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6e57236ed6
disk_check_media_change is mostly called from ->open where it makes little sense to mark the file system on the device as dead, as we are just opening it. So instead of calling bdev_mark_dead from disk_check_media_change move it into the few callers that are not in an open instance. This avoid calling into bdev_mark_dead and thus taking s_umount with open_mutex held. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20231017184823.1383356-4-hch@lst.de Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Christian Brauner <brauner@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Christian Brauner <brauner@kernel.org>
490 lines
12 KiB
C
490 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Disk events - monitor disk events like media change and eject request.
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*/
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#include <linux/export.h>
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#include <linux/moduleparam.h>
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#include <linux/blkdev.h>
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#include "blk.h"
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struct disk_events {
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struct list_head node; /* all disk_event's */
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struct gendisk *disk; /* the associated disk */
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spinlock_t lock;
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struct mutex block_mutex; /* protects blocking */
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int block; /* event blocking depth */
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unsigned int pending; /* events already sent out */
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unsigned int clearing; /* events being cleared */
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long poll_msecs; /* interval, -1 for default */
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struct delayed_work dwork;
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};
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static const char *disk_events_strs[] = {
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[ilog2(DISK_EVENT_MEDIA_CHANGE)] = "media_change",
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[ilog2(DISK_EVENT_EJECT_REQUEST)] = "eject_request",
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};
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static char *disk_uevents[] = {
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[ilog2(DISK_EVENT_MEDIA_CHANGE)] = "DISK_MEDIA_CHANGE=1",
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[ilog2(DISK_EVENT_EJECT_REQUEST)] = "DISK_EJECT_REQUEST=1",
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};
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/* list of all disk_events */
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static DEFINE_MUTEX(disk_events_mutex);
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static LIST_HEAD(disk_events);
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/* disable in-kernel polling by default */
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static unsigned long disk_events_dfl_poll_msecs;
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static unsigned long disk_events_poll_jiffies(struct gendisk *disk)
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{
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struct disk_events *ev = disk->ev;
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long intv_msecs = 0;
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/*
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* If device-specific poll interval is set, always use it. If
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* the default is being used, poll if the POLL flag is set.
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*/
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if (ev->poll_msecs >= 0)
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intv_msecs = ev->poll_msecs;
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else if (disk->event_flags & DISK_EVENT_FLAG_POLL)
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intv_msecs = disk_events_dfl_poll_msecs;
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return msecs_to_jiffies(intv_msecs);
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}
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/**
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* disk_block_events - block and flush disk event checking
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* @disk: disk to block events for
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*
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* On return from this function, it is guaranteed that event checking
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* isn't in progress and won't happen until unblocked by
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* disk_unblock_events(). Events blocking is counted and the actual
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* unblocking happens after the matching number of unblocks are done.
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*
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* Note that this intentionally does not block event checking from
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* disk_clear_events().
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*
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* CONTEXT:
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* Might sleep.
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*/
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void disk_block_events(struct gendisk *disk)
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{
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struct disk_events *ev = disk->ev;
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unsigned long flags;
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bool cancel;
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if (!ev)
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return;
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/*
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* Outer mutex ensures that the first blocker completes canceling
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* the event work before further blockers are allowed to finish.
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*/
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mutex_lock(&ev->block_mutex);
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spin_lock_irqsave(&ev->lock, flags);
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cancel = !ev->block++;
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spin_unlock_irqrestore(&ev->lock, flags);
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if (cancel)
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cancel_delayed_work_sync(&disk->ev->dwork);
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mutex_unlock(&ev->block_mutex);
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}
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static void __disk_unblock_events(struct gendisk *disk, bool check_now)
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{
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struct disk_events *ev = disk->ev;
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unsigned long intv;
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unsigned long flags;
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spin_lock_irqsave(&ev->lock, flags);
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if (WARN_ON_ONCE(ev->block <= 0))
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goto out_unlock;
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if (--ev->block)
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goto out_unlock;
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intv = disk_events_poll_jiffies(disk);
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if (check_now)
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queue_delayed_work(system_freezable_power_efficient_wq,
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&ev->dwork, 0);
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else if (intv)
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queue_delayed_work(system_freezable_power_efficient_wq,
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&ev->dwork, intv);
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out_unlock:
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spin_unlock_irqrestore(&ev->lock, flags);
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}
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/**
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* disk_unblock_events - unblock disk event checking
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* @disk: disk to unblock events for
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*
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* Undo disk_block_events(). When the block count reaches zero, it
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* starts events polling if configured.
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*
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* CONTEXT:
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* Don't care. Safe to call from irq context.
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*/
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void disk_unblock_events(struct gendisk *disk)
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{
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if (disk->ev)
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__disk_unblock_events(disk, false);
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}
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/**
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* disk_flush_events - schedule immediate event checking and flushing
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* @disk: disk to check and flush events for
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* @mask: events to flush
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*
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* Schedule immediate event checking on @disk if not blocked. Events in
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* @mask are scheduled to be cleared from the driver. Note that this
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* doesn't clear the events from @disk->ev.
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*
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* CONTEXT:
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* If @mask is non-zero must be called with disk->open_mutex held.
