linux-kernel - [PATCH v1 1/1] ceph: Amend checking to fix `make W=1` build breakage

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Message-ID: <20251110144404.369928-1-andriy.shevchenko@linux.intel.com>
Date: Mon, 10 Nov 2025 15:44:04 +0100
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	ceph-devel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	llvm@...ts.linux.dev
Cc: Xiubo Li <xiubli@...hat.com>,
	Ilya Dryomov <idryomov@...il.com>,
	Nathan Chancellor <nathan@...nel.org>,
	Nick Desaulniers <nick.desaulniers+lkml@...il.com>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH v1 1/1] ceph: Amend checking to fix `make W=1` build breakage

In a few cases the code compares 32-bit value to a SIZE_MAX derived
constant which is much higher than that value on 64-bit platforms,
Clang, in particular, is not happy about this

fs/ceph/snap.c:377:10: error: result of comparison of constant 2305843009213693948 with expression of type 'u32' (aka 'unsigned int') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
  377 |         if (num > (SIZE_MAX - sizeof(*snapc)) / sizeof(u64))
      |             ~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix this by casting to size_t. Note, that possible replacement of SIZE_MAX
by U32_MAX may lead to the behaviour changes on the corner cases.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 fs/ceph/snap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index c65f2b202b2b..521507ea8260 100644
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -374,7 +374,7 @@ static int build_snap_context(struct ceph_mds_client *mdsc,
 
 	/* alloc new snap context */
 	err = -ENOMEM;
-	if (num > (SIZE_MAX - sizeof(*snapc)) / sizeof(u64))
+	if ((size_t)num > (SIZE_MAX - sizeof(*snapc)) / sizeof(u64))
 		goto fail;
 	snapc = ceph_create_snap_context(num, GFP_NOFS);
 	if (!snapc)
-- 
2.50.1