linux-kernel - [PATCH 4.14 01/36] block: break discard submissions into the user defined size

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Message-Id: <20181228113126.631472098@linuxfoundation.org>
Date:   Fri, 28 Dec 2018 12:52:17 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Darrick J. Wong" <darrick.wong@...cle.com>,
        Omar Sandoval <osandov@...com>, Jens Axboe <axboe@...nel.dk>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.14 01/36] block: break discard submissions into the user defined size

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

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

[ Upstream commit af097f5d199e2aa3ab3ef777f0716e487b8f7b08 ]

Don't build discards bigger than what the user asked for, if the
user decided to limit the size by writing to 'discard_max_bytes'.

Reviewed-by: Darrick J. Wong <darrick.wong@...cle.com>
Reviewed-by: Omar Sandoval <osandov@...com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 block/blk-lib.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/block/blk-lib.c b/block/blk-lib.c
index 2bc544ce3d2e..53a45663e688 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -59,10 +59,16 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		unsigned int req_sects;
 		sector_t end_sect, tmp;
 
-		/* Make sure bi_size doesn't overflow */
-		req_sects = min_t(sector_t, nr_sects, UINT_MAX >> 9);
+		/*
+		 * Issue in chunks of the user defined max discard setting,
+		 * ensuring that bi_size doesn't overflow
+		 */
+		req_sects = min_t(sector_t, nr_sects,
+					q->limits.max_discard_sectors);
+		if (req_sects > UINT_MAX >> 9)
+			req_sects = UINT_MAX >> 9;
 
-		/**
+		/*
 		 * If splitting a request, and the next starting sector would be
 		 * misaligned, stop the discard at the previous aligned sector.
 		 */
-- 
2.19.1