Merge branch 'for-2.6.38/event-handling' into for-2.6.38/core

1 files changed, 516 insertions, 28 deletions

diff --git a/block/genhd.c b/block/genhd.c
index 399d37ec7412..6a5b772aa201 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -18,6 +18,7 @@
 #include <linux/buffer_head.h>
 #include <linux/mutex.h>
 #include <linux/idr.h>
+#include <linux/log2.h>
 
 #include "blk.h"
 
@@ -35,6 +36,10 @@ static DEFINE_IDR(ext_devt_idr);
 
 static struct device_type disk_type;
 
+static void disk_add_events(struct gendisk *disk);
+static void disk_del_events(struct gendisk *disk);
+static void disk_release_events(struct gendisk *disk);
+
 /**
  * disk_get_part - get partition
  * @disk: disk to look partition from
@@ -502,6 +507,64 @@ static int exact_lock(dev_t devt, void *data)
         return 0;
 }
 
+void register_disk(struct gendisk *disk)
+{
+        struct device *ddev = disk_to_dev(disk);
+        struct block_device *bdev;
+        struct disk_part_iter piter;
+        struct hd_struct *part;
+        int err;
+
+        ddev->parent = disk->driverfs_dev;
+
+        dev_set_name(ddev, disk->disk_name);
+
+        /* delay uevents, until we scanned partition table */
+        dev_set_uevent_suppress(ddev, 1);
+
+        if (device_add(ddev))
+                return;
+        if (!sysfs_deprecated) {
+                err = sysfs_create_link(block_depr, &ddev->kobj,
+                                        kobject_name(&ddev->kobj));
+                if (err) {
+                        device_del(ddev);
+                        return;
+                }
+        }
+        disk->part0.holder_dir = kobject_create_and_add("holders", &ddev->kobj);
+        disk->slave_dir = kobject_create_and_add("slaves", &ddev->kobj);
+
+        /* No minors to use for partitions */
+        if (!disk_partitionable(disk))
+                goto exit;
+
+        /* No such device (e.g., media were just removed) */
+        if (!get_capacity(disk))
+                goto exit;
+
+        bdev = bdget_disk(disk, 0);
+        if (!bdev)
+                goto exit;
+
+        bdev->bd_invalidated = 1;
+        err = blkdev_get(bdev, FMODE_READ, NULL);
+        if (err < 0)
+                goto exit;
+        blkdev_put(bdev, FMODE_READ);
+
+exit:
+        /* announce disk after possible partitions are created */
+        dev_set_uevent_suppress(ddev, 0);
+        kobject_uevent(&ddev->kobj, KOBJ_ADD);
+
+        /* announce possible partitions */
+        disk_part_iter_init(&piter, disk, 0);
+        while ((part = disk_part_iter_next(&piter)))
+                kobject_uevent(&part_to_dev(part)->kobj, KOBJ_ADD);
+        disk_part_iter_exit(&piter);
+}
+
 /**
  * add_disk - add partitioning information to kernel list
  * @disk: per-device partitioning information
@@ -551,18 +614,48 @@ void add_disk(struct gendisk *disk)
         retval = sysfs_create_link(&disk_to_dev(disk)->kobj, &bdi->dev->kobj,
                                    "bdi");
         WARN_ON(retval);
-}
 
+        disk_add_events(disk);
+}
 EXPORT_SYMBOL(add_disk);
-EXPORT_SYMBOL(del_gendisk);     /* in partitions/check.c */
 
-void unlink_gendisk(struct gendisk *disk)
+void del_gendisk(struct gendisk *disk)
 {
+        struct disk_part_iter piter;
+        struct hd_struct *part;
+
+        disk_del_events(disk);
+
+        /* invalidate stuff */
+        disk_part_iter_init(&piter, disk,
+                             DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE);
+        while ((part = disk_part_iter_next(&piter))) {
+                invalidate_partition(disk, part->partno);
+                delete_partition(disk, part->partno);
+        }
+        disk_part_iter_exit(&piter);
+
+        invalidate_partition(disk, 0);
+        blk_free_devt(disk_to_dev(disk)->devt);
+        set_capacity(disk, 0);
+        disk->flags &= ~GENHD_FL_UP;
+
         sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi");
         bdi_unregister(&disk->queue->backing_dev_info);
         blk_unregister_queue(disk);
         blk_unregister_region(disk_devt(disk), disk->minors);
+
+        part_stat_set_all(&disk->part0, 0);
+        disk->part0.stamp = 0;
+
+        kobject_put(disk->part0.holder_dir);
+        kobject_put(disk->slave_dir);
+        disk->driverfs_dev = NULL;
+        if (!sysfs_deprecated)
+                sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk)));
+        device_del(disk_to_dev(disk));
 }
+EXPORT_SYMBOL(del_gendisk);
 
