Re: [PATCH v8 09/10] xfs: make the calculation generic in xfs_sb_validate_fsb_count()

[Dave Chinner]

On Tue, Jun 25, 2024 at 11:44:19AM +0000, Pankaj Raghav (Samsung) wrote:
> From: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
> 
> Instead of assuming that PAGE_SHIFT is always higher than the blocklog,
> make the calculation generic so that page cache count can be calculated
> correctly for LBS.
> 
> Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
> Signed-off-by: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
> ---
>  fs/xfs/xfs_mount.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> index 09eef1721ef4..3949f720b535 100644
> --- a/fs/xfs/xfs_mount.c
> +++ b/fs/xfs/xfs_mount.c
> @@ -132,11 +132,16 @@ xfs_sb_validate_fsb_count(
>  	xfs_sb_t	*sbp,
>  	uint64_t	nblocks)
>  {
> +	uint64_t		max_bytes;
> +
>  	ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
>  	ASSERT(sbp->sb_blocklog >= BBSHIFT);
>  
> +	if (check_shl_overflow(nblocks, sbp->sb_blocklog, &max_bytes))
> +		return -EFBIG;
> +
>  	/* Limited by ULONG_MAX of page cache index */
> -	if (nblocks >> (PAGE_SHIFT - sbp->sb_blocklog) > ULONG_MAX)
> +	if (max_bytes >> PAGE_SHIFT > ULONG_MAX)
>  		return -EFBIG;
>  	return 0;

looks fine.

Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx>
-- 
Dave Chinner
david@xxxxxxxxxxxxx