---

yaml
---
r: 213265
b: refs/heads/master
c: 69b491c
h: refs/heads/master
i:
  213263: b44cf95
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: e3a20c0b02e1704ab115dfa9d012caf0fbc45ed0
+refs/heads/master: 69b491c214d7fd4d4df972ae5377be99ca3753db

trunk/fs/xfs/linux-2.6/xfs_sync.c

@@ -837,15 +837,28 @@ xfs_reclaim_inodes_ag(
 	int			error = 0;
 	int			last_error = 0;
 	xfs_agnumber_t		ag;
+	int			trylock = flags & SYNC_TRYLOCK;
+	int			skipped;
 
+restart:
 	ag = 0;
+	skipped = 0;
 	while ((pag = xfs_perag_get_tag(mp, ag, XFS_ICI_RECLAIM_TAG))) {
 		unsigned long	first_index = 0;
 		int		done = 0;
 		int		nr_found = 0;
 
 		ag = pag->pag_agno + 1;
 
+		if (trylock) {
+			if (!mutex_trylock(&pag->pag_ici_reclaim_lock)) {
+				skipped++;
+				continue;
+			}
+			first_index = pag->pag_ici_reclaim_cursor;
+		} else
+			mutex_lock(&pag->pag_ici_reclaim_lock);
+
 		do {
 			struct xfs_inode *batch[XFS_LOOKUP_BATCH];
 			int	i;
@@ -898,8 +911,25 @@ xfs_reclaim_inodes_ag(
 
 		} while (nr_found && !done && *nr_to_scan > 0);
 
+		if (trylock && !done)
+			pag->pag_ici_reclaim_cursor = first_index;
+		else
+			pag->pag_ici_reclaim_cursor = 0;
+		mutex_unlock(&pag->pag_ici_reclaim_lock);
 		xfs_perag_put(pag);
 	}
+
+	/*
+	 * if we skipped any AG, and we still have scan count remaining, do
+	 * another pass this time using blocking reclaim semantics (i.e
+	 * waiting on the reclaim locks and ignoring the reclaim cursors). This
+	 * ensure that when we get more reclaimers than AGs we block rather
+	 * than spin trying to execute reclaim.
+	 */
+	if (trylock && skipped && *nr_to_scan > 0) {
+		trylock = 0;
+		goto restart;
+	}
 	return XFS_ERROR(last_error);
 }
 

trunk/fs/xfs/xfs_ag.h

@@ -230,6 +230,8 @@ typedef struct xfs_perag {
 	rwlock_t	pag_ici_lock;	/* incore inode lock */
 	struct radix_tree_root pag_ici_root;	/* incore inode cache root */
 	int		pag_ici_reclaimable;	/* reclaimable inodes */
+	struct mutex	pag_ici_reclaim_lock;	/* serialisation point */
+	unsigned long	pag_ici_reclaim_cursor;	/* reclaim restart point */
 
 	/* for rcu-safe freeing */
 	struct rcu_head	rcu_head;

trunk/fs/xfs/xfs_mount.c

@@ -477,6 +477,7 @@ xfs_initialize_perag(
 		pag->pag_agno = index;
 		pag->pag_mount = mp;
 		rwlock_init(&pag->pag_ici_lock);
+		mutex_init(&pag->pag_ici_reclaim_lock);
 		INIT_RADIX_TREE(&pag->pag_ici_root, GFP_ATOMIC);
 
 		if (radix_tree_preload(GFP_NOFS))