block: make /sys/block/<dev>/queue/discard_max_bytes writeable

[cascardo/linux.git] / block / blk-sysfs.c

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 6264b38..b1f34e4 100644 (file)
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -145,12 +145,43 @@ static ssize_t queue_discard_granularity_show(struct request_queue *q, char *pag
        return queue_var_show(q->limits.discard_granularity, page);
 }
 
+static ssize_t queue_discard_max_hw_show(struct request_queue *q, char *page)
+{
+       unsigned long long val;
+
+       val = q->limits.max_hw_discard_sectors << 9;
+       return sprintf(page, "%llu\n", val);
+}
+
 static ssize_t queue_discard_max_show(struct request_queue *q, char *page)
 {
        return sprintf(page, "%llu\n",
                       (unsigned long long)q->limits.max_discard_sectors << 9);
 }
 
+static ssize_t queue_discard_max_store(struct request_queue *q,
+                                      const char *page, size_t count)
+{
+       unsigned long max_discard;
+       ssize_t ret = queue_var_store(&max_discard, page, count);
+
+       if (ret < 0)
+               return ret;
+
+       if (max_discard & (q->limits.discard_granularity - 1))
+               return -EINVAL;
+
+       max_discard >>= 9;
+       if (max_discard > UINT_MAX)
+               return -EINVAL;
+
+       if (max_discard > q->limits.max_hw_discard_sectors)
+               max_discard = q->limits.max_hw_discard_sectors;
+
+       q->limits.max_discard_sectors = max_discard;
+       return ret;
+}
+
 static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *page)
 {
        return queue_var_show(queue_discard_zeroes_data(q), page);
@@ -360,9 +391,15 @@ static struct queue_sysfs_entry queue_discard_granularity_entry = {
        .show = queue_discard_granularity_show,
 };
 
+static struct queue_sysfs_entry queue_discard_max_hw_entry = {
+       .attr = {.name = "discard_max_hw_bytes", .mode = S_IRUGO },
+       .show = queue_discard_max_hw_show,
+};
+
 static struct queue_sysfs_entry queue_discard_max_entry = {
-       .attr = {.name = "discard_max_bytes", .mode = S_IRUGO },
+       .attr = {.name = "discard_max_bytes", .mode = S_IRUGO | S_IWUSR },
        .show = queue_discard_max_show,
+       .store = queue_discard_max_store,
 };
 
 static struct queue_sysfs_entry queue_discard_zeroes_data_entry = {
@@ -421,6 +458,7 @@ static struct attribute *default_attrs[] = {
        &queue_io_opt_entry.attr,
        &queue_discard_granularity_entry.attr,
        &queue_discard_max_entry.attr,
+       &queue_discard_max_hw_entry.attr,
        &queue_discard_zeroes_data_entry.attr,
        &queue_write_same_max_entry.attr,
        &queue_nonrot_entry.attr,