From: Laurent Vivier This patch allows to use partitions with network block devices (NBD). A new parameter is introduced to define how many partition we want to be able to manage per network block device. This parameter is "max_part". For instance, to manage 63 partitions / loop device, we will do: [on the server side] # nbd-server 1234 /dev/sdb [on the client side] # modprobe nbd max_part=63 # ls -l /dev/nbd* brw-rw---- 1 root disk 43, 0 2008-03-25 11:14 /dev/nbd0 brw-rw---- 1 root disk 43, 64 2008-03-25 11:11 /dev/nbd1 brw-rw---- 1 root disk 43, 640 2008-03-25 11:11 /dev/nbd10 brw-rw---- 1 root disk 43, 704 2008-03-25 11:11 /dev/nbd11 brw-rw---- 1 root disk 43, 768 2008-03-25 11:11 /dev/nbd12 brw-rw---- 1 root disk 43, 832 2008-03-25 11:11 /dev/nbd13 brw-rw---- 1 root disk 43, 896 2008-03-25 11:11 /dev/nbd14 brw-rw---- 1 root disk 43, 960 2008-03-25 11:11 /dev/nbd15 brw-rw---- 1 root disk 43, 128 2008-03-25 11:11 /dev/nbd2 brw-rw---- 1 root disk 43, 192 2008-03-25 11:11 /dev/nbd3 brw-rw---- 1 root disk 43, 256 2008-03-25 11:11 /dev/nbd4 brw-rw---- 1 root disk 43, 320 2008-03-25 11:11 /dev/nbd5 brw-rw---- 1 root disk 43, 384 2008-03-25 11:11 /dev/nbd6 brw-rw---- 1 root disk 43, 448 2008-03-25 11:11 /dev/nbd7 brw-rw---- 1 root disk 43, 512 2008-03-25 11:11 /dev/nbd8 brw-rw---- 1 root disk 43, 576 2008-03-25 11:11 /dev/nbd9 # nbd-client localhost 1234 /dev/nbd0 Negotiation: ..size = 80418240KB bs=1024, sz=80418240 -------NOTE, RFC: partition table is not automatically read. The driver sets bdev->bd_invalidated to 1 to force the read of the partition table of the device, but this is done only on an open of the device. So we have to do a "touch /dev/nbdX" or something like that. It can't be done from the nbd-client or nbd driver because at this level we can't ask to read the partition table and to serve the request at the same time (-> deadlock) If someone has a better idea, I'm open to any suggestion. -------NOTE, RFC # fdisk -l /dev/nbd0 Disk /dev/nbd0: 82.3 GB, 82348277760 bytes 255 heads, 63 sectors/track, 10011 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/nbd0p1 * 1 9965 80043831 83 Linux /dev/nbd0p2 9966 10011 369495 5 Extended /dev/nbd0p5 9966 10011 369463+ 82 Linux swap / Solaris # ls -l /dev/nbd0* brw-rw---- 1 root disk 43, 0 2008-03-25 11:16 /dev/nbd0 brw-rw---- 1 root disk 43, 1 2008-03-25 11:16 /dev/nbd0p1 brw-rw---- 1 root disk 43, 2 2008-03-25 11:16 /dev/nbd0p2 brw-rw---- 1 root disk 43, 5 2008-03-25 11:16 /dev/nbd0p5 # mount /dev/nbd0p1 /mnt # ls /mnt bin dev initrd lost+found opt sbin sys var boot etc initrd.img media proc selinux tmp vmlinuz cdrom home lib mnt root srv usr # umount /mnt # nbd-client -d /dev/nbd0 # ls -l /dev/nbd0* brw-rw---- 1 root disk 43, 0 2008-03-25 11:16 /dev/nbd0 -------NOTE On "nbd-client -d", we can do an iocl(BLKRRPART) to update partition table: as the size of the device is 0, we don't have to serve the partition manager request (-> no deadlock). -------NOTE Signed-off-by: Paul Clements --- ./drivers/block/nbd.c.LOCAL 2008-03-31 13:08:13.000000000 -0400 +++ ./drivers/block/nbd.c 2008-04-01 17:03:05.000000000 -0400 @@ -56,6 +56,7 @@ static unsigned int debugflags; static unsigned int nbds_max = 16; static struct nbd_device *nbd_dev; +static int max_part; /* * Use just one lock (or at most 1 per NIC). Two arguments for this: @@ -603,10 +604,13 @@ static int nbd_ioctl(struct inode *inode error = -EINVAL; file = fget(arg); if (file) { + struct block_device *bdev = inode->i_bdev; inode = file->f_path.dentry->d_inode; if (S_ISSOCK(inode->i_mode)) { lo->file = file; lo->sock = SOCKET_I(inode); + if (max_part > 0) + bdev->bd_invalidated = 1; error = 0; } else { fput(file); @@ -656,6 +660,8 @@ static int nbd_ioctl(struct inode *inode lo->bytesize = 0; inode->i_bdev->bd_inode->i_size = 0; set_capacity(lo->disk, 0); + if (max_part > 0) + ioctl_by_bdev(inode->i_bdev, BLKRRPART, 0); return lo->harderror; case NBD_CLEAR_QUE: /* @@ -689,6 +695,7 @@ static int __init nbd_init(void) { int err = -ENOMEM; int i; + int part_shift; BUILD_BUG_ON(sizeof(struct nbd_request) != 28); @@ -696,8 +703,17 @@ static int __init nbd_init(void) if (!nbd_dev) return -ENOMEM; + if (max_part < 0) { + printk(KERN_CRIT "nbd: max_part must be >= 0\n"); + return -EINVAL; + } + + part_shift = 0; + if (max_part > 0) + part_shift = fls(max_part); + for (i = 0; i < nbds_max; i++) { - struct gendisk *disk = alloc_disk(1); + struct gendisk *disk = alloc_disk(1 << part_shift); elevator_t *old_e; if (!disk) goto out; @@ -741,10 +757,9 @@ static int __init nbd_init(void) nbd_dev[i].blksize = 1024; nbd_dev[i].bytesize = 0; disk->major = NBD_MAJOR; - disk->first_minor = i; + disk->first_minor = i << part_shift; disk->fops = &nbd_fops; disk->private_data = &nbd_dev[i]; - disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO; sprintf(disk->disk_name, "nbd%d", i); set_capacity(disk, 0); add_disk(disk); @@ -782,7 +797,9 @@ MODULE_DESCRIPTION("Network Block Device MODULE_LICENSE("GPL"); module_param(nbds_max, int, 0444); -MODULE_PARM_DESC(nbds_max, "How many network block devices to initialize."); +MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)"); +module_param(max_part, int, 0444); +MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)"); #ifndef NDEBUG module_param(debugflags, int, 0644); MODULE_PARM_DESC(debugflags, "flags for controlling debug output");