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Subject: Re: [PATCH] block: respect virtual boundary mask in bvecs
To:     Ming Lei <tom.leiming@gmail.com>,
        Johannes Thumshirn <jthumshirn@suse.de>
Cc:     Ming Lei <ming.lei@redhat.com>, Jens Axboe <axboe@fb.com>,
        linux-block <linux-block@vger.kernel.org>,
        Hannes Reinecke <hare@suse.de>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Jan Kara <jack@suse.cz>
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 <20181105105548.GC12367@ming.t460p>
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 <CACVXFVNOAc1HEPmfu9n8vMjqY2hK8fVqe4Em-g+dvSRLavpO8w@mail.gmail.com>
From:   Sagi Grimberg <sagi@grimberg.me>
Message-ID: <f670cdbd-ece6-9051-e6f8-0814a44fe82b@grimberg.me>
Date:   Tue, 6 Nov 2018 19:14:22 -0800
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> blktrace won't help on this issue because .bv_offset isn't recorded.
> 
> This patch makes sense on >4KB PAGE_SIZE. If your issue happens on
> ARCH with 4K PAGE_SIZE, maybe you should root cause why it makes a
> difference on iSer. And it is highly possible there is bug somewhere.

I don't suspect that this is the case. unless all the vec elements
happen to have an offset but if that is the case I don't think that
this patch would've solved this.

It can't really be an iser issue because iser does not control bio
splitting/merging... it can only ask the block layer to obay the
virt_boundary.