6 files changed, 424 insertions, 368 deletions

diff --git a/block/as-iosched.c b/block/as-iosched.c
index 43fa20495688..8da3cf66894c 100644
--- a/block/as-iosched.c
+++ b/block/as-iosched.c
@@ -182,6 +182,9 @@ struct as_rq {
 
 static kmem_cache_t *arq_pool;
 
+static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq);
+static void as_antic_stop(struct as_data *ad);
+
 /*
  * IO Context helper functions
  */
@@ -370,7 +373,7 @@ static struct as_rq *as_find_first_arq(struct as_data *ad, int data_dir)
  * existing request against the same sector), which can happen when using
  * direct IO, then return the alias.
  */
-static struct as_rq *as_add_arq_rb(struct as_data *ad, struct as_rq *arq)
+static struct as_rq *__as_add_arq_rb(struct as_data *ad, struct as_rq *arq)
 {
         struct rb_node **p = &ARQ_RB_ROOT(ad, arq)->rb_node;
         struct rb_node *parent = NULL;
@@ -397,6 +400,16 @@ static struct as_rq *as_add_arq_rb(struct as_data *ad, struct as_rq *arq)
         return NULL;
 }
 
+static void as_add_arq_rb(struct as_data *ad, struct as_rq *arq)
+{
+        struct as_rq *alias;
+
+        while ((unlikely(alias = __as_add_arq_rb(ad, arq)))) {
+                as_move_to_dispatch(ad, alias);
+                as_antic_stop(ad);
+        }
+}
+
 static inline void as_del_arq_rb(struct as_data *ad, struct as_rq *arq)
 {
         if (!ON_RB(&arq->rb_node)) {
@@ -1133,23 +1146,6 @@ static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq)
         /*
          * take it off the sort and fifo list, add to dispatch queue
          */
-        while (!list_empty(&rq->queuelist)) {
-                struct request *__rq = list_entry_rq(rq->queuelist.next);
-                struct as_rq *__arq = RQ_DATA(__rq);
-
-                list_del(&__rq->queuelist);
-
-                elv_dispatch_add_tail(ad->q, __rq);
-
-                if (__arq->io_context && __arq->io_context->aic)
-                        atomic_inc(&__arq->io_context->aic->nr_dispatched);
-
-                WARN_ON(__arq->state != AS_RQ_QUEUED);
-                __arq->state = AS_RQ_DISPATCHED;
-
-                ad->nr_dispatched++;
-        }
-
         as_remove_queued_request(ad->q, rq);
         WARN_ON(arq->state != AS_RQ_QUEUED);
 
@@ -1326,49 +1322,12 @@ fifo_expired:
 }
 
 /*
- * Add arq to a list behind alias
- */
-static inline void
-as_add_aliased_request(struct as_data *ad, struct as_rq *arq,
-                                struct as_rq *alias)
-{
-        struct request  *req = arq->request;
-        struct list_head *insert = alias->request->queuelist.prev;
-
-        /*
-         * Transfer list of aliases
-         */
-        while (!list_empty(&req->queuelist)) {
-                struct request *__rq = list_entry_rq(req->queuelist.next);
-                struct as_rq *__arq = RQ_DATA(__rq);
-
-                list_move_tail(&__rq->queuelist, &alias->request->queuelist);
-
-                WARN_ON(__arq->state != AS_RQ_QUEUED);
-        }
-
-        /*
-         * Another request with the same start sector on the rbtree.
-         * Link this request to that sector. They are untangled in
-         * as_move_to_dispatch
-         */
-        list_add(&arq->request->queuelist, insert);
-
-        /*
-         * Don't want to have to handle merges.
-         */
-        as_del_arq_hash(arq);
-        arq->request->flags |= REQ_NOMERGE;
-}
-
-/*
  * add arq to rbtree and fifo
  */
 static void as_add_request(request_queue_t *q, struct request *rq)
 {
         struct as_data *ad = q->elevator->elevator_data;
         struct as_rq *arq = RQ_DATA(rq);
-        struct as_rq *alias;
         int data_dir;
 
         arq->state = AS_RQ_NEW;
@@ -1387,33 +1346,17 @@ static void as_add_request(request_queue_t *q, struct request *rq)
                 atomic_inc(&arq->io_context->aic->nr_queued);
         }
 
