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Subject: Re: [PATCH V10 09/19] block: introduce bio_bvecs()
From: Sagi Grimberg <sagi@grimberg.me>
References: <20181115085306.9910-1-ming.lei@redhat.com>
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To: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Dave Chinner <dchinner@redhat.com>, Kent Overstreet <kent.overstreet@gmail.com>, Mike Snitzer <snitzer@redhat.com>, dm-devel@redhat.com, Alexander Viro <viro@zeniv.linux.org.uk>, linux-fsdevel@vger.kernel.org, Shaohua Li <shli@kernel.org>, linux-raid@vger.kernel.org, linux-erofs@lists.ozlabs.org, David Sterba <dsterba@suse.com>, linux-btrfs@vger.kernel.org, "Darrick J . Wong" <darrick.wong@oracle.com>, linux-xfs@vger.kernel.org, Gao Xiang <gaoxiang25@huawei.com>, Theodore Ts'o <tytso@mit.edu>, linux-ext4@vger.kernel.org, Coly Li <colyli@suse.de>, linux-bcache@vger.kernel.org, Boaz Harrosh <ooo@electrozaur.com>, Bob Peterson <rpeterso@redhat.com>, cluster-devel@redhat.com


>> Yeah, that is the most common example, given merge is enabled
>> in most of cases. If the driver or device doesn't care merge,
>> you can disable it and always get single bio request, then the
>> bio's bvec table can be reused for send().
> 
> Does bvec_iter span bvecs with your patches? I didn't see that change?

Wait, I see that the bvec is still a single array per bio. When you said
a table I thought you meant a 2-dimentional array...

Unless I'm not mistaken, I think that the change is pretty simple then.
However, nvme-tcp still needs to be bio aware unless we have some
abstraction in place.. Which will mean that nvme-tcp will need to
open-code bio_bvecs.