[PATCH 3.16 042/192] Btrfs: skip commit transaction if we don't have enough pinned bytes

[Ben Hutchings]

3.16.49-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Liu Bo <bo.li.liu@xxxxxxxxxx>

commit 28785f70ef882e4798cd5706066a55dbf7adf80e upstream.

We commit transaction in order to reclaim space from pinned bytes because
it could process delayed refs, and in may_commit_transaction(), we check
first if pinned bytes are enough for the required space, we then check if
that plus bytes reserved for delayed insert are enough for the required
space.

This changes the code to the above logic.

Fixes: b150a4f10d87 ("Btrfs: use a percpu to keep track of possibly pinned bytes")
Tested-by: Nikolay Borisov <nborisov@xxxxxxxx>
Reported-by: Nikolay Borisov <nborisov@xxxxxxxx>
Reviewed-by: Nikolay Borisov <nborisov@xxxxxxxx>
Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 fs/btrfs/extent-tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4230,7 +4230,7 @@ static int may_commit_transaction(struct
 
 	spin_lock(&delayed_rsv->lock);
 	if (percpu_counter_compare(&space_info->total_bytes_pinned,
-				   bytes - delayed_rsv->size) >= 0) {
+				   bytes - delayed_rsv->size) < 0) {
 		spin_unlock(&delayed_rsv->lock);
 		return -ENOSPC;
 	}