Update Linux to v5.4.148

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.148.tar.gz

Change-Id: Ib3d26c5ba9b022e2e03533005c4fed4d7c30b61b
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index 95d9aeb..4885851 100644
--- a/fs/btrfs/xattr.c
+++ b/fs/btrfs/xattr.c
@@ -227,11 +227,33 @@
 {
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct btrfs_trans_handle *trans;
+	const bool start_trans = (current->journal_info == NULL);
 	int ret;
 
-	trans = btrfs_start_transaction(root, 2);
-	if (IS_ERR(trans))
-		return PTR_ERR(trans);
+	if (start_trans) {
+		/*
+		 * 1 unit for inserting/updating/deleting the xattr
+		 * 1 unit for the inode item update
+		 */
+		trans = btrfs_start_transaction(root, 2);
+		if (IS_ERR(trans))
+			return PTR_ERR(trans);
+	} else {
+		/*
+		 * This can happen when smack is enabled and a directory is being
+		 * created. It happens through d_instantiate_new(), which calls
+		 * smack_d_instantiate(), which in turn calls __vfs_setxattr() to
+		 * set the transmute xattr (XATTR_NAME_SMACKTRANSMUTE) on the
+		 * inode. We have already reserved space for the xattr and inode
+		 * update at btrfs_mkdir(), so just use the transaction handle.
+		 * We don't join or start a transaction, as that will reset the
+		 * block_rsv of the handle and trigger a warning for the start
+		 * case.
+		 */
+		ASSERT(strncmp(name, XATTR_SECURITY_PREFIX,
+			       XATTR_SECURITY_PREFIX_LEN) == 0);
+		trans = current->journal_info;
+	}
 
 	ret = btrfs_setxattr(trans, inode, name, value, size, flags);
 	if (ret)
@@ -242,7 +264,8 @@
 	ret = btrfs_update_inode(trans, root, inode);
 	BUG_ON(ret);
 out:
-	btrfs_end_transaction(trans);
+	if (start_trans)
+		btrfs_end_transaction(trans);
 	return ret;
 }