CIFS: Implement cifs_strict_fsync

Invalidate inode mapping if we don't have at least Level II oplock in
cifs_strict_fsync. Also remove filemap_write_and_wait call from cifs_fsync
because it is previously called from vfs_fsync_range. Add file operations'
structures for strict cache mode.

Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Pavel Shilovsky <piastryyy@gmail.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 1b26c27..5790fab7 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1528,27 +1528,47 @@
 	return rc;
 }
 
-int cifs_fsync(struct file *file, int datasync)
+int cifs_strict_fsync(struct file *file, int datasync)
 {
 	int xid;
 	int rc = 0;
 	struct cifsTconInfo *tcon;
 	struct cifsFileInfo *smbfile = file->private_data;
 	struct inode *inode = file->f_path.dentry->d_inode;
+	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 
 	xid = GetXid();
 
 	cFYI(1, "Sync file - name: %s datasync: 0x%x",
 		file->f_path.dentry->d_name.name, datasync);
 
-	rc = filemap_write_and_wait(inode->i_mapping);
-	if (rc == 0) {
-		struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
+	if (!CIFS_I(inode)->clientCanCacheRead)
+		cifs_invalidate_mapping(inode);
 
-		tcon = tlink_tcon(smbfile->tlink);
-		if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOSSYNC))
-			rc = CIFSSMBFlush(xid, tcon, smbfile->netfid);
-	}
+	tcon = tlink_tcon(smbfile->tlink);
+	if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOSSYNC))
+		rc = CIFSSMBFlush(xid, tcon, smbfile->netfid);
+
+	FreeXid(xid);
+	return rc;
+}
+
+int cifs_fsync(struct file *file, int datasync)
+{
+	int xid;
+	int rc = 0;
+	struct cifsTconInfo *tcon;
+	struct cifsFileInfo *smbfile = file->private_data;
+	struct cifs_sb_info *cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
+
+	xid = GetXid();
+
+	cFYI(1, "Sync file - name: %s datasync: 0x%x",
+		file->f_path.dentry->d_name.name, datasync);
+
+	tcon = tlink_tcon(smbfile->tlink);
+	if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOSSYNC))
+		rc = CIFSSMBFlush(xid, tcon, smbfile->netfid);
 
 	FreeXid(xid);
 	return rc;