btrfs: add an ordered_extent pointer to struct btrfs_bio

Add a pointer to the ordered_extent to the existing union in struct
btrfs_bio, so all code dealing with data write bios can just use a
pointer dereference to retrieve the ordered_extent instead of doing
multiple rbtree lookups per I/O.

The reference to this ordered_extent is dropped at end I/O time,
which implies that an extra one must be acquired when the bio is split.
This also requires moving the btrfs_extract_ordered_extent call into
btrfs_split_bio so that the invariant of always having a valid
ordered_extent reference for the btrfs_bio is kept.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 1 insertions, 8 deletions

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 782bbf081c26..cbacaa80526c 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -799,19 +799,12 @@ blk_status_t btrfs_csum_one_bio(struct btrfs_bio *bbio)
  */
 blk_status_t btrfs_alloc_dummy_sum(struct btrfs_bio *bbio)
 {
-	struct btrfs_ordered_extent *ordered =
-		btrfs_lookup_ordered_extent(bbio->inode, bbio->file_offset);
-
-	if (WARN_ON_ONCE(!ordered))
-		return BLK_STS_IOERR;
-
 	bbio->sums = kmalloc(sizeof(*bbio->sums), GFP_NOFS);
 	if (!bbio->sums)
 		return BLK_STS_RESOURCE;
 	bbio->sums->len = bbio->bio.bi_iter.bi_size;
 	bbio->sums->logical = bbio->bio.bi_iter.bi_sector << SECTOR_SHIFT;
-	btrfs_add_ordered_sum(ordered, bbio->sums);
-	btrfs_put_ordered_extent(ordered);
+	btrfs_add_ordered_sum(bbio->ordered, bbio->sums);
 	return 0;
 }