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From: Ming Lei <ming.lei@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, Ming Lei <ming.lei@redhat.com>,
	Stephen Rust <srust@blockbridge.com>
Subject: [PATCH 2/2] brd: warn on un-aligned buffer
Date: Wed,  4 Dec 2019 19:31:15 +0800
Message-ID: <20191204113115.17818-3-ming.lei@redhat.com> (raw)
In-Reply-To: <20191204113115.17818-1-ming.lei@redhat.com>

Queue dma alignment limit requires users(fs, target, ...) of block layer
to pass aligned buffer.

So far brd doesn't support un-aligned buffer, even though it is easy
to support it.

However, given brd is often used for debug purpose, and there are other
drivers which can't support un-aligned buffer too.

So add warning so that brd users know what to fix.

Reported-by: Stephen Rust <srust@blockbridge.com>
Cc: Stephen Rust <srust@blockbridge.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/block/brd.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index c2e5b2ad88bc..a8730cc4db10 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -297,6 +297,10 @@ static blk_qc_t brd_make_request(struct request_queue *q, struct bio *bio)
 		unsigned int len = bvec.bv_len;
 		int err;
 
+		/* Don't support un-aligned buffer */
+		WARN_ON_ONCE((bvec.bv_offset & (SECTOR_SIZE - 1)) ||
+				(len & (SECTOR_SIZE - 1)));
+
 		err = brd_do_bvec(brd, bvec.bv_page, len, bvec.bv_offset,
 				  bio_op(bio), sector);
 		if (err)
-- 
2.20.1


  parent reply index

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-04 11:31 [PATCH 0/2] brd: remove max_hw_sectors limit and " Ming Lei
2019-12-04 11:31 ` [PATCH 1/2] brd: remove max_hw_sectors queue limit Ming Lei
2019-12-04 11:31 ` Ming Lei [this message]
2019-12-04 16:04 ` [PATCH 0/2] brd: remove max_hw_sectors limit and warn on un-aligned buffer Jens Axboe

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