[PATCH] Modify RAMDISK (brd) device to be able to manage partitions

[PATCH] Modify RAMDISK (brd) device to be able to manage partitions

[Laurent Vivier]

To keep in sync with loop device, this patch updates drivers/block/brd.c to 
manage partitions.

Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
---
 Documentation/kernel-parameters.txt |    2 +
 drivers/block/brd.c                 |   36 ++++++++++++++++++++++++++++++----
 2 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 9a5b665..43af1dd 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1602,6 +1602,8 @@ and is between 256 and 4096 characters. It is defined in the file
 	ramdisk_size=	[RAM] Sizes of RAM disks in kilobytes
 			See Documentation/ramdisk.txt.
 
+	ramdisk_max_part=	[RAM] Maximum number of partitions per RAM disk.
+
 	rcupdate.blimit=	[KNL,BOOT]
 			Set maximum number of finished RCU callbacks to process
 			in one batch.
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 8536480..55758f5 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -386,10 +386,14 @@ static struct block_device_operations brd_fops = {
  */
 static int rd_nr;
 int rd_size = CONFIG_BLK_DEV_RAM_SIZE;
+static int rd_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(rd_max_part, int, 0);
+MODULE_PARM_DESC(rd_max_part, "Maximum number of partition by RAM disk");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS_BLOCKDEV_MAJOR(RAMDISK_MAJOR);
 
@@ -404,8 +408,25 @@ static int __init ramdisk_size2(char *str)
 {
 	return ramdisk_size(str);
 }
+static int __init max_part_setup(char *str)
+{
+	rd_max_part = simple_strtol(str, NULL, 0);
+	if (rd_max_part < 1) {
+		/* there is at least one partition */
+		printk(KERN_ERR "nrd: max_part cannot be lesser than 1\n");
+		return 0;
+	}
+	if (rd_max_part > (1UL << (MINORBITS - 1)) {
+		/* we must keep at least one bit for nrd device number */
+		printk(KERN_ERR "nrd: max_part cannot be greater than %lu\n",
+		       1UL << (MINORBITS - 1));
+		return 0;
+	}
+	return 1;
+}
 __setup("ramdisk=", ramdisk_size);
 __setup("ramdisk_size=", ramdisk_size2);
+__setup("ramdisk_max_part=", max_part_setup);
 #endif
 
 /*
@@ -434,11 +455,11 @@ static struct brd_device *brd_alloc(int i)
 	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;
@@ -522,7 +543,12 @@ 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 (rd_max_part > 0)
+		part_shift = fls(rd_max_part);
+
+	if (rd_nr > 1UL << (MINORBITS - part_shift))
 		return -EINVAL;
 
 	if (rd_nr) {
@@ -530,7 +556,7 @@ 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"))
@@ -569,7 +595,7 @@ 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);
-- 
1.5.2.4

Re: [PATCH] Modify RAMDISK (brd) device to be able to manage partitions

[Nick Piggin]

On Thursday 03 April 2008 22:44, Laurent Vivier wrote:
> This patch adds partition management for Block RAM Device (BRD).
>
> This patch is done to keep in sync BRD and loop device drivers.

Hi Laurent,

Thanks very much for this. I will ensure Andrew gets this.

Nick

>
> 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 <Laurent.Vivier@bull.net>
> ---
>  drivers/block/brd.c |   19 ++++++++++++++-----
>  1 files changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/block/brd.c b/drivers/block/brd.c
> index 8536480..8baf781 100644
> --- a/drivers/block/brd.c
> +++ b/drivers/block/brd.c
> @@ -386,10 +386,14 @@ static struct block_device_operations brd_fops = {
>   */
>  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);
>
> @@ -434,11 +438,11 @@ static struct brd_device *brd_alloc(int i)
>  	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;
> @@ -522,7 +526,12 @@ 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) {
> @@ -530,7 +539,7 @@ 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"))
> @@ -569,7 +578,7 @@ 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);

[PATCH] Modify RAMDISK (brd) device to be able to manage partitions

[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 <Laurent.Vivier@bull.net>
---
 drivers/block/brd.c |   19 ++++++++++++++-----
 1 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 8536480..8baf781 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -386,10 +386,14 @@ static struct block_device_operations brd_fops = {
  */
 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);
 
@@ -434,11 +438,11 @@ static struct brd_device *brd_alloc(int i)
 	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;
@@ -522,7 +526,12 @@ 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) {
@@ -530,7 +539,7 @@ 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"))
@@ -569,7 +578,7 @@ 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);
-- 
1.5.2.4