From: Ming Lei <ming.lei@xxxxxxxxxx> [ Upstream commit efcf5932230b9472cfdbe01c858726f29ac5ec7d ] 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 disk->fops->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() needn't to touch disk->fops or defined callbacks. Cc: Christoph Hellwig <hch@xxxxxx> Cc: czhong@xxxxxxxxxx Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> Link: https://lore.kernel.org/r/20211111020343.316126-1-ming.lei@xxxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- block/bdev.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/block/bdev.c b/block/bdev.c index 485a258b0ab37..e52af269004bc 100644 --- a/block/bdev.c +++ b/block/bdev.c @@ -750,8 +750,7 @@ 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; } @@ -761,7 +760,6 @@ 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); } @@ -817,12 +815,14 @@ 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); @@ -844,7 +844,8 @@ 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); @@ -953,6 +954,7 @@ 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); -- 2.33.0