-        alias = as_add_arq_rb(ad, arq);
-        if (!alias) {
-                /*
-                 * set expire time (only used for reads) and add to fifo list
-                 */
-                arq->expires = jiffies + ad->fifo_expire[data_dir];
-                list_add_tail(&arq->fifo, &ad->fifo_list[data_dir]);
+        as_add_arq_rb(ad, arq);
+        if (rq_mergeable(arq->request))
+                as_add_arq_hash(ad, arq);
 
-                if (rq_mergeable(arq->request))
-                        as_add_arq_hash(ad, arq);
-                as_update_arq(ad, arq); /* keep state machine up to date */
-
-        } else {
-                as_add_aliased_request(ad, arq, alias);
-
-                /*
-                 * have we been anticipating this request?
-                 * or does it come from the same process as the one we are
-                 * anticipating for?
-                 */
-                if (ad->antic_status == ANTIC_WAIT_REQ
-                                || ad->antic_status == ANTIC_WAIT_NEXT) {
-                        if (as_can_break_anticipation(ad, arq))
-                                as_antic_stop(ad);
-                }
-        }
+        /*
+         * set expire time (only used for reads) and add to fifo list
+         */
+        arq->expires = jiffies + ad->fifo_expire[data_dir];
+        list_add_tail(&arq->fifo, &ad->fifo_list[data_dir]);
 
+        as_update_arq(ad, arq); /* keep state machine up to date */
         arq->state = AS_RQ_QUEUED;
 }
 
@@ -1536,23 +1479,8 @@ static void as_merged_request(request_queue_t *q, struct request *req)
          * if the merge was a front merge, we need to reposition request
          */
         if (rq_rb_key(req) != arq->rb_key) {
-                struct as_rq *alias, *next_arq = NULL;
-
-                if (ad->next_arq[arq->is_sync] == arq)
-                        next_arq = as_find_next_arq(ad, arq);
-
-                /*
-                 * Note! We should really be moving any old aliased requests
-                 * off this request and try to insert them into the rbtree. We
-                 * currently don't bother. Ditto the next function.
-                 */
                 as_del_arq_rb(ad, arq);
-                if ((alias = as_add_arq_rb(ad, arq))) {
-                        list_del_init(&arq->fifo);
-                        as_add_aliased_request(ad, arq, alias);
-                        if (next_arq)
-                                ad->next_arq[arq->is_sync] = next_arq;
-                }
+                as_add_arq_rb(ad, arq);
                 /*
                  * Note! At this stage of this and the next function, our next
                  * request may not be optimal - eg the request may have "grown"
@@ -1579,18 +1507,8 @@ static void as_merged_requests(request_queue_t *q, struct request *req,
         as_add_arq_hash(ad, arq);
 
         if (rq_rb_key(req) != arq->rb_key) {
-                struct as_rq *alias, *next_arq = NULL;
-
-                if (ad->next_arq[arq->is_sync] == arq)
-                        next_arq = as_find_next_arq(ad, arq);
-
                 as_del_arq_rb(ad, arq);
-                if ((alias = as_add_arq_rb(ad, arq))) {
-                        list_del_init(&arq->fifo);
-                        as_add_aliased_request(ad, arq, alias);
-                        if (next_arq)
-                                ad->next_arq[arq->is_sync] = next_arq;
-                }
+                as_add_arq_rb(ad, arq);
         }
 
         /*
@@ -1610,18 +1528,6 @@ static void as_merged_requests(request_queue_t *q, struct request *req,
         }
 
