From: Christian Brauner <brauner@xxxxxxxxxx>
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 meand 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.
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
---
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 b0585536b407a5..f47ffcfdfcec22 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 @@ 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);
/*
--
2.39.2
