Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        "Darrick J. Wong" <darrick.wong@oracle.com>,
        Omar Sandoval <osandov@fb.com>, Jens Axboe <axboe@kernel.dk>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 01/22] block: break discard submissions into the user defined size
Date:   Fri, 28 Dec 2018 12:52:38 +0100
Message-Id: <20181228113126.222869065@linuxfoundation.org>
In-Reply-To: <20181228113126.144310132@linuxfoundation.org>
References: <20181228113126.144310132@linuxfoundation.org>
User-Agent: quilt/0.65
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

4.9-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@oracle.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.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 46fe9248410d..d8b89c58af3d 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -63,10 +63,16 @@ 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