Btrfs: check to see if the inode is in the log before fsyncing

We have this check down in the actual logging code, but this is after we
start a transaction and all that good stuff.  So move the helper
inode_in_log() out so we can call it in fsync() and avoid starting a
transaction altogether and just exit if we've already fsync()'ed this file
recently.  You would notice this issue if you fsync()'ed a file over and
over again until the transaction committed.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 2e63cdc..876cddd 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1552,7 +1552,8 @@
 	 * syncing
 	 */
 	smp_mb();
-	if (BTRFS_I(inode)->last_trans <=
+	if (btrfs_inode_in_log(inode, root->fs_info->generation) ||
+	    BTRFS_I(inode)->last_trans <=
 	    root->fs_info->last_trans_committed) {
 		BTRFS_I(inode)->last_trans = 0;
 		mutex_unlock(&inode->i_mutex);