1 files changed, 298 insertions, 0 deletions

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
new file mode 100644
index 000000000000..d9b9afab3456
--- /dev/null
+++ b/block/blk-sysfs.c
@@ -0,0 +1,298 @@
+/*
+ * Functions related to sysfs handling
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/blktrace_api.h>
+
+#include "blk.h"
+
+struct queue_sysfs_entry {
+        struct attribute attr;
+        ssize_t (*show)(struct request_queue *, char *);
+        ssize_t (*store)(struct request_queue *, const char *, size_t);
+};
+
+static ssize_t
+queue_var_show(unsigned int var, char *page)
+{
+        return sprintf(page, "%d\n", var);
+}
+
+static ssize_t
+queue_var_store(unsigned long *var, const char *page, size_t count)
+{
+        char *p = (char *) page;
+
+        *var = simple_strtoul(p, &p, 10);
+        return count;
+}
+
+static ssize_t queue_requests_show(struct request_queue *q, char *page)
+{
+        return queue_var_show(q->nr_requests, (page));
+}
+
+static ssize_t
+queue_requests_store(struct request_queue *q, const char *page, size_t count)
+{
+        struct request_list *rl = &q->rq;
+        unsigned long nr;
+        int ret = queue_var_store(&nr, page, count);
+        if (nr < BLKDEV_MIN_RQ)
+                nr = BLKDEV_MIN_RQ;
+
+        spin_lock_irq(q->queue_lock);
+        q->nr_requests = nr;
+        blk_queue_congestion_threshold(q);
+
+        if (rl->count[READ] >= queue_congestion_on_threshold(q))
+                blk_set_queue_congested(q, READ);
+        else if (rl->count[READ] < queue_congestion_off_threshold(q))
+                blk_clear_queue_congested(q, READ);
+
+        if (rl->count[WRITE] >= queue_congestion_on_threshold(q))
+                blk_set_queue_congested(q, WRITE);
+        else if (rl->count[WRITE] < queue_congestion_off_threshold(q))
+                blk_clear_queue_congested(q, WRITE);
+
+        if (rl->count[READ] >= q->nr_requests) {
+                blk_set_queue_full(q, READ);
+        } else if (rl->count[READ]+1 <= q->nr_requests) {
+                blk_clear_queue_full(q, READ);
+                wake_up(&rl->wait[READ]);
+        }
+
+        if (rl->count[WRITE] >= q->nr_requests) {
+                blk_set_queue_full(q, WRITE);
+        } else if (rl->count[WRITE]+1 <= q->nr_requests) {
+                blk_clear_queue_full(q, WRITE);
+                wake_up(&rl->wait[WRITE]);
+        }
+        spin_unlock_irq(q->queue_lock);
+        return ret;
+}
+
+static ssize_t queue_ra_show(struct request_queue *q, char *page)
+{
+        int ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10);
+
+        return queue_var_show(ra_kb, (page));
+}
+
+static ssize_t
+queue_ra_store(struct request_queue *q, const char *page, size_t count)
+{
+        unsigned long ra_kb;
+        ssize_t ret = queue_var_store(&ra_kb, page, count);
+
+        spin_lock_irq(q->queue_lock);
+        q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10);
+        spin_unlock_irq(q->queue_lock);
+
+        return ret;
+}
+
+static ssize_t queue_max_sectors_show(struct request_queue *q, char *page)
+{
+        int max_sectors_kb = q->max_sectors >> 1;
+
+        return queue_var_show(max_sectors_kb, (page));
+}
+
+static ssize_t
+queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
+{
+        unsigned long max_sectors_kb,
+                        max_hw_sectors_kb = q->max_hw_sectors >> 1,
+                        page_kb = 1 << (PAGE_CACHE_SHIFT - 10);
+        ssize_t ret = queue_var_store(&max_sectors_kb, page, count);
+
+        if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
+                return -EINVAL;
+        /*
+         * Take the queue lock to update the readahead and max_sectors
+         * values synchronously:
+         */
+        spin_lock_irq(q->queue_lock);
+        q->max_sectors = max_sectors_kb << 1;
+        spin_unlock_irq(q->queue_lock);
+
+        return ret;
+}
+
+static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
+{
+        int max_hw_sectors_kb = q->max_hw_sectors >> 1;
+
+        return queue_var_show(max_hw_sectors_kb, (page));
+}
+
+
+static struct queue_sysfs_entry queue_requests_entry = {
+        .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
+        .show = queue_requests_show,
+        .store = queue_requests_store,
+};
+
+static struct queue_sysfs_entry queue_ra_entry = {
+        .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
+        .show = queue_ra_show,
+        .store = queue_ra_store,
+};
+
+static struct queue_sysfs_entry queue_max_sectors_entry = {
