From c6a4759ea0c9a7e7661f34f6943dafb1c6ae1b1c Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Thu, 6 Apr 2017 17:02:06 -0400 Subject: [PATCH] nbd: add device refcounting In order to support deleting the device on disconnect we need to refcount the actual nbd_device struct. So add the refcounting framework and change how we free the normal devices at rmmod time so we can catch reference leaks. Signed-off-by: Josef Bacik Signed-off-by: Jens Axboe --- drivers/block/nbd.c | 104 +++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 86 insertions(+), 18 deletions(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index cb45d79..4237e72 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -99,10 +99,12 @@ struct nbd_device { int index; refcount_t config_refs; + refcount_t refs; struct nbd_config *config; struct mutex config_lock; struct gendisk *disk; + struct list_head list; struct task_struct *task_recv; struct task_struct *task_setup; }; @@ -165,6 +167,28 @@ static struct device_attribute pid_attr = { .show = pid_show, }; +static void nbd_dev_remove(struct nbd_device *nbd) +{ + struct gendisk *disk = nbd->disk; + if (disk) { + del_gendisk(disk); + blk_cleanup_queue(disk->queue); + blk_mq_free_tag_set(&nbd->tag_set); + put_disk(disk); + } + kfree(nbd); +} + +static void nbd_put(struct nbd_device *nbd) +{ + if (refcount_dec_and_mutex_lock(&nbd->refs, + &nbd_index_mutex)) { + idr_remove(&nbd_index_idr, nbd->index); + mutex_unlock(&nbd_index_mutex); + nbd_dev_remove(nbd); + } +} + static int nbd_disconnected(struct nbd_config *config) { return test_bit(NBD_DISCONNECTED, &config->runtime_flags) || @@ -1005,6 +1029,7 @@ static void nbd_config_put(struct nbd_device *nbd) } nbd_reset(nbd); mutex_unlock(&nbd->config_lock); + nbd_put(nbd); module_put(THIS_MODULE); } } @@ -1199,6 +1224,10 @@ static int nbd_open(struct block_device *bdev, fmode_t mode) ret = -ENXIO; goto out; } + if (!refcount_inc_not_zero(&nbd->refs)) { + ret = -ENXIO; + goto out; + } if (!refcount_inc_not_zero(&nbd->config_refs)) { struct nbd_config *config; @@ -1214,6 +1243,7 @@ static int nbd_open(struct block_device *bdev, fmode_t mode) goto out; } refcount_set(&nbd->config_refs, 1); + refcount_inc(&nbd->refs); mutex_unlock(&nbd->config_lock); } out: @@ -1225,6 +1255,7 @@ static void nbd_release(struct gendisk *disk, fmode_t mode) { struct nbd_device *nbd = disk->private_data; nbd_config_put(nbd); + nbd_put(nbd); } static const struct block_device_operations nbd_fops = @@ -1378,18 +1409,6 @@ static const struct blk_mq_ops nbd_mq_ops = { .timeout = nbd_xmit_timeout, }; -static void nbd_dev_remove(struct nbd_device *nbd) -{ - struct gendisk *disk = nbd->disk; - if (disk) { - del_gendisk(disk); - blk_cleanup_queue(disk->queue); - blk_mq_free_tag_set(&nbd->tag_set); - put_disk(disk); - } - kfree(nbd); -} - static int nbd_dev_add(int index) { struct nbd_device *nbd; @@ -1452,6 +1471,8 @@ static int nbd_dev_add(int index) mutex_init(&nbd->config_lock); refcount_set(&nbd->config_refs, 0); + refcount_set(&nbd->refs, 1); + INIT_LIST_HEAD(&nbd->list); disk->major = NBD_MAJOR; disk->first_minor = index << part_shift; disk->fops = &nbd_fops; @@ -1549,16 +1570,26 @@ again: } else { nbd = idr_find(&nbd_index_idr, index); } - mutex_unlock(&nbd_index_mutex); if (!nbd) { printk(KERN_ERR "nbd: couldn't find device at index %d\n", index); + mutex_unlock(&nbd_index_mutex); + return -EINVAL; + } + if (!refcount_inc_not_zero(&nbd->refs)) { + mutex_unlock(&nbd_index_mutex); + if (index == -1) + goto again; + printk(KERN_ERR "nbd: device at index %d is going down\n", + index); return -EINVAL; } + mutex_unlock(&nbd_index_mutex); mutex_lock(&nbd->config_lock); if (refcount_read(&nbd->config_refs)) { mutex_unlock(&nbd->config_lock); + nbd_put(nbd); if (index == -1) goto again; printk(KERN_ERR "nbd: nbd%d already in use\n", index); @@ -1566,11 +1597,13 @@ again: } if (WARN_ON(nbd->config)) { mutex_unlock(&nbd->config_lock); + nbd_put(nbd); return -EINVAL; } config = nbd->config = nbd_alloc_config(); if (!nbd->config) { mutex_unlock(&nbd->config_lock); + nbd_put(nbd); printk(KERN_ERR "nbd: couldn't allocate config\n"); return -ENOMEM; } @@ -1655,14 +1688,23 @@ static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info) index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]); mutex_lock(&nbd_index_mutex); nbd = idr_find(&nbd_index_idr, index); - mutex_unlock(&nbd_index_mutex); if (!nbd) { + mutex_unlock(&nbd_index_mutex); printk(KERN_ERR "nbd: couldn't find device at index %d\n", index); return -EINVAL; } - if (!refcount_inc_not_zero(&nbd->config_refs)) + if (!refcount_inc_not_zero(&nbd->refs)) { + mutex_unlock(&nbd_index_mutex); + printk(KERN_ERR "nbd: device at index %d is going down\n", + index); + return -EINVAL; + } + mutex_unlock(&nbd_index_mutex); + if (!refcount_inc_not_zero(&nbd->config_refs)) { + nbd_put(nbd); return 0; + } mutex_lock(&nbd->config_lock); nbd_disconnect(nbd); mutex_unlock(&nbd->config_lock); @@ -1670,6 +1712,7 @@ static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info) &nbd->config->runtime_flags)) nbd_config_put(nbd); nbd_config_put(nbd); + nbd_put(nbd); return 0; } @@ -1690,16 +1733,24 @@ static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info) index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]); mutex_lock(&nbd_index_mutex); nbd = idr_find(&nbd_index_idr, index); - mutex_unlock(&nbd_index_mutex); if (!nbd) { + mutex_unlock(&nbd_index_mutex); printk(KERN_ERR "nbd: couldn't find a device at index %d\n", index); return -EINVAL; } + if (!refcount_inc_not_zero(&nbd->refs)) { + mutex_unlock(&nbd_index_mutex); + printk(KERN_ERR "nbd: device at index %d is going down\n", + index); + return -EINVAL; + } + mutex_unlock(&nbd_index_mutex); if (!refcount_inc_not_zero(&nbd->config_refs)) { dev_err(nbd_to_dev(nbd), "not configured, cannot reconfigure\n"); + nbd_put(nbd); return -EINVAL; } @@ -1758,6 +1809,7 @@ static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info) out: mutex_unlock(&nbd->config_lock); nbd_config_put(nbd); + nbd_put(nbd); return ret; } @@ -2003,16 +2055,32 @@ static int __init nbd_init(void) static int nbd_exit_cb(int id, void *ptr, void *data) { + struct list_head *list = (struct list_head *)data; struct nbd_device *nbd = ptr; - nbd_dev_remove(nbd); + + refcount_inc(&nbd->refs); + list_add_tail(&nbd->list, list); return 0; } static void __exit nbd_cleanup(void) { + struct nbd_device *nbd; + LIST_HEAD(del_list); + nbd_dbg_close(); - idr_for_each(&nbd_index_idr, &nbd_exit_cb, NULL); + mutex_lock(&nbd_index_mutex); + idr_for_each(&nbd_index_idr, &nbd_exit_cb, &del_list); + mutex_unlock(&nbd_index_mutex); + + list_for_each_entry(nbd, &del_list, list) { + if (refcount_read(&nbd->refs) != 2) + printk(KERN_ERR "nbd: possibly leaking a device\n"); + nbd_put(nbd); + nbd_put(nbd); + } + idr_destroy(&nbd_index_idr); genl_unregister_family(&nbd_genl_family); destroy_workqueue(recv_workqueue); -- 2.7.4