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block: RCU protect disk->conv_zones_bitmap

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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@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20241107064300.227731-2-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Damien Le Moal 2024-11-07 15:42:59 +09:00 committed by Jens Axboe
parent 8e71afb94d
commit d7cb6d7414
2 changed files with 32 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

43
block/blk-zoned.c
View File

@ -350,9 +350,15 @@ fail:
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);

2
include/linux/blkdev.h
View File

@ -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;