memstick/ms_block: simplify refcounting

Implement the ->free_disk method to free the msb_data structure only once
the last gendisk reference goes away instead of keeping a local refcount.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220215094514.3828912-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/memstick/core/ms_block.c b/drivers/memstick/core/ms_block.c
index 0cda6c6..3993bdd 100644 (file)
--- a/drivers/memstick/core/ms_block.c
+++ b/drivers/memstick/core/ms_block.c
@@ -1943,22 +1943,6 @@ static void msb_io_work(struct work_struct *work)
 static DEFINE_IDR(msb_disk_idr); /*set of used disk numbers */
 static DEFINE_MUTEX(msb_disk_lock); /* protects against races in open/release */
 
-static int msb_bd_open(struct block_device *bdev, fmode_t mode)
-{
-       struct gendisk *disk = bdev->bd_disk;
-       struct msb_data *msb = disk->private_data;
-
-       dbg_verbose("block device open");
-
-       mutex_lock(&msb_disk_lock);
-
-       if (msb && msb->card)
-               msb->usage_count++;
-
-       mutex_unlock(&msb_disk_lock);
-       return 0;
-}
-
 static void msb_data_clear(struct msb_data *msb)
 {
        kfree(msb->boot_page);
@@ -1968,33 +1952,6 @@ static void msb_data_clear(struct msb_data *msb)
        msb->card = NULL;
 }
 
-static int msb_disk_release(struct gendisk *disk)
-{
-       struct msb_data *msb = disk->private_data;
-
-       dbg_verbose("block device release");
-       mutex_lock(&msb_disk_lock);
-
-       if (msb) {
-               if (msb->usage_count)
-                       msb->usage_count--;
-
-               if (!msb->usage_count) {
-                       disk->private_data = NULL;
-                       idr_remove(&msb_disk_idr, msb->disk_id);
-                       put_disk(disk);
-                       kfree(msb);
-               }
-       }
-       mutex_unlock(&msb_disk_lock);
-       return 0;
-}
-
-static void msb_bd_release(struct gendisk *disk, fmode_t mode)
-{
-       msb_disk_release(disk);
-}
-
 static int msb_bd_getgeo(struct block_device *bdev,
                                 struct hd_geometry *geo)
 {
@@ -2003,6 +1960,17 @@ static int msb_bd_getgeo(struct block_device *bdev,
        return 0;
 }
 
+static void msb_bd_free_disk(struct gendisk *disk)
+{
+       struct msb_data *msb = disk->private_data;
+
+       mutex_lock(&msb_disk_lock);
+       idr_remove(&msb_disk_idr, msb->disk_id);
+       mutex_unlock(&msb_disk_lock);
+
+       kfree(msb);
+}
+
 static blk_status_t msb_queue_rq(struct blk_mq_hw_ctx *hctx,
                                 const struct blk_mq_queue_data *bd)
 {
@@ -2096,10 +2064,9 @@ static void msb_start(struct memstick_dev *card)
 }
 
 static const struct block_device_operations msb_bdops = {
-       .open    = msb_bd_open,
-       .release = msb_bd_release,
-       .getgeo  = msb_bd_getgeo,
-       .owner   = THIS_MODULE
+       .owner          = THIS_MODULE,
+       .getgeo         = msb_bd_getgeo,
+       .free_disk      = msb_bd_free_disk, 
 };
 
 static const struct blk_mq_ops msb_mq_ops = {
@@ -2147,7 +2114,6 @@ static int msb_init_disk(struct memstick_dev *card)
        set_capacity(msb->disk, capacity);
        dbg("Set total disk size to %lu sectors", capacity);
 
-       msb->usage_count = 1;
        msb->io_queue = alloc_ordered_workqueue("ms_block", WQ_MEM_RECLAIM);
        INIT_WORK(&msb->io_work, msb_io_work);
        sg_init_table(msb->prealloc_sg, MS_BLOCK_MAX_SEGS+1);
@@ -2229,7 +2195,7 @@ static void msb_remove(struct memstick_dev *card)
        msb_data_clear(msb);
        mutex_unlock(&msb_disk_lock);
 
-       msb_disk_release(msb->disk);
+       put_disk(msb->disk);
        memstick_set_drvdata(card, NULL);
 }
 

diff --git a/drivers/memstick/core/ms_block.h b/drivers/memstick/core/ms_block.h
index 122e1a8..7058f9a 100644 (file)
--- a/drivers/memstick/core/ms_block.h
+++ b/drivers/memstick/core/ms_block.h
@@ -143,7 +143,6 @@ struct ms_boot_page {
 } __packed;
 
 struct msb_data {
-       unsigned int                    usage_count;
        struct memstick_dev             *card;
        struct gendisk                  *disk;
        struct request_queue            *queue;