cifs: Allow directIO read/write during cache=strict

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@samsung.com>
Signed-off-by: Ashish Sangwan <a.sangwan@samsung.com>
Signed-off-by: Steve French <smfrench@gmail.com>

fs/cifs/dir.c

@@ -497,6 +497,14 @@ 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) {
+		if (CIFS_SB(inode->i_sb)->mnt_cifs_flags & CIFS_MOUNT_NO_BRL)
+			file->f_op = &cifs_file_direct_nobrl_ops;
+		else
+			file->f_op = &cifs_file_direct_ops;
+		}
+
 	file_info = cifs_new_fileinfo(&fid, file, tlink, oplock);
 	if (file_info == NULL) {
 		if (server->ops->close)

fs/cifs/file.c

@@ -467,6 +467,14 @@ 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) {
+		if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_BRL)
+			file->f_op = &cifs_file_direct_nobrl_ops;
+		else
+			file->f_op = &cifs_file_direct_ops;
+	}
+
 	if (server->oplocks)
 		oplock = REQ_OPLOCK;
 	else