btrfs: send: use btrfs_file_extent_end() in send_write_or_clone()

send_write_or_clone() basically has an open-coded copy of
btrfs_file_extent_end() except that it (incorrectly) aligns to PAGE_SIZE
instead of sectorsize. Fix and simplify the code by using
btrfs_file_extent_end().

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/send.c

@@ -5400,51 +5400,29 @@ static int send_write_or_clone(struct send_ctx *sctx,
 			       struct clone_root *clone_root)
 {
 	int ret = 0;
-	struct btrfs_file_extent_item *ei;
 	u64 offset = key->offset;
-	u64 len;
-	u8 type;
+	u64 end;
 	u64 bs = sctx->send_root->fs_info->sb->s_blocksize;
 
-	ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
-			struct btrfs_file_extent_item);
-	type = btrfs_file_extent_type(path->nodes[0], ei);
-	if (type == BTRFS_FILE_EXTENT_INLINE) {
-		len = btrfs_file_extent_ram_bytes(path->nodes[0], ei);
-		/*
-		 * it is possible the inline item won't cover the whole page,
-		 * but there may be items after this page.  Make
-		 * sure to send the whole thing
-		 */
-		len = PAGE_ALIGN(len);
-	} else {
-		len = btrfs_file_extent_num_bytes(path->nodes[0], ei);
-	}
+	end = min_t(u64, btrfs_file_extent_end(path), sctx->cur_inode_size);
+	if (offset >= end)
+		return 0;
 
-	if (offset >= sctx->cur_inode_size) {
-		ret = 0;
-		goto out;
-	}
-	if (offset + len > sctx->cur_inode_size)
-		len = sctx->cur_inode_size - offset;
-	if (len == 0) {
-		ret = 0;
-		goto out;
-	}
-
-	if (clone_root && IS_ALIGNED(offset + len, bs)) {
+	if (clone_root && IS_ALIGNED(end, bs)) {
+		struct btrfs_file_extent_item *ei;
 		u64 disk_byte;
 		u64 data_offset;
 
+		ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
+				    struct btrfs_file_extent_item);
 		disk_byte = btrfs_file_extent_disk_bytenr(path->nodes[0], ei);
 		data_offset = btrfs_file_extent_offset(path->nodes[0], ei);
 		ret = clone_range(sctx, clone_root, disk_byte, data_offset,
-				  offset, len);
+				  offset, end - offset);
 	} else {
-		ret = send_extent_data(sctx, offset, len);
+		ret = send_extent_data(sctx, offset, end - offset);
 	}
-	sctx->cur_inode_next_write_offset = offset + len;
-out:
+	sctx->cur_inode_next_write_offset = end;
 	return ret;
 }