Introduction

diff ./drivers/md/md.c~current~ ./drivers/md/md.c
@@ -762,7 +762,7 @@ static void super_90_sync(mddev_t *mddev
 	struct list_head *tmp;
 	mdk_rdev_t *rdev2;
 	int next_spare = mddev->raid_disks;
-	char nm[20];
+
 
 	/* make rdev->sb match mddev data..
 	 *

@@ -776,7 +776,6 @@ static void super_90_sync(mddev_t *mddev
 	 */
 	int i;
 	int active=0, working=0,failed=0,spare=0,nr_disks=0;
-	unsigned int fixdesc=0;
 
 	rdev->sb_size = MD_SB_BYTES;
 

@@ -830,16 +829,7 @@ static void super_90_sync(mddev_t *mddev
 			desc_nr = rdev2->raid_disk;
 		else
 			desc_nr = next_spare++;
-		if (desc_nr != rdev2->desc_nr) {
-			fixdesc |= (1 << desc_nr);
-			rdev2->desc_nr = desc_nr;
-			if (rdev2->raid_disk >= 0) {
-				sprintf(nm, "rd%d", rdev2->raid_disk);
-				sysfs_remove_link(&mddev->kobj, nm);
-			}
-			sysfs_remove_link(&rdev2->kobj, "block");
-			kobject_del(&rdev2->kobj);
-		}
+		rdev2->desc_nr = desc_nr;
 		d = &sb->disks[rdev2->desc_nr];
 		nr_disks++;
 		d->number = rdev2->desc_nr;

@@ -866,25 +856,6 @@ static void super_90_sync(mddev_t *mddev
 		if (test_bit(WriteMostly, &rdev2->flags))
 			d->state |= (1<<MD_DISK_WRITEMOSTLY);
 	}
-	if (fixdesc)
-		ITERATE_RDEV(mddev,rdev2,tmp)
-			if (fixdesc & (1<<rdev2->desc_nr)) {
-				snprintf(rdev2->kobj.name, KOBJ_NAME_LEN, "dev%d",
-					 rdev2->desc_nr);
-				/* kobject_add gets a ref on the parent, so
-				 * we have to drop the one we already have
-				 */
-				kobject_add(&rdev2->kobj);
-				kobject_put(rdev->kobj.parent);
-				sysfs_create_link(&rdev2->kobj,
-						  &rdev2->bdev->bd_disk->kobj,
-						  "block");
-				if (rdev2->raid_disk >= 0) {
-					sprintf(nm, "rd%d", rdev2->raid_disk);
-					sysfs_create_link(&mddev->kobj,
-							  &rdev2->kobj, nm);
-				}
-			}
 	/* now set the "removed" and "faulty" bits on any missing devices */
 	for (i=0 ; i < mddev->raid_disks ; i++) {
 		mdp_disk_t *d = &sb->disks[i];

@@ -1237,13 +1208,14 @@ static int bind_rdev_to_array(mdk_rdev_t
 		if (find_rdev_nr(mddev, rdev->desc_nr))
 			return -EBUSY;
 	}
+	bdevname(rdev->bdev,b);
+	if (kobject_set_name(&rdev->kobj, "dev-%s", b) < 0)
+		return -ENOMEM;
 			
 	list_add(&rdev->same_set, &mddev->disks);
 	rdev->mddev = mddev;
-	printk(KERN_INFO "md: bind<%s>\n", bdevname(rdev->bdev,b));
+	printk(KERN_INFO "md: bind<%s>\n", b);
 
-	rdev->kobj.k_name = NULL;
-	snprintf(rdev->kobj.name, KOBJ_NAME_LEN, "dev%d", rdev->desc_nr);
 	rdev->kobj.parent = &mddev->kobj;
 	kobject_add(&rdev->kobj);
 

diff ./drivers/md/md.c~current~ ./drivers/md/md.c
@@ -131,6 +131,8 @@ static ctl_table raid_root_table[] = {
 
 static struct block_device_operations md_fops;
 
+static int start_readonly;
+
 /*
  * Enables to iterate over all existing md arrays
  * all_mddevs_lock protects this list.

