Messages in this thread Patch in this message | | | From | Ian Kent <> | Subject | [PATCH 2/2] autofs4 - use simple_empty() for empty directory check | Date | Fri, 14 Dec 2012 10:23:29 +0800 |
| |
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> ---
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 30a6ab66..c934476 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)
| |