linux-kernel - [PATCH 4.18 015/350] block: make sure discard bio is aligned with logical block size

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Date:   Sun, 11 Nov 2018 14:17:59 -0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Mike Snitzer <snitzer@...hat.com>,
        Christoph Hellwig <hch@....de>, Xiao Ni <xni@...hat.com>,
        Mariusz Dabrowski <mariusz.dabrowski@...el.com>,
        Rui Salvaterra <rsalvaterra@...il.com>,
        Ming Lei <ming.lei@...hat.com>, Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 4.18 015/350] block: make sure discard bio is aligned with logical block size

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ming Lei <ming.lei@...hat.com>

commit 1adfc5e4136f5967d591c399aff95b3b035f16b7 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: stable@...r.kernel.org
Cc: Mike Snitzer <snitzer@...hat.com>
Cc: Christoph Hellwig <hch@....de>
Cc: Xiao Ni <xni@...hat.com>
Cc: Mariusz Dabrowski <mariusz.dabrowski@...el.com>
Fixes: 744889b7cbb56a6 ("block: don't deal with discard limit in blkdev_issue_discard()")
Fixes: a22c4d7e34402cc ("block: re-add discard_granularity and alignment checks")
Reported-by: Rui Salvaterra <rsalvaterra@...il.com>
Tested-by: Rui Salvaterra <rsalvaterra@...il.com>
Signed-off-by: Ming Lei <ming.lei@...hat.com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 block/blk-lib.c   |    3 +--
 block/blk-merge.c |    3 ++-
 block/blk.h       |   10 ++++++++++
 3 files changed, 13 insertions(+), 3 deletions(-)

--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -58,8 +58,7 @@ int __blkdev_issue_discard(struct block_
 
 		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;
 
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -27,7 +27,8 @@ static struct bio *blk_bio_discard_split
 	/* 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)) {
--- a/block/blk.h
+++ b/block/blk.h
@@ -327,6 +327,16 @@ static inline unsigned long blk_rq_deadl
 }
 
 /*
+ * 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
  */
 void get_io_context(struct io_context *ioc);