Re: [PATCH] fuse: remove page alignment check for writeback len

["Darrick J. Wong" <djwong@kernel.org>]

On Wed, Jul 23, 2025 at 04:08:50PM -0700, Joanne Koong wrote:
> Remove incorrect page alignment check for the writeback len arg in
> fuse_iomap_writeback_range(). len will always be block-aligned as passed
> in by iomap. On regular fuse filesystems, i_blkbits is set to PAGE_SHIFT
> so this is not a problem but for fuseblk filesystems, the block size is
> set to a default of 512 bytes or a block size passed in at mount time.
> 
> Please note that non-page-aligned lens are fine for the logic in
> fuse_iomap_writeback_range(). The check was originally added as a
> safeguard to detect conspicuously wrong ranges.
> 
> Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
> Fixes: ef7e7cbb323f ("fuse: use iomap for writeback")
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>

Seems fine to me,
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> 
> [1] report:
> https://lore.kernel.org/linux-fsdevel/CA+G9fYs5AdVM-T2Tf3LciNCwLZEHetcnSkHsjZajVwwpM2HmJw@mail.gmail.com/
> ---
>  fs/fuse/file.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> index f16426fd2bf5..883dc94a0ce0 100644
> --- a/fs/fuse/file.c
> +++ b/fs/fuse/file.c
> @@ -2155,8 +2155,6 @@ static ssize_t fuse_iomap_writeback_range(struct iomap_writepage_ctx *wpc,
>  	loff_t offset = offset_in_folio(folio, pos);
>  
>  	WARN_ON_ONCE(!data);
> -	/* len will always be page aligned */
> -	WARN_ON_ONCE(len & (PAGE_SIZE - 1));
>  
>  	if (!data->ff) {
>  		data->ff = fuse_write_file_get(fi);
> -- 
> 2.47.3
> 
>