On Mon, Apr 12, 2021 at 12:23:33PM +0200, Jan Kara wrote:
> A code in iomap alloc may overblock block number when converting it to
"overflow"?
> byte offset. Luckily this is mostly harmless as we will just use more
> expensive method of writing using unwritten extents even though we are
> writing beyond i_size.
>
> Fixes: 378f32bab371 ("ext4: introduce direct I/O write using iomap infrastructure")
> Signed-off-by: Jan Kara <jack@xxxxxxx>
> ---
> fs/ext4/inode.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 0948a43f1b3d..7cebbb2d2e34 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3420,7 +3420,7 @@ static int ext4_iomap_alloc(struct inode *inode, struct ext4_map_blocks *map,
> * i_disksize out to i_size. This could be beyond where direct I/O is
> * happening and thus expose allocated blocks to direct I/O reads.
> */
> - else if ((map->m_lblk * (1 << blkbits)) >= i_size_read(inode))
> + else if (((loff_t)map->m_lblk << blkbits) >= i_size_read(inode))
> m_flags = EXT4_GET_BLOCKS_CREATE;
> else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
> m_flags = EXT4_GET_BLOCKS_IO_CREATE_EXT;
> --
> 2.26.2
>
