btrfs: defrag: use auto kfree in defrag_one_range() for folios array

Use AUTO_KFREE() for the folios array, avoiding two kfree() calls, one of
them in a very specific error path.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>

Author: fdmanana

fs/btrfs/defrag.c

@@ -1169,7 +1169,7 @@ static int defrag_one_range(struct btrfs_inode *inode, u64 start, u32 len,
 	struct defrag_target_range *entry;
 	struct defrag_target_range *tmp;
 	LIST_HEAD(target_list);
-	struct folio **folios;
+	struct folio AUTO_KFREE(*folios);
 	const u32 sectorsize = inode->root->fs_info->sectorsize;
 	u64 cur = start;
 	const unsigned int nr_pages = ((start + len - 1) >> PAGE_SHIFT) -
@@ -1196,10 +1196,8 @@ static int defrag_one_range(struct btrfs_inode *inode, u64 start, u32 len,
 	 * range or the extent lock.
 	 */
 	ret = btrfs_delalloc_reserve_space(inode, &data_reserved, start, len);
-	if (ret < 0) {
-		kfree(folios);
+	if (ret < 0)
 		return ret;
-	}
 
 	/* Prepare all pages */
 	for (int i = 0; cur < start + len && i < nr_pages; i++) {
@@ -1251,7 +1249,6 @@ static int defrag_one_range(struct btrfs_inode *inode, u64 start, u32 len,
 		folio_unlock(folios[i]);
 		folio_put(folios[i]);
 	}
-	kfree(folios);
 	btrfs_delalloc_release_extents(inode, len);
 	if (last_defrag_end < start + len)
 		btrfs_delalloc_release_space(inode, data_reserved, last_defrag_end,