+        .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
+        .show = queue_max_sectors_show,
+        .store = queue_max_sectors_store,
+};
+
+static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
+        .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
+        .show = queue_max_hw_sectors_show,
+};
+
+static struct queue_sysfs_entry queue_iosched_entry = {
+        .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
+        .show = elv_iosched_show,
+        .store = elv_iosched_store,
+};
+
+static struct attribute *default_attrs[] = {
+        &queue_requests_entry.attr,
+        &queue_ra_entry.attr,
+        &queue_max_hw_sectors_entry.attr,
+        &queue_max_sectors_entry.attr,
+        &queue_iosched_entry.attr,
+        NULL,
+};
+
+#define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
+
+static ssize_t
+queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
+{
+        struct queue_sysfs_entry *entry = to_queue(attr);
+        struct request_queue *q =
+                container_of(kobj, struct request_queue, kobj);
+        ssize_t res;
+
+        if (!entry->show)
+                return -EIO;
+        mutex_lock(&q->sysfs_lock);
+        if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
+                mutex_unlock(&q->sysfs_lock);
+                return -ENOENT;
+        }
+        res = entry->show(q, page);
+        mutex_unlock(&q->sysfs_lock);
+        return res;
+}
+
+static ssize_t
+queue_attr_store(struct kobject *kobj, struct attribute *attr,
+                    const char *page, size_t length)
+{
+        struct queue_sysfs_entry *entry = to_queue(attr);
+        struct request_queue *q = container_of(kobj, struct request_queue, kobj);
+
+        ssize_t res;
+
+        if (!entry->store)
+                return -EIO;
+        mutex_lock(&q->sysfs_lock);
+        if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
+                mutex_unlock(&q->sysfs_lock);
+                return -ENOENT;
+        }
+        res = entry->store(q, page, length);
+        mutex_unlock(&q->sysfs_lock);
+        return res;
+}
+
+/**
+ * blk_cleanup_queue: - release a &struct request_queue when it is no longer needed
+ * @kobj:    the kobj belonging of the request queue to be released
+ *
+ * Description:
+ *     blk_cleanup_queue is the pair to blk_init_queue() or
+ *     blk_queue_make_request().  It should be called when a request queue is
+ *     being released; typically when a block device is being de-registered.
+ *     Currently, its primary task it to free all the &struct request
+ *     structures that were allocated to the queue and the queue itself.
+ *
+ * Caveat:
+ *     Hopefully the low level driver will have finished any
+ *     outstanding requests first...
+ **/
+static void blk_release_queue(struct kobject *kobj)
+{
+        struct request_queue *q =
+                container_of(kobj, struct request_queue, kobj);
+        struct request_list *rl = &q->rq;
+
+        blk_sync_queue(q);
+
+        if (rl->rq_pool)
+                mempool_destroy(rl->rq_pool);
+
+        if (q->queue_tags)
+                __blk_queue_free_tags(q);
+
+        blk_trace_shutdown(q);
+
+        bdi_destroy(&q->backing_dev_info);
+        kmem_cache_free(blk_requestq_cachep, q);
+}
+
+static struct sysfs_ops queue_sysfs_ops = {
+        .show   = queue_attr_show,
+        .store  = queue_attr_store,
+};
+
+struct kobj_type blk_queue_ktype = {
+        .sysfs_ops      = &queue_sysfs_ops,
+        .default_attrs  = default_attrs,
+        .release        = blk_release_queue,
+};
+
+int blk_register_queue(struct gendisk *disk)
+{
+        int ret;
+
+        struct request_queue *q = disk->queue;
+
+        if (!q || !q->request_fn)
+                return -ENXIO;
+
+        ret = kobject_add(&q->kobj, kobject_get(&disk->dev.kobj),
+                          "%s", "queue");
+        if (ret < 0)
+                return ret;
+
+        kobject_uevent(&q->kobj, KOBJ_ADD);
+
+        ret = elv_register_queue(q);
+        if (ret) {
+                kobject_uevent(&q->kobj, KOBJ_REMOVE);
+                kobject_del(&q->kobj);
+                return ret;
+        }
+
+        return 0;
+}
+
+void blk_unregister_queue(struct gendisk *disk)
+{
+        struct request_queue *q = disk->queue;
+
+        if (q && q->request_fn) {
+                elv_unregister_queue(q);
+
+                kobject_uevent(&q->kobj, KOBJ_REMOVE);
+                kobject_del(&q->kobj);
+                kobject_put(&disk->dev.kobj);
+        }
+}