linux-kernel - Re: [PATCH 46/60] block: deal with dirtying pages for multipage bvec

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Date:   Mon, 31 Oct 2016 08:40:21 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Ming Lei <tom.leiming@...il.com>
Cc:     Jens Axboe <axboe@...com>, linux-kernel@...r.kernel.org,
        linux-block@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Christoph Hellwig <hch@...radead.org>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Jens Axboe <axboe@...nel.dk>
Subject: Re: [PATCH 46/60] block: deal with dirtying pages for multipage bvec

On Sat, Oct 29, 2016 at 04:08:45PM +0800, Ming Lei wrote:
> In bio_check_pages_dirty(), bvec->bv_page is used as flag
> for marking if the page has been dirtied & released, and if
> no, it will be dirtied in deferred workqueue.
> 
> With multipage bvec, we can't do that any more, so change
> the logic into checking all pages in one mp bvec, and only
> release all these pages if all are dirtied, otherwise dirty
> them all in deferred wrokqueue.

Just defer the whole bio to the workqueue if we need to redirty any,
that avoids having all these complex iteratations.