block: split softirq handling into blk-softirq.c

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

3 files changed, 105 insertions, 90 deletions

diff --git a/block/Makefile b/block/Makefile
index 208000b0750d..0da976ce67dd 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -4,8 +4,8 @@
 
 obj-$(CONFIG_BLOCK) := elevator.o blk-core.o blk-tag.o blk-sysfs.o \
                         blk-barrier.o blk-settings.o blk-ioc.o blk-map.o \
-                        blk-exec.o blk-merge.o ioctl.o genhd.o scsi_ioctl.o \
-                        cmd-filter.o
+                        blk-exec.o blk-merge.o blk-softirq.o ioctl.o genhd.o \
+                        scsi_ioctl.o cmd-filter.o
 
 obj-$(CONFIG_BLK_DEV_BSG)       += bsg.o
 obj-$(CONFIG_IOSCHED_NOOP)      += noop-iosched.o
diff --git a/block/blk-core.c b/block/blk-core.c
index 98138f002524..527b3382a610 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -26,8 +26,6 @@
 #include <linux/swap.h>
 #include <linux/writeback.h>
 #include <linux/task_io_accounting_ops.h>
-#include <linux/interrupt.h>
-#include <linux/cpu.h>
 #include <linux/blktrace_api.h>
 #include <linux/fault-inject.h>
 
@@ -50,8 +48,6 @@ struct kmem_cache *blk_requestq_cachep;
  */
 static struct workqueue_struct *kblockd_workqueue;
 
-static DEFINE_PER_CPU(struct list_head, blk_cpu_done);
-
 static void drive_stat_acct(struct request *rq, int new_io)
 {
         struct hd_struct *part;
@@ -1644,82 +1640,6 @@ static int __end_that_request_first(struct request *req, int error,
 }
 
 /*
- * splice the completion data to a local structure and hand off to
- * process_completion_queue() to complete the requests
- */
-static void blk_done_softirq(struct softirq_action *h)
-{
-        struct list_head *cpu_list, local_list;
-
-        local_irq_disable();
-        cpu_list = &__get_cpu_var(blk_cpu_done);
-        list_replace_init(cpu_list, &local_list);
-        local_irq_enable();
-
-        while (!list_empty(&local_list)) {
-                struct request *rq;
-
-                rq = list_entry(local_list.next, struct request, donelist);
-                list_del_init(&rq->donelist);
-                rq->q->softirq_done_fn(rq);
-        }
-}
-
-static int __cpuinit blk_cpu_notify(struct notifier_block *self,
-                                    unsigned long action, void *hcpu)
-{
-        /*
-         * If a CPU goes away, splice its entries to the current CPU
-         * and trigger a run of the softirq
-         */
-        if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
-                int cpu = (unsigned long) hcpu;
-
-                local_irq_disable();
-                list_splice_init(&per_cpu(blk_cpu_done, cpu),
-                                 &__get_cpu_var(blk_cpu_done));
-                raise_softirq_irqoff(BLOCK_SOFTIRQ);
-                local_irq_enable();
-        }
-
-        return NOTIFY_OK;
-}
-
-
-static struct notifier_block blk_cpu_notifier __cpuinitdata = {
-        .notifier_call  = blk_cpu_notify,
-};
-
-/**
- * blk_complete_request - end I/O on a request
- * @req:      the request being processed
- *
- * Description:
- *     Ends all I/O on a request. It does not handle partial completions,
- *     unless the driver actually implements this in its completion callback
- *     through requeueing. The actual completion happens out-of-order,
- *     through a softirq handler. The user must have registered a completion
- *     callback through blk_queue_softirq_done().
- **/
-
-void blk_complete_request(struct request *req)
-{
-        struct list_head *cpu_list;
-        unsigned long flags;
-
-        BUG_ON(!req->q->softirq_done_fn);
-
-        local_irq_save(flags);
-
-        cpu_list = &__get_cpu_var(blk_cpu_done);
-        list_add_tail(&req->donelist, cpu_list);
-        raise_softirq_irqoff(BLOCK_SOFTIRQ);
-
-        local_irq_restore(flags);
-}
-EXPORT_SYMBOL(blk_complete_request);
-
-/*
  * queue lock must be held
  */
 static void end_that_request_last(struct request *req, int error)
@@ -2053,8 +1973,6 @@ EXPORT_SYMBOL(kblockd_flush_work);
 
