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, 2 insertions, 2 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index bc39b18cf3d0..2bbc0e62102f 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -55,13 +55,13 @@ EXPORT_SYMBOL(I_BDEV);
 static void bdev_inode_switch_bdi(struct inode *inode,
                         struct backing_dev_info *dst)
 {
-        spin_lock(&inode_lock);
+        spin_lock(&inode_wb_list_lock);
         spin_lock(&inode->i_lock);
         inode->i_data.backing_dev_info = dst;
         if (inode->i_state & I_DIRTY)
                 list_move(&inode->i_wb_list, &dst->wb.b_dirty);
         spin_unlock(&inode->i_lock);
-        spin_unlock(&inode_lock);
+        spin_unlock(&inode_wb_list_lock);
 }
 
 static sector_t max_block(struct block_device *bdev)