 /**
  * get_gendisk - get partitioning information for a given device
@@ -1005,6 +1098,7 @@ static void disk_release(struct device *dev)
 {
         struct gendisk *disk = dev_to_disk(dev);
 
+        disk_release_events(disk);
         kfree(disk->random);
         disk_replace_part_tbl(disk, NULL);
         free_part_stats(&disk->part0);
@@ -1110,29 +1204,6 @@ static int __init proc_genhd_init(void)
 module_init(proc_genhd_init);
 #endif /* CONFIG_PROC_FS */
 
-static void media_change_notify_thread(struct work_struct *work)
-{
-        struct gendisk *gd = container_of(work, struct gendisk, async_notify);
-        char event[] = "MEDIA_CHANGE=1";
-        char *envp[] = { event, NULL };
-
-        /*
-         * set enviroment vars to indicate which event this is for
-         * so that user space will know to go check the media status.
-         */
-        kobject_uevent_env(&disk_to_dev(gd)->kobj, KOBJ_CHANGE, envp);
-        put_device(gd->driverfs_dev);
-}
-
-#if 0
-void genhd_media_change_notify(struct gendisk *disk)
-{
-        get_device(disk->driverfs_dev);
-        schedule_work(&disk->async_notify);
-}
-EXPORT_SYMBOL_GPL(genhd_media_change_notify);
-#endif  /*  0  */
-
 dev_t blk_lookup_devt(const char *name, int partno)
 {
         dev_t devt = MKDEV(0, 0);
@@ -1200,8 +1271,6 @@ struct gendisk *alloc_disk_node(int minors, int node_id)
                 disk_to_dev(disk)->class = &block_class;
                 disk_to_dev(disk)->type = &disk_type;
                 device_initialize(disk_to_dev(disk));
-                INIT_WORK(&disk->async_notify,
-                        media_change_notify_thread);
         }
         return disk;
 }
@@ -1293,3 +1362,422 @@ int invalidate_partition(struct gendisk *disk, int partno)
 }
 
