DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com BF0948553F
From: Ming Lei <ming.lei@redhat.com>
To: Jens Axboe <axboe@fb.com>, Christoph Hellwig <hch@infradead.org>,
        Huang Ying <ying.huang@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
        Ming Lei <ming.lei@redhat.com>, Mike Snitzer <snitzer@redhat.com>
Subject: [PATCH v3 10/49] dm: limit the max bio size as BIO_MAX_PAGES * PAGE_SIZE
Date: Tue,  8 Aug 2017 16:45:09 +0800
Message-Id: <20170808084548.18963-11-ming.lei@redhat.com>
In-Reply-To: <20170808084548.18963-1-ming.lei@redhat.com>
References: <20170808084548.18963-1-ming.lei@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 972
Lines: 34

For BIO based DM, some targets aren't ready for dealing with
bigger incoming bio than 1Mbyte, such as crypt target.

Cc: Mike Snitzer <snitzer@redhat.com>
Cc:dm-devel@redhat.com
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/md/dm.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 2edbcc2d7d3f..631348699fb8 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -922,7 +922,16 @@ int dm_set_target_max_io_len(struct dm_target *ti, sector_t len)
 		return -EINVAL;
 	}
 
-	ti->max_io_len = (uint32_t) len;
+	/*
+	 * BIO based queue uses its own splitting. When multipage bvecs
+	 * is switched on, size of the incoming bio may be too big to
+	 * be handled in some targets, such as crypt.
+	 *
+	 * When these targets are ready for the big bio, we can remove
+	 * the limit.
+	 */
+	ti->max_io_len = min_t(uint32_t, len,
+			       (BIO_MAX_PAGES * PAGE_SIZE));
 
 	return 0;
 }
-- 
2.9.4