---

yaml
---
r: 98849
b: refs/heads/master
c: 49641f1
h: refs/heads/master
i:
  98847: dd3a509
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 61ca9daa2ca3022dc9cb22bd98e69c1b61e412ad
+refs/heads/master: 49641f1acfdfd437ed9b0a70b86bf36626c02afe

trunk/fs/xfs/xfs_log.c

@@ -2427,13 +2427,20 @@ xlog_state_get_iclog_space(xlog_t	  *log,
 	if (iclog->ic_size - iclog->ic_offset < 2*sizeof(xlog_op_header_t)) {
 		xlog_state_switch_iclogs(log, iclog, iclog->ic_size);
 
-		/* If I'm the only one writing to this iclog, sync it to disk */
-		if (atomic_read(&iclog->ic_refcnt) == 1) {
+		/*
+		 * If I'm the only one writing to this iclog, sync it to disk.
+		 * We need to do an atomic compare and decrement here to avoid
+		 * racing with concurrent atomic_dec_and_lock() calls in
+		 * xlog_state_release_iclog() when there is more than one
+		 * reference to the iclog.
+		 */
+		if (!atomic_add_unless(&iclog->ic_refcnt, -1, 1)) {
+			/* we are the only one */
 			spin_unlock(&log->l_icloglock);
-			if ((error = xlog_state_release_iclog(log, iclog)))
+			error = xlog_state_release_iclog(log, iclog);
+			if (error)
 				return error;
 		} else {
-			atomic_dec(&iclog->ic_refcnt);
 			spin_unlock(&log->l_icloglock);
 		}
 		goto restart;