 EXPORT_SYMBOL(invalidate_partition);
+
+/*
+ * Disk events - monitor disk events like media change and eject request.
+ */
+struct disk_events {
+        struct list_head        node;           /* all disk_event's */
+        struct gendisk          *disk;          /* the associated disk */
+        spinlock_t              lock;
+
+        int                     block;          /* event blocking depth */
+        unsigned int            pending;        /* events already sent out */
+        unsigned int            clearing;       /* events being cleared */
+
+        long                    poll_msecs;     /* interval, -1 for default */
+        struct delayed_work     dwork;
+};
+
+static const char *disk_events_strs[] = {
+        [ilog2(DISK_EVENT_MEDIA_CHANGE)]        = "media_change",
+        [ilog2(DISK_EVENT_EJECT_REQUEST)]       = "eject_request",
+};
+
+static char *disk_uevents[] = {
+        [ilog2(DISK_EVENT_MEDIA_CHANGE)]        = "DISK_MEDIA_CHANGE=1",
+        [ilog2(DISK_EVENT_EJECT_REQUEST)]       = "DISK_EJECT_REQUEST=1",
+};
+
+/* 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 = 0;
+
+static unsigned long disk_events_poll_jiffies(struct gendisk *disk)
+{
+        struct disk_events *ev = disk->ev;
+        long intv_msecs = 0;
+
+        /*
+         * If device-specific poll interval is set, always use it.  If
+         * the default is being used, poll iff there are events which
+         * can't be monitored asynchronously.
+         */
+        if (ev->poll_msecs >= 0)
+                intv_msecs = ev->poll_msecs;
+        else if (disk->events & ~disk->async_events)
+                intv_msecs = disk_events_dfl_poll_msecs;
+
+        return msecs_to_jiffies(intv_msecs);
+}
+
+static void __disk_block_events(struct gendisk *disk, bool sync)
+{
+        struct disk_events *ev = disk->ev;
+        unsigned long flags;
+        bool cancel;
+
+        spin_lock_irqsave(&ev->lock, flags);
+        cancel = !ev->block++;
+        spin_unlock_irqrestore(&ev->lock, flags);
+
+        if (cancel) {
+                if (sync)
+                        cancel_delayed_work_sync(&disk->ev->dwork);
+                else
+                        cancel_delayed_work(&disk->ev->dwork);
+        }
+}
+
+static void __disk_unblock_events(struct gendisk *disk, bool check_now)
+{
+        struct disk_events *ev = disk->ev;
+        unsigned long intv;
+        unsigned long flags;
+
+        spin_lock_irqsave(&ev->lock, flags);
+
+        if (WARN_ON_ONCE(ev->block <= 0))
+                goto out_unlock;
+
+        if (--ev->block)
+                goto out_unlock;
+
+        /*
+         * Not exactly a latency critical operation, set poll timer
+         * slack to 25% and kick event check.
+         */
+        intv = disk_events_poll_jiffies(disk);
+        set_timer_slack(&ev->dwork.timer, intv / 4);
+        if (check_now)
+                queue_delayed_work(system_nrt_wq, &ev->dwork, 0);
+        else if (intv)
+                queue_delayed_work(system_nrt_wq, &ev->dwork, intv);
+out_unlock:
+        spin_unlock_irqrestore(&ev->lock, flags);
+}
+
+/**
+ * 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)
+{
+        if (disk->ev)
+                __disk_block_events(disk, true);
+}
+
+/**
+ * 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)
+{
+        if (disk->ev)
+                __disk_unblock_events(disk, true);
+}
+
+/**
+ * disk_check_events - schedule immediate event checking
+ * @disk: disk to check events for
+ *
+ * Schedule immediate event checking on @disk if not blocked.
+ *
+ * CONTEXT:
+ * Don't care.  Safe to call from irq context.
+ */
+void disk_check_events(struct gendisk *disk)
+{
+        if (disk->ev) {
+                __disk_block_events(disk, false);
+                __disk_unblock_events(disk, true);
+        }
+}
+EXPORT_SYMBOL_GPL(disk_check_events);
+
+/**
+ * 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 clearted
+ *
+ * Disk events are synchronously checked and pending events in @mask
+ * are cleared and returned.  This ignores the block count.
+ *
+ * CONTEXT:
+ * Might sleep.
+ */
+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;
+
+        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;
+                return 0;
+        }
+
+        /* tell the workfn about the events being cleared */
+        spin_lock_irq(&ev->lock);
+        ev->clearing |= mask;
+        spin_unlock_irq(&ev->lock);
+
+        /* uncondtionally schedule event check and wait for it to finish */
+        __disk_block_events(disk, true);
+        queue_delayed_work(system_nrt_wq, &ev->dwork, 0);
+        flush_delayed_work(&ev->dwork);
+        __disk_unblock_events(disk, false);
+
+        /* then, fetch and clear pending events */
+        spin_lock_irq(&ev->lock);
+        WARN_ON_ONCE(ev->clearing & mask);      /* cleared by workfn */
+        pending = ev->pending & mask;
+        ev->pending &= ~mask;
+        spin_unlock_irq(&ev->lock);
+
+        return pending;
+}
+
+static void disk_events_workfn(struct work_struct *work)
+{
+        struct delayed_work *dwork = to_delayed_work(work);
+        struct disk_events *ev = container_of(dwork, struct disk_events, dwork);
+        struct gendisk *disk = ev->disk;
+        char *envp[ARRAY_SIZE(disk_uevents) + 1] = { };
+        unsigned int clearing = ev->clearing;
+        unsigned int events;
+        unsigned long intv;
+        int nr_events = 0, i;
+
+        /* check events */
+        events = disk->fops->check_events(disk, clearing);
+
+        /* accumulate pending events and schedule next poll if necessary */
+        spin_lock_irq(&ev->lock);
+
+        events &= ~ev->pending;
+        ev->pending |= events;
+        ev->clearing &= ~clearing;
+
+        intv = disk_events_poll_jiffies(disk);
+        if (!ev->block && intv)
