block: add sysfs file for controlling io stats accounting

[safe/jmp/linux-2.6] / block / blk-sysfs.c

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index b538ab8..e29ddfc 100644 (file)
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -197,6 +197,27 @@ queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
        return ret;
 }
 
+static ssize_t queue_iostats_show(struct request_queue *q, char *page)
+{
+       return queue_var_show(blk_queue_io_stat(q), page);
+}
+
+static ssize_t queue_iostats_store(struct request_queue *q, const char *page,
+                                  size_t count)
+{
+       unsigned long stats;
+       ssize_t ret = queue_var_store(&stats, page, count);
+
+       spin_lock_irq(q->queue_lock);
+       if (stats)
+               queue_flag_set(QUEUE_FLAG_IO_STAT, q);
+       else
+               queue_flag_clear(QUEUE_FLAG_IO_STAT, q);
+       spin_unlock_irq(q->queue_lock);
+
+       return ret;
+}
+
 static struct queue_sysfs_entry queue_requests_entry = {
        .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
        .show = queue_requests_show,
@@ -249,6 +270,12 @@ static struct queue_sysfs_entry queue_rq_affinity_entry = {
        .store = queue_rq_affinity_store,
 };
 
+static struct queue_sysfs_entry queue_iostats_entry = {
+       .attr = {.name = "iostats", .mode = S_IRUGO | S_IWUSR },
+       .show = queue_iostats_show,
+       .store = queue_iostats_store,
+};
+
 static struct attribute *default_attrs[] = {
        &queue_requests_entry.attr,
        &queue_ra_entry.attr,
@@ -259,6 +286,7 @@ static struct attribute *default_attrs[] = {
        &queue_nonrot_entry.attr,
        &queue_nomerges_entry.attr,
        &queue_rq_affinity_entry.attr,
+       &queue_iostats_entry.attr,
        NULL,
 };