From 69e02c59a7d962dced8047401b81a8d897e1702e Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 9 Mar 2011 19:54:27 +0100 Subject: [PATCH] block: Don't check events while open is in progress Not all block drivers clear events immediately after reporting. Some do so in ->revalidate_disk() or other steps during ->open(). There is a slim chance event poll may happen between the clearing event check from check_disk_change() and the actual clearing of the events which would result in spurious events. Block event checks while block device open is in progress. There is no need to kick explicit event check afterwards as events are always checked during open. -v2: The original patch could have called disk_unblock_events() with an already released or %NULL @disk causing oops. Fixed by making sure references are put after disk_unblock_events() is called. It also makes the error path of __blkdev_get() a bit simpler. This problem was reported by Jens. Signed-off-by: Tejun Heo Cc: Jens Axboe Cc: Kay Sievers --- fs/block_dev.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index 7dd2c658d429..d42cad2757ae 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1087,6 +1087,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) if (!disk) goto out; + disk_block_events(disk); mutex_lock_nested(&bdev->bd_mutex, for_part); if (!bdev->bd_openers) { bdev->bd_disk = disk; @@ -1108,10 +1109,11 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) */ disk_put_part(bdev->bd_part); bdev->bd_part = NULL; - module_put(disk->fops->owner); - put_disk(disk); bdev->bd_disk = NULL; mutex_unlock(&bdev->bd_mutex); + disk_unblock_events(disk); + module_put(disk->fops->owner); + put_disk(disk); goto restart; } if (ret) @@ -1148,9 +1150,6 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9); } } else { - module_put(disk->fops->owner); - put_disk(disk); - disk = NULL; if (bdev->bd_contains == bdev) { if (bdev->bd_disk->fops->open) { ret = bdev->bd_disk->fops->open(bdev, mode); @@ -1160,11 +1159,15 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) if (bdev->bd_invalidated) rescan_partitions(bdev->bd_disk, bdev); } + /* only one opener holds refs to the module and disk */ + module_put(disk->fops->owner); + put_disk(disk); } bdev->bd_openers++; if (for_part) bdev->bd_part_count++; mutex_unlock(&bdev->bd_mutex); + disk_unblock_events(disk); return 0; out_clear: @@ -1177,9 +1180,9 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) bdev->bd_contains = NULL; out_unlock_bdev: mutex_unlock(&bdev->bd_mutex); + disk_unblock_events(disk); out: - if (disk) - module_put(disk->fops->owner); + module_put(disk->fops->owner); put_disk(disk); bdput(bdev); -- 2.20.1