Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 937af5ec authored by Boaz Harrosh's avatar Boaz Harrosh Committed by Jens Axboe
Browse files

brd: Fix all partitions BUGs 



This patch fixes up brd's partitions scheme, now enjoying all worlds.

The MAIN fix here is that currently, if one fdisks some partitions,
a BAD bug will make all partitions point to the same start-end sector
ie: 0 - brd_size And an mkfs of any partition would trash the partition
table and the other partition.

Another fix is that "mount -U uuid" will not work if show_part was not
specified, because of the GENHD_FL_SUPPRESS_PARTITION_INFO flag.
We now always load without it and remove the show_part parameter.

[We remove Dmitry's new module-param part_show it is now always
 show]

So NOW the logic goes like this:
* max_part - Just says how many minors to reserve between ramX
  devices. In any way, there can be as many partition as requested.
  If minors between devices ends, then dynamic 259-major ids will
  be allocated on the fly.
  The default is now max_part=1, which means all partitions devt(s)
  will be from the dynamic (259) major-range.
  (If persistent partition minors is needed use max_part=X)
  For example with /dev/sdX max_part is hard coded 16.

* Creation of new devices on the fly still/always work:
  mknod /path/devnod b 1 X
  fdisk -l /path/devnod
  Will create a new device if [X / max_part] was not already
  created before. (Just as before)

  partitions on the dynamically created device will work as well
  Same logic applies with minors as with the pre-created ones.

TODO: dynamic grow of device size. So each device can have it's
      own size.

CC: Dmitry Monakhov <dmonakhov@openvz.org>
Tested-by: default avatarRoss Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: default avatarBoaz Harrosh <boaz@plexistor.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent d4119ee0

drivers/block/brd.c

+38 −62
Original line number Original line Diff line number Diff line
@@ -438,19 +438,18 @@ static const struct block_device_operations brd_fops = { 
/*

/*

 * And now the modules code and kernel interface.

 * And now the modules code and kernel interface.

 */

 */

static int rd_nr;

static int rd_nr = CONFIG_BLK_DEV_RAM_COUNT;

int rd_size = CONFIG_BLK_DEV_RAM_SIZE;

static int max_part;

static int part_shift;

static int part_show = 0;

module_param(rd_nr, int, S_IRUGO);

module_param(rd_nr, int, S_IRUGO);

MODULE_PARM_DESC(rd_nr, "Maximum number of brd devices");

MODULE_PARM_DESC(rd_nr, "Maximum number of brd devices");



int rd_size = CONFIG_BLK_DEV_RAM_SIZE;

module_param(rd_size, int, S_IRUGO);

module_param(rd_size, int, S_IRUGO);

MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes.");

MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes.");



static int max_part = 1;

module_param(max_part, int, S_IRUGO);

module_param(max_part, int, S_IRUGO);

MODULE_PARM_DESC(max_part, "Maximum number of partitions per RAM disk");

MODULE_PARM_DESC(max_part, "Num Minors to reserve between devices");

module_param(part_show, int, S_IRUGO);



MODULE_PARM_DESC(part_show, "Control RAM disk visibility in /proc/partitions");

MODULE_LICENSE("GPL");

MODULE_LICENSE("GPL");

MODULE_ALIAS_BLOCKDEV_MAJOR(RAMDISK_MAJOR);

MODULE_ALIAS_BLOCKDEV_MAJOR(RAMDISK_MAJOR);

MODULE_ALIAS("rd");

MODULE_ALIAS("rd");
@@ -496,16 +495,15 @@ static struct brd_device *brd_alloc(int i) 
	brd->brd_queue->limits.discard_zeroes_data = 1;

	brd->brd_queue->limits.discard_zeroes_data = 1;

	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, brd->brd_queue);

	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, brd->brd_queue);





	disk = brd->brd_disk = alloc_disk(1 << part_shift);

	disk = brd->brd_disk = alloc_disk(max_part);

	if (!disk)

	if (!disk)

		goto out_free_queue;

		goto out_free_queue;

	disk->major		= RAMDISK_MAJOR;

	disk->major		= RAMDISK_MAJOR;

	disk->first_minor	= i << part_shift;

	disk->first_minor	= i * max_part;

	disk->fops		= &brd_fops;

	disk->fops		= &brd_fops;

	disk->private_data	= brd;

	disk->private_data	= brd;

	disk->queue		= brd->brd_queue;

	disk->queue		= brd->brd_queue;

	if (!part_show)

	disk->flags		= GENHD_FL_EXT_DEVT;

		disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;

	sprintf(disk->disk_name, "ram%d", i);

	sprintf(disk->disk_name, "ram%d", i);

	set_capacity(disk, rd_size * 2);

	set_capacity(disk, rd_size * 2);
@@ -527,10 +525,11 @@ static void brd_free(struct brd_device *brd) 
	kfree(brd);

	kfree(brd);

}

}





static struct brd_device *brd_init_one(int i)

static struct brd_device *brd_init_one(int i, bool *new)

{

{

	struct brd_device *brd;

	struct brd_device *brd;





	*new = false;

	list_for_each_entry(brd, &brd_devices, brd_list) {

	list_for_each_entry(brd, &brd_devices, brd_list) {

		if (brd->brd_number == i)

		if (brd->brd_number == i)

			goto out;

			goto out;
@@ -541,6 +540,7 @@ static struct brd_device *brd_init_one(int i) 
		add_disk(brd->brd_disk);

		add_disk(brd->brd_disk);

		list_add_tail(&brd->brd_list, &brd_devices);

		list_add_tail(&brd->brd_list, &brd_devices);

	}

	}

	*new = true;

out:

out:

	return brd;

	return brd;

