fix get_active_super()/umount() race

This one needs restarts... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fix get_active_super()/umount() race
This one needs restarts... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro
1 parent e7fe0585ca
Showing 1 changed file with 7 additions and 7 deletions Side-by-side Diff
fs/super.c
@@ -471,17 +471,17 @@
 	if (!bdev)
 		return NULL;
  
+restart:
 	spin_lock(&sb_lock);
 	list_for_each_entry(sb, &super_blocks, s_list) {
 		if (list_empty(&sb->s_instances))
 			continue;
-		if (sb->s_bdev != bdev)
-			continue;
-
-		if (grab_super(sb)) /* drops sb_lock */
-			return sb;
-
-		spin_lock(&sb_lock);
+		if (sb->s_bdev == bdev) {
+			if (grab_super(sb)) /* drops sb_lock */
+				return sb;
+			else
+				goto restart;
+		}
 	}
 	spin_unlock(&sb_lock);
 	return NULL;
...	...	@@ -471,17 +471,17 @@
471	471	if (!bdev)
472	472	return NULL;
473	473
	474	+restart:
474	475	spin_lock(&sb_lock);
475	476	list_for_each_entry(sb, &super_blocks, s_list) {
476	477	if (list_empty(&sb->s_instances))
477	478	continue;
478		- if (sb->s_bdev != bdev)
479		- continue;
480		-
481		- if (grab_super(sb)) /* drops sb_lock */
482		- return sb;
483		-
484		- spin_lock(&sb_lock);
	479	+ if (sb->s_bdev == bdev) {
	480	+ if (grab_super(sb)) /* drops sb_lock */
	481	+ return sb;
	482	+ else
	483	+ goto restart;
	484	+ }
485	485	}
486	486	spin_unlock(&sb_lock);
487	487	return NULL;