[PATCH 1/2] btrfs: consume the given iter directly instead of copying in csum_one_bio()

[Daniel Vacek <neelx@suse.com>]

This is just a small cleanup to avoid copying the iter twice in async case.
We already have a copy csum_one_bio() can consume directly. No need to copy
again the second time.
In the sync case we can copy in the caller (as we did before dd57c78aec39
("btrfs: introduce btrfs_bio::async_csum")).

Signed-off-by: Daniel Vacek <neelx@suse.com>
---
 fs/btrfs/file-item.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 581ca5653be9..5a5cffb18922 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -797,18 +797,16 @@ int btrfs_lookup_csums_bitmap(struct btrfs_root *root, struct btrfs_path *path,
 	return ret;
 }
 
-static void csum_one_bio(struct btrfs_bio *bbio, struct bvec_iter *src)
+static void csum_one_bio(struct btrfs_bio *bbio, struct bvec_iter *iter)
 {
 	struct btrfs_inode *inode = bbio->inode;
 	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 	struct btrfs_ordered_sum *sums = bbio->sums;
-	struct bvec_iter iter;
 	const u32 blocksize = fs_info->sectorsize;
 	int index = 0;
 
-	for (iter = *src; iter.bi_size; bio_advance_iter(&bbio->bio, &iter, blocksize)) {
-		btrfs_csum_one_bio_block(fs_info, &bbio->bio, &iter,
-					 sums->sums + index);
+	for (; iter->bi_size; bio_advance_iter(&bbio->bio, iter, blocksize)) {
+		btrfs_csum_one_bio_block(fs_info, &bbio->bio, iter, sums->sums + index);
 
 		index += fs_info->csum_size;
 	}
@@ -851,12 +849,14 @@ int btrfs_csum_one_bio(struct btrfs_bio *bbio, bool async)
 	btrfs_add_ordered_sum(ordered, sums);
 
 	if (!async) {
-		csum_one_bio(bbio, &bbio->bio.bi_iter);
+		struct bvec_iter iter = bio->bi_iter;
+
+		csum_one_bio(bbio, &iter);
 		return 0;
 	}
 	init_completion(&bbio->csum_done);
 	bbio->async_csum = true;
-	bbio->csum_saved_iter = bbio->bio.bi_iter;
+	bbio->csum_saved_iter = bio->bi_iter;
 	INIT_WORK(&bbio->csum_work, csum_one_bio_work);
 	schedule_work(&bbio->csum_work);
 	return 0;
-- 
2.53.0