block: export SSD/non-rotational queue flag through sysfs

For some devices (i.e. CFA ATA) we can't reliably detect whether
the device is of rotational or non-rotational type so we need to
leave the final decision about this setting to the user-space.

As a bonus do a minor CodingStyle fixup in queue_nomerges_store().

Suggested-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index a29cb78..b538ab8 100644 (file)
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -130,6 +130,27 @@ static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
        return queue_var_show(max_hw_sectors_kb, (page));
 }
 
+static ssize_t queue_nonrot_show(struct request_queue *q, char *page)
+{
+       return queue_var_show(!blk_queue_nonrot(q), page);
+}
+
+static ssize_t queue_nonrot_store(struct request_queue *q, const char *page,
+                                 size_t count)
+{
+       unsigned long nm;
+       ssize_t ret = queue_var_store(&nm, page, count);
+
+       spin_lock_irq(q->queue_lock);
+       if (nm)
+               queue_flag_clear(QUEUE_FLAG_NONROT, q);
+       else
+               queue_flag_set(QUEUE_FLAG_NONROT, q);
+       spin_unlock_irq(q->queue_lock);
+
+       return ret;
+}
+
 static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
 {
        return queue_var_show(blk_queue_nomerges(q), page);
@@ -146,8 +167,8 @@ static ssize_t queue_nomerges_store(struct request_queue *q, const char *page,
                queue_flag_set(QUEUE_FLAG_NOMERGES, q);
        else
                queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
-
        spin_unlock_irq(q->queue_lock);
+
        return ret;
 }
 
@@ -210,6 +231,12 @@ static struct queue_sysfs_entry queue_hw_sector_size_entry = {
        .show = queue_hw_sector_size_show,
 };
 
+static struct queue_sysfs_entry queue_nonrot_entry = {
+       .attr = {.name = "rotational", .mode = S_IRUGO | S_IWUSR },
+       .show = queue_nonrot_show,
+       .store = queue_nonrot_store,
+};
+
 static struct queue_sysfs_entry queue_nomerges_entry = {
        .attr = {.name = "nomerges", .mode = S_IRUGO | S_IWUSR },
        .show = queue_nomerges_show,
@@ -229,6 +256,7 @@ static struct attribute *default_attrs[] = {
        &queue_max_sectors_entry.attr,
        &queue_iosched_entry.attr,
        &queue_hw_sector_size_entry.attr,
+       &queue_nonrot_entry.attr,
        &queue_nomerges_entry.attr,
        &queue_rq_affinity_entry.attr,
        NULL,