From 5613df4f663cb8ca5fad3fc9e563baa83b0cebe1 Mon Sep 17 00:00:00 2001
From: Kirk McKusick <mckusick@FreeBSD.org>
Date: Sun, 8 Apr 2018 06:59:42 +0000
Subject: [PATCH] The ufs_disk_write() function is used to upgrade a read-only
 descriptor to a read-write descriptor. Do not close the read-only descriptor
 until the read-write is successfully obtained. Before this fix, a failed
 upgrade left no usable descriptor with which to work.

---
 lib/libufs/type.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/lib/libufs/type.c b/lib/libufs/type.c
index 498b71ab954d..bcbb1914c497 100644
--- a/lib/libufs/type.c
+++ b/lib/libufs/type.c
@@ -60,6 +60,7 @@ ufs_disk_close(struct uufsd *disk)
 {
 	ERROR(disk, NULL);
 	close(disk->d_fd);
+	disk->d_fd = -1;
 	if (disk->d_inoblock != NULL) {
 		free(disk->d_inoblock);
 		disk->d_inoblock = NULL;
@@ -181,19 +182,21 @@ again:	if ((ret = stat(name, &st)) < 0) {
 int
 ufs_disk_write(struct uufsd *disk)
 {
+	int fd;
+
 	ERROR(disk, NULL);
 
 	if (disk->d_mine & MINE_WRITE)
 		return (0);
 
-	close(disk->d_fd);
-
-	disk->d_fd = open(disk->d_name, O_RDWR);
-	if (disk->d_fd < 0) {
+	fd = open(disk->d_name, O_RDWR);
+	if (fd < 0) {
 		ERROR(disk, "failed to open disk for writing");
 		return (-1);
 	}
 
+	close(disk->d_fd);
+	disk->d_fd = fd;
 	disk->d_mine |= MINE_WRITE;
 
 	return (0);