[PATCH 12/13] xfs: make the calculation generic in xfs_sb_validate_fsb_count()

From: "Pankaj Raghav (Samsung)" <kernel@pankajraghav.com>
To: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, david@fromorbit.com,
	chandan.babu@oracle.com, akpm@linux-foundation.org,
	mcgrof@kernel.org, ziy@nvidia.com, hare@suse.de,
	djwong@kernel.org, gost.dev@samsung.com, linux-mm@kvack.org,
	willy@infradead.org, Pankaj Raghav <p.raghav@samsung.com>
Subject: [PATCH 12/13] xfs: make the calculation generic in xfs_sb_validate_fsb_count()
Date: Mon, 26 Feb 2024 10:49:35 +0100	[thread overview]
Message-ID: <20240226094936.2677493-13-kernel@pankajraghav.com> (raw)
In-Reply-To: <20240226094936.2677493-1-kernel@pankajraghav.com>

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>
---
 fs/xfs/xfs_mount.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index aabb25dc3efa..69af3b06be99 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -133,9 +133,15 @@ xfs_sb_validate_fsb_count(
 {
 	ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
 	ASSERT(sbp->sb_blocklog >= BBSHIFT);
+	uint64_t mapping_count;
+	uint64_t bytes;
 
+	if (check_mul_overflow(nblocks, (1 << sbp->sb_blocklog), &bytes))
+		return -EFBIG;
+
+	mapping_count = bytes >> PAGE_SHIFT;
 	/* Limited by ULONG_MAX of page cache index */
-	if (nblocks >> (PAGE_SHIFT - sbp->sb_blocklog) > ULONG_MAX)
+	if (mapping_count > ULONG_MAX)
 		return -EFBIG;
 	return 0;
 }
-- 
2.43.0

