cifs: ignore resource_id while getting fscache super cookie

We have a cyclic dependency between fscache super cookie
and root inode cookie. The super cookie relies on
tcon->resource_id, which gets populated from the root inode
number. However, fetching the root inode initializes inode
cookie as a child of super cookie, which is yet to be populated.

resource_id is only used as auxdata to check the validity of
super cookie. We can completely avoid setting resource_id to
remove the circular dependency. Since vol creation time and
vol serial numbers are used for auxdata, we should be fine.
Additionally, there will be auxiliary data check for each
inode cookie as well.

Fixes: 5bf91ef ("cifs: wait for tcon resource_id before getting fscache super")
CC: David Howells <[email protected]>
Signed-off-by: Shyam Prasad N <[email protected]>
Signed-off-by: Steve French <[email protected]>

Author: sprasad-microsoft

fs/cifs/connect.c

@@ -3064,6 +3064,13 @@ static int mount_get_conns(struct mount_ctx *mnt_ctx)
 	    (cifs_sb->ctx->rsize > server->ops->negotiate_rsize(tcon, ctx)))
 		cifs_sb->ctx->rsize = server->ops->negotiate_rsize(tcon, ctx);
 
+	/*
+	 * The cookie is initialized from volume info returned above.
+	 * Inside cifs_fscache_get_super_cookie it checks
+	 * that we do not get super cookie twice.
+	 */
+	cifs_fscache_get_super_cookie(tcon);
+
 out:
 	mnt_ctx->server = server;
 	mnt_ctx->ses = ses;

fs/cifs/inode.c

@@ -1356,11 +1356,6 @@ struct inode *cifs_root_iget(struct super_block *sb)
 		goto out;
 	}
 
-#ifdef CONFIG_CIFS_FSCACHE
-	/* populate tcon->resource_id */
-	tcon->resource_id = CIFS_I(inode)->uniqueid;
-#endif
-
 	if (rc && tcon->pipe) {
 		cifs_dbg(FYI, "ipc connection - fake read inode\n");
 		spin_lock(&inode->i_lock);
@@ -1375,14 +1370,6 @@ struct inode *cifs_root_iget(struct super_block *sb)
 		iget_failed(inode);
 		inode = ERR_PTR(rc);
 	}
-
-	/*
-	 * The cookie is initialized from volume info returned above.
-	 * Inside cifs_fscache_get_super_cookie it checks
-	 * that we do not get super cookie twice.
-	 */
-	cifs_fscache_get_super_cookie(tcon);
-
 out:
 	kfree(path);
 	free_xid(xid);