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*/
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void disk_flush_events(struct gendisk *disk, unsigned int mask)
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{
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struct disk_events *ev = disk->ev;
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if (!ev)
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return;
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spin_lock_irq(&ev->lock);
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ev->clearing |= mask;
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if (!ev->block)
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mod_delayed_work(system_freezable_power_efficient_wq,
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&ev->dwork, 0);
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spin_unlock_irq(&ev->lock);
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}
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/*
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* Tell userland about new events. Only the events listed in @disk->events are
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* reported, and only if DISK_EVENT_FLAG_UEVENT is set. Otherwise, events are
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* processed internally but never get reported to userland.
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*/
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static void disk_event_uevent(struct gendisk *disk, unsigned int events)
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{
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char *envp[ARRAY_SIZE(disk_uevents) + 1] = { };
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int nr_events = 0, i;
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for (i = 0; i < ARRAY_SIZE(disk_uevents); i++)
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if (events & disk->events & (1 << i))
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envp[nr_events++] = disk_uevents[i];
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if (nr_events)
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kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
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}
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static void disk_check_events(struct disk_events *ev,
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unsigned int *clearing_ptr)
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{
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struct gendisk *disk = ev->disk;
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unsigned int clearing = *clearing_ptr;
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unsigned int events;
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unsigned long intv;
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/* check events */
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events = disk->fops->check_events(disk, clearing);
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/* accumulate pending events and schedule next poll if necessary */
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spin_lock_irq(&ev->lock);
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events &= ~ev->pending;
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ev->pending |= events;
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*clearing_ptr &= ~clearing;
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intv = disk_events_poll_jiffies(disk);
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if (!ev->block && intv)
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queue_delayed_work(system_freezable_power_efficient_wq,
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&ev->dwork, intv);
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spin_unlock_irq(&ev->lock);
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if (events & DISK_EVENT_MEDIA_CHANGE)
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inc_diskseq(disk);
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if (disk->event_flags & DISK_EVENT_FLAG_UEVENT)
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disk_event_uevent(disk, events);
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}
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/**
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* disk_clear_events - synchronously check, clear and return pending events
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* @disk: disk to fetch and clear events from
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* @mask: mask of events to be fetched and cleared
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*
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* Disk events are synchronously checked and pending events in @mask
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* are cleared and returned. This ignores the block count.
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*
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* CONTEXT:
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* Might sleep.
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*/
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static unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
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{
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struct disk_events *ev = disk->ev;
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unsigned int pending;
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unsigned int clearing = mask;
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if (!ev)
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return 0;
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disk_block_events(disk);
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/*
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* store the union of mask and ev->clearing on the stack so that the
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* race with disk_flush_events does not cause ambiguity (ev->clearing
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* can still be modified even if events are blocked).
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*/
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spin_lock_irq(&ev->lock);
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clearing |= ev->clearing;
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ev->clearing = 0;
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spin_unlock_irq(&ev->lock);
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disk_check_events(ev, &clearing);
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/*
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* if ev->clearing is not 0, the disk_flush_events got called in the
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* middle of this function, so we want to run the workfn without delay.
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*/
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__disk_unblock_events(disk, ev->clearing ? true : false);
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/* then, fetch and clear pending events */
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spin_lock_irq(&ev->lock);
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pending = ev->pending & mask;
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ev->pending &= ~mask;
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spin_unlock_irq(&ev->lock);
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WARN_ON_ONCE(clearing & mask);
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return pending;
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}
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/**
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* disk_check_media_change - check if a removable media has been changed
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* @disk: gendisk to check
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*
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* Returns %true and marks the disk for a partition rescan whether a removable
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* media has been changed, and %false if the media did not change.
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*/
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bool disk_check_media_change(struct gendisk *disk)
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{
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unsigned int events;
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events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
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DISK_EVENT_EJECT_REQUEST);
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if (events & DISK_EVENT_MEDIA_CHANGE) {
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set_bit(GD_NEED_PART_SCAN, &disk->state);
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return true;
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}
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return false;
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}
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EXPORT_SYMBOL(disk_check_media_change);
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/**
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* disk_force_media_change - force a media change event
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* @disk: the disk which will raise the event
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*
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* Should be called when the media changes for @disk. Generates a uevent
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* and attempts to free all dentries and inodes and invalidates all block
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* device page cache entries in that case.
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*/
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void disk_force_media_change(struct gendisk *disk)
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{
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disk_event_uevent(disk, DISK_EVENT_MEDIA_CHANGE);
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inc_diskseq(disk);
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bdev_mark_dead(disk->part0, true);
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set_bit(GD_NEED_PART_SCAN, &disk->state);
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}
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EXPORT_SYMBOL_GPL(disk_force_media_change);
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/*
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* Separate this part out so that a different pointer for clearing_ptr can be
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* passed in for disk_clear_events.
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*/
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static void disk_events_workfn(struct work_struct *work)
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{
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struct delayed_work *dwork = to_delayed_work(work);
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struct disk_events *ev = container_of(dwork, struct disk_events, dwork);
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disk_check_events(ev, &ev->clearing);
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}
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/*
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* A disk events enabled device has the following sysfs nodes under
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* its /sys/block/X/ directory.
