On 1/25/15, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
> On Tue, Jan 13, 2015 at 11:44:46PM +0800, Ming Lei wrote:
>>
>> - if (dio->is_async && dio->rw == READ)
>> + if (dio->is_async && dio->rw == READ && dio->should_dirty)
>> bio_set_pages_dirty(bio);
>>
>> if (sdio->submit_io)
>> @@ -463,13 +464,14 @@ static int dio_bio_complete(struct dio *dio, struct
>> bio *bio)
>> if (!uptodate)
>> dio->io_error = -EIO;
>>
>> - if (dio->is_async && dio->rw == READ) {
>> + if (dio->is_async && dio->rw == READ && dio->should_dirty) {
>
> I'd rather have a ->should_dirrty flag that means we need to call
> bio_check_pages_dirty, And set that either if we have a kernel
> iovec/bvec or dio->is_async && dio->rw == READ.
It may not work for loop because the page may not become dirty
until the read dio is completed, so it just means the caller totally
handles the page dirty if I/O is from kernel.
>
> But why would we even set this if writing from an iovec?
Or just rename it as ->from_user?
>> bio_check_pages_dirty(bio); /* transfers ownership */
>> } else {
>> bio_for_each_segment_all(bvec, bio, i) {
>> struct page *page = bvec->bv_page;
>>
>> - if (dio->rw == READ && !PageCompound(page))
>> + if (dio->rw == READ && !PageCompound(page) &&
>> + dio->should_dirty)
>> set_page_dirty_lock(page);
>
> And this unk could also use some explanation.
This is same, just don't handle page dirty for kernel dio pages.
Thanks,
Ming Lei
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