btrfs: consume given iter directly instead of copying in csum_one_bio()

Avoid copying the iter twice in async case.  We already have a copy
csum_one_bio() can consume directly. No need to copy it again the second
time.  We can use this copy also in the sync case and get rid of the
parameter.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Daniel Vacek <neelx@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 581ca5653be93af866ea78caf6b50802b03993eb..2c6c14dfe39320af6a7c590cb0948bbcd841168b 100644 (file)
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -797,18 +797,18 @@ fail:
        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;
        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 (struct bvec_iter *iter = &bbio->csum_saved_iter;
+            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 +820,7 @@ 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 +850,13 @@ 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;