[3.13.y-ckt stable] Patch "Btrfs: make sure we wait on logged extents when fsycning two subvols" has been added to staging queue

[Kamal Mostafa]

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

    Btrfs: make sure we wait on logged extents when fsycning two subvols

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt15.

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

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 7060deeced7b0a8f41d4dd2bd4c34ebd5c991aa9 Mon Sep 17 00:00:00 2001
From: Josef Bacik <jbacik at fb.com>
Date: Thu, 6 Nov 2014 10:19:54 -0500
Subject: Btrfs: make sure we wait on logged extents when fsycning two subvols

commit 9dba8cf128ef98257ca719722280c9634e7e9dc7 upstream.

If we have two fsync()'s race on different subvols one will do all of its work
to get into the log_tree, wait on it's outstanding IO, and then allow the
log_tree to finish it's commit.  The problem is we were just free'ing that
subvols logged extents instead of waiting on them, so whoever lost the race
wouldn't really have their data on disk.  Fix this by waiting properly instead
of freeing the logged extents.  Thanks,

Signed-off-by: Josef Bacik <jbacik at fb.com>
Signed-off-by: Chris Mason <clm at fb.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 fs/btrfs/tree-log.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 9f7fc51..51c038d 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2526,9 +2526,9 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
 	if (atomic_read(&log_root_tree->log_commit[index2])) {
 		blk_finish_plug(&plug);
 		btrfs_wait_marked_extents(log, &log->dirty_log_pages, mark);
+		btrfs_wait_logged_extents(log, log_transid);
 		wait_log_commit(trans, log_root_tree,
 				log_root_tree->log_transid);
-		btrfs_free_logged_extents(log, log_transid);
 		mutex_unlock(&log_root_tree->log_mutex);
 		ret = 0;
 		goto out;
--
1.9.1