Allow dev_open to work on read-only /dev

/dev could be read-only in which case we cannot make devices
there.
So dev_open should first try to use an existing device name,
and if that doesn't work try creating a node in /dev or /tmp.

Reported-by:  Paweł Sikora <pluto@agmk.net>
Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/util.c b/util.c
index 0b9949abe38f2a7733ee417d5f9aa202e811ac31..c9bdd6eb8e1a565734ccf91f8a4f665c13db5169 100644 (file)
--- a/util.c
+++ b/util.c
@@ -959,19 +959,33 @@ int dev_open(char *dev, int flags)
        int minor;
 
        if (!dev) return -1;
+       flags |= O_DIRECT;
 
        major = strtoul(dev, &e, 0);
        if (e > dev && *e == ':' && e[1] &&
            (minor = strtoul(e+1, &e, 0)) >= 0 &&
            *e == 0) {
-               snprintf(devname, sizeof(devname), "/dev/.tmp.md.%d:%d:%d",
-                        (int)getpid(), major, minor);
-               if (mknod(devname, S_IFBLK|0600, makedev(major, minor))==0) {
-                       fd = open(devname, flags|O_DIRECT);
-                       unlink(devname);
+               char *path = map_dev(major, minor, 0);
+               if (path)
+                       fd = open(path, flags);
+               if (fd < 0) {
+                       snprintf(devname, sizeof(devname), "/dev/.tmp.md.%d:%d:%d",
+                                (int)getpid(), major, minor);
+                       if (mknod(devname, S_IFBLK|0600, makedev(major, minor))==0) {
+                               fd = open(devname, flags);
+                               unlink(devname);
+                       }
+               }
+               if (fd < 0) {
+                       snprintf(devname, sizeof(devname), "/tmp/.tmp.md.%d:%d:%d",
+                                (int)getpid(), major, minor);
+                       if (mknod(devname, S_IFBLK|0600, makedev(major, minor))==0) {
+                               fd = open(devname, flags);
+                               unlink(devname);
+                       }
                }
        } else
-               fd = open(dev, flags|O_DIRECT);
+               fd = open(dev, flags);
        return fd;
 }