From b5bd357cf8b65d31e32b1668293cbeedb6c06334 Mon Sep 17 00:00:00 2001 From: Luis Chamberlain Date: Fri, 19 Jun 2020 20:47:23 +0000 Subject: block: add docs for gendisk / request_queue refcount helpers This adds documentation for the gendisk / request_queue refcount helpers. Signed-off-by: Luis Chamberlain Reviewed-by: Christoph Hellwig Reviewed-by: Bart Van Assche Signed-off-by: Jens Axboe --- block/genhd.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 49 insertions(+), 1 deletion(-) (limited to 'block/genhd.c') diff --git a/block/genhd.c b/block/genhd.c index 1a7659327664..f741613d731f 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -876,6 +876,20 @@ static void invalidate_partition(struct gendisk *disk, int partno) bdput(bdev); } +/** + * del_gendisk - remove the gendisk + * @disk: the struct gendisk to remove + * + * Removes the gendisk and all its associated resources. This deletes the + * partitions associated with the gendisk, and unregisters the associated + * request_queue. + * + * This is the counter to the respective __device_add_disk() call. + * + * The final removal of the struct gendisk happens when its refcount reaches 0 + * with put_disk(), which should be called after del_gendisk(), if + * __device_add_disk() was used. + */ void del_gendisk(struct gendisk *disk) { struct disk_part_iter piter; @@ -1514,6 +1528,23 @@ int disk_expand_part_tbl(struct gendisk *disk, int partno) return 0; } +/** + * disk_release - releases all allocated resources of the gendisk + * @dev: the device representing this disk + * + * This function releases all allocated resources of the gendisk. + * + * The struct gendisk refcount is incremented with get_gendisk() or + * get_disk_and_module(), and its refcount is decremented with + * put_disk_and_module() or put_disk(). Once the refcount reaches 0 this + * function is called. + * + * Drivers which used __device_add_disk() have a gendisk with a request_queue + * assigned. Since the request_queue sits on top of the gendisk for these + * drivers we also call blk_put_queue() for them, and we expect the + * request_queue refcount to reach 0 at this point, and so the request_queue + * will also be freed prior to the disk. + */ static void disk_release(struct device *dev) { struct gendisk *disk = dev_to_disk(dev); @@ -1727,6 +1758,13 @@ struct gendisk *__alloc_disk_node(int minors, int node_id) } EXPORT_SYMBOL(__alloc_disk_node); +/** + * get_disk_and_module - increments the gendisk and gendisk fops module refcount + * @disk: the struct gendisk to to increment the refcount for + * + * This increments the refcount for the struct gendisk, and the gendisk's + * fops module owner. + */ struct kobject *get_disk_and_module(struct gendisk *disk) { struct module *owner; @@ -1747,6 +1785,13 @@ struct kobject *get_disk_and_module(struct gendisk *disk) } EXPORT_SYMBOL(get_disk_and_module); +/** + * put_disk - decrements the gendisk refcount + * @disk: the struct gendisk to to decrement the refcount for + * + * This decrements the refcount for the struct gendisk. When this reaches 0 + * we'll have disk_release() called. + */ void put_disk(struct gendisk *disk) { if (disk) @@ -1754,7 +1799,10 @@ void put_disk(struct gendisk *disk) } EXPORT_SYMBOL(put_disk); -/* +/** + * put_disk_and_module - decrements the module and gendisk refcount + * @disk: the struct gendisk to to decrement the refcount for + * * This is a counterpart of get_disk_and_module() and thus also of * get_gendisk(). */ -- cgit v1.2.3 From 763b58923aeb0a06c5a5f7e5fbb4c654c644d91d Mon Sep 17 00:00:00 2001 From: Luis Chamberlain Date: Fri, 19 Jun 2020 20:47:24 +0000 Subject: block: clarify context for refcount increment helpers Let us clarify the context under which the helpers to increment the refcount for the gendisk and request_queue can be called under. We make this explicit on the places where we may sleep with might_sleep(). We don't address the decrement context yet, as