fs: skip I_FREEING inodes in writeback_sb_inodes

Skip I_FREEING inodes just like I_WILL_FREE and I_NEW when walking the
writeback lists.  Currenly this can't happen, but once we move from
inode_lock to more fine grained locking we can have an inode that's
still on the writeback lists but has I_FREEING set, and we absolutely
need to skip it here, just like we do for all other inode list walks.

Based on a patch from Dave Chinner.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 7 insertions, 2 deletions

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 7a24cc957f05..f6af81add459 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -487,10 +487,16 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
                         return 0;
                 }
 
-                if (inode->i_state & (I_NEW | I_WILL_FREE)) {
+                /*
+                 * Don't bother with new inodes or inodes beeing freed, first
+                 * kind does not need peridic writeout yet, and for the latter
+                 * kind writeout is handled by the freer.
+                 */
+                if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
                         requeue_io(inode);
                         continue;
                 }
+
                 /*
                  * Was this inode dirtied after sync_sb_inodes was called?
                  * This keeps sync from extra jobs and livelock.
@@ -498,7 +504,6 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
                 if (inode_dirtied_after(inode, wbc->wb_start))
                         return 1;
 
-                BUG_ON(inode->i_state & I_FREEING);
                 __iget(inode);
                 pages_skipped = wbc->pages_skipped;
                 writeback_single_inode(inode, wbc);