Patch "btrfs: fix error handling when run_delayed_extent_op fails" has been added to the 4.4-stable tree

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

btrfs: fix error handling when run_delayed_extent_op fails

to the 4.4-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-error-handling-when-run_delayed_extent_op-fails.patch
and it can be found in the queue-4.4 subdirectory.

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

From: Jeff Mahoney <[email protected]>
Date: Tue, 20 Dec 2016 13:28:27 -0500
Subject: btrfs: fix error handling when run_delayed_extent_op fails

From: Jeff Mahoney <[email protected]>

commit aa7c8da35d1905d80e840d075f07d26ec90144b5 upstream.

In __btrfs_run_delayed_refs, the error path when run_delayed_extent_op fails sets locked_ref->processing = 0 but doesn't re-increment delayed_refs->num_heads_ready. As a result, we end up triggering the WARN_ON in btrfs_select_ref_head.

---
 fs/btrfs/extent-tree.c |    3 +++
 1 file changed, 3 insertions(+)

@@ -2570,7 +2570,10 @@ static noinline int __btrfs_run_delayed_
 					 */
 					if (must_insert_reserved)
 						locked_ref->must_insert_reserved = 1;
+					spin_lock(&delayed_refs->lock);
 					locked_ref->processing = 0;
+					delayed_refs->num_heads_ready++;
+					spin_unlock(&delayed_refs->lock);
 					btrfs_debug(fs_info, "run_delayed_extent_op returned %d", ret);
 					btrfs_delayed_ref_unlock(locked_ref);
 					return ret;

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

queue-4.4/btrfs-fix-error-handling-when-run_delayed_extent_op-fails.patch queue-4.4/btrfs-fix-locking-when-we-put-back-a-delayed-ref-that-s-too-new.patch