Re: [PATCH v4 10/11] xfs: make the calculation generic in xfs_sb_validate_fsb_count()

Darrick J. Wong
2024-04-26T15:16:19Z

On Thu, Apr 25, 2024 at 01:37:45PM +0200, 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.
>
> Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>

Looks ok,
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
> fs/xfs/xfs_mount.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> index df370eb5dc15..56d71282972a 100644
> --- a/fs/xfs/xfs_mount.c
> +++ b/fs/xfs/xfs_mount.c
> @@ -133,9 +133,16 @@ xfs_sb_validate_fsb_count(
> {
> ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
> ASSERT(sbp->sb_blocklog >= BBSHIFT);
> + uint64_t max_index;
> + uint64_t max_bytes;
> +
> + 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)
> + max_index = max_bytes >> PAGE_SHIFT;
> +
> + if (max_index > ULONG_MAX)
> return -EFBIG;
> return 0;
> }
> --
> 2.34.1
>
>