The reiser4-patch for 2.6.18 (also included in the mm-tree) contains some
changes to sync_sb_inodes, which produces a deadlock on SMP-configured
kernels.
diff -urN linux-2.6.18.orig/fs/fs-writeback.c linux-2.6.18/fs/fs-writeback.c
--- linux-2.6.18.orig/fs/fs-writeback.c 2006-11-20 00:43:20.178243289 +0300
+++ linux-2.6.18/fs/fs-writeback.c 2006-11-19 17:36:10.394665097 +0300
@@ -286,8 +286,6 @@
* WB_SYNC_HOLD is a hack for sys_sync(): reattach the inode to sb->s_dirty
so
* that it can be located for waiting on in __writeback_single_inode().
*
- * Called under inode_lock.
- *
* If `bdi' is non-zero then we're being asked to writeback a specific queue.
* This function assumes that the blockdev superblock's inodes are backed by
* a variety of queues, so all inodes are searched. For other superblocks,
@@ -303,11 +301,13 @@
* on the writer throttling path, and we get decent balancing between many
* throttled threads: we don't want them all piling up on __wait_on_inode.
*/
-static void
-sync_sb_inodes(struct super_block *sb, struct writeback_control *wbc)
+void
+generic_sync_sb_inodes(struct super_block *sb, struct writeback_control *wbc)
{
const unsigned long start = jiffies; /* livelock avoidance */
+ spin_lock(&inode_lock);
+
if (!wbc->for_kupdate || list_empty(&sb->s_io))
list_splice_init(&sb->s_dirty, &sb->s_io);
@@ -387,8 +387,19 @@
if (wbc->nr_to_write <= 0)
break;
}
+ spin_unlock(&inode_lock);
return; /* Leave any unwritten inodes on s_io */
}
+EXPORT_SYMBOL(generic_sync_sb_inodes);
+
+static void
+sync_sb_inodes(struct super_block *sb, struct writeback_control *wbc)
+{
+ if (sb->s_op->sync_inodes)
+ sb->s_op->sync_inodes(sb, wbc);
+ else
+ generic_sync_sb_inodes(sb, wbc);
+}
The spinlock, which is introduced here, is already held by sync_inodes_sb,
which themselve call sync_sb_inodes, the system hangs here.
