btrfs: get rid of trivial __btrfs_lookup_bio_sums() wrappers

Currently, we have two wrappers for __btrfs_lookup_bio_sums():
btrfs_lookup_bio_sums_dio(), which is used for direct I/O, and
btrfs_lookup_bio_sums(), which is used everywhere else. The only
difference is that the _dio variant looks up csums starting at the given
offset instead of using the page index, which isn't actually direct
I/O-specific. Let's clean up the signature and return value of
__btrfs_lookup_bio_sums(), rename it to btrfs_lookup_bio_sums(), and get
rid of the trivial helpers.

Reviewed-by: Nikolay Borisov <[e-mail]>
Signed-off-by: Omar Sandoval <[e-mail]>
Signed-off-by: David Sterba <[e-mail]>

fs/btrfs/compression.c

···
 
 			if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
 				ret = btrfs_lookup_bio_sums(inode, comp_bio,
-							    sums);
+							    false, 0, sums);
 				BUG_ON(ret); /* -ENOMEM */
 			}
 
···
 	BUG_ON(ret); /* -ENOMEM */
 
 	if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
-		ret = btrfs_lookup_bio_sums(inode, comp_bio, sums);
+		ret = btrfs_lookup_bio_sums(inode, comp_bio, false, 0, sums);
 		BUG_ON(ret); /* -ENOMEM */
 	}
 

fs/btrfs/ctree.h

···
 int btrfs_del_csums(struct btrfs_trans_handle *trans,
 		    struct btrfs_root *root, u64 bytenr, u64 len);
 blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio,
-				   u8 *dst);
-blk_status_t btrfs_lookup_bio_sums_dio(struct inode *inode, struct bio *bio,
-			      u64 logical_offset);
+				   bool at_offset, u64 offset, u8 *dst);
 int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
 			     struct btrfs_root *root,
 			     u64 objectid, u64 pos,

fs/btrfs/file-item.c

···
 	return ret;
 }
 
-static blk_status_t __btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio,
-				   u64 logical_offset, u8 *dst, int dio)
+/**
+ * btrfs_lookup_bio_sums - Look up checksums for a bio.
+ * @inode: inode that the bio is for.
+ * @bio: bio embedded in btrfs_io_bio.
+ * @at_offset: If true, look up checksums for the extent at @offset.
+ *             If false, use the page offsets from the bio.
+ * @offset: If @at_offset is true, offset in file to look up checksums for.
+ *          Ignored otherwise.
+ * @dst: Buffer of size btrfs_super_csum_size() used to return checksum. If
+ *       NULL, the checksum is returned in btrfs_io_bio(bio)->csum instead.
+ *
+ * Return: BLK_STS_RESOURCE if allocating memory fails, BLK_STS_OK otherwise.
+ */
+blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio,
+				   bool at_offset, u64 offset, u8 *dst)
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	struct bio_vec bvec;
···
 	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 	struct btrfs_path *path;
 	u8 *csum;
-	u64 offset = 0;
 	u64 item_start_offset = 0;
 	u64 item_last_offset = 0;
 	u64 disk_bytenr;
···
 	}
 
 	disk_bytenr = (u64)bio->bi_iter.bi_sector << 9;
-	if (dio)
-		offset = logical_offset;
 
 	bio_for_each_segment(bvec, bio, iter) {
 		page_bytes_left = bvec.bv_len;
 		if (count)
 			goto next;
 
-		if (!dio)
+		if (!at_offset)
 			offset = page_offset(bvec.bv_page) + bvec.bv_offset;
 		count = btrfs_find_ordered_sum(inode, offset, disk_bytenr,
 					       csum, nblocks);
···
 
 	WARN_ON_ONCE(count);
 	btrfs_free_path(path);
-	return 0;
-}
-
-blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio,
-				   u8 *dst)
-{
-	return __btrfs_lookup_bio_sums(inode, bio, 0, dst, 0);
-}
-
-blk_status_t btrfs_lookup_bio_sums_dio(struct inode *inode, struct bio *bio, u64 offset)
-{
-	return __btrfs_lookup_bio_sums(inode, bio, offset, NULL, 1);
+	return BLK_STS_OK;
 }
 
 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,

fs/btrfs/inode.c

···
 							   bio_flags);
 			goto out;
 		} else if (!skip_sum) {
-			ret = btrfs_lookup_bio_sums(inode, bio, NULL);
+			ret = btrfs_lookup_bio_sums(inode, bio, false, 0, NULL);
 			if (ret)
 				goto out;
 		}
···
 	 * contention.
 	 */
 	if (dip->logical_offset == file_offset) {
-		ret = btrfs_lookup_bio_sums_dio(inode, dip->orig_bio,
-						file_offset);
+		ret = btrfs_lookup_bio_sums(inode, dip->orig_bio, true,
+					    file_offset, NULL);
 		if (ret)
 			return ret;
 	}