From: Adrian Hunter <ext-adrian.hunter@nokia.com>
Date: Fri, 12 Sep 2008 09:27:47 +0000 (+0300)
Subject: UBIFS: TNC / GC race fixes
X-Git-Tag: v2.6.27-rc8~17^2~2
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=6dcfac4f13d6b32fbaa60b64a23249999e66af8e;p=linux-2.6-omap-h63xx.git

UBIFS: TNC / GC race fixes

- update GC sequence number if any nodes may have been moved
even if GC did not finish the LEB
- don't ignore error return when reading

Signed-off-by: Adrian Hunter <ext-adrian.hunter@nokia.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
---

diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c
index 13f1019c859..02aba36fe3d 100644
--- a/fs/ubifs/gc.c
+++ b/fs/ubifs/gc.c
@@ -334,15 +334,15 @@ int ubifs_garbage_collect_leb(struct ubifs_info *c, struct ubifs_lprops *lp)
 
 		err = move_nodes(c, sleb);
 		if (err)
-			goto out;
+			goto out_inc_seq;
 
 		err = gc_sync_wbufs(c);
 		if (err)
-			goto out;
+			goto out_inc_seq;
 
 		err = ubifs_change_one_lp(c, lnum, c->leb_size, 0, 0, 0, 0);
 		if (err)
-			goto out;
+			goto out_inc_seq;
 
 		/* Allow for races with TNC */
 		c->gced_lnum = lnum;
@@ -369,6 +369,14 @@ int ubifs_garbage_collect_leb(struct ubifs_info *c, struct ubifs_lprops *lp)
 out:
 	ubifs_scan_destroy(sleb);
 	return err;
+
+out_inc_seq:
+	/* We may have moved at least some nodes so allow for races with TNC */
+	c->gced_lnum = lnum;
+	smp_wmb();
+	c->gc_seq += 1;
+	smp_wmb();
+	goto out;
 }
 
 /**
diff --git a/fs/ubifs/tnc.c b/fs/ubifs/tnc.c
index 7da209ab937..7634c597088 100644
--- a/fs/ubifs/tnc.c
+++ b/fs/ubifs/tnc.c
@@ -1476,7 +1476,7 @@ again:
 	}
 
 	err = fallible_read_node(c, key, &zbr, node);
-	if (maybe_leb_gced(c, zbr.lnum, gc_seq1)) {
+	if (err <= 0 || maybe_leb_gced(c, zbr.lnum, gc_seq1)) {
 		/*
 		 * The node may have been GC'ed out from under us so try again
 		 * while keeping the TNC mutex locked.