From: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Date: Sun, 15 Dec 2019 19:58:59 +0000 (+0100)
Subject: shared/loop-util: spin on open() returning ENOENT too
X-Git-Tag: v245-rc1~261^2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=01813148619cb4b78427abe1cb8ccbe2b9916a03;p=thirdparty%2Fsystemd.git

shared/loop-util: spin on open() returning ENOENT too

https://github.com/systemd/systemd/pull/14261#discussion_r355001559
---

diff --git a/src/shared/loop-util.c b/src/shared/loop-util.c
index 8b4d13e6164..6cb45f1f1bc 100644
--- a/src/shared/loop-util.c
+++ b/src/shared/loop-util.c
@@ -112,14 +112,20 @@ int loop_device_make_full(
                         return -ENOMEM;
 
                 loop = open(loopdev, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|open_flags);
-                if (loop < 0)
-                        return -errno;
-                if (ioctl(loop, LOOP_SET_FD, fd) >= 0) {
-                        loop_with_fd = TAKE_FD(loop);
-                        break;
+                if (loop < 0) {
+                        /* Somebody might've gotten the same number from the kernel, used the device,
+                         * and called LOOP_CTL_REMOVE on it. Let's retry with a new number. */
+                        if (errno != ENOENT)
+                                return -errno;
+                } else {
+                        if (ioctl(loop, LOOP_SET_FD, fd) >= 0) {
+                                loop_with_fd = TAKE_FD(loop);
+                                break;
+                        }
+                        if (errno != EBUSY)
+                                return -errno;
                 }
-                if (errno != EBUSY)
-                        return -errno;
+
                 if (++n_attempts >= 64) /* Give up eventually */
                         return -EBUSY;