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authorTejun Heo <tj@kernel.org>2011-06-13 12:45:48 +0200
committerJens Axboe <jaxboe@fusionio.com>2011-06-13 12:45:48 +0200
commitd4c208b86b8be4254eba0e74071496e599f94639 (patch)
treea6fdc5fd90ea028433d268038c07919c4f47eed4
parent08e8138adebdd511e0955e8d6c051904bb4082af (diff)
downloadlinux-d4c208b86b8be4254eba0e74071496e599f94639.tar.bz2
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 <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> Cc: stable@kernel.org # >= v2.6.36 Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
-rw-r--r--fs/block_dev.c14
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)