diff options
| author | Tejun Heo <tj@kernel.org> | 2011-06-13 12:45:48 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-07-08 23:15:25 -0700 |
| commit | 01251271a43e01b1fbdffcb92136304f6650993e (patch) | |
| tree | a93705289571c529dd0d8f97d13029ed9ca763be | |
| parent | a8bb0163f9185d7df8aeda6aca2bef6d38ac10a0 (diff) | |
block: use the passed in @bdev when claiming if partno is zero
commit d4c208b86b8be4254eba0e74071496e599f94639 upstream.
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 <tj@kernel.org>
Reported-by: Alex Villacis Lasso <avillaci@ceibo.fiec.espol.edu.ec>
Tested-by: Alex Villacis Lasso <avillaci@ceibo.fiec.espol.edu.ec>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | fs/block_dev.c | 14 |
1 files changed, 13 insertions, 1 deletions
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) |