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loop: implement ->free_disk

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Ensure that the lo_device which is stored in the gendisk private
data is valid until the gendisk is freed.  Currently the loop driver
uses a lot of effort to make sure a device is not freed when it is
still in use, but to to fix a potential deadlock this will be relaxed
a bit soon.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220330052917.2566582-12-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2022-03-30 07:29:13 +02:00 committed by Jens Axboe
parent 1fe0b1acb1
commit d2c7f56f8b
1 changed files with 12 additions and 4 deletions
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16
drivers/block/loop.c
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@ -1761,6 +1761,14 @@ static void lo_release(struct gendisk *disk, fmode_t mode)
mutex_unlock(&lo->lo_mutex);
}
static void lo_free_disk(struct gendisk *disk)
{
struct loop_device *lo = disk->private_data;
mutex_destroy(&lo->lo_mutex);
kfree(lo);
}
static const struct block_device_operations lo_fops = {
.owner = THIS_MODULE,
.open = lo_open,
@ -1769,6 +1777,7 @@ static const struct block_device_operations lo_fops = {
#ifdef CONFIG_COMPAT
.compat_ioctl = lo_compat_ioctl,
#endif
.free_disk = lo_free_disk,
};
/*
@ -2060,15 +2069,14 @@ static void loop_remove(struct loop_device *lo)
{
/* Make this loop device unreachable from pathname. */
del_gendisk(lo->lo_disk);
blk_cleanup_disk(lo->lo_disk);
blk_cleanup_queue(lo->lo_disk->queue);
blk_mq_free_tag_set(&lo->tag_set);
mutex_lock(&loop_ctl_mutex);
idr_remove(&loop_index_idr, lo->lo_number);
mutex_unlock(&loop_ctl_mutex);
/* There is no route which can find this loop device. */
mutex_destroy(&lo->lo_mutex);
kfree(lo);
put_disk(lo->lo_disk);
}
static void loop_probe(dev_t dev)