From: Damien Le Moal <dlemoal@xxxxxxxxxx> [ Upstream commit d7cb6d7414ea1b33536fa6d11805cb8dceec1f97 ] 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: Damien Le Moal <dlemoal@xxxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx> Link: https://lore.kernel.org/r/20241107064300.227731-2-dlemoal@xxxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- block/blk-zoned.c | 43 ++++++++++++++++++++++++++++++------------ include/linux/blkdev.h | 2 +- 2 files changed, 32 insertions(+), 13 deletions(-) diff --git a/block/blk-zoned.c b/block/blk-zoned.c index af19296fa50df..74e39545562d5 100644 --- a/block/blk-zoned.c +++ b/block/blk-zoned.c @@ -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); @@ -1823,8 +1844,6 @@ 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); diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 50c3b959da281..3027ce2de7319 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -194,7 +194,7 @@ 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; -- 2.43.0
