block: freeze queue when updating zone resources

Modify disk_update_zone_resources() to freeze the device queue before
updating the number of zones, zone capacity and other zone related
resources. The locking order resulting from the call to
queue_limits_commit_update_frozen() is preserved, that is, the queue
limits lock is first taken by calling queue_limits_start_update() before
freezing the queue, and the queue is unfrozen after executing
queue_limits_commit_update(), which replaces the call to
queue_limits_commit_update_frozen().

This change ensures that there are no in-flights I/Os when the zone
resources are updated due to a zone revalidation. In case of error when
the limits are applied, directly call disk_free_zone_resources() from
disk_update_zone_resources() while the disk queue is still frozen to
avoid needing to freeze & unfreeze the queue again in
blk_revalidate_disk_zones(), thus simplifying that function code a
little.

Fixes: 0b83c86b444a ("block: Prevent potential deadlock in blk_revalidate_disk_zones()")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index 1621e8f7833868e98ff322e54bdb018b392099b9..39381f2b2e94716b42bc8b4a71616b8bffe439a7 100644 (file)
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -1557,8 +1557,13 @@ static int disk_update_zone_resources(struct gendisk *disk,
 {
        struct request_queue *q = disk->queue;
        unsigned int nr_seq_zones, nr_conv_zones;
-       unsigned int pool_size;
+       unsigned int pool_size, memflags;
        struct queue_limits lim;
+       int ret = 0;
+
+       lim = queue_limits_start_update(q);
+
+       memflags = blk_mq_freeze_queue(q);
 
        disk->nr_zones = args->nr_zones;
        disk->zone_capacity = args->zone_capacity;
@@ -1568,11 +1573,10 @@ static int disk_update_zone_resources(struct gendisk *disk,
        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);
-               return -ENODEV;
+               ret = -ENODEV;
+               goto unfreeze;
        }
 
-       lim = queue_limits_start_update(q);
-
        /*
         * Some devices can advertize zone resource limits that are larger than
         * the number of sequential zones of the zoned block device, e.g. a
@@ -1609,7 +1613,15 @@ static int disk_update_zone_resources(struct gendisk *disk,
        }
 
 commit:
-       return queue_limits_commit_update_frozen(q, &lim);
+       ret = queue_limits_commit_update(q, &lim);
+
+unfreeze:
+       if (ret)
+               disk_free_zone_resources(disk);
+
+       blk_mq_unfreeze_queue(q, memflags);
+
+       return ret;
 }
 
 static int blk_revalidate_conv_zone(struct blk_zone *zone, unsigned int idx,
@@ -1774,7 +1786,7 @@ int blk_revalidate_disk_zones(struct gendisk *disk)
        sector_t zone_sectors = q->limits.chunk_sectors;
        sector_t capacity = get_capacity(disk);
        struct blk_revalidate_zone_args args = { };
-       unsigned int noio_flag;
+       unsigned int memflags, noio_flag;
        int ret = -ENOMEM;
 
        if (WARN_ON_ONCE(!blk_queue_is_zoned(q)))
@@ -1824,20 +1836,14 @@ int blk_revalidate_disk_zones(struct gendisk *disk)
                ret = -ENODEV;
        }
 
-       /*
-        * Set the new disk zone parameters only once the queue is frozen and
-        * all I/Os are completed.
-        */
        if (ret > 0)
-               ret = disk_update_zone_resources(disk, &args);
-       else
-               pr_warn("%s: failed to revalidate zones\n", disk->disk_name);
-       if (ret) {
-               unsigned int memflags = blk_mq_freeze_queue(q);
+               return disk_update_zone_resources(disk, &args);
 
-               disk_free_zone_resources(disk);
-               blk_mq_unfreeze_queue(q, memflags);
-       }
+       pr_warn("%s: failed to revalidate zones\n", disk->disk_name);
+
+       memflags = blk_mq_freeze_queue(q);
+       disk_free_zone_resources(disk);
+       blk_mq_unfreeze_queue(q, memflags);
 
        return ret;
 }