block: always use a percpu variable for disk stats

percpu variables have a perfectly fine working stub implementation
for UP kernels, so use that.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk.h b/block/blk.h
index bdf5e94..0ecba2a 100644 (file)
--- a/block/blk.h
+++ b/block/blk.h
@@ -378,7 +378,7 @@ static inline void hd_struct_put(struct hd_struct *part)
 
 static inline void hd_free_part(struct hd_struct *part)
 {
-       free_part_stats(part);
+       free_percpu(part->dkstats);
        kfree(part->info);
        percpu_ref_exit(&part->ref);
 }

diff --git a/block/genhd.c b/block/genhd.c
index 094ed90..3e7df0a 100644 (file)
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -92,7 +92,6 @@ const char *bdevname(struct block_device *bdev, char *buf)
 }
 EXPORT_SYMBOL(bdevname);
 
-#ifdef CONFIG_SMP
 static void part_stat_read_all(struct hd_struct *part, struct disk_stats *stat)
 {
        int cpu;
@@ -112,12 +111,6 @@ static void part_stat_read_all(struct hd_struct *part, struct disk_stats *stat)
                stat->io_ticks += ptr->io_ticks;
        }
 }
-#else /* CONFIG_SMP */
-static void part_stat_read_all(struct hd_struct *part, struct disk_stats *stat)
-{
-       memcpy(stat, &part->dkstats, sizeof(struct disk_stats));
-}
-#endif /* CONFIG_SMP */
 
 static unsigned int part_in_flight(struct request_queue *q,
                struct hd_struct *part)
@@ -1688,14 +1681,15 @@ struct gendisk *__alloc_disk_node(int minors, int node_id)
 
        disk = kzalloc_node(sizeof(struct gendisk), GFP_KERNEL, node_id);
        if (disk) {
-               if (!init_part_stats(&disk->part0)) {
+               disk->part0.dkstats = alloc_percpu(struct disk_stats);
+               if (!disk->part0.dkstats) {
                        kfree(disk);
                        return NULL;
                }
                init_rwsem(&disk->lookup_sem);
                disk->node_id = node_id;
                if (disk_expand_part_tbl(disk, 0)) {
-                       free_part_stats(&disk->part0);
+                       free_percpu(disk->part0.dkstats);
                        kfree(disk);
                        return NULL;
                }

diff --git a/block/partitions/core.c b/block/partitions/core.c
index 297004f..78951e3 100644 (file)
--- a/block/partitions/core.c
+++ b/block/partitions/core.c
@@ -387,7 +387,8 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno,
        if (!p)
                return ERR_PTR(-EBUSY);
 
-       if (!init_part_stats(p)) {
+       p->dkstats = alloc_percpu(struct disk_stats);
+       if (!p->dkstats) {
                err = -ENOMEM;
                goto out_free;
        }
@@ -468,7 +469,7 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno,
 out_free_info:
        kfree(p->info);
 out_free_stats:
-       free_part_stats(p);
+       free_percpu(p->dkstats);
 out_free:
        kfree(p);
        return ERR_PTR(err);

diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index a938444..f0d6d77 100644 (file)
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -39,15 +39,6 @@ extern struct class block_class;
 #include <linux/fs.h>
 #include <linux/workqueue.h>
 
-struct disk_stats {
-       u64 nsecs[NR_STAT_GROUPS];
-       unsigned long sectors[NR_STAT_GROUPS];
-       unsigned long ios[NR_STAT_GROUPS];
-       unsigned long merges[NR_STAT_GROUPS];
-       unsigned long io_ticks;
-       local_t in_flight[2];
-};
-
 #define PARTITION_META_INFO_VOLNAMELTH 64
 /*
  * Enough for the string representation of any kind of UUID plus NULL.
@@ -72,11 +63,7 @@ struct hd_struct {
        seqcount_t nr_sects_seq;
 #endif
        unsigned long stamp;
-#ifdef CONFIG_SMP
        struct disk_stats __percpu *dkstats;
-#else
-       struct disk_stats dkstats;
-#endif
        struct percpu_ref ref;
 
        sector_t alignment_offset;

diff --git a/include/linux/part_stat.h b/include/linux/part_stat.h
index ece6076..6644197 100644 (file)
--- a/include/linux/part_stat.h
+++ b/include/linux/part_stat.h
@@ -4,19 +4,23 @@
 
 #include <linux/genhd.h>
 
+struct disk_stats {
+       u64 nsecs[NR_STAT_GROUPS];
+       unsigned long sectors[NR_STAT_GROUPS];
+       unsigned long ios[NR_STAT_GROUPS];
+       unsigned long merges[NR_STAT_GROUPS];
+       unsigned long io_ticks;
+       local_t in_flight[2];
+};
+
 /*
  * Macros to operate on percpu disk statistics:
  *
- * {disk|part|all}_stat_{add|sub|inc|dec}() modify the stat counters
- * and should be called between disk_stat_lock() and
- * disk_stat_unlock().
+ * {disk|part|all}_stat_{add|sub|inc|dec}() modify the stat counters and should
+ * be called between disk_stat_lock() and disk_stat_unlock().
  *
  * part_stat_read() can be called at any time.
- *
- * part_stat_{add|set_all}() and {init|free}_part_stats are for
- * internal use only.
  */
-#ifdef CONFIG_SMP
 #define part_stat_lock()       ({ rcu_read_lock(); get_cpu(); })
 #define part_stat_unlock()     do { put_cpu(); rcu_read_unlock(); } while (0)
 
@@ -44,43 +48,6 @@ static inline void part_stat_set_all(struct hd_struct *part, int value)
                                sizeof(struct disk_stats));
 }
 
-static inline int init_part_stats(struct hd_struct *part)
-{
-       part->dkstats = alloc_percpu(struct disk_stats);
-       if (!part->dkstats)
-               return 0;
-       return 1;
-}
-
-static inline void free_part_stats(struct hd_struct *part)
-{
-       free_percpu(part->dkstats);
-}
-
-#else /* !CONFIG_SMP */
-#define part_stat_lock()       ({ rcu_read_lock(); 0; })
-#define part_stat_unlock()     rcu_read_unlock()
-
-#define part_stat_get(part, field)             ((part)->dkstats.field)
-#define part_stat_get_cpu(part, field, cpu)    part_stat_get(part, field)
-#define part_stat_read(part, field)            part_stat_get(part, field)
-
-static inline void part_stat_set_all(struct hd_struct *part, int value)
-{
-       memset(&part->dkstats, value, sizeof(struct disk_stats));
-}
-
-static inline int init_part_stats(struct hd_struct *part)
-{
-       return 1;
-}
-
-static inline void free_part_stats(struct hd_struct *part)
-{
-}
-
-#endif /* CONFIG_SMP */
-
 #define part_stat_read_accum(part, field)                              \
        (part_stat_read(part, field[STAT_READ]) +                       \
         part_stat_read(part, field[STAT_WRITE]) +                      \