block: only define 'nr_sects_seq' in hd_part for 32bit SMP

The seqcount of 'nr_sects_seq' is only needed in case of 32bit SMP,
so define it just for 32bit SMP.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Cc: Yufen Yu <yuyufen@huawei.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Hou Tao <houtao1@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/genhd.c b/block/genhd.c
index af6cba2..1a51a9a 100644 (file)
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1731,7 +1731,7 @@ struct gendisk *__alloc_disk_node(int minors, int node_id)
                 * TODO: Ideally set_capacity() and get_capacity() should be
                 * converted to make use of bd_mutex and sequence counters.
                 */
-               seqcount_init(&disk->part0.nr_sects_seq);
+               hd_sects_seq_init(&disk->part0);
                if (hd_ref_init(&disk->part0)) {
                        hd_free_part(&disk->part0);
                        kfree(disk);

diff --git a/block/partitions/core.c b/block/partitions/core.c
index 8d8c872..297004f 100644 (file)
--- a/block/partitions/core.c
+++ b/block/partitions/core.c
@@ -392,7 +392,7 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno,
                goto out_free;
        }
 
-       seqcount_init(&p->nr_sects_seq);
+       hd_sects_seq_init(p);
        pdev = part_to_dev(p);
 
        p->start_sect = start;

diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index f9c226f..b474403 100644 (file)
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -68,7 +68,9 @@ struct hd_struct {
         * can be non-atomic on 32bit machines with 64bit sector_t.
         */
        sector_t nr_sects;
+#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
        seqcount_t nr_sects_seq;
+#endif
        sector_t alignment_offset;
        unsigned int discard_alignment;
        struct device __dev;
@@ -274,6 +276,13 @@ static inline void disk_put_part(struct hd_struct *part)
                put_device(part_to_dev(part));
 }
 
+static inline void hd_sects_seq_init(struct hd_struct *p)
+{
+#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
+       seqcount_init(&p->nr_sects_seq);
+#endif
+}
+
 /*
  * Smarter partition iterator without context limits.
  */