6 files changed, 36 insertions, 7 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 3689319a597..500c080a6a6 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -64,13 +64,27 @@ static void drive_stat_acct(struct request *rq, int new_io)
                 return;
 
         cpu = part_stat_lock();
-        part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq));
 
-        if (!new_io)
+        if (!new_io) {
+                part = rq->part;
                 part_stat_inc(cpu, part, merges[rw]);
-        else {
+        } else {
+                part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq));
+                if (!kref_test_and_get(&part->ref)) {
+                        /*
+                         * The partition is already being removed,
+                         * the request will be accounted on the disk only
+                         *
+                         * We take a reference on disk->part0 although that
+                         * partition will never be deleted, so we can treat
+                         * it as any other partition.
+                         */
+                        part = &rq->rq_disk->part0;
+                        kref_get(&part->ref);
+                }
                 part_round_stats(cpu, part);
                 part_inc_in_flight(part, rw);
+                rq->part = part;
         }
 
         part_stat_unlock();
@@ -128,6 +142,7 @@ void blk_rq_init(struct request_queue *q, struct request *rq)
         rq->ref_count = 1;
         rq->start_time = jiffies;
         set_start_time_ns(rq);
+        rq->part = NULL;
 }
 EXPORT_SYMBOL(blk_rq_init);
 
@@ -1776,7 +1791,7 @@ static void blk_account_io_completion(struct request *req, unsigned int bytes)
                 int cpu;
 
                 cpu = part_stat_lock();
-                part = disk_map_sector_rcu(req->rq_disk, blk_rq_pos(req));
+                part = req->part;
                 part_stat_add(cpu, part, sectors[rw], bytes >> 9);
                 part_stat_unlock();
         }
@@ -1796,13 +1811,14 @@ static void blk_account_io_done(struct request *req)
                 int cpu;
 
                 cpu = part_stat_lock();
-                part = disk_map_sector_rcu(req->rq_disk, blk_rq_pos(req));
+                part = req->part;
 
                 part_stat_inc(cpu, part, ios[rw]);
                 part_stat_add(cpu, part, ticks[rw], duration);
                 part_round_stats(cpu, part);
                 part_dec_in_flight(part, rw);
 
+                kref_put(&part->ref, __delete_partition);
                 part_stat_unlock();
         }
 }
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 77b7c26df6b..b06b83b89d8 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -351,11 +351,12 @@ static void blk_account_io_merge(struct request *req)
                 int cpu;
 
                 cpu = part_stat_lock();
-                part = disk_map_sector_rcu(req->rq_disk, blk_rq_pos(req));
+                part = req->part;
 
                 part_round_stats(cpu, part);
                 part_dec_in_flight(part, rq_data_dir(req));
 
+                kref_put(&part->ref, __delete_partition);
                 part_stat_unlock();
         }
 }
diff --git a/block/genhd.c b/block/genhd.c
index 16ccc0d2d5d..85c15059883 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1192,6 +1192,7 @@ struct gendisk *alloc_disk_node(int minors, int node_id)
                         return NULL;
                 }
                 disk->part_tbl->part[0] = &disk->part0;
+                kref_init(&disk->part0.ref);
 
                 disk->minors = minors;
                 rand_initialize_disk(disk);
diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index bdf8d3cc95a..48209f58522 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -381,6 +381,13 @@ static void delete_partition_rcu_cb(struct rcu_head *head)
         put_device(part_to_dev(part));
 }
 
+void __delete_partition(struct kref *ref)
+{
+        struct hd_struct *part = container_of(ref, struct hd_struct, ref);
+
+        call_rcu(&part->rcu_head, delete_partition_rcu_cb);
+}
+
 void delete_partition(struct gendisk *disk, int partno)
 {
         struct disk_part_tbl *ptbl = disk->part_tbl;
@@ -399,7 +406,7 @@ void delete_partition(struct gendisk *disk, int partno)
         kobject_put(part->holder_dir);
         device_del(part_to_dev(part));
 
-        call_rcu(&part->rcu_head, delete_partition_rcu_cb);
+        kref_put(&part->ref, __delete_partition);
 }
 
 static ssize_t whole_disk_show(struct device *dev,
@@ -498,6 +505,7 @@ struct hd_struct *add_partition(struct gendisk *disk, int partno,
         if (!dev_get_uevent_suppress(ddev))
                 kobject_uevent(&pdev->kobj, KOBJ_ADD);
 
+        kref_init(&p->ref);
         return p;
 
 out_free_info:
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index aae86fd10c4..482a7fd4883 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -115,6 +115,7 @@ struct request {
         void *elevator_private3;
 
         struct gendisk *rq_disk;
+        struct hd_struct *part;
         unsigned long start_time;
 #ifdef CONFIG_BLK_CGROUP
         unsigned long long start_time_ns;
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 7a7b9c1644e..2ba2792a3dd 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -116,6 +116,7 @@ struct hd_struct {
         struct disk_stats dkstats;
 #endif
         struct rcu_head rcu_head;
+        struct kref ref;
 };
 
 #define GENHD_FL_REMOVABLE                      1
@@ -583,6 +584,7 @@ extern struct hd_struct * __must_check add_partition(struct gendisk *disk,
                                                      sector_t len, int flags,
                                                      struct partition_meta_info
                                                        *info);
+extern void __delete_partition(struct kref *ref);
 extern void delete_partition(struct gendisk *, int);
 extern void printk_all_partitions(void);