ext4: refactor ext4_da_map_blocks()

Refactor and cleanup ext4_da_map_blocks(), reduce some unnecessary
parameters and branches, no logic changes.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240127015825.1608160-2-yi.zhang@huaweicloud.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/inode.c

@@ -1704,7 +1704,6 @@ static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
 	/* Lookup extent status tree firstly */
 	if (ext4_es_lookup_extent(inode, iblock, NULL, &es)) {
 		if (ext4_es_is_hole(&es)) {
-			retval = 0;
 			down_read(&EXT4_I(inode)->i_data_sem);
 			goto add_delayed;
 		}
@@ -1749,26 +1748,9 @@ static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
 		retval = ext4_ext_map_blocks(NULL, inode, map, 0);
 	else
 		retval = ext4_ind_map_blocks(NULL, inode, map, 0);
-
-add_delayed:
-	if (retval == 0) {
-		int ret;
-
-		/*
-		 * XXX: __block_prepare_write() unmaps passed block,
-		 * is it OK?
-		 */
-
-		ret = ext4_insert_delayed_block(inode, map->m_lblk);
-		if (ret != 0) {
-			retval = ret;
-			goto out_unlock;
-		}
-
-		map_bh(bh, inode->i_sb, invalid_block);
-		set_buffer_new(bh);
-		set_buffer_delay(bh);
-	} else if (retval > 0) {
+	if (retval < 0)
+		goto out_unlock;
+	if (retval > 0) {
 		unsigned int status;
 
 		if (unlikely(retval != map->m_len)) {
@@ -1783,11 +1765,24 @@ static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
 				EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
 		ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
 				      map->m_pblk, status);
+		goto out_unlock;
 	}
 
+add_delayed:
+	/*
+	 * XXX: __block_prepare_write() unmaps passed block,
+	 * is it OK?
+	 */
+	retval = ext4_insert_delayed_block(inode, map->m_lblk);
+	if (retval)
+		goto out_unlock;
+
+	map_bh(bh, inode->i_sb, invalid_block);
+	set_buffer_new(bh);
+	set_buffer_delay(bh);
+
 out_unlock:
 	up_read((&EXT4_I(inode)->i_data_sem));
-
 	return retval;
 }