+                queue_delayed_work(system_nrt_wq, &ev->dwork, intv);
+
+        spin_unlock_irq(&ev->lock);
+
+        /* tell userland about new events */
+        for (i = 0; i < ARRAY_SIZE(disk_uevents); i++)
+                if (events & (1 << i))
+                        envp[nr_events++] = disk_uevents[i];
+
+        if (nr_events)
+                kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
+}
+
+/*
+ * 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
+ * events_poll_msecs    : polling interval, 0: disable, -1: system default
+ */
+static ssize_t __disk_events_show(unsigned int events, char *buf)
+{
+        const char *delim = "";
+        ssize_t pos = 0;
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(disk_events_strs); i++)
+                if (events & (1 << i)) {
+                        pos += sprintf(buf + pos, "%s%s",
+                                       delim, disk_events_strs[i]);
+                        delim = " ";
+                }
+        if (pos)
+                pos += sprintf(buf + pos, "\n");
+        return pos;
+}
+
+static ssize_t disk_events_show(struct device *dev,
+                                struct device_attribute *attr, char *buf)
+{
+        struct gendisk *disk = dev_to_disk(dev);
+
+        return __disk_events_show(disk->events, buf);
+}
+
+static ssize_t disk_events_async_show(struct device *dev,
+                                      struct device_attribute *attr, char *buf)
+{
+        struct gendisk *disk = dev_to_disk(dev);
+
+        return __disk_events_show(disk->async_events, buf);
+}
+
+static ssize_t disk_events_poll_msecs_show(struct device *dev,
+                                           struct device_attribute *attr,
+                                           char *buf)
+{
+        struct gendisk *disk = dev_to_disk(dev);
+
+        return sprintf(buf, "%ld\n", disk->ev->poll_msecs);
+}
+
+static ssize_t disk_events_poll_msecs_store(struct device *dev,
+                                            struct device_attribute *attr,
+                                            const char *buf, size_t count)
+{
+        struct gendisk *disk = dev_to_disk(dev);
+        long intv;
+
+        if (!count || !sscanf(buf, "%ld", &intv))
+                return -EINVAL;
+
+        if (intv < 0 && intv != -1)
+                return -EINVAL;
+
+        __disk_block_events(disk, true);
+        disk->ev->poll_msecs = intv;
+        __disk_unblock_events(disk, true);
+
+        return count;
+}
+
+static const DEVICE_ATTR(events, S_IRUGO, disk_events_show, NULL);
+static const DEVICE_ATTR(events_async, S_IRUGO, disk_events_async_show, NULL);
+static const DEVICE_ATTR(events_poll_msecs, S_IRUGO|S_IWUSR,
+                         disk_events_poll_msecs_show,
+                         disk_events_poll_msecs_store);
+
+static const struct attribute *disk_events_attrs[] = {
+        &dev_attr_events.attr,
+        &dev_attr_events_async.attr,
+        &dev_attr_events_poll_msecs.attr,
+        NULL,
+};
+
+/*
+ * 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/events_dfl_poll_msecs.
+ */
+static int disk_events_set_dfl_poll_msecs(const char *val,
+                                          const struct kernel_param *kp)
+{
+        struct disk_events *ev;
+        int ret;
+
+        ret = param_set_ulong(val, kp);
+        if (ret < 0)
+                return ret;
+
+        mutex_lock(&disk_events_mutex);
+
+        list_for_each_entry(ev, &disk_events, node)
+                disk_check_events(ev->disk);
+
+        mutex_unlock(&disk_events_mutex);
+
+        return 0;
+}
+
+static const struct kernel_param_ops disk_events_dfl_poll_msecs_param_ops = {
+        .set    = disk_events_set_dfl_poll_msecs,
+        .get    = param_get_ulong,
+};
+
+#undef MODULE_PARAM_PREFIX
+#define MODULE_PARAM_PREFIX     "block."
+
+module_param_cb(events_dfl_poll_msecs, &disk_events_dfl_poll_msecs_param_ops,
+                &disk_events_dfl_poll_msecs, 0644);
+
+/*
+ * disk_{add|del|release}_events - initialize and destroy disk_events.
+ */
+static void disk_add_events(struct gendisk *disk)
+{
+        struct disk_events *ev;
+
+        if (!disk->fops->check_events || !(disk->events | disk->async_events))
+                return;
+
+        ev = kzalloc(sizeof(*ev), GFP_KERNEL);
+        if (!ev) {
+                pr_warn("%s: failed to initialize events\n", disk->disk_name);
+                return;
+        }
+
+        if (sysfs_create_files(&disk_to_dev(disk)->kobj,
+                               disk_events_attrs) < 0) {
+                pr_warn("%s: failed to create sysfs files for events\n",
+                        disk->disk_name);
+                kfree(ev);
+                return;
+        }
+
+        disk->ev = ev;
+
+        INIT_LIST_HEAD(&ev->node);
+        ev->disk = disk;
+        spin_lock_init(&ev->lock);
+        ev->block = 1;
+        ev->poll_msecs = -1;
+        INIT_DELAYED_WORK(&ev->dwork, disk_events_workfn);
+
+        mutex_lock(&disk_events_mutex);
+        list_add_tail(&ev->node, &disk_events);
+        mutex_unlock(&disk_events_mutex);
+
+        /*
+         * Block count is initialized to 1 and the following initial
+         * unblock kicks it into action.
+         */
+        __disk_unblock_events(disk, true);
+}
+
+static void disk_del_events(struct gendisk *disk)
+{
+        if (!disk->ev)
+                return;
+
+        __disk_block_events(disk, true);
+
+        mutex_lock(&disk_events_mutex);
+        list_del_init(&disk->ev->node);
+        mutex_unlock(&disk_events_mutex);
+
+        sysfs_remove_files(&disk_to_dev(disk)->kobj, disk_events_attrs);
+}
+
+static void disk_release_events(struct gendisk *disk)
+{
+        /* the block count should be 1 from disk_del_events() */
+        WARN_ON_ONCE(disk->ev && disk->ev->block != 1);
+        kfree(disk->ev);
+}