From: Filipe David Borba Manana <fdmanana@gmail.com>
Date: Sat, 11 Jan 2014 21:31:25 +0000 (+0000)
Subject: Btrfs: unlock inodes in correct order in clone ioctl
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=c57c2b3ed248b3f1712e4172eb85b361199582f2;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git

Btrfs: unlock inodes in correct order in clone ioctl

In the clone ioctl, when the source and target inodes are different,
we can acquire their mutexes in 2 possible different orders. After
we're done cloning, we were releasing the mutexes always in the same
order - the most correct way of doing it is to release them by the
reverse order they were acquired.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
---

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 332b624e25db..5ed5bd001084 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3263,9 +3263,17 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
 
 	unlock_extent(&BTRFS_I(src)->io_tree, off, off + len - 1);
 out_unlock:
-	mutex_unlock(&src->i_mutex);
-	if (!same_inode)
-		mutex_unlock(&inode->i_mutex);
+	if (!same_inode) {
+		if (inode < src) {
+			mutex_unlock(&src->i_mutex);
+			mutex_unlock(&inode->i_mutex);
+		} else {
+			mutex_unlock(&inode->i_mutex);
+			mutex_unlock(&src->i_mutex);
+		}
+	} else {
+		mutex_unlock(&src->i_mutex);
+	}
 out_fput:
 	fdput(src_file);
 out_drop_write: