Attachment 647705 Details for Bug 833535 – Patch - use simple_empty() for empty directory check

[patch] Patch - use simple_empty() for empty directory check

autofs4-use-simple_empty-for-empty-directory-check.patch (text/plain), 2.63 KB, created by Ian Kent on 2012-11-19 11:24:03 UTC

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Creator: Ian Kent

Created: 2012-11-19 11:24:03 UTC

Size: 2.63 KB

patch

obsolete

>autofs4 - use simple_empty() for empty directory check
>
>From: Ian Kent <raven@themaw.net>
>
>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.
>
>It happens because, when the 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 2e19f24..837dfb4 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);
>@@ -605,9 +598,7 @@ 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;
>@@ -678,15 +669,12 @@ 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)

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Attachments on bug 833535: 593444 | 609140 | 610823 | 611990 | 625260 | 636456 | 641908 | 647703 | 647705 | 649476 | 672268 | 672270