         /*
-         * Transfer list of aliases
-         */
-        while (!list_empty(&next->queuelist)) {
-                struct request *__rq = list_entry_rq(next->queuelist.next);
-                struct as_rq *__arq = RQ_DATA(__rq);
-
-                list_move_tail(&__rq->queuelist, &req->queuelist);
-
-                WARN_ON(__arq->state != AS_RQ_QUEUED);
-        }
-
-        /*
          * kill knowledge of next, this one is a goner
          */
         as_remove_queued_request(q, next);
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index ee0bb41694b0..74fae2daf87e 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -25,15 +25,15 @@
 /*
  * tunables
  */
-static int cfq_quantum = 4;             /* max queue in one round of service */
-static int cfq_queued = 8;              /* minimum rq allocate limit per-queue*/
-static int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
-static int cfq_back_max = 16 * 1024;    /* maximum backwards seek, in KiB */
-static int cfq_back_penalty = 2;        /* penalty of a backwards seek */
+static const int cfq_quantum = 4;               /* max queue in one round of service */
+static const int cfq_queued = 8;                /* minimum rq allocate limit per-queue*/
+static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
+static const int cfq_back_max = 16 * 1024;      /* maximum backwards seek, in KiB */
+static const int cfq_back_penalty = 2;          /* penalty of a backwards seek */
 
-static int cfq_slice_sync = HZ / 10;
+static const int cfq_slice_sync = HZ / 10;
 static int cfq_slice_async = HZ / 25;
-static int cfq_slice_async_rq = 2;
+static const int cfq_slice_async_rq = 2;
 static int cfq_slice_idle = HZ / 100;
 
 #define CFQ_IDLE_GRACE          (HZ / 10)
@@ -45,7 +45,7 @@ static int cfq_slice_idle = HZ / 100;
 /*
  * disable queueing at the driver/hardware level
  */
-static int cfq_max_depth = 2;
+static const int cfq_max_depth = 2;
 
 /*
  * for the hash of cfqq inside the cfqd
diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
index 9cbec09e8415..27e494b1bf97 100644
--- a/block/deadline-iosched.c
+++ b/block/deadline-iosched.c
@@ -19,10 +19,10 @@
 /*
  * See Documentation/block/deadline-iosched.txt
  */
-static int read_expire = HZ / 2;  /* max time before a read is submitted. */
-static int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
-static int writes_starved = 2;    /* max times reads can starve a write */
-static int fifo_batch = 16;       /* # of sequential requests treated as one
+static const int read_expire = HZ / 2;  /* max time before a read is submitted. */
+static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
+static const int writes_starved = 2;    /* max times reads can starve a write */
+static const int fifo_batch = 16;       /* # of sequential requests treated as one
                                      by the above parameters. For throughput. */
 
 static const int deadline_hash_shift = 5;
diff --git a/block/elevator.c b/block/elevator.c
index 6c3fc8a10bf2..39dcccc82ada 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -304,15 +304,7 @@ void elv_requeue_request(request_queue_t *q, struct request *rq)
 
         rq->flags &= ~REQ_STARTED;
 
-        /*
-         * if this is the flush, requeue the original instead and drop the flush
-         */
-        if (rq->flags & REQ_BAR_FLUSH) {
-                clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags);
-                rq = rq->end_io_data;
-        }
-
-        __elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0);
+        __elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE, 0);
 }
 
 static void elv_drain_elevator(request_queue_t *q)
@@ -332,8 +324,19 @@ static void elv_drain_elevator(request_queue_t *q)
 void __elv_add_request(request_queue_t *q, struct request *rq, int where,
                        int plug)
 {
+        struct list_head *pos;
+        unsigned ordseq;
+
+        if (q->ordcolor)
+                rq->flags |= REQ_ORDERED_COLOR;
+
         if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) {
                 /*
+                 * toggle ordered color
+                 */
+                q->ordcolor ^= 1;
+
+                /*
                  * barriers implicitly indicate back insertion
                  */
                 if (where == ELEVATOR_INSERT_SORT)
@@ -393,6 +396,30 @@ void __elv_add_request(request_queue_t *q, struct request *rq, int where,
                 q->elevator->ops->elevator_add_req_fn(q, rq);
                 break;
 
