On Thu, 21 Aug 2014 08:24:35 -0500
Steve French <smfrench@xxxxxxxxx> wrote:
> If you are opening O_DIRECT why wouldn't you use oplock, ie still
> request oplock, simply to minimize metadata traffic (you don't have to
> send stat across the wire). The reads and writes aren't cached but
> the inode metadata would be.
>
What updates the i_size if a DIO write extends the file?
> On Thu, Aug 21, 2014 at 6:26 AM, Jeff Layton <jlayton@xxxxxxxxxxxxxxx> wrote:
> > On Wed, 20 Aug 2014 19:39:11 +0900
> > Namjae Jeon <namjae.jeon@xxxxxxxxxxx> wrote:
> >
> >> Currently cifs have all or nothing approach for directIO operations.
> >> cache=strict mode does not allow directIO while cache=none mode performs
> >> all the operations as directIO even when user does not specify O_DIRECT
> >> flag. This patch enables strict cache mode to honour directIO semantics.
> >>
> >> Signed-off-by: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
> >> Signed-off-by: Ashish Sangwan <a.sangwan@xxxxxxxxxxx>
> >> ---
> >> fs/cifs/dir.c | 4 ++++
> >> fs/cifs/file.c | 4 ++++
> >> 2 files changed, 8 insertions(+), 0 deletions(-)
> >>
> >> diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
> >> index 3db0c5f..30e377c 100644
> >> --- a/fs/cifs/dir.c
> >> +++ b/fs/cifs/dir.c
> >> @@ -497,6 +497,10 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry,
> >> goto out;
> >> }
> >>
> >> + if (file->f_flags & O_DIRECT &&
> >> + CIFS_SB(inode->i_sb)->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO)
> >> + file->f_op = &cifs_file_direct_ops;
> >> +
> >> file_info = cifs_new_fileinfo(&fid, file, tlink, oplock);
> >> if (file_info == NULL) {
> >> if (server->ops->close)
> >> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> >> index bee733e..0d07740 100644
> >> --- a/fs/cifs/file.c
> >> +++ b/fs/cifs/file.c
> >> @@ -467,6 +467,10 @@ int cifs_open(struct inode *inode, struct file *file)
> >> cifs_dbg(FYI, "inode = 0x%p file flags are 0x%x for %s\n",
> >> inode, file->f_flags, full_path);
> >>
> >> + if (file->f_flags & O_DIRECT &&
> >> + cifs_sb->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO)
> >> + file->f_op = &cifs_file_direct_ops;
> >> +
> >> if (server->oplocks)
> >> oplock = REQ_OPLOCK;
> >> else
> >
> > Looks fine for the most part. You should also avoid requesting an
> > oplock if you're going to open O_DIRECT since you won't be using it
> > anyway.
> >
> > --
> > Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
>
>
>
--
Jeff Layton <jlayton@xxxxxxxxx>
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