linux/block/disk-events.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Disk events - monitor disk events like media change and eject request.
 */
#include <linux/export.h>
#include <linux/moduleparam.h>
#include <linux/blkdev.h>
#include "blk.h"

struct disk_events { … };

static const char *disk_events_strs[] = …;

static char *disk_uevents[] = …;

/* list of all disk_events */
static DEFINE_MUTEX(disk_events_mutex);
static LIST_HEAD(disk_events);

/* disable in-kernel polling by default */
static unsigned long disk_events_dfl_poll_msecs;

static unsigned long disk_events_poll_jiffies(struct gendisk *disk)
{ … }

/**
 * disk_block_events - block and flush disk event checking
 * @disk: disk to block events for
 *
 * On return from this function, it is guaranteed that event checking
 * isn't in progress and won't happen until unblocked by
 * disk_unblock_events().  Events blocking is counted and the actual
 * unblocking happens after the matching number of unblocks are done.
 *
 * Note that this intentionally does not block event checking from
 * disk_clear_events().
 *
 * CONTEXT:
 * Might sleep.
 */
void disk_block_events(struct gendisk *disk)
{ … }

static void __disk_unblock_events(struct gendisk *disk, bool check_now)
{ … }

/**
 * disk_unblock_events - unblock disk event checking
 * @disk: disk to unblock events for
 *
 * Undo disk_block_events().  When the block count reaches zero, it
 * starts events polling if configured.
 *
 * CONTEXT:
 * Don't care.  Safe to call from irq context.
 */
void disk_unblock_events(struct gendisk *disk)
{ … }

/**
 * disk_flush_events - schedule immediate event checking and flushing
 * @disk: disk to check and flush events for
 * @mask: events to flush
 *
 * Schedule immediate event checking on @disk if not blocked.  Events in
 * @mask are scheduled to be cleared from the driver.  Note that this
 * doesn't clear the events from @disk->ev.
 *
 * CONTEXT:
 * If @mask is non-zero must be called with disk->open_mutex held.
 */
void disk_flush_events(struct gendisk *disk, unsigned int mask)
{ … }

/*
 * Tell userland about new events.  Only the events listed in @disk->events are
 * reported, and only if DISK_EVENT_FLAG_UEVENT is set.  Otherwise, events are
 * processed internally but never get reported to userland.
 */
static void disk_event_uevent(struct gendisk *disk, unsigned int events)
{ … }

static void disk_check_events(struct disk_events *ev,
			      unsigned int *clearing_ptr)
{ … }

/**
 * disk_clear_events - synchronously check, clear and return pending events
 * @disk: disk to fetch and clear events from
 * @mask: mask of events to be fetched and cleared
 *
 * Disk events are synchronously checked and pending events in @mask
 * are cleared and returned.  This ignores the block count.
 *
 * CONTEXT:
 * Might sleep.
 */
static unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
{ … }

/**
 * disk_check_media_change - check if a removable media has been changed
 * @disk: gendisk to check
 *
 * Returns %true and marks the disk for a partition rescan whether a removable
 * media has been changed, and %false if the media did not change.
 */
bool disk_check_media_change(struct gendisk *disk)
{ … }
EXPORT_SYMBOL(…);

/**
 * disk_force_media_change - force a media change event
 * @disk: the disk which will raise the event
 *
 * Should be called when the media changes for @disk.  Generates a uevent
 * and attempts to free all dentries and inodes and invalidates all block
 * device page cache entries in that case.
 */
void disk_force_media_change(struct gendisk *disk)
{ … }
EXPORT_SYMBOL_GPL(…);

/*
 * Separate this part out so that a different pointer for clearing_ptr can be
 * passed in for disk_clear_events.
 */
static void disk_events_workfn(struct work_struct *work)
{ … }

/*
 * A disk events enabled device has the following sysfs nodes under
 * its /sys/block/X/ directory.
 *
 * events		: list of all supported events
 * events_async		: list of events which can be detected w/o polling
 *			  (always empty, only for backwards compatibility)
 * events_poll_msecs	: polling interval, 0: disable, -1: system default
 */
static ssize_t __disk_events_show(unsigned int events, char *buf)
{ … }

static ssize_t disk_events_show(struct device *dev,
				struct device_attribute *attr, char *buf)
{ … }

static ssize_t disk_events_async_show(struct device *dev,
				      struct device_attribute *attr, char *buf)
{ … }

static ssize_t disk_events_poll_msecs_show(struct device *dev,
					   struct device_attribute *attr,
					   char *buf)
{ … }

static ssize_t disk_events_poll_msecs_store(struct device *dev,
					    struct device_attribute *attr,
					    const char *buf, size_t count)
{ … }

DEVICE_ATTR(…);
DEVICE_ATTR(…);
DEVICE_ATTR(…);

/*
 * The default polling interval can be specified by the kernel
 * parameter block.events_dfl_poll_msecs which defaults to 0
 * (disable).  This can also be modified runtime by writing to
 * /sys/module/block/parameters/events_dfl_poll_msecs.
 */
static int disk_events_set_dfl_poll_msecs(const char *val,
					  const struct kernel_param *kp)
{ … }

static const struct kernel_param_ops disk_events_dfl_poll_msecs_param_ops = …;

#undef MODULE_PARAM_PREFIX
#define MODULE_PARAM_PREFIX …

module_param_cb(…);

/*
 * disk_{alloc|add|del|release}_events - initialize and destroy disk_events.
 */
int disk_alloc_events(struct gendisk *disk)
{ … }

void disk_add_events(struct gendisk *disk)
{ … }

void disk_del_events(struct gendisk *disk)
{ … }

void disk_release_events(struct gendisk *disk)
{ … }