On Wed, 26 Dec 2012 19:53:53 +0400 Pavel Shilovsky <[email protected]> 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 <[email protected]> > --- > 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 <[email protected]> -- 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
