On Wed, 26 Dec 2012 19:53:53 +0400
Pavel Shilovsky <piastry@xxxxxxxxxxx> wrote:
> If we have a read oplock and set a read lock in it, we can't write to the
> locked area - so, filemap_fdatawrite may fail with a no information for a
> userspace application even if we request a write to non-locked area. Fix
> this by writing directly to the server and then breaking oplock level from
> level2 to None.
>
> Also remove CONFIG_CIFS_SMB2 ifdefs because it's suitable for both CIFS
> and SMB2 protocols.
>
> Signed-off-by: Pavel Shilovsky <piastry@xxxxxxxxxxx>
> ---
> fs/cifs/file.c | 48 ++++++++++++++++++++----------------------------
> 1 file changed, 20 insertions(+), 28 deletions(-)
>
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index 1b322d0..22c3725 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -2505,42 +2505,34 @@ cifs_strict_writev(struct kiocb *iocb, const struct iovec *iov,
> struct cifsFileInfo *cfile = (struct cifsFileInfo *)
> iocb->ki_filp->private_data;
> struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
> + ssize_t written;
>
> -#ifdef CONFIG_CIFS_SMB2
> - /*
> - * If we have an oplock for read and want to write a data to the file
> - * we need to store it in the page cache and then push it to the server
> - * to be sure the next read will get a valid data.
> - */
> - if (!cinode->clientCanCacheAll && cinode->clientCanCacheRead) {
> - ssize_t written;
> - int rc;
> -
> - written = generic_file_aio_write(iocb, iov, nr_segs, pos);
> - rc = filemap_fdatawrite(inode->i_mapping);
> - if (rc)
> - return (ssize_t)rc;
> -
> - return written;
> + if (cinode->clientCanCacheAll) {
> + if (cap_unix(tcon->ses) &&
> + (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability))
> + && ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0))
> + return generic_file_aio_write(iocb, iov, nr_segs, pos);
> + return cifs_writev(iocb, iov, nr_segs, pos);
> }
> -#endif
> -
> /*
> * For non-oplocked files 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.
> */
> -
> - if (!cinode->clientCanCacheAll)
> - return cifs_user_writev(iocb, iov, nr_segs, pos);
> -
> - if (cap_unix(tcon->ses) &&
> - (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability)) &&
> - ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0))
> - return generic_file_aio_write(iocb, iov, nr_segs, pos);
> -
> - return cifs_writev(iocb, iov, nr_segs, pos);
> + written = cifs_user_writev(iocb, iov, nr_segs, pos);
> + if (written > 0 && cinode->clientCanCacheRead) {
> + /*
> + * Windows 7 server can delay breaking level2 oplock if a write
> + * request comes - break it on the client to prevent reading
> + * an old data.
> + */
> + cifs_invalidate_mapping(inode);
> + cFYI(1, "Set no oplock for inode=%p after a write operation",
> + inode);
> + cinode->clientCanCacheRead = false;
In the above case, do we also need to inform the server
that we're dropping the oplock here and that it doesn't
need to be recalled? Is there a way to send an
unsolicited "I'm dropping this oplock" to the server?
Also, I'm still not 100% comfortable with the lack of
locking around these clientCanCache* flags. It seems
unlikely but could we end up racing with the grant of a
CanCacheAll oplock here?
> + }
> + return written;
> }
>
> static struct cifs_readdata *
Looks like a much nicer scheme than you originally had. Even with the
lack of locking around the CanCache* flags, I think this doesn't make
things any worse.
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
--
To unsubscribe from this list: send the line "unsubscribe linux-cifs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
