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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 <ming.lei@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2023-10-17 20:48:20 +02:00
parent c30b9787a4
commit 51b4cb4f3e
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GPG Key ID: 91C61BC06578DCA2
1 changed files with 17 additions and 13 deletions
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30
block/partitions/core.c
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@ -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 @@ int bdev_disk_changed(struct gendisk *disk, bool invalidate)
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);
/*