fs: move i_wb_list out from under inode_lock

Protect the inode writeback list with a new global lock
inode_wb_list_lock and use it to protect the list manipulations and
traversals. This lock replaces the inode_lock as the inodes on the
list can be validity checked while holding the inode->i_lock and
hence the inode_lock is no longer needed to protect the list.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 4 insertions, 4 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index 499e9aa91450..d8b34d1a1071 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -80,8 +80,8 @@
  *  ->i_mutex
  *    ->i_alloc_sem             (various)
  *
- *  ->inode_lock
- *    ->sb_lock                 (fs/fs-writeback.c)
+ *  inode_wb_list_lock
+ *    sb_lock                   (fs/fs-writeback.c)
  *    ->mapping->tree_lock      (__sync_single_inode)
  *
  *  ->i_mmap_lock
@@ -98,9 +98,9 @@
  *    ->zone.lru_lock           (check_pte_range->isolate_lru_page)
  *    ->private_lock            (page_remove_rmap->set_page_dirty)
  *    ->tree_lock               (page_remove_rmap->set_page_dirty)
- *    ->inode_lock              (page_remove_rmap->set_page_dirty)
+ *    inode_wb_list_lock        (page_remove_rmap->set_page_dirty)
  *    ->inode->i_lock           (page_remove_rmap->set_page_dirty)
- *    ->inode_lock              (zap_pte_range->set_page_dirty)
+ *    inode_wb_list_lock        (zap_pte_range->set_page_dirty)
  *    ->inode->i_lock           (zap_pte_range->set_page_dirty)
  *    ->private_lock            (zap_pte_range->__set_page_dirty_buffers)
  *