4 files changed, 57 insertions, 25 deletions

diff --git a/block/blk-merge.c b/block/blk-merge.c
index b3ac40aef46b..89b97b5e0881 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -97,19 +97,22 @@ void blk_recalc_rq_segments(struct request *rq)
 
 void blk_recount_segments(struct request_queue *q, struct bio *bio)
 {
-        bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE,
-                        &q->queue_flags);
-        bool merge_not_need = bio->bi_vcnt < queue_max_segments(q);
+        unsigned short seg_cnt;
+
+        /* estimate segment number by bi_vcnt for non-cloned bio */
+        if (bio_flagged(bio, BIO_CLONED))
+                seg_cnt = bio_segments(bio);
+        else
+                seg_cnt = bio->bi_vcnt;
 
-        if (no_sg_merge && !bio_flagged(bio, BIO_CLONED) &&
-                        merge_not_need)
-                bio->bi_phys_segments = bio->bi_vcnt;
+        if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags) &&
+                        (seg_cnt < queue_max_segments(q)))
+                bio->bi_phys_segments = seg_cnt;
         else {
                 struct bio *nxt = bio->bi_next;
 
                 bio->bi_next = NULL;
-                bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio,
-                                no_sg_merge && merge_not_need);
+                bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, false);
                 bio->bi_next = nxt;
         }
 
diff --git a/block/blk-mq.c b/block/blk-mq.c
index b5896d436fc9..92ceef0d2ab9 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -107,11 +107,7 @@ static void blk_mq_usage_counter_release(struct percpu_ref *ref)
         wake_up_all(&q->mq_freeze_wq);
 }
 
-/*
- * Guarantee no request is in use, so we can change any data structure of
- * the queue afterward.
- */
-void blk_mq_freeze_queue(struct request_queue *q)
+static void blk_mq_freeze_queue_start(struct request_queue *q)
 {
         bool freeze;
 
@@ -123,9 +119,23 @@ void blk_mq_freeze_queue(struct request_queue *q)
                 percpu_ref_kill(&q->mq_usage_counter);
                 blk_mq_run_queues(q, false);
         }
+}
+
+static void blk_mq_freeze_queue_wait(struct request_queue *q)
+{
         wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->mq_usage_counter));
 }
 
+/*
+ * Guarantee no request is in use, so we can change any data structure of
+ * the queue afterward.
+ */
+void blk_mq_freeze_queue(struct request_queue *q)
+{
+        blk_mq_freeze_queue_start(q);
+        blk_mq_freeze_queue_wait(q);
+}
+
 static void blk_mq_unfreeze_queue(struct request_queue *q)
 {
         bool wake;
@@ -1921,7 +1931,7 @@ void blk_mq_free_queue(struct request_queue *q)
 /* Basically redo blk_mq_init_queue with queue frozen */
 static void blk_mq_queue_reinit(struct request_queue *q)
 {
-        blk_mq_freeze_queue(q);
+        WARN_ON_ONCE(!q->mq_freeze_depth);
 
         blk_mq_sysfs_unregister(q);
 
@@ -1936,8 +1946,6 @@ static void blk_mq_queue_reinit(struct request_queue *q)
         blk_mq_map_swqueue(q);
 
         blk_mq_sysfs_register(q);
-
-        blk_mq_unfreeze_queue(q);
 }
 
 static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
@@ -1956,8 +1964,25 @@ static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
                 return NOTIFY_OK;
 
         mutex_lock(&all_q_mutex);
+
+        /*
+         * We need to freeze and reinit all existing queues.  Freezing
+         * involves synchronous wait for an RCU grace period and doing it
+         * one by one may take a long time.  Start freezing all queues in
+         * one swoop and then wait for the completions so that freezing can
+         * take place in parallel.
+         */
+        list_for_each_entry(q, &all_q_list, all_q_node)
+                blk_mq_freeze_queue_start(q);
+        list_for_each_entry(q, &all_q_list, all_q_node)
+                blk_mq_freeze_queue_wait(q);
+
         list_for_each_entry(q, &all_q_list, all_q_node)
                 blk_mq_queue_reinit(q);
+
+        list_for_each_entry(q, &all_q_list, all_q_node)
+                blk_mq_unfreeze_queue(q);
+
         mutex_unlock(&all_q_mutex);
         return NOTIFY_OK;
 }
diff --git a/block/ioprio.c b/block/ioprio.c
index e50170ca7c33..31666c92b46a 100644
--- a/block/ioprio.c
+++ b/block/ioprio.c
@@ -157,14 +157,16 @@ out:
 
 int ioprio_best(unsigned short aprio, unsigned short bprio)
 {
-        unsigned short aclass = IOPRIO_PRIO_CLASS(aprio);
-        unsigned short bclass = IOPRIO_PRIO_CLASS(bprio);
+        unsigned short aclass;
+        unsigned short bclass;
 
-        if (aclass == IOPRIO_CLASS_NONE)
-                aclass = IOPRIO_CLASS_BE;
-        if (bclass == IOPRIO_CLASS_NONE)
-                bclass = IOPRIO_CLASS_BE;
+        if (!ioprio_valid(aprio))
+                aprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
+        if (!ioprio_valid(bprio))
+                bprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
 
+        aclass = IOPRIO_PRIO_CLASS(aprio);
+        bclass = IOPRIO_PRIO_CLASS(bprio);
         if (aclass == bclass)
                 return min(aprio, bprio);
         if (aclass > bclass)
diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index c7bbc190f16f..28163fad3c5d 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -458,7 +458,7 @@ int sg_scsi_ioctl(struct request_queue *q, struct gendisk *disk, fmode_t mode,
         rq = blk_get_request(q, in_len ? WRITE : READ, __GFP_WAIT);
         if (IS_ERR(rq)) {
                 err = PTR_ERR(rq);
-                goto error;
+                goto error_free_buffer;
         }
         blk_rq_set_block_pc(rq);
 
@@ -531,9 +531,11 @@ int sg_scsi_ioctl(struct request_queue *q, struct gendisk *disk, fmode_t mode,
         }
         
 error:
+        blk_put_request(rq);
+
+error_free_buffer:
         kfree(buffer);
-        if (rq)
-                blk_put_request(rq);
+
         return err;
 }
 EXPORT_SYMBOL_GPL(sg_scsi_ioctl);