Patch "Btrfs: fix unexpected return value of fiemap" has been added to the 4.5-stable tree

This is a note to let you know that I've just added the patch titled

Btrfs: fix unexpected return value of fiemap

to the 4.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
btrfs-fix-unexpected-return-value-of-fiemap.patch
and it can be found in the queue-4.5 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Liu Bo <[email protected]>
Date: Tue, 17 May 2016 17:21:48 -0700
Subject: Btrfs: fix unexpected return value of fiemap

From: Liu Bo <[email protected]>

commit 2d324f59f343967a03eeb2690f0ff178304d0687 upstream.

btrfs's fiemap is supposed to return 0 on success and return < 0 on error. however, ret becomes 1 after looking up the last file extent:

btrfs_lookup_file_extent ->

    btrfs_search_slot(..., ins_len=0, cow=0)

and if the offset is beyond EOF, we'll get 'path' pointed to the place of potentail insertion, and ret == 1.

This may confuse applications using ioctl(FIEL_IOC_FIEMAP).

---
 fs/btrfs/extent_io.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

@@ -4385,8 +4385,12 @@ int extent_fiemap(struct inode *inode, s
 	if (ret < 0) {
 		btrfs_free_path(path);
 		return ret;
+	} else {
+		WARN_ON(!ret);
+		if (ret == 1)
+			ret = 0;
 	}
-	WARN_ON(!ret);
+
 	path->slots[0]--;
 	btrfs_item_key_to_cpu(path->nodes[0], &found_key, path->slots[0]);
 	found_type = found_key.type;

Patches currently in stable-queue which might be from [email protected] are

queue-4.5/btrfs-fix-unexpected-return-value-of-fiemap.patch queue-4.5/btrfs-do-not-create-empty-block-group-if-we-have-allocated-data.patch queue-4.5/btrfs-fix-divide-error-upon-chunk-s-stripe_len.patch