[3.16.y-ckt stable] Patch "btrfs: incorrect handling for fiemap_fill_next_extent return" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    btrfs: incorrect handling for fiemap_fill_next_extent return

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt14.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 9ee6babbfc946f41f14cdec00921d9ea77330785 Mon Sep 17 00:00:00 2001
From: Chengyu Song <csong84 at gatech.edu>
Date: Tue, 24 Mar 2015 18:12:56 -0400
Subject: btrfs: incorrect handling for fiemap_fill_next_extent return

commit 26e726afe01c1c82072cf23a5ed89ce25f39d9f2 upstream.

fiemap_fill_next_extent returns 0 on success, -errno on error, 1 if this was
the last extent that will fit in user array. If 1 is returned, the return
value may eventually returned to user space, which should not happen, according
to manpage of ioctl.

Signed-off-by: Chengyu Song <csong84 at gatech.edu>
Reviewed-by: David Sterba <dsterba at suse.cz>
Reviewed-by: Liu Bo <bo.li.liu at oracle.com>
Signed-off-by: Chris Mason <clm at fb.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 fs/btrfs/extent_io.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 09b4e3165e2c..a7db105139d2 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4359,8 +4359,11 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		}
 		ret = fiemap_fill_next_extent(fieinfo, em_start, disko,
 					      em_len, flags);
-		if (ret)
+		if (ret) {
+			if (ret == 1)
+				ret = 0;
 			goto out_free;
+		}
 	}
 out_free:
 	free_extent_map(em);