blk-mq: fix possible deadlocks

[blktests-ci]

Pull request for series with
subject: blk-mq: fix possible deadlocks
version: 9
url: https://patchwork.kernel.org/project/linux-block/list/?series=1049630

[blktests-ci]

Upstream branch: e7aa572
series: https://patchwork.kernel.org/project/linux-block/list/?series=1049630
version: 9

[blktests-ci]

Upstream branch: 05f7e89
series: https://patchwork.kernel.org/project/linux-block/list/?series=1049630
version: 9

[blktests-ci]

Upstream branch: c22e26b
series: https://patchwork.kernel.org/project/linux-block/list/?series=1049630
version: 9

Pull request is NOT updated. Failed to apply https://patchwork.kernel.org/project/linux-block/list/?series=1049630
error message:

Cmd('git') failed due to: exit code(128)
  cmdline: git am --3way
  stdout: 'Applying: blk-wbt: factor out a helper wbt_set_lat()
Using index info to reconstruct a base tree...
M	block/blk-sysfs.c
M	block/blk-wbt.c
M	block/blk-wbt.h
Falling back to patching base and 3-way merge...
Auto-merging block/blk-wbt.c
CONFLICT (content): Merge conflict in block/blk-wbt.c
Auto-merging block/blk-sysfs.c
Patch failed at 0001 blk-wbt: factor out a helper wbt_set_lat()'
  stderr: 'error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config set advice.mergeConflict false"'

conflict:

diff --cc block/blk-wbt.c
index 1415f2bf8611,0a37d97bda75..000000000000
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@@ -93,7 -93,7 +93,11 @@@ struct rq_wb 
  	struct rq_depth rq_depth;
  };
  
++<<<<<<< HEAD
 +static int wbt_init(struct gendisk *disk, struct rq_wb *rwb);
++=======
+ static int wbt_init(struct gendisk *disk);
++>>>>>>> blk-wbt: factor out a helper wbt_set_lat()
  
  static inline struct rq_wb *RQWB(struct rq_qos *rqos)
  {
@@@ -940,11 -903,22 +944,15 @@@ static const struct rq_qos_ops wbt_rqos
  #endif
  };
  
++<<<<<<< HEAD
 +static int wbt_init(struct gendisk *disk, struct rq_wb *rwb)
++=======
+ static int wbt_init(struct gendisk *disk)
++>>>>>>> blk-wbt: factor out a helper wbt_set_lat()
  {
  	struct request_queue *q = disk->queue;
 -	struct rq_wb *rwb;
 -	int i;
  	int ret;
 -
 -	rwb = kzalloc(sizeof(*rwb), GFP_KERNEL);
 -	if (!rwb)
 -		return -ENOMEM;
 -
 -	rwb->cb = blk_stat_alloc_callback(wb_timer_fn, wbt_data_dir, 2, rwb);
 -	if (!rwb->cb) {
 -		kfree(rwb);
 -		return -ENOMEM;
 -	}
 +	int i;
  
  	for (i = 0; i < WBT_NUM_RWQ; i++)
  		rq_wait_init(&rwb->rq_wait[i]);
@@@ -964,60 -938,57 +972,102 @@@
  	ret = rq_qos_add(&rwb->rqos, disk, RQ_QOS_WBT, &wbt_rqos_ops);
  	mutex_unlock(&q->rq_qos_mutex);
  	if (ret)
 -		goto err_free;
 +		return ret;
  
  	blk_stat_add_callback(q, rwb->cb);
 -
  	return 0;
 +}
  
 -err_free:
 -	blk_stat_free_callback(rwb->cb);
 -	kfree(rwb);
 -	return ret;
 +int wbt_set_lat(struct gendisk *disk, s64 val)
 +{
 +	struct request_queue *q = disk->queue;
 +	struct rq_qos *rqos = wbt_rq_qos(q);
 +	struct rq_wb *rwb = NULL;
 +	unsigned int memflags;
 +	int ret = 0;
 +
 +	if (!rqos) {
 +		rwb = wbt_alloc();
 +		if (!rwb)
 +			return -ENOMEM;
 +	}
 +
 +	/*
 +	 * Ensure that the queue is idled, in case the latency update
 +	 * ends up either enabling or disabling wbt completely. We can't
 +	 * have IO inflight if that happens.
 +	 */
 +	memflags = blk_mq_freeze_queue(q);
 +	if (!rqos) {
 +		ret = wbt_init(disk, rwb);
 +		if (ret) {
 +			wbt_free(rwb);
 +			goto out;
 +		}
 +	}
  
 +	if (val == -1)
 +		val = wbt_default_latency_nsec(q);
 +	else if (val >= 0)
 +		val *= 1000ULL;
 +
 +	if (wbt_get_min_lat(q) == val)
 +		goto out;
 +
 +	blk_mq_quiesce_queue(q);
 +
 +	mutex_lock(&disk->rqos_state_mutex);
 +	wbt_set_min_lat(q, val);
 +	mutex_unlock(&disk->rqos_state_mutex);
 +
 +	blk_mq_unquiesce_queue(q);
 +out:
 +	blk_mq_unfreeze_queue(q, memflags);
 +	mutex_lock(&q->debugfs_mutex);
 +	blk_mq_debugfs_register_rq_qos(q);
 +	mutex_unlock(&q->debugfs_mutex);
 +
 +	return ret;
  }
+ 
+ int wbt_set_lat(struct gendisk *disk, s64 val)
+ {
+ 	struct request_queue *q = disk->queue;
+ 	unsigned int memflags;
+ 	struct rq_qos *rqos;
+ 	int ret = 0;
+ 
+ 	/*
+ 	 * Ensure that the queue is idled, in case the latency update
+ 	 * ends up either enabling or disabling wbt completely. We can't
+ 	 * have IO inflight if that happens.
+ 	 */
+ 	memflags = blk_mq_freeze_queue(q);
+ 
+ 	rqos = wbt_rq_qos(q);
+ 	if (!rqos) {
+ 		ret = wbt_init(disk);
+ 		if (ret)
+ 			goto out;
+ 	}
+ 
+ 	if (val == -1)
+ 		val = wbt_default_latency_nsec(q);
+ 	else if (val >= 0)
+ 		val *= 1000ULL;
+ 
+ 	if (wbt_get_min_lat(q) == val)
+ 		goto out;
+ 
+ 	blk_mq_quiesce_queue(q);
+ 
+ 	mutex_lock(&disk->rqos_state_mutex);
+ 	wbt_set_min_lat(q, val);
+ 	mutex_unlock(&disk->rqos_state_mutex);
+ 
+ 	blk_mq_unquiesce_queue(q);
+ out:
+ 	blk_mq_unfreeze_queue(q, memflags);
+ 
+ 	return ret;
+ }