linux-kernel - [PATCH v2] blk: avoid divide-by-zero with zero granularity

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Date:   Tue, 12 Jan 2021 23:55:02 +0800
From:   Li Feng <fengli@...rtx.com>
To:     Jens Axboe <axboe@...nel.dk>,
        linux-block@...r.kernel.org (open list:BLOCK LAYER),
        linux-kernel@...r.kernel.org (open list)
Cc:     lifeng1519@...il.com, Li Feng <fengli@...rtx.com>
Subject: [PATCH v2] blk: avoid divide-by-zero with zero granularity

If the physical_block_size and io_min is less than a sector, the
'granularity >> SECTOR_SHIFT' will be zero.

Signed-off-by: Li Feng <fengli@...rtx.com>
---
 include/linux/blkdev.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index f94ee3089e01..ffffb04ad113 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1485,7 +1485,11 @@ static inline int queue_alignment_offset(const struct request_queue *q)
 static inline int queue_limit_alignment_offset(struct queue_limits *lim, sector_t sector)
 {
 	unsigned int granularity = max(lim->physical_block_size, lim->io_min);
-	unsigned int alignment = sector_div(sector, granularity >> SECTOR_SHIFT)
+	unsigned int alignment;
+	if (granularity >> SECTOR_SHIFT == 0)
+		return 0;
+
+	alignment = sector_div(sector, granularity >> SECTOR_SHIFT)
 		<< SECTOR_SHIFT;
 
 	return (granularity + lim->alignment_offset - alignment) % granularity;
-- 
2.29.2