@@ -2029,6 +2031,9 @@ static int do_md_run(mddev_t * mddev)
 	mddev->resync_max_sectors = mddev->size << 1; /* may be over-ridden by personality */
 	mddev->barriers_work = 1;
 
+	if (start_readonly)
+		mddev->ro = 2; /* read-only, but switch on first write */
+
 	/* before we start the array running, initialise the bitmap */
 	err = bitmap_create(mddev);
 	if (err)

@@ -2141,7 +2146,7 @@ static int do_md_stop(mddev_t * mddev, i
 
 		if (ro) {
 			err  = -ENXIO;
-			if (mddev->ro)
+			if (mddev->ro==1)
 				goto out;
 			mddev->ro = 1;
 		} else {

@@ -3258,12 +3263,22 @@ static int md_ioctl(struct inode *inode,
 
 	/*
 	 * The remaining ioctls are changing the state of the
-	 * superblock, so we do not allow read-only arrays
-	 * here:
+	 * superblock, so we do not allow them on read-only arrays.
+	 * However non-MD ioctls (e.g. get-size) will still come through
+	 * here and hit the 'default' below, so only disallow
+	 * 'md' ioctls, and switch to rw mode if started auto-readonly.
 	 */
-	if (mddev->ro) {
-		err = -EROFS;
-		goto abort_unlock;
+	if (_IOC_TYPE(cmd) == MD_MAJOR &&
+	    mddev->ro && mddev->pers) {
+		if (mddev->ro == 2) {
+			mddev->ro = 0;
+		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+		md_wakeup_thread(mddev->thread);
+
+		} else {
+			err = -EROFS;
+			goto abort_unlock;
+		}
 	}
 
 	switch (cmd)

@@ -3651,8 +3666,10 @@ static int md_seq_show(struct seq_file *
 		seq_printf(seq, "%s : %sactive", mdname(mddev),
 						mddev->pers ? "" : "in");
 		if (mddev->pers) {
-			if (mddev->ro)
+			if (mddev->ro==1)
 				seq_printf(seq, " (read-only)");
+			if (mddev->ro==2)
+				seq_printf(seq, "(auto-read-only)");
 			seq_printf(seq, " %s", mddev->pers->name);
 		}
 

@@ -3696,7 +3713,9 @@ static int md_seq_show(struct seq_file *
 				status_resync (seq, mddev);
 				seq_printf(seq, "\n      ");
 			} else if (mddev->curr_resync == 1 || mddev->curr_resync == 2)
-				seq_printf(seq, "	resync=DELAYED\n      ");
+				seq_printf(seq, "\tresync=DELAYED\n      ");
+			else if (mddev->recovery_cp < MaxSector)
+				seq_printf(seq, "\tresync=PENDING\n      ");
 		} else
 			seq_printf(seq, "\n       ");
 

@@ -3833,6 +3852,13 @@ void md_write_start(mddev_t *mddev, stru
 	if (bio_data_dir(bi) != WRITE)
 		return;
 
+	BUG_ON(mddev->ro == 1);
+	if (mddev->ro == 2) {
+		/* need to switch to read/write */
+		mddev->ro = 0;
+		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+		md_wakeup_thread(mddev->thread);
+	}
 	atomic_inc(&mddev->writes_pending);
 	if (mddev->in_sync) {
 		spin_lock_irq(&mddev->write_lock);

@@ -4429,6 +4455,23 @@ static __exit void md_exit(void)
 module_init(md_init)
 module_exit(md_exit)
 
+static int get_ro(char *buffer, struct kernel_param *kp)
+{
+	return sprintf(buffer, "%d", start_readonly);
+}
+static int set_ro(const char *val, struct kernel_param *kp)
+{
+	char *e;
+	int num = simple_strtoul(val, &e, 10);
+	if (*val && (*e == '\0' || *e == '\n')) {
+		start_readonly = num;
+		return 0;;
+	}
+	return -EINVAL;
+}
+
+module_param_call(start_ro, set_ro, get_ro, NULL, 0600);
+
 EXPORT_SYMBOL(register_md_personality);
 EXPORT_SYMBOL(unregister_md_personality);
 EXPORT_SYMBOL(md_error);