block: make sure discard bio is aligned with logical block size

commit 1adfc5e upstream.

Obviously the created discard bio has to be aligned with logical block size.

This patch introduces the helper of bio_allowed_max_sectors() for
this purpose.

Cc: [email protected]
Cc: Mike Snitzer <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Xiao Ni <[email protected]>
Cc: Mariusz Dabrowski <[email protected]>
Fixes: 744889b ("block: don't deal with discard limit in blkdev_issue_discard()")
Fixes: a22c4d7 ("block: re-add discard_granularity and alignment checks")
Reported-by: Rui Salvaterra <[email protected]>
Tested-by: Rui Salvaterra <[email protected]>
Signed-off-by: Ming Lei <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Ming Lei

block/blk-lib.c

@@ -58,8 +58,7 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 
 		if (!req_sects)
 			goto fail;
-		if (req_sects > UINT_MAX >> 9)
-			req_sects = UINT_MAX >> 9;
+		req_sects = min(req_sects, bio_allowed_max_sectors(q));
 
 		end_sect = sector + req_sects;
 

block/blk-merge.c

@@ -27,7 +27,8 @@ static struct bio *blk_bio_discard_split(struct request_queue *q,
 	/* Zero-sector (unknown) and one-sector granularities are the same.  */
 	granularity = max(q->limits.discard_granularity >> 9, 1U);
 
-	max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
+	max_discard_sectors = min(q->limits.max_discard_sectors,
+			bio_allowed_max_sectors(q));
 	max_discard_sectors -= max_discard_sectors % granularity;
 
 	if (unlikely(!max_discard_sectors)) {

block/blk.h

@@ -328,6 +328,16 @@ static inline unsigned long blk_rq_deadline(struct request *rq)
 	return rq->__deadline & ~0x1UL;
 }
 
+/*
+ * The max size one bio can handle is UINT_MAX becasue bvec_iter.bi_size
+ * is defined as 'unsigned int', meantime it has to aligned to with logical
+ * block size which is the minimum accepted unit by hardware.
+ */
+static inline unsigned int bio_allowed_max_sectors(struct request_queue *q)
+{
+	return round_down(UINT_MAX, queue_logical_block_size(q)) >> 9;
+}
+
 /*
  * Internal io_context interface
  */