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>
---
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 a287577d1ad6..7a7855555d6d 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -350,9 +350,14 @@ 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);
+ bool is_conv;
+
+ rcu_read_lock();
+ is_conv = disk->conv_zones_bitmap &&
+ test_bit(disk_zone_no(disk, sector), disk->conv_zones_bitmap);
+ rcu_read_unlock();
+
+ return is_conv;
}
static bool disk_zone_is_last(struct gendisk *disk, struct blk_zone *zone)
@@ -1455,6 +1460,25 @@ 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);
+ bitmap = rcu_replace_pointer(disk->conv_zones_bitmap, bitmap,
+ lockdep_is_held(&disk->zone_wplugs_lock));
+ if (disk->conv_zones_bitmap)
+ nr_conv_zones = bitmap_weight(disk->conv_zones_bitmap,
+ disk->nr_zones);
+ 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);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 6d1413bd69a5..5687eb2a019c 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -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;
--
2.47.0
