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

Dave Chinner
2024-07-01T02:34:22Z

On Tue, Jun 25, 2024 at 11:44:19AM +0000, Pankaj Raghav (Samsung) wrote:
> From: Pankaj Raghav <p.raghav@samsung.com>
>
> 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@kernel.org>
> Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
> ---
> 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@redhat.com>
--
Dave Chinner
david@fromorbit.com