that needs some extra work and fixes, but will be addressed in the next patch. Signed-off-by: Luis Chamberlain Reviewed-by: Christoph Hellwig Reviewed-by: Bart Van Assche Signed-off-by: Jens Axboe --- block/blk-core.c | 2 ++ block/genhd.c | 6 ++++++ 2 files changed, 8 insertions(+) (limited to 'block/genhd.c') diff --git a/block/blk-core.c b/block/blk-core.c index 13777c0c97f0..f68398cb2ef6 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -610,6 +610,8 @@ EXPORT_SYMBOL(blk_alloc_queue); * @q: the request_queue structure to increment the refcount for * * Increment the refcount of the request_queue kobject. + * + * Context: Any context. */ bool blk_get_queue(struct request_queue *q) { diff --git a/block/genhd.c b/block/genhd.c index f741613d731f..1be86b1f43ec 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -985,11 +985,15 @@ static ssize_t disk_badblocks_store(struct device *dev, * * This function gets the structure containing partitioning * information for the given device @devt. + * + * Context: can sleep */ struct gendisk *get_gendisk(dev_t devt, int *partno) { struct gendisk *disk = NULL; + might_sleep(); + if (MAJOR(devt) != BLOCK_EXT_MAJOR) { struct kobject *kobj; @@ -1764,6 +1768,8 @@ EXPORT_SYMBOL(__alloc_disk_node); * * This increments the refcount for the struct gendisk, and the gendisk's * fops module owner. + * + * Context: Any context. */ struct kobject *get_disk_and_module(struct gendisk *disk) { -- cgit v1.2.3 From e8c7d14ac6c37c173ec606907d38802b00302988 Mon Sep 17 00:00:00 2001 From: Luis Chamberlain Date: Fri, 19 Jun 2020 20:47:25 +0000 Subject: block: revert back to synchronous request_queue removal Commit dc9edc44de6c ("block: Fix a blk_exit_rl() regression") merged on v4.12 moved the work behind blk_release_queue() into a workqueue after a splat floated around which indicated some work on blk_release_queue() could sleep in blk_exit_rl(). This splat would be possible when a driver called blk_put_queue() or blk_cleanup_queue() (which calls blk_put_queue() as its final call) from an atomic context. blk_put_queue() decrements the refcount for the request_queue kobject, and upon reaching 0 blk_release_queue() is called. Although blk_exit_rl() is now removed through commit db6d99523560 ("block: remove request_list code") on v5.0, we reserve the right to be able to sleep within blk_release_queue() context. The last reference for the request_queue must not be called from atomic context. *When* the last reference to the request_queue reaches 0 varies, and so let's take the opportunity to document when that is expected to happen and also document the context of the related calls as best as possible so we can avoid future issues, and with the hopes that the synchronous request_queue removal sticks. We revert back to synchronous request_queue removal because asynchronous removal creates a regression with expected userspace interaction with several drivers. An example is when removing the loopback driver, one uses ioctls from userspace to do so, but upon return and if successful, one expects the device to be removed. Likewise if one races to add another device the new one may not be added as it is still being removed. This was expected behavior before and it now fails as the device is still present and busy still. Moving to asynchronous request_queue removal could have broken many scripts which relied on the removal to have been completed if there was no error. Document this expectation as well so that this doesn't regress userspace again. Using asynchronous request_queue removal however has helped us find other bugs. In the future we can test what could break with this arrangement by enabling CONFIG_DEBUG_KOBJECT_RELEASE. While at it, update the docs with the context expectations for the request_queue / gendisk refcount decrement, and make these expectations explicit by using might_sleep(). Fixes: dc9edc44de6c ("block: Fix a blk_exit_rl() regression") Suggested-by: