From 85ef06d1d252f6a2e73b678591ab71caad4667bb Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 1 Jul 2011 16:17:47 +0200 Subject: [PATCH] block: flush MEDIA_CHANGE from drivers on close(2) Currently, only open(2) is defined as the 'clearing' point. It has two roles - first, it's an acknowledgement from userland indicating that the event has been received and kernel can clear pending states and proceed to generate more events. Secondly, it's passed on to device drivers as a hint indicating that a synchronization point has been reached and it might want to take a deeper look at the device. The latter currently is only used by sr which uses two different mechanisms - GET_EVENT_MEDIA_STATUS_NOTIFICATION and TEST_UNIT_READY to discover events, where the former is lighter weight and safe to be used repeatedly but may not provide full coverage. Among other things, GET_EVENT can't detect media removal while TUR can. This patch makes close(2) - blkdev_put() - indicate clearing hint for MEDIA_CHANGE to drivers. disk_check_events() is renamed to disk_flush_events() and updated to take @mask for events to flush which is or'd to ev->clearing and will be passed to the driver on the next ->check_events() invocation. This change makes sr generate MEDIA_CHANGE when media is ejected from userland - e.g. with eject(1). Note: Given the current usage, it seems @clearing hint is needlessly complex. disk_clear_events() can simply clear all events and the hint can be boolean @flush. Signed-off-by: Tejun Heo Cc: Kay Sievers Signed-off-by: Jens Axboe --- block/genhd.c | 22 ++++++++++++---------- fs/block_dev.c | 23 ++++++++++++++--------- include/linux/genhd.h | 2 +- 3 files changed, 27 insertions(+), 20 deletions(-) diff --git a/block/genhd.c b/block/genhd.c index 82d97c3594a8..fbd7605a5865 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -1500,30 +1500,32 @@ void disk_unblock_events(struct gendisk *disk) } /** - * disk_check_events - schedule immediate event checking - * @disk: disk to check events for + * 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. + * 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: - * Don't care. Safe to call from irq context. + * If @mask is non-zero must be called with bdev->bd_mutex held. */ -void disk_check_events(struct gendisk *disk) +void disk_flush_events(struct gendisk *disk, unsigned int mask) { struct disk_events *ev = disk->ev; - unsigned long flags; if (!ev) return; - spin_lock_irqsave(&ev->lock, flags); + spin_lock_irq(&ev->lock); + ev->clearing |= mask; if (!ev->block) { cancel_delayed_work(&ev->dwork); queue_delayed_work(system_nrt_wq, &ev->dwork, 0); } - spin_unlock_irqrestore(&ev->lock, flags); + spin_unlock_irq(&ev->lock); } -EXPORT_SYMBOL_GPL(disk_check_events); /** * disk_clear_events - synchronously check, clear and return pending events @@ -1713,7 +1715,7 @@ static int disk_events_set_dfl_poll_msecs(const char *val, mutex_lock(&disk_events_mutex); list_for_each_entry(ev, &disk_events, node) - disk_check_events(ev->disk); + disk_flush_events(ev->disk, 0); mutex_unlock(&disk_events_mutex); diff --git a/fs/block_dev.c b/fs/block_dev.c index 610e8e0b04b8..6ff7f070016f 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1447,6 +1447,8 @@ static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) int blkdev_put(struct block_device *bdev, fmode_t mode) { + mutex_lock(&bdev->bd_mutex); + if (mode & FMODE_EXCL) { bool bdev_free; @@ -1455,7 +1457,6 @@ int blkdev_put(struct block_device *bdev, fmode_t mode) * are protected with bdev_lock. bd_mutex is to * synchronize disk_holder unlinking. */ - mutex_lock(&bdev->bd_mutex); spin_lock(&bdev_lock); WARN_ON_ONCE(--bdev->bd_holders < 0); @@ -1473,17 +1474,21 @@ int blkdev_put(struct block_device *bdev, fmode_t mode) * If this was the last claim, remove holder link and * unblock evpoll if it was a write holder. */ - if (bdev_free) { - if (bdev->bd_write_holder) { - disk_unblock_events(bdev->bd_disk); - disk_check_events(bdev->bd_disk); - bdev->bd_write_holder = false; - } + if (bdev_free && bdev->bd_write_holder) { + disk_unblock_events(bdev->bd_disk); + bdev->bd_write_holder = false; } - - mutex_unlock(&bdev->bd_mutex); } + /* + * Trigger event checking and tell drivers to flush MEDIA_CHANGE + * event. This is to ensure detection of media removal commanded + * from userland - e.g. eject(1). + */ + disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE); + + mutex_unlock(&bdev->bd_mutex); + return __blkdev_put(bdev, mode, 0); } EXPORT_SYMBOL(blkdev_put); diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 300d7582006e..02fa4697a0e5 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -420,7 +420,7 @@ static inline int get_disk_ro(struct gendisk *disk) extern void disk_block_events(struct gendisk *disk); extern void disk_unblock_events(struct gendisk *disk); -extern void disk_check_events(struct gendisk *disk); +extern void disk_flush_events(struct gendisk *disk, unsigned int mask); extern unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask); /* drivers/char/random.c */