[PATCH 13/13] btrfs: add tracing for failed reservations

[Jeff Mahoney <jeffm@suse.com>]

When debugging ENOSPC issues, it's nice to be able to see which
reservations failed as well as the ones which succeeded.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
---
 fs/btrfs/extent-tree.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/fs/btrfs/extent-tree.c	2013-11-03 16:53:15.466324826 -0500
+++ b/fs/btrfs/extent-tree.c	2013-11-03 16:53:15.550323570 -0500
@@ -3709,6 +3709,9 @@ commit_trans:
 			goto again;
 		}
 
+		trace_btrfs_space_reservation(root->fs_info,
+					      "space_info:enospc",
+					      data_sinfo->flags, bytes, 1);
 		return -ENOSPC;
 	}
 	data_sinfo->bytes_may_use += bytes;
@@ -4360,6 +4363,10 @@ out:
 		    !block_rsv_use_bytes(global_rsv, orig_bytes))
 			ret = 0;
 	}
+	if (ret == -ENOSPC)
+		trace_btrfs_space_reservation(root->fs_info,
+					      "space_info:enospc",
+					      space_info->flags, orig_bytes, 1);
 	if (flushing) {
 		spin_lock(&space_info->lock);
 		space_info->flush = 0;