Nicolai Stange Signed-off-by: Luis Chamberlain Reviewed-by: Christoph Hellwig Reviewed-by: Bart Van Assche Cc: Bart Van Assche Cc: Omar Sandoval Cc: Hannes Reinecke Cc: Nicolai Stange Cc: Greg Kroah-Hartman Cc: Michal Hocko Cc: yu kuai Signed-off-by: Jens Axboe --- block/blk-core.c | 8 ++++++++ block/blk-sysfs.c | 43 ++++++++++++++++++++++--------------------- block/genhd.c | 17 +++++++++++++++++ include/linux/blkdev.h | 2 -- 4 files changed, 47 insertions(+), 23 deletions(-) (limited to 'block/genhd.c') diff --git a/block/blk-core.c b/block/blk-core.c index f68398cb2ef6..a99b22fac38a 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -327,6 +327,9 @@ EXPORT_SYMBOL_GPL(blk_clear_pm_only); * * Decrements the refcount of the request_queue kobject. When this reaches 0 * we'll have blk_release_queue() called. + * + * Context: Any context, but the last reference must not be dropped from + * atomic context. */ void blk_put_queue(struct request_queue *q) { @@ -359,9 +362,14 @@ EXPORT_SYMBOL_GPL(blk_set_queue_dying); * * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and * put it. All future requests will be failed immediately with -ENODEV. + * + * Context: can sleep */ void blk_cleanup_queue(struct request_queue *q) { + /* cannot be called from atomic context */ + might_sleep(); + WARN_ON_ONCE(blk_queue_registered(q)); /* mark @q DYING, no new request or merges will be allowed afterwards */ diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 02643e149d5e..561624d4cc4e 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -873,22 +873,32 @@ static void blk_exit_queue(struct request_queue *q) bdi_put(q->backing_dev_info); } - /** - * __blk_release_queue - release a request queue - * @work: pointer to the release_work member of the request queue to be released + * blk_release_queue - releases all allocated resources of the request_queue + * @kobj: pointer to a kobject, whose container is a request_queue + * + * This function releases all allocated resources of the request queue. + * + * The struct request_queue refcount is incremented with blk_get_queue() and + * decremented with blk_put_queue(). Once the refcount reaches 0 this function + * is called. + * + * For drivers that have a request_queue on a gendisk and added with + * __device_add_disk() the refcount to request_queue will reach 0 with + * the last put_disk() called by the driver. For drivers which don't use + * __device_add_disk() this happens with blk_cleanup_queue(). * - * Description: - * This function is called when a block device is being unregistered. The - * process of releasing a request queue starts with blk_cleanup_queue, which - * set the appropriate flags and then calls blk_put_queue, that decrements - * the reference counter of the request queue. Once the reference counter - * of the request queue reaches zero, blk_release_queue is called to release - * all allocated resources of the request queue. + * Drivers exist which depend on the release of the request_queue to be + * synchronous, it should not be deferred. + * + * Context: can sleep */ -static void __blk_release_queue(struct work_struct *work) +static void blk_release_queue(struct kobject *kobj) { - struct request_queue *q = container_of(work, typeof(*q), release_work); + struct request_queue *q = + container_of(kobj, struct request_queue, kobj); + + might_sleep(); if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags)) blk_stat_remove_callback(q, q->poll_cb); @@ -917,15 +927,6 @@ static void __blk_release_queue(struct work_struct *work) call_rcu(&q->rcu_head, blk_free_queue_rcu); } -static void blk_release_queue(struct kobject *kobj) -{ - struct request_queue *q = - container_of(kobj, struct request_queue, kobj); - - INIT_WORK(&q->release_work, __blk_release_queue); - schedule_work(&q->release_work); -} - static const struct sysfs_ops queue_sysfs_ops = { .show = queue_attr_show, .store = queue_attr_store, diff --git a/block/genhd.c b/block/genhd.c index 1be86b1f43ec..60ae4e1b4d38 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -889,12 +889,19 @@ static void invalidate_partition(struct gendisk *disk, int partno) * The final removal of the struct gendisk happens when its refcount reaches 0 * with put_disk(), which should be called after del_gendisk(), if * __device_add_disk() was used. + * + * Drivers exist which depend on the release of the gendisk to be synchronous, + * it should not be deferred. + * + * Context: can sleep */ void del_gendisk(struct gendisk *disk) { struct disk_part_iter piter; struct hd_struct *part; + might_sleep(); + blk_integrity_del(disk); disk_del_events(disk); @@ -1548,11 +1555,15 @@ int disk_expand_part_tbl(struct gendisk *disk, int partno) * drivers we also call blk_put_queue() for them, and we expect the * request_queue refcount to reach 0 at this point, and so the request_queue * will also be freed prior to the disk. + * + * Context: can sleep */ static void disk_release(struct device *dev) { struct gendisk *disk = dev_to_disk(dev); + might_sleep(); + blk_free_devt(dev->devt); disk_release_events(disk); kfree(disk->random); @@ -1797,6 +1808,9 @@ EXPORT_SYMBOL(get_disk_and_module); * * This decrements the refcount for the struct gendisk. When this reaches 0 * we'll have disk_release() called. + * + * Context: Any context, but the last reference must not be dropped from + * atomic context. */ void put_disk(struct gendisk *disk) { @@ -1811,6 +1825,9 @@ EXPORT_SYMBOL(put_disk); * * This is a counterpart of get_disk_and_module() and thus also of * get_gendisk(). + * + * Context: Any context, but the last reference must not be dropped from + * atomic context. */ void put_disk_and_module(struct gendisk *disk) { diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 98712cfc7a34..e214e0e9f868 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -584,8 +584,6 @@ struct request_queue { size_t cmd_size; - struct work_struct release_work; - #define BLK_MAX_WRITE_HINTS 5 u64 write_hints[BLK_MAX_WRITE_HINTS]; }; -- cgit v1.2.3 From a564e23f0f99759f453dbefcb9160dec6d99df96 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 8 Jul 2020 14:25:41 +0200 Subject: md: switch to ->check_events for media change notifications md is the last driver using the legacy media_changed method. Switch it over to (not so) new ->clear_events approach, which also removes the need for the ->revalidate_disk method. Signed-off-by: Christoph Hellwig [axboe: remove unused 'bdops' variable in disk_clear_events()] Signed-off-by: Jens Axboe --- Documentation/filesystems/locking.rst | 4 +--- block/genhd.c | 8 +------- drivers/md/md.c | 19 ++++++++----------- include/linux/blkdev.h | 2 -- 4 files changed, 10 insertions(+), 23 deletions(-) (limited to 'block/genhd.c') diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst index 318605de83f3..17bea12538c3 100644 --- a/Documentation/filesystems/locking.rst +++ b/Documentation/filesystems/locking.rst @@ -467,7 +467,6 @@ prototypes:: int (*compat_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long); int (*direct_access) (struct block_device *, sector_t, void **, unsigned long *); - int (*media_changed) (struct gendisk *); void (*unlock_native_capacity) (struct gendisk *); int (*revalidate_disk) (struct gendisk *); int (*getgeo)(struct block_device *, struct hd_geometry *); @@ -483,14 +482,13 @@ release: yes ioctl: no compat_ioctl: no direct_access: no -media_changed: no unlock_native_capacity: no revalidate_disk: no getgeo: no swap_slot_free_notify: no (see below) ======================= =================== -media_changed, unlock_native_capacity and revalidate_disk are called only from +unlock_native_capacity and revalidate_disk are called only from check_disk_change(). swap_slot_free_notify is called with swap_lock and sometimes the page lock diff --git a/block/genhd.c b/block/genhd.c index 60ae4e1b4d38..c42a49f2f537 