disk->fops->owner is grabbed in blkdev_get_no_open() after the disk kobject refcount is increased. This way can't make sure that disk->fops->owner is still alive since del_gendisk() still can move on if the kobject refcount of disk is grabbed by open() and ->open() isn't called yet.

Fixes the issue by moving try_module_get() into blkdev_get_by_dev() with ->open_mutex() held, then we can drain the in-progress open() in del_gendisk(). Meantime new open() won't succeed because disk becomes not alive.

This way is reasonable because blkdev_get_no_open() doesn't need to grab disk->fops->owner which is required only if callback in disk->fops is needed.

Cc: Christoph Hellwig hch@lst.de Cc: stable@vger.kernel.org Cc: czhong@redhat.com Signed-off-by: Ming Lei ming.lei@redhat.com --- block/bdev.c | 12 +++++++----- block/genhd.c | 6 ++++++ 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/block/bdev.c b/block/bdev.c index b4dab2fb6a74..b1d087e5e205 100644 --- a/block/bdev.c +++ b/block/bdev.c @@ -753,8 +753,7 @@ struct block_device *blkdev_get_no_open(dev_t dev)

if (!bdev) return NULL; - if ((bdev->bd_disk->flags & GENHD_FL_HIDDEN) || - !try_module_get(bdev->bd_disk->fops->owner)) { + if ((bdev->bd_disk->flags & GENHD_FL_HIDDEN)) { put_device(&bdev->bd_device); return NULL; } @@ -764,7 +763,6 @@ struct block_device *blkdev_get_no_open(dev_t dev)

void blkdev_put_no_open(struct block_device *bdev) { - module_put(bdev->bd_disk->fops->owner); put_device(&bdev->bd_device); }

@@ -820,12 +818,14 @@ struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder) ret = -ENXIO; if (!disk_live(disk)) goto abort_claiming; + if (!try_module_get(disk->fops->owner)) + goto abort_claiming; if (bdev_is_partition(bdev)) ret = blkdev_get_part(bdev, mode); else ret = blkdev_get_whole(bdev, mode); if (ret) - goto abort_claiming; + goto put_module; if (mode & FMODE_EXCL) { bd_finish_claiming(bdev, holder);

@@ -847,7 +847,8 @@ struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder) if (unblock_events) disk_unblock_events(disk); return bdev; - +put_module: + module_put(disk->fops->owner); abort_claiming: if (mode & FMODE_EXCL) bd_abort_claiming(bdev, holder); @@ -956,6 +957,7 @@ void blkdev_put(struct block_device *bdev, fmode_t mode) blkdev_put_whole(bdev, mode); mutex_unlock(&disk->open_mutex);

+ module_put(disk->fops->owner); blkdev_put_no_open(bdev); } EXPORT_SYMBOL(blkdev_put); diff --git a/block/genhd.c b/block/genhd.c index a4e9e8ebd941..5f427fdc9e23 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -576,6 +576,12 @@ void del_gendisk(struct gendisk *disk) blk_integrity_del(disk); disk_del_events(disk);

+ /* + * New open() will be failed since disk becomes not alive, and old + * open() has either grabbed the module refcnt or been failed in + * case of deleting from module_exit(), so disk->fops->owner won't + * be unloaded if the disk is opened. + */ mutex_lock(&disk->open_mutex); remove_inode_hash(disk->part0->bd_inode); blk_drop_partitions(disk);