Allow scanning of devices listed in /proc/partitions independant of /dev

If a device found in /proc/partitions isn't listed in /dev, then
mknod a temporary name and open that.

Signed-off-by: Neil Brown <neilb@suse.de>

Assemble.c

@@ -195,7 +195,7 @@ int Assemble(struct supertype *st, char *mddev, int mdfd,
 			super = NULL;
 		}
 		
-		dfd = open(devname, O_RDONLY|O_EXCL, 0);
+		dfd = dev_open(devname, O_RDONLY|O_EXCL);
 		if (dfd < 0) {
 			if ((inargv && verbose >= 0) || verbose > 0)
 				fprintf(stderr, Name ": cannot open device %s: %s\n",
@@ -287,7 +287,7 @@ int Assemble(struct supertype *st, char *mddev, int mdfd,
 			
 			st->ss->update_super(&info, super, update, devname, verbose);
 			
-			dfd = open(devname, O_RDWR|O_EXCL, 0);
+			dfd = dev_open(devname, O_RDWR|O_EXCL);
 			if (dfd < 0) 
 				fprintf(stderr, Name ": Cannot open %s for superblock update\n",
 					devname);
@@ -418,7 +418,7 @@ int Assemble(struct supertype *st, char *mddev, int mdfd,
 				devices[chosen_drive].devname, devices[chosen_drive].raid_disk,
 				(int)(devices[chosen_drive].events),
 				(int)(devices[most_recent].events));
-		fd = open(devices[chosen_drive].devname, O_RDWR|O_EXCL);
+		fd = dev_open(devices[chosen_drive].devname, O_RDWR|O_EXCL);
 		if (fd < 0) {
 			fprintf(stderr, Name ": Couldn't open %s for write - not updating\n",
 				devices[chosen_drive].devname);
@@ -468,7 +468,7 @@ int Assemble(struct supertype *st, char *mddev, int mdfd,
 		if (!devices[j].uptodate)
 			continue;
 		chosen_drive = j;
-		if ((fd=open(devices[j].devname, O_RDONLY|O_EXCL))< 0) {
+		if ((fd=dev_open(devices[j].devname, O_RDONLY|O_EXCL))< 0) {
 			fprintf(stderr, Name ": Cannot open %s: %s\n",
 				devices[j].devname, strerror(errno));
 			return 1;
@@ -534,7 +534,7 @@ int Assemble(struct supertype *st, char *mddev, int mdfd,
 
 	if (change) {
 		int fd;
-		fd = open(devices[chosen_drive].devname, O_RDWR|O_EXCL);
+		fd = dev_open(devices[chosen_drive].devname, O_RDWR|O_EXCL);
 		if (fd < 0) {
 			fprintf(stderr, Name ": Could open %s for write - cannot Assemble array.\n",
 				devices[chosen_drive].devname);

ChangeLog

@@ -4,6 +4,8 @@ Changes Prior to this release
     -   Support little-endian (Rather than hostendian) bitmaps.
     -   Return correct error code from 'mdadm -S'
     -   Remove extra blank line from 'mdadm -Eb' output.
+    -   Allow scanning of devices listed in /proc/partitions even
+	if they don't appear in /dev.
 
 Changes Prior to 2.1 release
     -   Fix assembling of raid10 array when devices are missing.

Examine.c

@@ -51,7 +51,7 @@ int Examine(mddev_dev_t devlist, int brief, int scan, int SparcAdjust, struct su
 	 *   utime, state etc
 	 *
 	 * If (brief) gather devices for same array and just print a mdadm.conf line including devices=
-	 * if devlist==NULL, use conf_get_devs(
+	 * if devlist==NULL, use conf_get_devs()
 	 */
 	int fd; 
 	void *super = NULL;
@@ -71,7 +71,7 @@ int Examine(mddev_dev_t devlist, int brief, int scan, int SparcAdjust, struct su
 	for (; devlist ; devlist=devlist->next) {
 		struct supertype *st = forcest;
 
-		fd = open(devlist->devname, O_RDONLY);
+		fd = dev_open(devlist->devname, O_RDONLY);
 		if (fd < 0) {
 			if (!scan)
 				fprintf(stderr,Name ": cannot open %s: %s\n",

config.c

@@ -214,6 +214,8 @@ mddev_dev_t load_partitions(void)
 	while (fgets(buf, 1024, f)) {
 		int major, minor;
 		char *name, *mp;
+		mddev_dev_t d;
+
 		buf[1023] = '\0';
 		if (buf[0] != ' ')
 			continue;
@@ -223,14 +225,15 @@ mddev_dev_t load_partitions(void)
 		minor = strtoul(mp, NULL, 10);
 
 		name = map_dev(major, minor);
-		if (name) {
-			mddev_dev_t d;
-
-			d = malloc(sizeof(*d));
-			d->devname = strdup(name);
-			d->next = rv;
-			rv = d;
+		if (!name) {
+			snprintf(buf, 1024, "%d:%d", major, minor);
+			name = buf;
 		}
+
+		d = malloc(sizeof(*d));
+		d->devname = strdup(name);
+		d->next = rv;
+		rv = d;
 	}
 	fclose(f);
 	return rv;

mdadm.h

@@ -278,6 +278,7 @@ extern int check_reiser(int fd, char *name);
 extern int check_raid(int fd, char *name);
 
 extern int get_mdp_major(void);
+extern int dev_open(char *dev, int flags);
 extern int is_standard(char *dev, int *nump);
 
 

util.c

@@ -589,7 +589,28 @@ void put_md_name(char *name)
 		unlink(name);
 }
 
-
+int dev_open(char *dev, int flags)
+{
+	/* like 'open', but if 'dev' matches %d:%d, create a temp
+	 * block device and open that
+	 */
+	char *e;
+	int fd = -1;
+	char devname[32];
+	int major = strtoul(dev, &e, 0);
+	int minor;
+	if (e > dev && *e == ':' && e[1] &&
+	    (minor = strtoul(e+1, &e, 0)) >= 0 &&
+	    *e == 0) {
+		snprintf(devname, sizeof(devname), "/dev/.tmp.md.%d:%d", major, minor);
+		if (mknod(devname, S_IFBLK|0600, makedev(major, minor))==0) {
+			fd = open(devname, flags);
+			unlink(devname);
+		}
+	} else
+		fd = open(dev, flags);
+	return fd;
+}
 
 struct superswitch *superlist[] = { &super0, &super1, NULL };