From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Thu, 8 Sep 2022 20:04:08 +0000 (+0900)
Subject: loop-util: always check if backing file is not attached yet
X-Git-Tag: v252-rc1~219^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=53274fdb59ea2c68253cb143791de1aea5168183;p=thirdparty%2Fsystemd.git

loop-util: always check if backing file is not attached yet

An image file without partition table may be attached.
---

diff --git a/src/shared/loop-util.c b/src/shared/loop-util.c
index 69f35951798..1cc3f2642eb 100644
--- a/src/shared/loop-util.c
+++ b/src/shared/loop-util.c
@@ -264,6 +264,14 @@ static int loop_configure(
         if (lock_fd < 0)
                 return lock_fd;
 
+        /* Let's see if backing file is really unattached. Someone may already attach a backing file without
+         * taking BSD lock. */
+        r = loop_is_bound(fd);
+        if (r < 0)
+                return r;
+        if (r > 0)
+                return -EBUSY;
+
         /* Let's see if the device is really detached, i.e. currently has no associated partition block
          * devices. On various kernels (such as 5.8) it is possible to have a loopback block device that
          * superficially is detached but still has partition block devices associated for it. Let's then
@@ -273,14 +281,8 @@ static int loop_configure(
         if (r < 0)
                 return r;
         if (r > 0) {
-                r = loop_is_bound(fd);
-                if (r < 0)
-                        return r;
-                if (r > 0)
-                        return -EBUSY;
-
-                /* Unbound but has children? Remove all partitions, and report this to the caller, to try
-                 * again, and count this as an attempt. */
+                /* Remove all partitions, and report this to the caller, to try again, and count this as
+                 * an attempt. */
 
                 r = block_device_remove_all_partitions(dev, fd);
                 if (r < 0)