 int __init blk_dev_init(void)
 {
-        int i;
-
         kblockd_workqueue = create_workqueue("kblockd");
         if (!kblockd_workqueue)
                 panic("Failed to create kblockd\n");
@@ -2065,12 +1983,6 @@ int __init blk_dev_init(void)
         blk_requestq_cachep = kmem_cache_create("blkdev_queue",
                         sizeof(struct request_queue), 0, SLAB_PANIC, NULL);
 
-        for_each_possible_cpu(i)
-                INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i));
-
-        open_softirq(BLOCK_SOFTIRQ, blk_done_softirq);
-        register_hotcpu_notifier(&blk_cpu_notifier);
-
         return 0;
 }
 
diff --git a/block/blk-softirq.c b/block/blk-softirq.c
new file mode 100644
index 000000000000..9e1c43bff662
--- /dev/null
+++ b/block/blk-softirq.c
@@ -0,0 +1,103 @@
+/*
+ * Functions related to softirq rq completions
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/interrupt.h>
+#include <linux/cpu.h>
+
+#include "blk.h"
+
+static DEFINE_PER_CPU(struct list_head, blk_cpu_done);
+
+static int __cpuinit blk_cpu_notify(struct notifier_block *self,
+                                    unsigned long action, void *hcpu)
+{
+        /*
+         * If a CPU goes away, splice its entries to the current CPU
+         * and trigger a run of the softirq
+         */
+        if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
+                int cpu = (unsigned long) hcpu;
+
+                local_irq_disable();
+                list_splice_init(&per_cpu(blk_cpu_done, cpu),
+                                 &__get_cpu_var(blk_cpu_done));
+                raise_softirq_irqoff(BLOCK_SOFTIRQ);
+                local_irq_enable();
+        }
+
+        return NOTIFY_OK;
+}
+
+
+static struct notifier_block blk_cpu_notifier __cpuinitdata = {
+        .notifier_call  = blk_cpu_notify,
+};
+
+/*
+ * splice the completion data to a local structure and hand off to
+ * process_completion_queue() to complete the requests
+ */
+static void blk_done_softirq(struct softirq_action *h)
+{
+        struct list_head *cpu_list, local_list;
+
+        local_irq_disable();
+        cpu_list = &__get_cpu_var(blk_cpu_done);
+        list_replace_init(cpu_list, &local_list);
+        local_irq_enable();
+
+        while (!list_empty(&local_list)) {
+                struct request *rq;
+
+                rq = list_entry(local_list.next, struct request, donelist);
+                list_del_init(&rq->donelist);
+                rq->q->softirq_done_fn(rq);
+        }
+}
+
+/**
+ * blk_complete_request - end I/O on a request
+ * @req:      the request being processed
+ *
+ * Description:
+ *     Ends all I/O on a request. It does not handle partial completions,
+ *     unless the driver actually implements this in its completion callback
+ *     through requeueing. The actual completion happens out-of-order,
+ *     through a softirq handler. The user must have registered a completion
+ *     callback through blk_queue_softirq_done().
+ **/
+
+void blk_complete_request(struct request *req)
+{
+        struct list_head *cpu_list;
+        unsigned long flags;
+
+        BUG_ON(!req->q->softirq_done_fn);
+
+        local_irq_save(flags);
+
+        cpu_list = &__get_cpu_var(blk_cpu_done);
+        list_add_tail(&req->donelist, cpu_list);
+        raise_softirq_irqoff(BLOCK_SOFTIRQ);
+
+        local_irq_restore(flags);
+}
+EXPORT_SYMBOL(blk_complete_request);
+
+int __init blk_softirq_init(void)
+{
+        int i;
+
+        for_each_possible_cpu(i)
+                INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i));
+
+        open_softirq(BLOCK_SOFTIRQ, blk_done_softirq);
+        register_hotcpu_notifier(&blk_cpu_notifier);
+        return 0;
+}
+subsys_initcall(blk_softirq_init);