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -2056,18 +2056,12 @@ void disk_flush_events(struct gendisk *disk, unsigned int mask) */ unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask) { - const struct block_device_operations *bdops = disk->fops; struct disk_events *ev = disk->ev; unsigned int pending; unsigned int clearing = mask; - if (!ev) { - /* for drivers still using the old ->media_changed method */ - if ((mask & DISK_EVENT_MEDIA_CHANGE) && - bdops->media_changed && bdops->media_changed(disk)) - return DISK_EVENT_MEDIA_CHANGE; + if (!ev) return 0; - } disk_block_events(disk); diff --git a/drivers/md/md.c b/drivers/md/md.c index 8bb69c61afe0..77dfe4765c31 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -5670,6 +5670,7 @@ static int md_alloc(dev_t dev, char *name) * remove it now. */ disk->flags |= GENHD_FL_EXT_DEVT; + disk->events |= DISK_EVENT_MEDIA_CHANGE; mddev->gendisk = disk; /* As soon as we call add_disk(), another thread could get * through to md_open, so make sure it doesn't get too far @@ -7806,20 +7807,17 @@ static void md_release(struct gendisk *disk, fmode_t mode) mddev_put(mddev); } -static int md_media_changed(struct gendisk *disk) -{ - struct mddev *mddev = disk->private_data; - - return mddev->changed; -} - -static int md_revalidate(struct gendisk *disk) +static unsigned int md_check_events(struct gendisk *disk, unsigned int clearing) { struct mddev *mddev = disk->private_data; + unsigned int ret = 0; + if (mddev->changed) + ret = DISK_EVENT_MEDIA_CHANGE; mddev->changed = 0; - return 0; + return ret; } + static const struct block_device_operations md_fops = { .owner = THIS_MODULE, @@ -7831,8 +7829,7 @@ static const struct block_device_operations md_fops = .compat_ioctl = md_compat_ioctl, #endif .getgeo = md_getgeo, - .media_changed = md_media_changed, - .revalidate_disk= md_revalidate, + .check_events = md_check_events, }; static int md_thread(void *arg) diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 408eb66a82fd..71173a1ffa8b 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1781,8 +1781,6 @@ struct block_device_operations { int (*compat_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long); unsigned int (*check_events) (struct gendisk *disk, unsigned int clearing); - /* ->media_changed() is DEPRECATED, use ->check_events() instead */ - int (*media_changed) (struct gendisk *); void (*unlock_native_capacity) (struct gendisk *); int (*revalidate_disk) (struct gendisk *); int (*getgeo)(struct block_device *, struct hd_geometry *); -- cgit v1.2.3 From ef45fe470e1e5410db4af87abc5d5055427945ac Mon Sep 17 00:00:00 2001 From: Boris Burkov Date: Mon, 1 Jun 2020 13:12:05 -0700 Subject: blk-cgroup: show global disk stats in root cgroup io.stat In order to improve consistency and usability in cgroup stat accounting, we would like to support the root cgroup's io.stat. Since the root cgroup has processes doing io even if the system has no explicitly created cgroups, we need to be careful to avoid overhead in that case. For that reason, the rstat algorithms don't handle the root cgroup, so just turning the file on wouldn't give correct statistics. To get around this, we simulate flushing the iostat struct by filling it out directly from global disk stats. The result is a root cgroup io.stat file consistent with both /proc/diskstats and io.stat. Note that in order to collect the disk stats, we needed to iterate over devices. To facilitate that, we had to change the linkage of a disk_type to external so that it can be used from blk-cgroup.c to iterate over disks. Suggested-by: Tejun Heo Signed-off-by: Boris Burkov Acked-by: Tejun Heo Signed-off-by: Jens Axboe --- Documentation/admin-guide/cgroup-v2.rst | 3 +- block/blk-cgroup.c | 57 +++++++++++++++++++++++++++++++-- block/genhd.c | 4 +-- include/linux/genhd.h | 1 + 4 files changed, 58 insertions(+), 7 deletions(-) (limited to 'block/genhd.c') diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index