}

}
@@ -556,70 +556,46 @@ static struct kobject *brd_probe(dev_t dev, int *part, void *data) 
{

{

	struct brd_device *brd;

	struct brd_device *brd;

	struct kobject *kobj;

	struct kobject *kobj;

	bool new;





	mutex_lock(&brd_devices_mutex);

	mutex_lock(&brd_devices_mutex);

	brd = brd_init_one(MINOR(dev) >> part_shift);

	brd = brd_init_one(MINOR(dev) / max_part, &new);

	kobj = brd ? get_disk(brd->brd_disk) : NULL;

	kobj = brd ? get_disk(brd->brd_disk) : NULL;

	mutex_unlock(&brd_devices_mutex);

	mutex_unlock(&brd_devices_mutex);





	if (new)

		*part = 0;

		*part = 0;



	return kobj;

	return kobj;

}

}





static int __init brd_init(void)

static int __init brd_init(void)

{

{

	int i, nr;

	unsigned long range;

	struct brd_device *brd, *next;

	struct brd_device *brd, *next;

	int i;





	/*

	/*

	 * brd module now has a feature to instantiate underlying device

	 * brd module now has a feature to instantiate underlying device

	 * structure on-demand, provided that there is an access dev node.

	 * structure on-demand, provided that there is an access dev node.

	 * However, this will not work well with user space tool that doesn't

	 * know about such "feature".  In order to not break any existing

	 * tool, we do the following:

	 *

	 *

	 * (1) if rd_nr is specified, create that many upfront, and this

	 * (1) if rd_nr is specified, create that many upfront. else

	 *     also becomes a hard limit.

	 *     it defaults to CONFIG_BLK_DEV_RAM_COUNT

	 * (2) if rd_nr is not specified, create CONFIG_BLK_DEV_RAM_COUNT

	 * (2) User can further extend brd devices by create dev node themselves

	 *     (default 16) rd device on module load, user can further

	 *     and have kernel automatically instantiate actual device

	 *     extend brd device by create dev node themselves and have

	 *     on-demand. Example:

	 *     kernel automatically instantiate actual device on-demand.

	 *		mknod /path/devnod_name b 1 X	# 1 is the rd major

	 *		fdisk -l /path/devnod_name

	 *	If (X / max_part) was not already created it will be created

	 *	dynamically.

	 */

	 */





	part_shift = 0;

	if (max_part > 0) {

		part_shift = fls(max_part);



		/*

		 * Adjust max_part according to part_shift as it is exported

		 * to user space so that user can decide correct minor number

		 * if [s]he want to create more devices.

		 *

		 * Note that -1 is required because partition 0 is reserved

		 * for the whole disk.

		 */

		max_part = (1UL << part_shift) - 1;

	}



	if ((1UL << part_shift) > DISK_MAX_PARTS)

		return -EINVAL;



	if (rd_nr > 1UL << (MINORBITS - part_shift))

		return -EINVAL;



	if (rd_nr) {

		nr = rd_nr;

		range = rd_nr << part_shift;

	} else {

		nr = CONFIG_BLK_DEV_RAM_COUNT;

		range = 1UL << MINORBITS;

	}



	if (register_blkdev(RAMDISK_MAJOR, "ramdisk"))

	if (register_blkdev(RAMDISK_MAJOR, "ramdisk"))

		return -EIO;

		return -EIO;





	for (i = 0; i < nr; i++) {

	if (unlikely(!max_part))

		max_part = 1;



	for (i = 0; i < rd_nr; i++) {

		brd = brd_alloc(i);

		brd = brd_alloc(i);

		if (!brd)

		if (!brd)

			goto out_free;

			goto out_free;
@@ -631,10 +607,10 @@ static int __init brd_init(void) 
	list_for_each_entry(brd, &brd_devices, brd_list)

	list_for_each_entry(brd, &brd_devices, brd_list)

		add_disk(brd->brd_disk);

		add_disk(brd->brd_disk);





	blk_register_region(MKDEV(RAMDISK_MAJOR, 0), range,

	blk_register_region(MKDEV(RAMDISK_MAJOR, 0), 1UL << MINORBITS,

				  THIS_MODULE, brd_probe, NULL, NULL);

				  THIS_MODULE, brd_probe, NULL, NULL);





	printk(KERN_INFO "brd: module loaded\n");

	pr_info("brd: module loaded\n");

	return 0;

	return 0;





out_free:

out_free:
@@ -644,21 +620,21 @@ static int __init brd_init(void) 
	}

	}

	unregister_blkdev(RAMDISK_MAJOR, "ramdisk");

	unregister_blkdev(RAMDISK_MAJOR, "ramdisk");





	pr_info("brd: module NOT loaded !!!\n");

	return -ENOMEM;

	return -ENOMEM;

}

}





static void __exit brd_exit(void)

static void __exit brd_exit(void)

{

{

	unsigned long range;

	struct brd_device *brd, *next;

	struct brd_device *brd, *next;





	range = rd_nr ? rd_nr << part_shift : 1UL << MINORBITS;



	list_for_each_entry_safe(brd, next, &brd_devices, brd_list)

	list_for_each_entry_safe(brd, next, &brd_devices, brd_list)

		brd_del_one(brd);

		brd_del_one(brd);





	blk_unregister_region(MKDEV(RAMDISK_MAJOR, 0), range);

	blk_unregister_region(MKDEV(RAMDISK_MAJOR, 0), 1UL << MINORBITS);

	unregister_blkdev(RAMDISK_MAJOR, "ramdisk");

	unregister_blkdev(RAMDISK_MAJOR, "ramdisk");



	pr_info("brd: module unloaded\n");

}

}





module_init(brd_init);

module_init(brd_init);