Commit d7cb6d74 authored by Damien Le Moal's avatar Damien Le Moal Committed by Jens Axboe
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block: RCU protect disk->conv_zones_bitmap 



Ensure that a disk revalidation changing the conventional zones bitmap
of a disk does not cause invalid memory references when using the
disk_zone_is_conv() helper by RCU protecting the disk->conv_zones_bitmap
pointer.

disk_zone_is_conv() is modified to operate under the RCU read lock and
the function disk_set_conv_zones_bitmap() is added to update a disk
conv_zones_bitmap pointer using rcu_replace_pointer() with the disk
zone_wplugs_lock spinlock held.

disk_free_zone_resources() is modified to call
disk_update_zone_resources() with a NULL bitmap pointer to free the disk
conv_zones_bitmap. disk_set_conv_zones_bitmap() is also used in
disk_update_zone_resources() to set the new (revalidated) bitmap and
free the old one.

Signed-off-by: default avatarDamien Le Moal <dlemoal@kernel.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20241107064300.227731-2-dlemoal@kernel.org


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 8e71afb9

block/blk-zoned.c

+31 −12
Original line number Diff line number Diff line
@@ -350,9 +350,15 @@ int blkdev_zone_mgmt_ioctl(struct block_device *bdev, blk_mode_t mode, 


static inline bool disk_zone_is_conv(struct gendisk *disk, sector_t sector)

{

	if (!disk->conv_zones_bitmap)

		return false;

	return test_bit(disk_zone_no(disk, sector), disk->conv_zones_bitmap);

	unsigned long *bitmap;

	bool is_conv;



	rcu_read_lock();

	bitmap = rcu_dereference(disk->conv_zones_bitmap);

	is_conv = bitmap && test_bit(disk_zone_no(disk, sector), bitmap);

	rcu_read_unlock();



	return is_conv;

}



static bool disk_zone_is_last(struct gendisk *disk, struct blk_zone *zone)
@@ -1455,6 +1461,24 @@ static void disk_destroy_zone_wplugs_hash_table(struct gendisk *disk) 
	disk->zone_wplugs_hash_bits = 0;

}



static unsigned int disk_set_conv_zones_bitmap(struct gendisk *disk,

					       unsigned long *bitmap)

{

	unsigned int nr_conv_zones = 0;

	unsigned long flags;



	spin_lock_irqsave(&disk->zone_wplugs_lock, flags);

	if (bitmap)

		nr_conv_zones = bitmap_weight(bitmap, disk->nr_zones);

	bitmap = rcu_replace_pointer(disk->conv_zones_bitmap, bitmap,

				     lockdep_is_held(&disk->zone_wplugs_lock));

	spin_unlock_irqrestore(&disk->zone_wplugs_lock, flags);



	kfree_rcu_mightsleep(bitmap);



	return nr_conv_zones;

}



void disk_free_zone_resources(struct gendisk *disk)

{

	if (!disk->zone_wplugs_pool)
@@ -1478,8 +1502,7 @@ void disk_free_zone_resources(struct gendisk *disk) 
	mempool_destroy(disk->zone_wplugs_pool);

	disk->zone_wplugs_pool = NULL;



	bitmap_free(disk->conv_zones_bitmap);

	disk->conv_zones_bitmap = NULL;

	disk_set_conv_zones_bitmap(disk, NULL);

	disk->zone_capacity = 0;

	disk->last_zone_capacity = 0;

	disk->nr_zones = 0;
@@ -1538,17 +1561,15 @@ static int disk_update_zone_resources(struct gendisk *disk, 
				      struct blk_revalidate_zone_args *args)

{

	struct request_queue *q = disk->queue;

	unsigned int nr_seq_zones, nr_conv_zones = 0;

	unsigned int nr_seq_zones, nr_conv_zones;

	unsigned int pool_size;

	struct queue_limits lim;



	disk->nr_zones = args->nr_zones;

	disk->zone_capacity = args->zone_capacity;

	disk->last_zone_capacity = args->last_zone_capacity;

	swap(disk->conv_zones_bitmap, args->conv_zones_bitmap);

	if (disk->conv_zones_bitmap)

		nr_conv_zones = bitmap_weight(disk->conv_zones_bitmap,

					      disk->nr_zones);

	nr_conv_zones =

		disk_set_conv_zones_bitmap(disk, args->conv_zones_bitmap);

	if (nr_conv_zones >= disk->nr_zones) {

		pr_warn("%s: Invalid number of conventional zones %u / %u\n",

			disk->disk_name, nr_conv_zones, disk->nr_zones);
@@ -1817,8 +1838,6 @@ int blk_revalidate_disk_zones(struct gendisk *disk) 
		disk_free_zone_resources(disk);

	blk_mq_unfreeze_queue(q);



	kfree(args.conv_zones_bitmap);



	return ret;

}

EXPORT_SYMBOL_GPL(blk_revalidate_disk_zones);

include/linux/blkdev.h

+1 −1
Original line number Diff line number Diff line
@@ -195,7 +195,7 @@ struct gendisk { 
	unsigned int		nr_zones;

	unsigned int		zone_capacity;

	unsigned int		last_zone_capacity;

	unsigned long		*conv_zones_bitmap;

	unsigned long __rcu	*conv_zones_bitmap;

	unsigned int            zone_wplugs_hash_bits;

	spinlock_t              zone_wplugs_lock;

	struct mempool_s	*zone_wplugs_pool;