From: David Sterba <dsterba@suse.cz>
Date: Fri, 28 Mar 2014 16:38:48 +0000 (+0100)
Subject: btrfs: do commit in sync_fs if there are pending changes
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=6b5fe46dfa52;p=linux-beck.git

btrfs: do commit in sync_fs if there are pending changes

If a pending change is requested, it's not processed unless there is a
transaction commit about to happen, not even after sync or SYNC_FS
ioctl. For example a remount that toggles the inode_cache option will
not take effect after sync on a quiescent filesystem.

Signed-off-by: David Sterba <dsterba@suse.cz>
---

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 54bd91ece35b..1da16d59e115 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -993,9 +993,17 @@ int btrfs_sync_fs(struct super_block *sb, int wait)
 	trans = btrfs_attach_transaction_barrier(root);
 	if (IS_ERR(trans)) {
 		/* no transaction, don't bother */
-		if (PTR_ERR(trans) == -ENOENT)
-			return 0;
-		return PTR_ERR(trans);
+		if (PTR_ERR(trans) == -ENOENT) {
+			/*
+			 * Exit unless we have some pending changes
+			 * that need to go through commit
+			 */
+			if (fs_info->pending_changes == 0)
+				return 0;
+			trans = btrfs_start_transaction(root, 0);
+		} else {
+			return PTR_ERR(trans);
+		}
 	}
 	return btrfs_commit_transaction(trans, root);
 }