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Date:   Wed, 24 Mar 2021 19:13:07 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Benjamin Block <bblock@linux.ibm.com>
Cc:     Christoph Hellwig <hch@lst.de>,
        Matthew Wilcox <willy@infradead.org>,
        Jens Axboe <axboe@kernel.dk>,
        Khalid Aziz <khalid@gonehiking.org>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Hannes Reinecke <hare@suse.com>,
        Ondrej Zary <linux@rainbow-software.org>,
        linux-block@vger.kernel.org, linux-scsi@vger.kernel.org
Subject: Re: [PATCH 7/8] block: refactor the bounce buffering code
Message-ID: <20210324181307.GA15902@lst.de>
References: <20210318063923.302738-1-hch@lst.de> <20210318063923.302738-8-hch@lst.de> <20210318112950.GL3420@casper.infradead.org> <20210318125340.GA21262@lst.de> <YFt5kPs30x4kPu77@t480-pf1aa2c2.linux.ibm.com> <20210324174458.GA13589@lst.de> <YFt/7BdzecUmdySU@t480-pf1aa2c2.linux.ibm.com>
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On Wed, Mar 24, 2021 at 07:07:40PM +0100, Benjamin Block wrote:
> But map_request() -> multipath_clone_and_map() -> dm_dispatch_clone_request() 
> doesn't call blk_mq_submit_bio() for requests that have been queued in a
> request based mpath device. The requests gets cloned and then dispatched
> on the lower queue. Or am I missing something?

Indeed.  I keep forgetting about the fact that dm-mpath bypassed
the normal submit_bio_noacct path.