From: Laurent Vivier This patch adds partition management for Block RAM Device (BRD). This patch is done to keep in sync BRD and loop device drivers. This patch adds a parameter to the module, max_part, to specify the maximum number of partitions per RAM device. Example: # modprobe brd max_part=63 # ls -l /dev/ram* brw-rw---- 1 root disk 1, 0 2008-04-03 13:39 /dev/ram0 brw-rw---- 1 root disk 1, 64 2008-04-03 13:39 /dev/ram1 brw-rw---- 1 root disk 1, 640 2008-04-03 13:39 /dev/ram10 brw-rw---- 1 root disk 1, 704 2008-04-03 13:39 /dev/ram11 brw-rw---- 1 root disk 1, 768 2008-04-03 13:39 /dev/ram12 brw-rw---- 1 root disk 1, 832 2008-04-03 13:39 /dev/ram13 brw-rw---- 1 root disk 1, 896 2008-04-03 13:39 /dev/ram14 brw-rw---- 1 root disk 1, 960 2008-04-03 13:39 /dev/ram15 brw-rw---- 1 root disk 1, 128 2008-04-03 13:39 /dev/ram2 brw-rw---- 1 root disk 1, 192 2008-04-03 13:39 /dev/ram3 brw-rw---- 1 root disk 1, 256 2008-04-03 13:39 /dev/ram4 brw-rw---- 1 root disk 1, 320 2008-04-03 13:39 /dev/ram5 brw-rw---- 1 root disk 1, 384 2008-04-03 13:39 /dev/ram6 brw-rw---- 1 root disk 1, 448 2008-04-03 13:39 /dev/ram7 brw-rw---- 1 root disk 1, 512 2008-04-03 13:39 /dev/ram8 brw-rw---- 1 root disk 1, 576 2008-04-03 13:39 /dev/ram9 # fdisk /dev/ram0 Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel Building a new DOS disklabel. Changes will remain in memory only, until you decide to write them. After that, of course, the previous content won't be recoverable. Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite) Command (m for help): o Building a new DOS disklabel. Changes will remain in memory only, until you decide to write them. After that, of course, the previous content won't be recoverable. Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite) Command (m for help): n Command action e extended p primary partition (1-4) p Partition number (1-4): 1 First cylinder (1-2, default 1): 1 Last cylinder or +size or +sizeM or +sizeK (1-2, default 2): 2 Command (m for help): w The partition table has been altered! Calling ioctl() to re-read partition table. Syncing disks. # ls -l /dev/ram0* brw-rw---- 1 root disk 1, 0 2008-04-03 13:40 /dev/ram0 brw-rw---- 1 root disk 1, 1 2008-04-03 13:40 /dev/ram0p1 # mkfs /dev/ram0p1 mke2fs 1.40-WIP (14-Nov-2006) Filesystem label= OS type: Linux Block size=1024 (log=0) Fragment size=1024 (log=0) 4016 inodes, 16032 blocks 801 blocks (5.00%) reserved for the super user First data block=1 Maximum filesystem blocks=16515072 2 block groups 8192 blocks per group, 8192 fragments per group 2008 inodes per group Superblock backups stored on blocks: 8193 Writing inode tables: done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 26 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override. # mount /dev/ram0p1 /mnt df /mnt Filesystem 1K-blocks Used Available Use% Mounted on /dev/ram0p1 15521 138 14582 1% /mnt # ls -l /mnt total 12 drwx------ 2 root root 12288 2008-04-03 13:41 lost+found # umount /mnt # rmmod brd Signed-off-by: Laurent Vivier Cc: Nick Piggin Cc: Al Viro Cc: Jens Axboe Signed-off-by: Andrew Morton --- drivers/block/brd.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff -puN drivers/block/brd.c~modify-ramdisk-brd-device-to-be-able-to-manage-partitions drivers/block/brd.c --- a/drivers/block/brd.c~modify-ramdisk-brd-device-to-be-able-to-manage-partitions +++ a/drivers/block/brd.c @@ -387,10 +387,14 @@ static struct block_device_operations br */ static int rd_nr; int rd_size = CONFIG_BLK_DEV_RAM_SIZE; +static int max_part; +static int part_shift; module_param(rd_nr, int, 0); MODULE_PARM_DESC(rd_nr, "Maximum number of brd devices"); module_param(rd_size, int, 0); MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes."); +module_param(max_part, int, 0); +MODULE_PARM_DESC(max_part, "Maximum number of partitions per RAM disk"); MODULE_LICENSE("GPL"); MODULE_ALIAS_BLOCKDEV_MAJOR(RAMDISK_MAJOR); @@ -435,11 +439,11 @@ static struct brd_device *brd_alloc(int blk_queue_max_sectors(brd->brd_queue, 1024); blk_queue_bounce_limit(brd->brd_queue, BLK_BOUNCE_ANY); - disk = brd->brd_disk = alloc_disk(1); + disk = brd->brd_disk = alloc_disk(1 << part_shift); if (!disk) goto out_free_queue; disk->major = RAMDISK_MAJOR; - disk->first_minor = i; + disk->first_minor = i << part_shift; disk->fops = &brd_fops; disk->private_data = brd; disk->queue = brd->brd_queue; @@ -523,7 +527,12 @@ static int __init brd_init(void) * themselves and have kernel automatically instantiate actual * device on-demand. */ - if (rd_nr > 1UL << MINORBITS) + + part_shift = 0; + if (max_part > 0) + part_shift = fls(max_part); + + if (rd_nr > 1UL << (MINORBITS - part_shift)) return -EINVAL; if (rd_nr) { @@ -531,7 +540,7 @@ static int __init brd_init(void) range = rd_nr; } else { nr = CONFIG_BLK_DEV_RAM_COUNT; - range = 1UL << MINORBITS; + range = 1UL << (MINORBITS - part_shift); } if (register_blkdev(RAMDISK_MAJOR, "ramdisk")) @@ -570,7 +579,7 @@ static void __exit brd_exit(void) unsigned long range; struct brd_device *brd, *next; - range = rd_nr ? rd_nr : 1UL << MINORBITS; + range = rd_nr ? rd_nr : 1UL << (MINORBITS - part_shift); list_for_each_entry_safe(brd, next, &brd_devices, brd_list) brd_del_one(brd); _