Commit 965f47ae authored by Stefan Roesch's avatar Stefan Roesch Committed by David Sterba
Browse files

btrfs: make btrfs_buffered_write nowait compatible 



We need to avoid unconditionally calling balance_dirty_pages_ratelimited
as it could wait for some reason. Use balance_dirty_pages_ratelimited_flags
with the BDP_ASYNC in case the buffered write is nowait, returning
EAGAIN eventually.

It also moves the function after the again label. This can cause the
function to be called a bit later, but this should have no impact in the
real world.

Reviewed-by: default avatarFilipe Manana <fdmanana@suse.com>
Signed-off-by: default avatarStefan Roesch <shr@fb.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 304e45ac

fs/btrfs/file.c

+5 −2
Original line number Diff line number Diff line
@@ -1653,6 +1653,7 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb, 
	loff_t old_isize = i_size_read(inode);

	unsigned int ilock_flags = 0;

	const bool nowait = (iocb->ki_flags & IOCB_NOWAIT);

	unsigned int bdp_flags = (nowait ? BDP_ASYNC : 0);



	if (nowait)

		ilock_flags |= BTRFS_ILOCK_TRY;
@@ -1755,6 +1756,10 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb, 


		release_bytes = reserve_bytes;

again:

		ret = balance_dirty_pages_ratelimited_flags(inode->i_mapping, bdp_flags);

		if (ret)

			break;



		/*

		 * This is going to setup the pages array with the number of

		 * pages we want, so we don't really need to worry about the
@@ -1858,8 +1863,6 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb, 


		cond_resched();



		balance_dirty_pages_ratelimited(inode->i_mapping);



		pos += copied;

		num_written += copied;

	}