Merge branch 'for-3.1/core' of git://git.kernel.dk/linux-block

* 'for-3.1/core' of git://git.kernel.dk/linux-block: (24 commits)
  block: strict rq_affinity
  backing-dev: use synchronize_rcu_expedited instead of synchronize_rcu
  block: fix patch import error in max_discard_sectors check
  block: reorder request_queue to remove 64 bit alignment padding
  CFQ: add think time check for group
  CFQ: add think time check for service tree
  CFQ: move think time check variables to a separate struct
  fixlet: Remove fs_excl from struct task.
  cfq: Remove special treatment for metadata rqs.
  block: document blk_plug list access
  block: avoid building too big plug list
  compat_ioctl: fix make headers_check regression
  block: eliminate potential for infinite loop in blkdev_issue_discard
  compat_ioctl: fix warning caused by qemu
  block: flush MEDIA_CHANGE from drivers on close(2)
  blk-throttle: Make total_nr_queued unsigned
  block: Add __attribute__((format(printf...) and fix fallout
  fs/partitions/check.c: make local symbols static
  block:remove some spare spaces in genhd.c
  block:fix the comment error in blkdev.h
  ...

28 files changed, 229 insertions, 208 deletions

diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt
index f65274081c8d..d8147b336c35 100644
--- a/Documentation/block/queue-sysfs.txt
+++ b/Documentation/block/queue-sysfs.txt
@@ -45,9 +45,13 @@ device.
 
 rq_affinity (RW)
 ----------------
-If this option is enabled, the block layer will migrate request completions
-to the CPU that originally submitted the request. For some workloads
-this provides a significant reduction in CPU cycles due to caching effects.
+If this option is '1', the block layer will migrate request completions to the
+cpu "group" that originally submitted the request. For some workloads this
+provides a significant reduction in CPU cycles due to caching effects.
+
+For storage configurations that need to maximize distribution of completion
+processing setting this option to '2' forces the completion to run on the
+requesting cpu (bypassing the "group" aggregation logic).
 
 scheduler (RW)
 --------------
diff --git a/block/blk-core.c b/block/blk-core.c
index 1d49e1c7c905..f8cb09951830 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1282,10 +1282,8 @@ get_rq:
         init_request_from_bio(req, bio);
 
         if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) ||
-            bio_flagged(bio, BIO_CPU_AFFINE)) {
-                req->cpu = blk_cpu_to_group(get_cpu());
-                put_cpu();
-        }
+            bio_flagged(bio, BIO_CPU_AFFINE))
+                req->cpu = smp_processor_id();
 
         plug = current->plug;
         if (plug) {
@@ -1305,7 +1303,10 @@ get_rq:
                                 plug->should_sort = 1;
                 }
                 list_add_tail(&req->queuelist, &plug->list);
+                plug->count++;
                 drive_stat_acct(req, 1);
+                if (plug->count >= BLK_MAX_REQUEST_COUNT)
+                        blk_flush_plug_list(plug, false);
         } else {
                 spin_lock_irq(q->queue_lock);
                 add_acct_request(q, req, where);
@@ -2629,6 +2630,7 @@ void blk_start_plug(struct blk_plug *plug)
         INIT_LIST_HEAD(&plug->list);
         INIT_LIST_HEAD(&plug->cb_list);
         plug->should_sort = 0;
+        plug->count = 0;
 
         /*
          * If this is a nested plug, don't actually assign it. It will be
@@ -2712,6 +2714,7 @@ void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
                 return;
 
         list_splice_init(&plug->list, &list);
+        plug->count = 0;
 
         if (plug->should_sort) {
                 list_sort(NULL, &list, plug_rq_cmp);
diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index 342eae9b0d3c..6f9bbd978653 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -82,26 +82,26 @@ void exit_io_context(struct task_struct *task)
 
 struct io_context *alloc_io_context(gfp_t gfp_flags, int node)
 {
-        struct io_context *ret;
+        struct io_context *ioc;
 
-        ret = kmem_cache_alloc_node(iocontext_cachep, gfp_flags, node);
-        if (ret) {
-                atomic_long_set(&ret->refcount, 1);
-                atomic_set(&ret->nr_tasks, 1);
-                spin_lock_init(&ret->lock);
-                ret->ioprio_changed = 0;
-                ret->ioprio = 0;
-                ret->last_waited = 0; /* doesn't matter... */
-                ret->nr_batch_requests = 0; /* because this is 0 */
-                INIT_RADIX_TREE(&ret->radix_root, GFP_ATOMIC | __GFP_HIGH);
-                INIT_HLIST_HEAD(&ret->cic_list);
-                ret->ioc_data = NULL;
+        ioc = kmem_cache_alloc_node(iocontext_cachep, gfp_flags, node);
+        if (ioc) {
+                atomic_long_set(&ioc->refcount, 1);
+                atomic_set(&ioc->nr_tasks, 1);
+                spin_lock_init(&ioc->lock);
+                ioc->ioprio_changed = 0;
+                ioc->ioprio = 0;
+                ioc->last_waited = 0; /* doesn't matter... */
+                ioc->nr_batch_requests = 0; /* because this is 0 */
+                INIT_RADIX_TREE(&ioc->radix_root, GFP_ATOMIC | __GFP_HIGH);
+                INIT_HLIST_HEAD(&ioc->cic_list);
+                ioc->ioc_data = NULL;
 #if defined(CONFIG_BLK_CGROUP) || defined(CONFIG_BLK_CGROUP_MODULE)
-                ret->cgroup_changed = 0;
+                ioc->cgroup_changed = 0;
 #endif
         }
 
-        return ret;
+        return ioc;
 }
 
 /*
@@ -139,19 +139,19 @@ struct io_context *current_io_context(gfp_t gfp_flags, int node)
  */
 struct io_context *get_io_context(gfp_t gfp_flags, int node)
 {
-        struct io_context *ret = NULL;
+        struct io_context *ioc = NULL;
 
         /*
          * Check for unlikely race with exiting task. ioc ref count is
          * zero when ioc is being detached.
          */
         do {
-                ret = current_io_context(gfp_flags, node);
-                if (unlikely(!ret))
+                ioc = current_io_context(gfp_flags, node);
+                if (unlikely(!ioc))
                         break;
-        } while (!atomic_long_inc_not_zero(&ret->refcount));
+        } while (!atomic_long_inc_not_zero(&ioc->refcount));
 
-        return ret;
+        return ioc;
 }
 EXPORT_SYMBOL(get_io_context);
 
diff --git a/block/blk-lib.c b/block/blk-lib.c
index 78e627e2581d..2b461b496a78 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -59,7 +59,10 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
          * granularity
          */