+        case ELEVATOR_INSERT_REQUEUE:
+                /*
+                 * If ordered flush isn't in progress, we do front
+                 * insertion; otherwise, requests should be requeued
+                 * in ordseq order.
+                 */
+                rq->flags |= REQ_SOFTBARRIER;
+
+                if (q->ordseq == 0) {
+                        list_add(&rq->queuelist, &q->queue_head);
+                        break;
+                }
+
+                ordseq = blk_ordered_req_seq(rq);
+
+                list_for_each(pos, &q->queue_head) {
+                        struct request *pos_rq = list_entry_rq(pos);
+                        if (ordseq <= blk_ordered_req_seq(pos_rq))
+                                break;
+                }
+
+                list_add_tail(&rq->queuelist, pos);
+                break;
+
         default:
                 printk(KERN_ERR "%s: bad insertion point %d\n",
                        __FUNCTION__, where);
@@ -422,25 +449,16 @@ static inline struct request *__elv_next_request(request_queue_t *q)
 {
         struct request *rq;
 
-        if (unlikely(list_empty(&q->queue_head) &&
-                     !q->elevator->ops->elevator_dispatch_fn(q, 0)))
-                return NULL;
-
-        rq = list_entry_rq(q->queue_head.next);
-
-        /*
-         * if this is a barrier write and the device has to issue a
-         * flush sequence to support it, check how far we are
-         */
-        if (blk_fs_request(rq) && blk_barrier_rq(rq)) {
-                BUG_ON(q->ordered == QUEUE_ORDERED_NONE);
+        while (1) {
+                while (!list_empty(&q->queue_head)) {
+                        rq = list_entry_rq(q->queue_head.next);
+                        if (blk_do_ordered(q, &rq))
+                                return rq;
+                }
 
-                if (q->ordered == QUEUE_ORDERED_FLUSH &&
-                    !blk_barrier_preflush(rq))
-                        rq = blk_start_pre_flush(q, rq);
+                if (!q->elevator->ops->elevator_dispatch_fn(q, 0))
+                        return NULL;
         }
-
-        return rq;
 }
 
 struct request *elv_next_request(request_queue_t *q)
@@ -498,7 +516,7 @@ struct request *elv_next_request(request_queue_t *q)
                         blkdev_dequeue_request(rq);
                         rq->flags |= REQ_QUIET;
                         end_that_request_chunk(rq, 0, nr_bytes);
-                        end_that_request_last(rq);
+                        end_that_request_last(rq, 0);
                 } else {
                         printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__,
                                                                 ret);
@@ -593,7 +611,21 @@ void elv_completed_request(request_queue_t *q, struct request *rq)
          * request is released from the driver, io must be done
          */
         if (blk_account_rq(rq)) {
+                struct request *first_rq = list_entry_rq(q->queue_head.next);
+
                 q->in_flight--;
+
+                /*
+                 * Check if the queue is waiting for fs requests to be
+                 * drained for flush sequence.
+                 */
+                if (q->ordseq && q->in_flight == 0 &&
+                    blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN &&
+                    blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) {
+                        blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0);
+                        q->request_fn(q);
+                }
+
                 if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn)
                         e->ops->elevator_completed_req_fn(q, rq);
         }
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index d4beb9a89ee0..91d3b4828c49 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -36,6 +36,8 @@
 static void blk_unplug_work(void *data);
 static void blk_unplug_timeout(unsigned long data);
 static void drive_stat_acct(struct request *rq, int nr_sectors, int new_io);
+static void init_request_from_bio(struct request *req, struct bio *bio);
+static int __make_request(request_queue_t *q, struct bio *bio);
 
 /*
  * For the allocated request tables
@@ -288,8 +290,8 @@ static inline void rq_init(request_queue_t *q, struct request *rq)
 