ce3e05e41724..2d7c5907e0ce 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -1483,8 +1483,7 @@ IO Interface Files ~~~~~~~~~~~~~~~~~~ io.stat - A read-only nested-keyed file which exists on non-root - cgroups. + A read-only nested-keyed file. Lines are keyed by $MAJ:$MIN device numbers and not ordered. The following nested keys are defined. diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 696d28151c9a..619a79b51068 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -782,12 +782,66 @@ static void blkcg_rstat_flush(struct cgroup_subsys_state *css, int cpu) rcu_read_unlock(); } +/* + * The rstat algorithms intentionally don't handle the root cgroup to avoid + * incurring overhead when no cgroups are defined. For that reason, + * cgroup_rstat_flush in blkcg_print_stat does not actually fill out the + * iostat in the root cgroup's blkcg_gq. + * + * However, we would like to re-use the printing code between the root and + * non-root cgroups to the extent possible. For that reason, we simulate + * flushing the root cgroup's stats by explicitly filling in the iostat + * with disk level statistics. + */ +static void blkcg_fill_root_iostats(void) +{ + struct class_dev_iter iter; + struct device *dev; + + class_dev_iter_init(&iter, &block_class, NULL, &disk_type); + while ((dev = class_dev_iter_next(&iter))) { + struct gendisk *disk = dev_to_disk(dev); + struct hd_struct *part = disk_get_part(disk, 0); + struct blkcg_gq *blkg = blk_queue_root_blkg(disk->queue); + struct blkg_iostat tmp; + int cpu; + + memset(&tmp, 0, sizeof(tmp)); + for_each_possible_cpu(cpu) { + struct disk_stats *cpu_dkstats; + + cpu_dkstats = per_cpu_ptr(part->dkstats, cpu); + tmp.ios[BLKG_IOSTAT_READ] += + cpu_dkstats->ios[STAT_READ]; + tmp.ios[BLKG_IOSTAT_WRITE] += + cpu_dkstats->ios[STAT_WRITE]; + tmp.ios[BLKG_IOSTAT_DISCARD] += + cpu_dkstats->ios[STAT_DISCARD]; + // convert sectors to bytes + tmp.bytes[BLKG_IOSTAT_READ] += + cpu_dkstats->sectors[STAT_READ] << 9; + tmp.bytes[BLKG_IOSTAT_WRITE] += + cpu_dkstats->sectors[STAT_WRITE] << 9; + tmp.bytes[BLKG_IOSTAT_DISCARD] += + cpu_dkstats->sectors[STAT_DISCARD] << 9; + + u64_stats_update_begin(&blkg->iostat.sync); + blkg_iostat_set(&blkg->iostat.cur, &tmp); + u64_stats_update_end(&blkg->iostat.sync); + } + } +} + static int blkcg_print_stat(struct seq_file *sf, void *v) { struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); struct blkcg_gq *blkg; - cgroup_rstat_flush(blkcg->css.cgroup); + if (!seq_css(sf)->parent) + blkcg_fill_root_iostats(); + else + cgroup_rstat_flush(blkcg->css.cgroup); + rcu_read_lock(); hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { @@ -876,7 +930,6 @@ static int blkcg_print_stat(struct seq_file *sf, void *v) static struct cftype blkcg_files[] = { { .name = "stat", - .flags = CFTYPE_NOT_ON_ROOT, .seq_show = blkcg_print_stat, }, { } /* terminate */ diff --git a/block/genhd.c b/block/genhd.c index c42a49f2f537..8b1e9f48957c 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -38,8 +38,6 @@ static struct kobject *block_depr; static DEFINE_SPINLOCK(ext_devt_lock); static DEFINE_IDR(ext_devt_idr); -static const struct device_type disk_type; - static void disk_check_events(struct disk_events *ev, unsigned int *clearing_ptr); static void disk_alloc_events(struct gendisk *disk); @@ -1587,7 +1585,7 @@ static char *block_devnode(struct device *dev, umode_t *mode, return NULL; } -static const struct device_type disk_type = { +const struct device_type disk_type = { .name = "disk", .groups = disk_attr_groups, .release = disk_release, diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 31a54072ffd6..4ab853461dff 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -24,6 +24,7 @@ #define disk_to_dev(disk) (&(disk)->part0.__dev) #define part_to_dev(part) (&((part)->__dev)) +extern const struct device_type disk_type; extern struct device_type part_type; extern struct class block_class; -- cgit v1.2.3