[PATCH v2 1/3] 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.
We can use this copy also in the sync case and get rid of the parameter.

Signed-off-by: Daniel Vacek <neelx@suse.com>
---

v2: Use the bbio::csum_saved_iter in both cases and simplify even further.
---
 fs/btrfs/file-item.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 581ca5653be9..4a7681557ec1 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -797,18 +797,17 @@ 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 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;
+	struct bvec_iter *iter = &bbio->csum_saved_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;
 	}
@@ -820,7 +819,7 @@ static void csum_one_bio_work(struct work_struct *work)
 
 	ASSERT(btrfs_op(&bbio->bio) == BTRFS_MAP_WRITE);
 	ASSERT(bbio->async_csum == true);
-	csum_one_bio(bbio, &bbio->csum_saved_iter);
+	csum_one_bio(bbio);
 	complete(&bbio->csum_done);
 }
 
@@ -850,13 +849,13 @@ int btrfs_csum_one_bio(struct btrfs_bio *bbio, bool async)
 	bbio->sums = sums;
 	btrfs_add_ordered_sum(ordered, sums);
 
+	bbio->csum_saved_iter = bio->bi_iter;
 	if (!async) {
-		csum_one_bio(bbio, &bbio->bio.bi_iter);
+		csum_one_bio(bbio);
 		return 0;
 	}
 	init_completion(&bbio->csum_done);
 	bbio->async_csum = true;
-	bbio->csum_saved_iter = bbio->bio.bi_iter;
 	INIT_WORK(&bbio->csum_work, csum_one_bio_work);
 	schedule_work(&bbio->csum_work);
 	return 0;
-- 
2.53.0