f2fs: refactor the hole reporting and allocation logic in f2fs_map_blocks

Add a is_hole local variable to figure out if the block number might need
allocation, and untangle to logic to report the hole or fill it with a
block allocation.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/data.c

@@ -1547,6 +1547,7 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map, int flag)
 	block_t blkaddr;
 	unsigned int start_pgofs;
 	int bidx = 0;
+	bool is_hole;
 
 	if (!maxblocks)
 		return 0;
@@ -1587,51 +1588,48 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map, int flag)
 
 next_block:
 	blkaddr = f2fs_data_blkaddr(&dn);
-
-	if (__is_valid_data_blkaddr(blkaddr) &&
+	is_hole = !__is_valid_data_blkaddr(blkaddr);
+	if (!is_hole &&
 	    !f2fs_is_valid_blkaddr(sbi, blkaddr, DATA_GENERIC_ENHANCE)) {
 		err = -EFSCORRUPTED;
 		f2fs_handle_error(sbi, ERROR_INVALID_BLKADDR);
 		goto sync_out;
 	}
 
-	if (__is_valid_data_blkaddr(blkaddr)) {
-		/* use out-place-update for driect IO under LFS mode */
-		if (f2fs_lfs_mode(sbi) && flag == F2FS_GET_BLOCK_DIO &&
-							map->m_may_create) {
-			err = __allocate_data_block(&dn, map->m_seg_type);
-			if (err)
-				goto sync_out;
-			blkaddr = dn.data_blkaddr;
-			set_inode_flag(inode, FI_APPEND_WRITE);
-		}
-	} else {
-		if (map->m_may_create) {
+	/* use out-place-update for direct IO under LFS mode */
+	if (map->m_may_create &&
+	    (is_hole || (f2fs_lfs_mode(sbi) && flag == F2FS_GET_BLOCK_DIO))) {
 		if (unlikely(f2fs_cp_error(sbi))) {
 			err = -EIO;
 			goto sync_out;
 		}
-			if (flag == F2FS_GET_BLOCK_PRE_AIO) {
+
+		switch (flag) {
+		case F2FS_GET_BLOCK_PRE_AIO:
 			if (blkaddr == NULL_ADDR) {
 				prealloc++;
 				last_ofs_in_node = dn.ofs_in_node;
 			}
-			} else {
-				WARN_ON(flag != F2FS_GET_BLOCK_PRE_DIO &&
-					flag != F2FS_GET_BLOCK_DIO);
-				err = __allocate_data_block(&dn,
-							map->m_seg_type);
-				if (!err) {
+			break;
+		case F2FS_GET_BLOCK_PRE_DIO:
+		case F2FS_GET_BLOCK_DIO:
+			err = __allocate_data_block(&dn, map->m_seg_type);
+			if (err)
+				goto sync_out;
 			if (flag == F2FS_GET_BLOCK_PRE_DIO)
 				file_need_truncate(inode);
 			set_inode_flag(inode, FI_APPEND_WRITE);
-				}
-			}
-			if (err)
+			break;
+		default:
+			WARN_ON_ONCE(1);
+			err = -EIO;
 			goto sync_out;
-			map->m_flags |= F2FS_MAP_NEW;
+		}
+
 		blkaddr = dn.data_blkaddr;
-		} else {
+		if (is_hole)
+			map->m_flags |= F2FS_MAP_NEW;
+	} else if (is_hole) {
 		if (f2fs_compressed_file(inode) &&
 		    f2fs_sanity_check_cluster(&dn) &&
 		    (flag != F2FS_GET_BLOCK_FIEMAP ||
@@ -1641,26 +1639,27 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map, int flag)
 					ERROR_CORRUPTED_CLUSTER);
 			goto sync_out;
 		}
-			if (flag == F2FS_GET_BLOCK_BMAP) {
-				map->m_pblk = 0;
+
+		switch (flag) {
+		case F2FS_GET_BLOCK_PRECACHE:
 			goto sync_out;
-			}
-			if (flag == F2FS_GET_BLOCK_PRECACHE)
+		case F2FS_GET_BLOCK_BMAP:
+			map->m_pblk = 0;
 			goto sync_out;
-			if (flag == F2FS_GET_BLOCK_FIEMAP &&
-						blkaddr == NULL_ADDR) {
+		case F2FS_GET_BLOCK_FIEMAP:
+			if (blkaddr == NULL_ADDR) {
 				if (map->m_next_pgofs)
 					*map->m_next_pgofs = pgofs + 1;
 				goto sync_out;
 			}
-			if (flag != F2FS_GET_BLOCK_FIEMAP) {
+			break;
+		default:
 			/* for defragment case */
 			if (map->m_next_pgofs)
 				*map->m_next_pgofs = pgofs + 1;
 			goto sync_out;
 		}
 	}
-	}
 
 	if (flag == F2FS_GET_BLOCK_PRE_AIO)
 		goto skip;