2010/9/12 Jeff Layton <jlayton@xxxxxxxxx>:
> This should probably be a set of patches that outlines each change.
> There are 3, AFAICT:
Ok, no problem with this, I will post it soon.
> 1) it bypasses the cache for reads when we have no oplock. Seems
> straightforward.
>
> 2) the cache is invalidated on close. So, no caching of data between
> open and close. Again ugly for performance but good for strict cache
> consistency.
>
> 3) write_end is doing a single page synchronous write when there is no
> oplock. This is going to be really ugly. Anytime you don't have an
> oplock, you'll be doing PAGE_SIZE writes to the server. Why not instead
> simply have cifs_file_aio_write do a filemap_write_and_wait or
> something if it there is no oplock?
I think I didn't understand you in this case. Let's look on the code:
1622 >-------if (!PageUptodate(page) || !CIFS_I(inode)->clientCanCacheAll) {
1623 >------->-------char *page_data;
1624 >------->-------unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
1625 >------->-------int xid;
1626
1627 >------->-------xid = GetXid();
1628 >------->-------/* this is probably better than directly calling
1629 >------->------- partialpage_write since in this function the
file handle is
1630 >------->------- known which we might as well>leverage */
1631 >------->-------/* BB check if anything else missing out of ppw
1632 >------->------- such as updating last write time */
1633 >------->-------page_data = kmap(page);
1634 >------->-------rc = cifs_write(file, page_data + offset, copied, &pos);
We are writing 'copied' bytes from 'offset' of 'page_data'. Why do you
think that we are doing PAGE_SIZE write to the server?
1635 >------->-------/* if (rc < 0) should we set writebehind rc? */
1636 >------->-------kunmap(page);
1637
1638 >------->-------FreeXid(xid);
1639 >-------} else {
--
Best regards,
Pavel Shilovsky.
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