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Subject: Re: [PATCH 0/4] block: fix bio_will_gap()
To: Ming Lei <ming.lei@canonical.com>, Jens Axboe <axboe@kernel.dk>,
        linux-kernel@vger.kernel.org
References: <1455519687-23873-1-git-send-email-ming.lei@canonical.com>
Cc: linux-block@vger.kernel.org, Christoph Hellwig <hch@infradead.org>
From: Sagi Grimberg <sagig@dev.mellanox.co.il>
Message-ID: <56C18D59.5050704@dev.mellanox.co.il>
Date: Mon, 15 Feb 2016 10:33:29 +0200
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> Hi,
>
> After bio splitting is introduced, the splitted bio can be fast-cloned,
> which is correct because biovecs has become immutable since v3.13.
>
> Unfortunately bio_will_gap() isn't ready for this kind of change,
> because it figures out the last bvec via 'bi_io_vec[prev->bi_vcnt - 1]'
> directly.
>
> It is observed that lots of BIOs are merges even the virt boundary
> limit is violated, and the issue is reported from Sagi Grimberg.

This set makes the virt_boundary violation go away...