mount-util: fix error code

If multiple service is starting simultaneously with a shared image,
then one of the service may fail to create a mount node:

systemd[695]: Bind-mounting /usr/lib/os-release on /run/systemd/unit-root/run/host/os-release (MS_BIND|MS_REC "")...
systemd[696]: Bind-mounting /usr/lib/os-release on /run/systemd/unit-root/run/host/os-release (MS_BIND|MS_REC "")...
systemd[695]: Failed to mount /usr/lib/os-release (type n/a) on /run/systemd/unit-root/run/host/os-release (MS_BIND|MS_REC ""): No such file or directory
systemd[696]: Failed to mount /usr/lib/os-release (type n/a) on /run/systemd/unit-root/run/host/os-release (MS_BIND|MS_REC ""): No such file or directory
systemd[695]: Bind-mounting /usr/lib/os-release on /run/systemd/unit-root/run/host/os-release (MS_BIND|MS_REC "")...
systemd[696]: Failed to create destination mount point node '/run/systemd/unit-root/run/host/os-release': Operation not permitted
systemd[695]: Successfully mounted /usr/lib/os-release to /run/systemd/unit-root/run/host/os-release

The function apply_one_mount() in src/core/namespace.c gracefully
handles -EEXIST from make_mount_point_inode_from_path(), but it erroneously
returned -EPERM previously. This fixes the issue.

Fixes one of the issues in #24147, especially reported at
https://github.com/systemd/systemd/issues/24147#issuecomment-1236194671.

diff --git a/src/shared/mount-util.c b/src/shared/mount-util.c
index 290bbec4dfbd9f66ad27b6f25720406692ada980..2dd73b508d1b0d5139bc622d46196e78df30d7f8 100644 (file)
--- a/src/shared/mount-util.c
+++ b/src/shared/mount-util.c
@@ -1138,7 +1138,7 @@ int make_mount_point_inode_from_stat(const struct stat *st, const char *dest, mo
         if (S_ISDIR(st->st_mode))
                 return mkdir_label(dest, mode);
         else
-                return mknod(dest, S_IFREG|(mode & ~0111), 0);
+                return RET_NERRNO(mknod(dest, S_IFREG|(mode & ~0111), 0));
 }
 
 int make_mount_point_inode_from_path(const char *source, const char *dest, mode_t mode) {