2010/11/29 Suresh Jayaraman <[email protected]>: > On 11/29/2010 05:07 PM, Jeff Layton wrote: >> On Mon, 29 Nov 2010 13:58:05 +0300 >> Pavel Shilovsky <[email protected]> wrote: >> >>> 2010/11/28 Jeff Layton <[email protected]>: >>>> On Sun, 28 Nov 2010 06:36:04 -0500 >>>> Jeff Layton <[email protected]> wrote: >>>> >>>>> On Sun, 28 Nov 2010 11:12:49 +0300 >>>>> Pavel Shilovsky <[email protected]> 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 <[email protected]> >>>>>> --- >>>>>> �fs/cifs/cifsfs.c | � 40 ++++++++++++++++++++++++++++++++++++---- >>>>>> �1 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, >>>>>> �static ssize_t cifs_file_aio_write(struct kiocb *iocb, const struct >>>>>> iovec *iov, >>>>>> � � � � � � � � � � � � � � � �unsigned long nr_segs, loff_t pos) >>>>>> �{ >>>>>> - � struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode; >>>>>> + � struct inode *inode; >>>>>> + � struct cifs_sb_info *cifs_sb; >>>>>> � � ssize_t written; >>>>>> >>>>>> - � written = generic_file_aio_write(iocb, iov, nr_segs, pos); >>>>>> - � if (!CIFS_I(inode)->clientCanCacheAll) >>>>>> - � � � � � filemap_fdatawrite(inode->i_mapping); >>>>>> + � inode = iocb->ki_filp->f_path.dentry->d_inode; >>>>>> + >>>>>> + � if (CIFS_I(inode)->clientCanCacheAll) >>>>>> + � � � � � return generic_file_aio_write(iocb, iov, nr_segs, pos); >>>>>> + >>>>>> + � cifs_sb = CIFS_SB(iocb->ki_filp->f_path.dentry->d_sb); >>>>>> + >>>>>> + � if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO) == 0) { >>>>>> + � � � � � int rc; >>>>>> + >>>>>> + � � � � � written = generic_file_aio_write(iocb, iov, nr_segs, pos); >>>>>> + >>>>>> + � � � � � rc = filemap_fdatawrite(inode->i_mapping); >>>>>> + � � � � � if (rc) >>>>>> + � � � � � � � � � cFYI(1, "cifs_file_aio_write: %d rc on %p inode", >>>>>> + � � � � � � � � � � � �rc, inode); >>>>>> + � � � � � return written; >>>>>> + � } >>>>>> + >>>>>> + � /* in strict cache mode we need to write the data to the server >>>>>> exactly >>>>>> + � � �from the pos to pos+len-1 rather than flush all affected pages >>>>>> + � � �because it may cause a error with mandatory locks on these pages >>>>>> but >>>>>> + � � �not on the region from pos to ppos+len-1 */ >>>>> >>>>> � � � Again, please fix the comment style. Here: ^^^^ >>>>> >>>>>> + � written = cifs_user_write(iocb->ki_filp, iov->iov_base, >>>>>> + � � � � � � � � � � � � � � iov->iov_len, &pos); >>>>>> + >>>>>> + � iocb->ki_pos = pos; >>>>>> + >>>>>> + � /* if we were successful - invalidate inode pages the write affected >>>>>> */ >>>>>> + � if (written > 0) >>>>>> + � � � � � invalidate_mapping_pages(inode->i_mapping, >>>>>> + � � � � � � � � � � � � � � � � � � � � (pos-written) >> >>>>>> PAGE_CACHE_SHIFT, >>>>>> + � � � � � � � � � � � � � � � � � � � � (pos-1) >> PAGE_CACHE_SHIFT); >>>>>> + >>>>>> � � return written; >>>>>> �} >>>>>> >>>>> >>>>> May god have mercy on anyone who tries to mix strictcache and mmap. >>>>> >>>>> Reviewed-by: Jeff Layton <[email protected]> >>>> >>>> (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? -- Best regards, Pavel Shilovsky. -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
