---

yaml --- r: 131497 b: refs/heads/master c: ada723d h: refs/heads/master i: 131495: 0b62e61 v: v3
git-mirror · Feb 18, 2009 · 0d10c0f · 0d10c0f
1 parent 765fedf
commit 0d10c0f
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Showing 2 changed files with 17 additions and 2 deletions.
diff --git a/[refs] b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 27c0c8e511fa9e2389503926840fac606d90a049
+refs/heads/master: ada723dcd681e2dffd7d73345cc8fda0eb0df9bd
diff --git a/trunk/fs/super.c b/trunk/fs/super.c
@@ -82,7 +82,22 @@ static struct super_block *alloc_super(struct file_system_type *type)
 		 * lock ordering than usbfs:
 		 */
 		lockdep_set_class(&s->s_lock, &type->s_lock_key);
-		down_write(&s->s_umount);
+		/*
+		 * sget() can have s_umount recursion.
+		 *
+		 * When it cannot find a suitable sb, it allocates a new
+		 * one (this one), and tries again to find a suitable old
+		 * one.
+		 *
+		 * In case that succeeds, it will acquire the s_umount
+		 * lock of the old one. Since these are clearly distrinct
+		 * locks, and this object isn't exposed yet, there's no
+		 * risk of deadlocks.
+		 *
+		 * Annotate this by putting this lock in a different
+		 * subclass.
+		 */
+		down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING);
 		s->s_count = S_BIAS;
 		atomic_set(&s->s_active, 1);
 		mutex_init(&s->s_vfs_rename_mutex);