themaw.net>2012-12-14 10:23:29 +0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-12-13 19:13:25 -0800
commit0259cb02c4004d3088b0999799f8f5c8801f6b97 (patch)
treeb93489768a12a36fbb2ec33d1e04742f84238d9e
parentf55fb0c24386cee8b78f60d60186716bd0909493 (diff)
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.c22
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)