writeback: Fix lock imbalance in writeback_sb_inodes()

Fix bug introduced by 169ebd9. We have to have wb_list_lock locked when restarting writeback loop after having waited for inode writeback. Bug description by Ted Tso: I can reproduce this fairly easily by using ext4 w/o a journal, running under KVM with 1024megs memory, with fsstress (xfstests #13): [ 45.153294] ===================================== [ 45.154784] [ BUG: bad unlock balance detected! ] [ 45.155591] 3.5.0-rc1-00002-gb22b1f1 #124 Not tainted [ 45.155591] ------------------------------------- [ 45.155591] flush-254:16/2499 is trying to release lock (&(&wb->list_lock)->rlock) at: [ 45.155591] [<c022c3da>] writeback_sb_inodes+0x160/0x327 [ 45.155591] but there are no more locks to release! Reported-by: Theodore Ts'o <[email protected]> Tested-by: Theodore Ts'o <[email protected]> Signed-off-by: Jan Kara <[email protected]> Signed-off-by: Fengguang Wu <[email protected]>
raspberrypi · Jun 8, 2012 · ead188f · ead188f
1 parent f8f5701
commit ead188f
Showing 1 changed file with 1 addition and 0 deletions.
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
@@ -664,6 +664,7 @@ static long writeback_sb_inodes(struct super_block *sb,
 			/* Wait for I_SYNC. This function drops i_lock... */
 			inode_sleep_on_writeback(inode);
 			/* Inode may be gone, start again */
+			spin_lock(&wb->list_lock);
 			continue;
 		}
 		inode->i_state |= I_SYNC;