linux-kernel - Re: [PATCH] splice: partial write handling fix

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Message-ID: <87fy86oc07.fsf@sw.ru>
Date:	Thu, 15 Mar 2007 16:46:32 +0300
From:	Dmitriy Monakhov <dmonakhov@...ru>
To:	Jens Axboe <jens.axboe@...cle.com>
Cc:	Dmitriy Monakhov <dmonakhov@...ru>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] splice: partial write handling fix

Jens Axboe <jens.axboe@...cle.com> writes:

> On Wed, Mar 14 2007, Dmitriy Monakhov wrote:
>> currently if partial write has happened while ->commit_write() then page
>> wasn't marked as accessed and rebalanced. 
>
> The ->commit_write() return values aren't very well designed imho. Is
> your fix correct getting the pipe_to_file() return value correct now?
I think yes, after my patch this path look like follows:

        ret = mapping->a_ops->commit_write(file, page, offset, offset+this_len);
        if (ret) {
                if(ret == AOP_TRUNCATED_PAGE) {
                        page_cache_release(page);
                        goto find_page;
                }
                if (ret < 0)
                        goto out;
                /*
                 * Partial write has happened, so 'ret' already initialized by
                 * number of bytes written, Where is nothing we have to do here.
                 */
        } else
                ret = this_len;
        /*
         * Return the number of bytes written and mark page as
         * accessed, we are now done!
         */
        mark_page_accessed(page);
        balance_dirty_pages_ratelimited(mapping);
out:
        page_cache_release(page);
        unlock_page(page);
out_ret:
        return ret;
}

But off corse this patch does't fix issues spotted by Nick. 
>
> -- 
> Jens Axboe
>
> -
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