[PATCH 18/19] z2ram: use separate gendisk for the different modes

Christoph Hellwig
2020-09-03T08:02:04Z

Use separate gendisks (which share a tag_set) for the different operating
modes instead of redirecting the gendisk lookup using a probe callback.
This avoids potential problems with aliased block_device instances and
will eventually allow for removing the blk_register_region framework.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/block/z2ram.c | 100 ++++++++++++++++++++++++------------------
1 file changed, 58 insertions(+), 42 deletions(-)

diff --git a/drivers/block/z2ram.c b/drivers/block/z2ram.c
index eafecc9a72b38d..c1d20818e64920 100644
--- a/drivers/block/z2ram.c
+++ b/drivers/block/z2ram.c
@@ -63,7 +63,7 @@ static int current_device = -1;

static DEFINE_SPINLOCK(z2ram_lock);

-static struct gendisk *z2ram_gendisk;
+static struct gendisk *z2ram_gendisk[Z2MINOR_COUNT];

static blk_status_t z2_queue_rq(struct blk_mq_hw_ctx *hctx,
const struct blk_mq_queue_data *bd)
@@ -283,7 +283,7 @@ static int z2_open(struct block_device *bdev, fmode_t mode)

current_device = device;
z2ram_size <<= Z2RAM_CHUNKSHIFT;
- set_capacity(z2ram_gendisk, z2ram_size >> 9);
+ set_capacity(z2ram_gendisk[device], z2ram_size >> 9);
}

mutex_unlock(&z2ram_mutex);
@@ -315,71 +315,87 @@ static const struct block_device_operations z2_fops = {
.release = z2_release,
};

-static struct kobject *z2_find(dev_t dev, int *part, void *data)
-{
- *part = 0;
- return get_disk_and_module(z2ram_gendisk);
-}
-
-static struct request_queue *z2_queue;
static struct blk_mq_tag_set tag_set;

static const struct blk_mq_ops z2_mq_ops = {
.queue_rq = z2_queue_rq,
};

+static int z2ram_register_disk(int minor)
+{
+ struct request_queue *q;
+ struct gendisk *disk;
+
+ disk = alloc_disk(1);
+ if (!disk)
+ return -ENOMEM;
+
+ q = blk_mq_init_queue(&tag_set);
+ if (IS_ERR(q)) {
+ put_disk(disk);
+ return PTR_ERR(q);
+ }
+
+ disk->major = Z2RAM_MAJOR;
+ disk->first_minor = minor;
+ disk->fops = &z2_fops;
+ if (minor)
+ sprintf(disk->disk_name, "z2ram%d", minor);
+ else
+ sprintf(disk->disk_name, "z2ram");
+ disk->queue = q;
+
+ z2ram_gendisk[minor] = disk;
+ add_disk(disk);
+ return 0;
+}
+
static int __init z2_init(void)
{
- int ret;
+ int ret, i;

if (!MACH_IS_AMIGA)
return -ENODEV;

- ret = -EBUSY;
if (register_blkdev(Z2RAM_MAJOR, DEVICE_NAME))
- goto err;
-
- ret = -ENOMEM;
- z2ram_gendisk = alloc_disk(1);
- if (!z2ram_gendisk)
- goto out_disk;
-
- z2_queue = blk_mq_init_sq_queue(&tag_set, &z2_mq_ops, 16,
- BLK_MQ_F_SHOULD_MERGE);
- if (IS_ERR(z2_queue)) {
- ret = PTR_ERR(z2_queue);
- z2_queue = NULL;
- goto out_queue;
+ return -EBUSY;
+
+ tag_set.ops = &z2_mq_ops;
+ tag_set.nr_hw_queues = 1;
+ tag_set.nr_maps = 1;
+ tag_set.queue_depth = 16;
+ tag_set.numa_node = NUMA_NO_NODE;
+ tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
+ ret = blk_mq_alloc_tag_set(&tag_set);
+ if (ret)
+ goto out_unregister_blkdev;
+
+ for (i = 0; i < Z2MINOR_COUNT; i++) {
+ ret = z2ram_register_disk(i);
+ if (ret && i == 0)
+ goto out_free_tagset;
}

- z2ram_gendisk->major = Z2RAM_MAJOR;
- z2ram_gendisk->first_minor = 0;
- z2ram_gendisk->fops = &z2_fops;
- sprintf(z2ram_gendisk->disk_name, "z2ram");
-
- z2ram_gendisk->queue = z2_queue;
- add_disk(z2ram_gendisk);
- blk_register_region(MKDEV(Z2RAM_MAJOR, 0), Z2MINOR_COUNT, THIS_MODULE,
- z2_find, NULL, NULL);
-
return 0;

-out_queue:
- put_disk(z2ram_gendisk);
-out_disk:
+out_free_tagset:
+ blk_mq_free_tag_set(&tag_set);
+out_unregister_blkdev:
unregister_blkdev(Z2RAM_MAJOR, DEVICE_NAME);
-err:
return ret;
}

static void __exit z2_exit(void)
{
int i, j;
- blk_unregister_region(MKDEV(Z2RAM_MAJOR, 0), Z2MINOR_COUNT);
+
unregister_blkdev(Z2RAM_MAJOR, DEVICE_NAME);
- del_gendisk(z2ram_gendisk);
- put_disk(z2ram_gendisk);
- blk_cleanup_queue(z2_queue);
+
+ for (i = 0; i < Z2MINOR_COUNT; i++) {
+ del_gendisk(z2ram_gendisk[i]);
+ blk_cleanup_queue(z2ram_gendisk[i]->queue);
+ put_disk(z2ram_gendisk[i]);
+ }
blk_mq_free_tag_set(&tag_set);

if (current_device != -1) {
--
2.28.0