On 11/29/2010 05:56 PM, Pavel Shilovsky wrote:
> 2010/11/29 Suresh Jayaraman <sjayaraman@xxxxxxx>:
>> On 11/29/2010 05:07 PM, Jeff Layton wrote:
>>> On Mon, 29 Nov 2010 13:58:05 +0300
>>> Pavel Shilovsky <piastryyy@xxxxxxxxx> wrote:
>>>
>>>> 2010/11/28 Jeff Layton <jlayton@xxxxxxxxxx>:
>>>>> On Sun, 28 Nov 2010 06:36:04 -0500
>>>>> Jeff Layton <jlayton@xxxxxxxxxx> wrote:
>>>>>
>>>>>> On Sun, 28 Nov 2010 11:12:49 +0300
>>>>>> Pavel Shilovsky <piastryyy@xxxxxxxxx> wrote:
>>>>>>
>>>>>>> On strict cache mode if we don't have Exclusive oplock we write a data to
>>>>>>> the server through cifs_user_write. Then if we Level II oplock store it in
>>>>>>> the cache, otherwise - invalidate inode pages affected by this writing.
>>>>>>>
>>>>>>> Signed-off-by: Pavel Shilovsky <piastryyy@xxxxxxxxx>
>>>>>>> ---
>>>>>>> ïfs/cifs/cifsfs.c | ï 40 ++++++++++++++++++++++++++++++++++++----
>>>>>>> ï1 files changed, 36 insertions(+), 4 deletions(-)
>>>>>>>
>>>>>>> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
>>>>>>> index bbb5294..901c82b 100644
>>>>>>> --- a/fs/cifs/cifsfs.c
>>>>>>> +++ b/fs/cifs/cifsfs.c
>>>>>>> @@ -598,12 +598,44 @@ static ssize_t cifs_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
>>>>>>> ïstatic ssize_t cifs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
>>>>>>> ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ïunsigned long nr_segs, loff_t pos)
>>>>>>> ï{
>>>>>>> - ï struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
>>>>>>> + ï struct inode *inode;
>>>>>>> + ï struct cifs_sb_info *cifs_sb;
>>>>>>> ï ï ssize_t written;
>>>>>>>
>>>>>>> - ï written = generic_file_aio_write(iocb, iov, nr_segs, pos);
>>>>>>> - ï if (!CIFS_I(inode)->clientCanCacheAll)
>>>>>>> - ï ï ï ï ï filemap_fdatawrite(inode->i_mapping);
>>>>>>> + ï inode = iocb->ki_filp->f_path.dentry->d_inode;
>>>>>>> +
>>>>>>> + ï if (CIFS_I(inode)->clientCanCacheAll)
>>>>>>> + ï ï ï ï ï return generic_file_aio_write(iocb, iov, nr_segs, pos);
>>>>>>> +
>>>>>>> + ï cifs_sb = CIFS_SB(iocb->ki_filp->f_path.dentry->d_sb);
>>>>>>> +
>>>>>>> + ï if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO) == 0) {
>>>>>>> + ï ï ï ï ï int rc;
>>>>>>> +
>>>>>>> + ï ï ï ï ï written = generic_file_aio_write(iocb, iov, nr_segs, pos);
>>>>>>> +
>>>>>>> + ï ï ï ï ï rc = filemap_fdatawrite(inode->i_mapping);
>>>>>>> + ï ï ï ï ï if (rc)
>>>>>>> + ï ï ï ï ï ï ï ï ï cFYI(1, "cifs_file_aio_write: %d rc on %p inode",
>>>>>>> + ï ï ï ï ï ï ï ï ï ï ï ïrc, inode);
>>>>>>> + ï ï ï ï ï return written;
>>>>>>> + ï }
>>>>>>> +
>>>>>>> + ï /* in strict cache mode we need to write the data to the server exactly
>>>>>>> + ï ï ïfrom the pos to pos+len-1 rather than flush all affected pages
>>>>>>> + ï ï ïbecause it may cause a error with mandatory locks on these pages but
>>>>>>> + ï ï ïnot on the region from pos to ppos+len-1 */
>>>>>>
>>>>>> ï ï ï Again, please fix the comment style. Here: ^^^^
>>>>>>
>>>>>>> + ï written = cifs_user_write(iocb->ki_filp, iov->iov_base,
>>>>>>> + ï ï ï ï ï ï ï ï ï ï ï ï ï ï iov->iov_len, &pos);
>>>>>>> +
>>>>>>> + ï iocb->ki_pos = pos;
>>>>>>> +
>>>>>>> + ï /* if we were successful - invalidate inode pages the write affected */
>>>>>>> + ï if (written > 0)
>>>>>>> + ï ï ï ï ï invalidate_mapping_pages(inode->i_mapping,
>>>>>>> + ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï (pos-written) >> PAGE_CACHE_SHIFT,
>>>>>>> + ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï (pos-1) >> PAGE_CACHE_SHIFT);
>>>>>>> +
>>>>>>> ï ï return written;
>>>>>>> ï}
>>>>>>>
>>>>>>
>>>>>> May god have mercy on anyone who tries to mix strictcache and mmap.
>>>>>>
>>>>>> Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
>>>>>
>>>>> (cc'ing Suresh so he can comment)
>>>>>
>>>>> Actually...I'm going to withdraw my Reviewed-by tag here for now. This
>>>>> bare invalidate_mapping_pages doesn't deal with fscache.
>>>>>
>>>>> I think I need to understand what's intended when someone specifies
>>>>> strictcache and fsc before I can ack this. The simple answer would be
>>>>> that they are mutually exclusive, but if that's the case then the patch
>>>>> that adds the mount option needs to deal with that appropriately.
>>>>
>>>>
>>>> I don't think they can live together. I think we should do smth like a
>>>> following in mount options parsing:
>>>>
>>>> ...
>>>> if (opt == fscache) {
>>>> vol->fscahe = 1;
>>>> vol->strictcache = 0;
>>>> }
>>>> ...
>>>> if (opt == strictcache) {
>>>> vol->strictcache = 1;
>>>> vol->fscache = 0;
>>>> }
>>>>
>>>> So, if user specify both only the last will affect the client
>>>> behavior. Also we should add this information into cifs manpage.
>>>> Thoughts?
>>>>
>>>
>>> That would one way to deal with it.
>>>
>>> On the other hand though...fscache allows you to keep more data cached
>>> than you have RAM. This could be useful in a strictcache situation as
>>> well. Consider the case of an application on a client that has a lot of
>>> large files open for read. The server may grant oplocks on all of them.
>>> fscache would allow for fewer round trips to the server in such a case.
>>>
>>> So, another way to deal with it would be to simply invalidate the
>>> fscache whenever you'd invalidate the in-ram cache. I'm not sure what
>>> to do for the cifs_file_aio_write case where you're invalidating just a
>>> small range however.
>>>
>>
>> Yes, we seem to have those two options while the later has the advantage
>> that Jeff mentioned. I think we could do the later without much of a
>> problme. We just need to retire the cookies and get new ones
>> (relinquishing with retire set to 1) i.e. by calling
>> cifs_fscache_reset_inode_cookie(). FS-Cache does not provide data
>> invalidation by itself. For the cifs_file_aio_write case too we could
>> set invalid_mapping and get fresh cookies.
>>
>>
>
> What's about mmap and fsync patch? How do you think they mix with fscache?
>
Basically, relinquishing cookie when you are invalidating inode should
make them work without issues I think. But, I would also test your
patches (once you post the patchset that includes fscache handling as
well) to be sure.
Thanks,
--
Suresh Jayaraman
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