From 85ef06d1d252f6a2e73b678591ab71caad4667bb Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 1 Jul 2011 16:17:47 +0200 Subject: 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 --- fs/block_dev.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) (limited to 'fs/block_dev.c') 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); -- cgit v1.2.3-55-g7522