[PATCH 48/78] amiflop: use separate gendisks for Amiga vs MS-DOS mode

[Christoph Hellwig <hch@xxxxxx>]

Use separate gendisks (which share a tag_set) for the native Amgiga vs
the MS-DOS mode 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@xxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
---
 drivers/block/amiflop.c | 98 +++++++++++++++++++++++------------------
 1 file changed, 55 insertions(+), 43 deletions(-)

diff --git a/drivers/block/amiflop.c b/drivers/block/amiflop.c
index 71c2b156455860..9e2d0c6a387721 100644
--- a/drivers/block/amiflop.c
+++ b/drivers/block/amiflop.c
@@ -201,7 +201,7 @@ struct amiga_floppy_struct {
        int busy;                       /* true when drive is active */
        int dirty;                      /* true when trackbuf is not on disk */
        int status;                     /* current error code for unit */
-       struct gendisk *gendisk;
+       struct gendisk *gendisk[2];
        struct blk_mq_tag_set tag_set;
 };
 
@@ -1669,6 +1669,11 @@ static int floppy_open(struct block_device *bdev, 
fmode_t mode)
                return -EBUSY;
        }
 
+       if (unit[drive].type->code == FD_NODRIVE) {
+               mutex_unlock(&amiflop_mutex);
+               return -ENXIO;
+       }
+
        if (mode & (FMODE_READ|FMODE_WRITE)) {
                bdev_check_media_change(bdev);
                if (mode & FMODE_WRITE) {
@@ -1695,7 +1700,7 @@ static int floppy_open(struct block_device *bdev, fmode_t 
mode)
        unit[drive].dtype=&data_types[system];
        unit[drive].blocks=unit[drive].type->heads*unit[drive].type->tracks*
                data_types[system].sects*unit[drive].type->sect_mult;
-       set_capacity(unit[drive].gendisk, unit[drive].blocks);
+       set_capacity(unit[drive].gendisk[system], unit[drive].blocks);
 
        printk(KERN_INFO "fd%d: accessing %s-disk with %s-layout\n",drive,
               unit[drive].type->name, data_types[system].name);
@@ -1772,36 +1777,68 @@ static const struct blk_mq_ops amiflop_mq_ops = {
        .queue_rq = amiflop_queue_rq,
 };
 
-static struct gendisk *fd_alloc_disk(int drive)
+static int fd_alloc_disk(int drive, int system)
 {
        struct gendisk *disk;
 
        disk = alloc_disk(1);
        if (!disk)
                goto out;
-
-       disk->queue = blk_mq_init_sq_queue(&unit[drive].tag_set, 
&amiflop_mq_ops,
-                                               2, BLK_MQ_F_SHOULD_MERGE);
-       if (IS_ERR(disk->queue)) {
-               disk->queue = NULL;
+       disk->queue = blk_mq_init_queue(&unit[drive].tag_set);
+       if (IS_ERR(disk->queue))
                goto out_put_disk;
-       }
 
+       disk->major = FLOPPY_MAJOR;
+       disk->first_minor = drive + system;
+       disk->fops = &floppy_fops;
+       disk->events = DISK_EVENT_MEDIA_CHANGE;
+       if (system)
+               sprintf(disk->disk_name, "fd%d_msdos", drive);
+       else
+               sprintf(disk->disk_name, "fd%d", drive);
+       disk->private_data = &unit[drive];
+       set_capacity(disk, 880 * 2);
+
+       unit[drive].gendisk[system] = disk;
+       add_disk(disk);
+       return 0;
+
+out_put_disk:
+       disk->queue = NULL;
+       put_disk(disk);
+out:
+       return -ENOMEM;
+}
+
+static int fd_alloc_drive(int drive)
+{
        unit[drive].trackbuf = kmalloc(FLOPPY_MAX_SECTORS * 512, GFP_KERNEL);
        if (!unit[drive].trackbuf)
-               goto out_cleanup_queue;
+               goto out;
 
-       return disk;
+       memset(&unit[drive].tag_set, 0, sizeof(unit[drive].tag_set));
+       unit[drive].tag_set.ops = &amiflop_mq_ops;
+       unit[drive].tag_set.nr_hw_queues = 1;
+       unit[drive].tag_set.nr_maps = 1;
+       unit[drive].tag_set.queue_depth = 2;
+       unit[drive].tag_set.numa_node = NUMA_NO_NODE;
+       unit[drive].tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
+       if (blk_mq_alloc_tag_set(&unit[drive].tag_set))
+               goto out_cleanup_trackbuf;
 
-out_cleanup_queue:
-       blk_cleanup_queue(disk->queue);
-       disk->queue = NULL;
+       pr_cont(" fd%d", drive);
+
+       if (fd_alloc_disk(drive, 0) || fd_alloc_disk(drive, 1))
+               goto out_cleanup_tagset;
+       return 0;
+
+out_cleanup_tagset:
        blk_mq_free_tag_set(&unit[drive].tag_set);
-out_put_disk:
-       put_disk(disk);
+out_cleanup_trackbuf:
+       kfree(unit[drive].trackbuf);
 out:
        unit[drive].type->code = FD_NODRIVE;
-       return NULL;
+       return -ENOMEM;
 }
 
 static int __init fd_probe_drives(void)
@@ -1812,29 +1849,16 @@ static int __init fd_probe_drives(void)
        drives=0;
        nomem=0;
        for(drive=0;drive<FD_MAX_UNITS;drive++) {
-               struct gendisk *disk;
                fd_probe(drive);
                if (unit[drive].type->code == FD_NODRIVE)
                        continue;
 
-               disk = fd_alloc_disk(drive);
-               if (!disk) {
+               if (fd_alloc_drive(drive) < 0) {
                        pr_cont(" no mem for fd%d", drive);
                        nomem = 1;
                        continue;
                }
-               unit[drive].gendisk = disk;
                drives++;
-
-               pr_cont(" fd%d",drive);
-               disk->major = FLOPPY_MAJOR;
-               disk->first_minor = drive;
-               disk->fops = &floppy_fops;
-               disk->events = DISK_EVENT_MEDIA_CHANGE;
-               sprintf(disk->disk_name, "fd%d", drive);
-               disk->private_data = &unit[drive];
-               set_capacity(disk, 880*2);
-               add_disk(disk);
        }
        if ((drives > 0) || (nomem == 0)) {
                if (drives == 0)
@@ -1846,15 +1870,6 @@ static int __init fd_probe_drives(void)
        return -ENOMEM;
 }
  
-static struct kobject *floppy_find(dev_t dev, int *part, void *data)
-{
-       int drive = *part & 3;
-       if (unit[drive].type->code == FD_NODRIVE)
-               return NULL;
-       *part = 0;
-       return get_disk_and_module(unit[drive].gendisk);
-}
-
 static int __init amiga_floppy_probe(struct platform_device *pdev)
 {
        int i, ret;
@@ -1884,9 +1899,6 @@ static int __init amiga_floppy_probe(struct 
platform_device *pdev)
        if (fd_probe_drives() < 1) /* No usable drives */
                goto out_probe;
 
-       blk_register_region(MKDEV(FLOPPY_MAJOR, 0), 256, THIS_MODULE,
-                               floppy_find, NULL, NULL);
-
        /* initialize variables */
        timer_setup(&motor_on_timer, motor_on_callback, 0);
        motor_on_timer.expires = 0;
-- 
2.29.2