Messages in this thread Patch in this message | | | Date | Thu, 24 Feb 2011 09:56:32 +0100 | From | Tejun Heo <> | Subject | [PATCH 2.6.38-rc6] block: bd_link_disk_holder() should hold on to holder_dir |
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The new implementation of bd_link_disk_holder() added by 49731baa41d (block: restore multiple bd_link_disk_holder() support) didn't get an extra reference for the holder_dir kobject of the slave bdev; however, bdev kills holder_dir on removal, not release, so if the slave bdev is removed while there are holder links, the holder_dir will be destroyed while there still are holder links, which leads to oops later when bd_unlink_disk_order() tries to remove those links.
Make bd_link_disk_holder() grab an extra reference for the slave's holder_dir and put it in bd_unlink_disk_holder().
Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: "Hawrylewicz Czarnowski, Przemyslaw" <przemyslaw.hawrylewicz.czarnowski@intel.com> Tested-by: "Hawrylewicz Czarnowski, Przemyslaw" <przemyslaw.hawrylewicz.czarnowski@intel.com> Cc: Neil Brown <neilb@suse.de> Cc: Jens Axboe <axboe@kernel.dk> --- Jens, Linus, it's pretty late in the release cycle and I'm not sure Jens is back yet so I'm writing to you both. It's an isolated and relatively safe fix. I think how it gets routed doesn't matter too much.
Thank you.
fs/block_dev.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/fs/block_dev.c b/fs/block_dev.c index 4fb8a34..94d41db 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -873,6 +873,11 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj); if (ret) goto out_del; + /* + * bdev could be deleted beneath us which would implicitly destroy + * the holder directory. Hold on to it. + */ + kobject_get(bdev->bd_part->holder_dir); list_add(&holder->list, &bdev->bd_holder_disks); goto out_unlock; @@ -909,6 +914,7 @@ void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk) del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); del_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj); + kobject_put(bdev->bd_part->holder_dir); list_del_init(&holder->list); kfree(holder); }
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