[PATCH 3/3] btrfs: Avoid possible qgroup_rsv_size overflow in btrfs_calculate_inode_block_rsv_size

[Nikolay Borisov <nborisov@suse.com>]

qgroup_rsv_size is calculated as the product of
outstanding_extent * fs_info->nodesize. The product is calculated with
32 bith precision since both variables are defined as u32. Yet
qgroup_rsv_size expects a 64 bit result.

Avoid possible multiplication overflow by casting outstanding_extent to
u64.

Fixes-coverity-id: 1435101
ff6bc37eb7f6 ("btrfs: qgroup: Use independent and accurate per inode qgroup rsv")

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
---
 fs/btrfs/extent-tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index b085d8215f0e..beddf9eef4a2 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -6173,7 +6173,7 @@ static void btrfs_calculate_inode_block_rsv_size(struct btrfs_fs_info *fs_info,
 	 *
 	 * This is overestimating in most cases.
 	 */
-	qgroup_rsv_size = outstanding_extents * fs_info->nodesize;
+	qgroup_rsv_size = (u64) outstanding_extents * fs_info->nodesize;
 
 	spin_lock(&block_rsv->lock);
 	block_rsv->size = reserve_size;
-- 
2.17.1