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*
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* events : list of all supported events
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* events_async : list of events which can be detected w/o polling
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* (always empty, only for backwards compatibility)
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* events_poll_msecs : polling interval, 0: disable, -1: system default
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*/
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static ssize_t __disk_events_show(unsigned int events, char *buf)
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{
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const char *delim = "";
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ssize_t pos = 0;
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int i;
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for (i = 0; i < ARRAY_SIZE(disk_events_strs); i++)
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if (events & (1 << i)) {
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pos += sprintf(buf + pos, "%s%s",
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delim, disk_events_strs[i]);
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delim = " ";
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}
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if (pos)
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pos += sprintf(buf + pos, "\n");
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return pos;
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}
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static ssize_t disk_events_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct gendisk *disk = dev_to_disk(dev);
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if (!(disk->event_flags & DISK_EVENT_FLAG_UEVENT))
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return 0;
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return __disk_events_show(disk->events, buf);
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}
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static ssize_t disk_events_async_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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return 0;
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}
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static ssize_t disk_events_poll_msecs_show(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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struct gendisk *disk = dev_to_disk(dev);
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if (!disk->ev)
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return sprintf(buf, "-1\n");
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return sprintf(buf, "%ld\n", disk->ev->poll_msecs);
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}
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static ssize_t disk_events_poll_msecs_store(struct device *dev,
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struct device_attribute *attr,
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const char *buf, size_t count)
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{
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struct gendisk *disk = dev_to_disk(dev);
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long intv;
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if (!count || !sscanf(buf, "%ld", &intv))
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return -EINVAL;
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if (intv < 0 && intv != -1)
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return -EINVAL;
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if (!disk->ev)
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return -ENODEV;
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disk_block_events(disk);
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disk->ev->poll_msecs = intv;
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__disk_unblock_events(disk, true);
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return count;
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}
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DEVICE_ATTR(events, 0444, disk_events_show, NULL);
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DEVICE_ATTR(events_async, 0444, disk_events_async_show, NULL);
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DEVICE_ATTR(events_poll_msecs, 0644, disk_events_poll_msecs_show,
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disk_events_poll_msecs_store);
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/*
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* The default polling interval can be specified by the kernel
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* parameter block.events_dfl_poll_msecs which defaults to 0
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* (disable). This can also be modified runtime by writing to
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* /sys/module/block/parameters/events_dfl_poll_msecs.
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*/
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static int disk_events_set_dfl_poll_msecs(const char *val,
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const struct kernel_param *kp)
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{
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struct disk_events *ev;
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int ret;
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ret = param_set_ulong(val, kp);
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if (ret < 0)
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return ret;
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mutex_lock(&disk_events_mutex);
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list_for_each_entry(ev, &disk_events, node)
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disk_flush_events(ev->disk, 0);
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mutex_unlock(&disk_events_mutex);
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return 0;
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}
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static const struct kernel_param_ops disk_events_dfl_poll_msecs_param_ops = {
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.set = disk_events_set_dfl_poll_msecs,
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.get = param_get_ulong,
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};
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#undef MODULE_PARAM_PREFIX
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#define MODULE_PARAM_PREFIX "block."
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module_param_cb(events_dfl_poll_msecs, &disk_events_dfl_poll_msecs_param_ops,
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&disk_events_dfl_poll_msecs, 0644);
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/*
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* disk_{alloc|add|del|release}_events - initialize and destroy disk_events.
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*/
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int disk_alloc_events(struct gendisk *disk)
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{
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struct disk_events *ev;
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if (!disk->fops->check_events || !disk->events)
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return 0;
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ev = kzalloc(sizeof(*ev), GFP_KERNEL);
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if (!ev) {
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pr_warn("%s: failed to initialize events\n", disk->disk_name);
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return -ENOMEM;
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}
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INIT_LIST_HEAD(&ev->node);
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ev->disk = disk;
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spin_lock_init(&ev->lock);
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mutex_init(&ev->block_mutex);
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ev->block = 1;
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ev->poll_msecs = -1;
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INIT_DELAYED_WORK(&ev->dwork, disk_events_workfn);
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disk->ev = ev;
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return 0;
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}
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void disk_add_events(struct gendisk *disk)
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{
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if (!disk->ev)
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return;
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mutex_lock(&disk_events_mutex);
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list_add_tail(&disk->ev->node, &disk_events);
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mutex_unlock(&disk_events_mutex);
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/*
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* Block count is initialized to 1 and the following initial
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* unblock kicks it into action.
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*/
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__disk_unblock_events(disk, true);
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}
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void disk_del_events(struct gendisk *disk)
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{
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if (disk->ev) {
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disk_block_events(disk);
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mutex_lock(&disk_events_mutex);
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list_del_init(&disk->ev->node);
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mutex_unlock(&disk_events_mutex);
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}
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}
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void disk_release_events(struct gendisk *disk)
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{
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/* the block count should be 1 from disk_del_events() */
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WARN_ON_ONCE(disk->ev && disk->ev->block != 1);
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kfree(disk->ev);
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}
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