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Commit d73d5046 authored by Tao Ma's avatar Tao Ma Committed by Theodore Ts'o
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ext4: Use correct locking for ext4_end_io_nolock() 



We must hold i_completed_io_lock when manipulating anything on the
i_completed_io_list linked list.  This includes io->lock, which we
were checking in ext4_end_io_nolock().

So move this check to ext4_end_io_work().  This also has the bonus of
avoiding extra work if it is already done without needing to take the
mutex.

Signed-off-by: default avatarTao Ma <boyu.mt@taobao.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 6d6a4351

fs/ext4/fsync.c

+0 −3
Original line number Diff line number Diff line
@@ -83,9 +83,6 @@ int ext4_flush_completed_IO(struct inode *inode) 
	int ret = 0;

	int ret2 = 0;



	if (list_empty(&ei->i_completed_io_list))

		return ret;



	dump_completed_IO(inode);

	spin_lock_irqsave(&ei->i_completed_io_lock, flags);

	while (!list_empty(&ei->i_completed_io_list)){

fs/ext4/page-io.c

+11 −3
Original line number Diff line number Diff line
@@ -87,6 +87,9 @@ void ext4_free_io_end(ext4_io_end_t *io) 


/*

 * check a range of space and convert unwritten extents to written.

 *

 * Called with inode->i_mutex; we depend on this when we manipulate

 * io->flag, since we could otherwise race with ext4_flush_completed_IO()

 */

int ext4_end_io_nolock(ext4_io_end_t *io)

{
@@ -100,9 +103,6 @@ int ext4_end_io_nolock(ext4_io_end_t *io) 
		   "list->prev 0x%p\n",

		   io, inode->i_ino, io->list.next, io->list.prev);



	if (list_empty(&io->list))

		return ret;



	if (!(io->flag & EXT4_IO_END_UNWRITTEN))

		return ret;
@@ -142,6 +142,13 @@ static void ext4_end_io_work(struct work_struct *work) 
	unsigned long		flags;

	int			ret;



	spin_lock_irqsave(&ei->i_completed_io_lock, flags);

	if (list_empty(&io->list)) {

		spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);

		goto free;

	}

	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);



	if (!mutex_trylock(&inode->i_mutex)) {

		/*

		 * Requeue the work instead of waiting so that the work
@@ -170,6 +177,7 @@ static void ext4_end_io_work(struct work_struct *work) 
		list_del_init(&io->list);

	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);

	mutex_unlock(&inode->i_mutex);

free:

	ext4_free_io_end(io);

}