linux-kernel - [PATCH 03/16] block: don't check events while open is in progress

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Date:	Tue, 28 Dec 2010 18:28:59 +0100
From:	Tejun Heo <tj@...nel.org>
To:	axboe@...nel.dk, linux-kernel@...r.kernel.org,
	kay.sievers@...y.org, hch@...radead.org
Cc:	Tejun Heo <tj@...nel.org>
Subject: [PATCH 03/16] 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.

Signed-off-by: Tejun Heo <tj@...nel.org>
Cc: Jens Axboe <axboe@...nel.dk>
Cc: Kay Sievers <kay.sievers@...y.org>
---
 fs/block_dev.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 58026da..f6390fd 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1016,6 +1016,7 @@ 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;
@@ -1041,6 +1042,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
 					put_disk(disk);
 					bdev->bd_disk = NULL;
 					mutex_unlock(&bdev->bd_mutex);
+					disk_unblock_events(disk);
 					goto restart;
 				}
 				if (ret)
@@ -1094,6 +1096,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
 	if (for_part)
 		bdev->bd_part_count++;
 	mutex_unlock(&bdev->bd_mutex);
+	disk_unblock_events(disk);
 	return 0;
 
  out_clear:
@@ -1106,6 +1109,7 @@ 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);
-- 
1.7.1

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