ext4: simplify list handling in ext4_do_flush_completed_IO()

The function splices i_completed_io_list to its private list
first.  From that moment on we don't need any lock for working with
io_end structures because all io_end structure on the list are only
our own. So we can remove the other two lists in the function and free
io_end immediately after we are done with it.

CC: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 1 insertions, 17 deletions

diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index a0290176ee75..3fb385cd9670 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -160,14 +160,11 @@ void ext4_add_complete_io(ext4_io_end_t *io_end)
 static int ext4_do_flush_completed_IO(struct inode *inode)
 {
         ext4_io_end_t *io;
-        struct list_head unwritten, complete, to_free;
+        struct list_head unwritten;
         unsigned long flags;
         struct ext4_inode_info *ei = EXT4_I(inode);
         int err, ret = 0;
 
-        INIT_LIST_HEAD(&complete);
-        INIT_LIST_HEAD(&to_free);
-
         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
         dump_completed_IO(inode);
         list_replace_init(&ei->i_completed_io_list, &unwritten);
@@ -181,20 +178,7 @@ static int ext4_do_flush_completed_IO(struct inode *inode)
                 err = ext4_end_io(io);
                 if (unlikely(!ret && err))
                         ret = err;
-
-                list_add_tail(&io->list, &complete);
-        }
-        spin_lock_irqsave(&ei->i_completed_io_lock, flags);
-        while (!list_empty(&complete)) {
-                io = list_entry(complete.next, ext4_io_end_t, list);
                 io->flag &= ~EXT4_IO_END_UNWRITTEN;
-                list_move(&io->list, &to_free);
-        }
-        spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
-
-        while (!list_empty(&to_free)) {
-                io = list_entry(to_free.next, ext4_io_end_t, list);
-                list_del_init(&io->list);
                 ext4_free_io_end(io);
         }
         return ret;