[added,to,the,4.1,stable,tree] md: avoid warning for 32-bit sector_t

Message ID 20180301152116.1486-446-alexander.levin@microsoft.com
State New
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Series
  • [added,to,the,4.1,stable,tree] md: avoid warning for 32-bit sector_t
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Commit Message

Sasha Levin March 1, 2018, 3:27 p.m.
From: Arnd Bergmann <arnd@arndb.de>


This patch has been added to the 4.1 stable tree. If you have any
objections, please let us know.

-- 
2.14.1

Patch

===============

[ Upstream commit 3312c951efaba55080958974047414576b9e5d63 ]

When CONFIG_LBDAF is not set, sector_t is only 32-bits wide, which
means we cannot have devices with more than 2TB, and the code that
is trying to handle compatibility support for large devices in
md version 0.90 is meaningless but also causes a compile-time warning:

drivers/md/md.c: In function 'super_90_load':
drivers/md/md.c:1029:19: warning: large integer implicitly truncated to unsigned type [-Woverflow]
drivers/md/md.c: In function 'super_90_rdev_size_change':
drivers/md/md.c:1323:17: warning: large integer implicitly truncated to unsigned type [-Woverflow]

This adds a check for CONFIG_LBDAF to avoid even getting into this
code path, and also adds an explicit cast to let the compiler know
it doesn't have to warn about the truncation.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 drivers/md/md.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 1fdcd5735418..03bcc1ab2e9d 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1043,8 +1043,9 @@  static int super_90_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor
 	 * (not needed for Linear and RAID0 as metadata doesn't
 	 * record this size)
 	 */
-	if (rdev->sectors >= (2ULL << 32) && sb->level >= 1)
-		rdev->sectors = (2ULL << 32) - 2;
+	if (IS_ENABLED(CONFIG_LBDAF) && (u64)rdev->sectors >= (2ULL << 32) &&
+	    sb->level >= 1)
+		rdev->sectors = (sector_t)(2ULL << 32) - 2;
 
 	if (rdev->sectors < ((sector_t)sb->size) * 2 && sb->level >= 1)
 		/* "this cannot possibly happen" ... */
@@ -1337,8 +1338,9 @@  super_90_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
 	/* Limit to 4TB as metadata cannot record more than that.
 	 * 4TB == 2^32 KB, or 2*2^32 sectors.
 	 */
-	if (num_sectors >= (2ULL << 32) && rdev->mddev->level >= 1)
-		num_sectors = (2ULL << 32) - 2;
+	if (IS_ENABLED(CONFIG_LBDAF) && (u64)num_sectors >= (2ULL << 32) &&
+	    rdev->mddev->level >= 1)
+		num_sectors = (sector_t)(2ULL << 32) - 2;
 	md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
 		       rdev->sb_page);
 	md_super_wait(rdev->mddev);