From 4c49ff3fe128ca68dabd07537415c419ad7f82f9 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 1 Jun 2011 08:27:41 +0200 Subject: block: blkdev_get() should access ->bd_disk only after success d4dc210f69 (block: don't block events on excl write for non-optical devices) added dereferencing of bdev->bd_disk to test GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE; however, bdev->bd_disk can be %NULL if open failed which can lead to an oops. Test the flag after testing open was successful, not before. Signed-off-by: Tejun Heo Reported-by: David Miller Tested-by: David Miller Cc: stable@kernel.org Signed-off-by: Jens Axboe --- fs/block_dev.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'fs/block_dev.c') diff --git a/fs/block_dev.c b/fs/block_dev.c index 1f2b19978333..1a2421f908f0 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1272,8 +1272,8 @@ int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder) * individual writeable reference is too fragile given the * way @mode is used in blkdev_get/put(). */ - if ((disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE) && - !res && (mode & FMODE_WRITE) && !bdev->bd_write_holder) { + if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder && + (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) { bdev->bd_write_holder = true; disk_block_events(disk); } -- cgit v1.2.3 From d4c208b86b8be4254eba0e74071496e599f94639 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 13 Jun 2011 12:45:48 +0200 Subject: block: use the passed in @bdev when claiming if partno is zero 6b4517a791 (block: implement bd_claiming and claiming block) introduced claiming block to support O_EXCL blkdev opens properly. bd_start_claiming() looks up the part 0 bdev and starts claiming block. The function assumed that there is only one part 0 bdev and always used bdget_disk(disk, 0) to look it up; unfortunately, this isn't true for some drivers (floppy) which use multiple block devices to denote different operating parameters for the same physical device. There can be multiple part 0 bdev's for the same device number. This incorrect assumption caused the wrong bdev to be used during claiming leading to unbalanced bd_holders as reported in the following bug. https://bugzilla.kernel.org/show_bug.cgi?id=28522 This patch updates bd_start_claiming() such that it uses the bdev specified as argument if its partno is zero. Note that this means that different bdev's can be used for the same device and O_EXCL check can be effectively bypassed. It has always been broken that way and floppy is fortunately on its way out. Leave that breakage alone. Signed-off-by: Tejun Heo Reported-by: Alex Villacis Lasso Tested-by: Alex Villacis Lasso Cc: stable@kernel.org # >= v2.6.36 Signed-off-by: Jens Axboe --- fs/block_dev.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) (limited to 'fs/block_dev.c') diff --git a/fs/block_dev.c b/fs/block_dev.c index 1a2421f908f0..610e8e0b04b8 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -762,7 +762,19 @@ static struct block_device *bd_start_claiming(struct block_device *bdev, if (!disk) return ERR_PTR(-ENXIO); - whole = bdget_disk(disk, 0); + /* + * Normally, @bdev should equal what's returned from bdget_disk() + * if partno is 0; however, some drivers (floppy) use multiple + * bdev's for the same physical device and @bdev may be one of the + * aliases. Keep @bdev if partno is 0. This means claimer + * tracking is broken for those devices but it has always been that + * way. + */ + if (partno) + whole = bdget_disk(disk, 0); + else + whole = bdgrab(bdev); + module_put(disk->fops->owner); put_disk(disk); if (!whole) -- cgit v1.2.3