From 51b4cb4f3e2265cf8303ffd9a4f239ee3805d3ca Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Tue, 17 Oct 2023 20:48:20 +0200 Subject: [PATCH] block: WARN_ON_ONCE() when we remove active partitions The logic for disk->open_partitions is: blkdev_get_by_*() -> bdev_is_partition() -> blkdev_get_part() -> blkdev_get_whole() // bdev_whole->bd_openers++ -> if (part->bd_openers == 0) disk->open_partitions++ part->bd_openers In other words, when we first claim/open a partition we increment disk->open_partitions and only when all part->bd_openers are closed will disk->open_partitions be zero. That should mean that disk->open_partitions is always > 0 as long as there's anyone that has an open partition. So the check for disk->open_partitions should mean that we can never remove an active partition that has a holder and holder ops set. Assert that in the code. The main disk isn't removed so that check doesn't work for disk->part0 which is what we want. After all we only care about partition not about the main disk. Link: https://lore.kernel.org/r/20231017184823.1383356-3-hch@lst.de Reviewed-by: Ming Lei Reviewed-by: Jan Kara Reviewed-by: Jens Axboe Signed-off-by: Christian Brauner --- block/partitions/core.c | 30 +++++++++++++++++------------- 1 file changed, 17 insertions(+), 13 deletions(-) diff --git a/block/partitions/core.c b/block/partitions/core.c index b0585536b407..f47ffcfdfcec 100644 --- a/block/partitions/core.c +++ b/block/partitions/core.c @@ -274,17 +274,6 @@ void drop_partition(struct block_device *part) put_device(&part->bd_device); } -static void delete_partition(struct block_device *part) -{ - /* - * Remove the block device from the inode hash, so that it cannot be - * looked up any more even when openers still hold references. - */ - remove_inode_hash(part->bd_inode); - bdev_mark_dead(part, false); - drop_partition(part); -} - static ssize_t whole_disk_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -674,8 +663,23 @@ rescan: sync_blockdev(disk->part0); invalidate_bdev(disk->part0); - xa_for_each_start(&disk->part_tbl, idx, part, 1) - delete_partition(part); + xa_for_each_start(&disk->part_tbl, idx, part, 1) { + /* + * Remove the block device from the inode hash, so that + * it cannot be looked up any more even when openers + * still hold references. + */ + remove_inode_hash(part->bd_inode); + + /* + * If @disk->open_partitions isn't elevated but there's + * still an active holder of that block device things + * are broken. + */ + WARN_ON_ONCE(atomic_read(&part->bd_openers)); + invalidate_bdev(part); + drop_partition(part); + } clear_bit(GD_NEED_PART_SCAN, &disk->state); /*