Commit 9b4a9b28 authored Aug 18, 2017 by Liu Bo Committed by David Sterba Oct 30, 2017

Btrfs: do not async submit for nodatasum inodes



While we submit direct writes, if the inode is flagged with nodatasum,
there's no benefit to submit asynchronously, because

a) we don't have to calculate checksum across processors,

b) and direct IO has started a plug, but async submit makes us queue
IO on each device's scheduled IO list instead of DIO's plug list, so
that IOs get much less merges in general.

Lets use sync submit for nodatasum inodes.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

parent 9cd3a7eb

fs/btrfs/inode.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -8577,7 +8577,7 @@ __btrfs_submit_dio_bio(struct bio bio, struct inode inode, u64 file_offset,
		goto err;
		}
		map:
		ret = btrfs_map_bio(fs_info, bio, 0, async_submit);
		ret = btrfs_map_bio(fs_info, bio, 0, 0);
		err:
		bio_put(bio);
		return ret;

Admin message