ksmbd: use ksmbd_vfs_lock_parent to get stable parent dentry

Use ksmbd_vfs_lock_parent to get stable parent dentry and remove
PARENT_INODE macro.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/ksmbd/smb2pdu.c

@@ -5538,6 +5538,9 @@ static int set_rename_info(struct ksmbd_work *work, struct ksmbd_file *fp,
 			   char *buf)
 {
 	struct ksmbd_file *parent_fp;
+	struct dentry *parent;
+	struct dentry *dentry = fp->filp->f_path.dentry;
+	int ret;
 
 	if (!(fp->daccess & FILE_DELETE_LE)) {
 		pr_err("no right to delete : 0x%x\n", fp->daccess);
@@ -5547,7 +5550,17 @@ static int set_rename_info(struct ksmbd_work *work, struct ksmbd_file *fp,
 	if (ksmbd_stream_fd(fp))
 		goto next;
 
-	parent_fp = ksmbd_lookup_fd_inode(PARENT_INODE(fp));
+	parent = dget_parent(dentry);
+	ret = ksmbd_vfs_lock_parent(parent, dentry);
+	if (ret) {
+		dput(parent);
+		return ret;
+	}
+
+	parent_fp = ksmbd_lookup_fd_inode(d_inode(parent));
+	inode_unlock(d_inode(parent));
+	dput(parent);
+
 	if (parent_fp) {
 		if (parent_fp->daccess & FILE_DELETE_LE) {
 			pr_err("parent dir is opened with delete access\n");

fs/ksmbd/vfs.c

@@ -69,7 +69,7 @@ static void ksmbd_vfs_inherit_owner(struct ksmbd_work *work,
  *
  * the reference count of @parent isn't incremented.
  */
-static int ksmbd_vfs_lock_parent(struct dentry *parent, struct dentry *child)
+int ksmbd_vfs_lock_parent(struct dentry *parent, struct dentry *child)
 {
 	struct dentry *dentry;
 	int ret = 0;

fs/ksmbd/vfs.h

@@ -192,6 +192,7 @@ struct ksmbd_kstat {
 	__le32			file_attributes;
 };
 
+int ksmbd_vfs_lock_parent(struct dentry *parent, struct dentry *child);
 int ksmbd_vfs_may_delete(struct dentry *dentry);
 int ksmbd_vfs_query_maximal_access(struct dentry *dentry, __le32 *daccess);
 int ksmbd_vfs_create(struct ksmbd_work *work, const char *name, umode_t mode);

fs/ksmbd/vfs_cache.h

@@ -25,8 +25,6 @@
 #define KSMBD_NO_FID		(UINT_MAX)
 #define SMB2_NO_FID		(0xFFFFFFFFFFFFFFFFULL)
 
-#define PARENT_INODE(fp)	d_inode((fp)->filp->f_path.dentry->d_parent)
-
 #define ATTR_FP(fp) ((fp)->attrib_only && \
 		     ((fp)->cdoption != FILE_OVERWRITE_IF_LE && \
 		      (fp)->cdoption != FILE_OVERWRITE_LE && \