xfs: make the calculation generic in xfs_sb_validate_fsb_count()

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>
Link: https://lore.kernel.org/r/20240822135018.1931258-10-kernel@pankajraghav.com
Acked-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Daniel Gomez <da.gomez@samsung.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 09eef1721ef4f4f81454229aca90db235d5c1fec..3949f720b5354b025409cf404bbfe2919fd97732 100644 (file)
--- 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;
 }