 /**
  * blk_queue_ordered - does this queue support ordered writes
- * @q:     the request queue
- * @flag:  see below
+ * @q:        the request queue
+ * @ordered:  one of QUEUE_ORDERED_*
  *
  * Description:
  *   For journalled file systems, doing ordered writes on a commit
@@ -298,28 +300,30 @@ static inline void rq_init(request_queue_t *q, struct request *rq)
  *   feature should call this function and indicate so.
  *
  **/
-void blk_queue_ordered(request_queue_t *q, int flag)
-{
-        switch (flag) {
-                case QUEUE_ORDERED_NONE:
-                        if (q->flush_rq)
-                                kmem_cache_free(request_cachep, q->flush_rq);
-                        q->flush_rq = NULL;
-                        q->ordered = flag;
-                        break;
-                case QUEUE_ORDERED_TAG:
-                        q->ordered = flag;
-                        break;
-                case QUEUE_ORDERED_FLUSH:
-                        q->ordered = flag;
-                        if (!q->flush_rq)
-                                q->flush_rq = kmem_cache_alloc(request_cachep,
-                                                                GFP_KERNEL);
-                        break;
-                default:
-                        printk("blk_queue_ordered: bad value %d\n", flag);
-                        break;
+int blk_queue_ordered(request_queue_t *q, unsigned ordered,
+                      prepare_flush_fn *prepare_flush_fn)
+{
+        if (ordered & (QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH) &&
+            prepare_flush_fn == NULL) {
+                printk(KERN_ERR "blk_queue_ordered: prepare_flush_fn required\n");
+                return -EINVAL;
+        }
+
+        if (ordered != QUEUE_ORDERED_NONE &&
+            ordered != QUEUE_ORDERED_DRAIN &&
+            ordered != QUEUE_ORDERED_DRAIN_FLUSH &&
+            ordered != QUEUE_ORDERED_DRAIN_FUA &&
+            ordered != QUEUE_ORDERED_TAG &&
+            ordered != QUEUE_ORDERED_TAG_FLUSH &&
+            ordered != QUEUE_ORDERED_TAG_FUA) {
+                printk(KERN_ERR "blk_queue_ordered: bad value %d\n", ordered);
+                return -EINVAL;
         }
+
+        q->next_ordered = ordered;
+        q->prepare_flush_fn = prepare_flush_fn;
+
+        return 0;
 }
 
 EXPORT_SYMBOL(blk_queue_ordered);
@@ -344,167 +348,265 @@ EXPORT_SYMBOL(blk_queue_issue_flush_fn);
 /*
  * Cache flushing for ordered writes handling
  */
-static void blk_pre_flush_end_io(struct request *flush_rq)
+inline unsigned blk_ordered_cur_seq(request_queue_t *q)
 {
-        struct request *rq = flush_rq->end_io_data;
-        request_queue_t *q = rq->q;
-
-        elv_completed_request(q, flush_rq);
-
-        rq->flags |= REQ_BAR_PREFLUSH;
-
-        if (!flush_rq->errors)
-                elv_requeue_request(q, rq);
-        else {
-                q->end_flush_fn(q, flush_rq);
-                clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags);
-                q->request_fn(q);
-        }
+        if (!q->ordseq)
+                return 0;
+        return 1 << ffz(q->ordseq);
 }
 
-static void blk_post_flush_end_io(struct request *flush_rq)
+unsigned blk_ordered_req_seq(struct request *rq)
 {
-        struct request *rq = flush_rq->end_io_data;
         request_queue_t *q = rq->q;
 
-        elv_completed_request(q, flush_rq);
+        BUG_ON(q->ordseq == 0);
 
-        rq->flags |= REQ_BAR_POSTFLUSH;
+        if (rq == &q->pre_flush_rq)
+                return QUEUE_ORDSEQ_PREFLUSH;
+        if (rq == &q->bar_rq)
+                return QUEUE_ORDSEQ_BAR;
+        if (rq == &q->post_flush_rq)
+                return QUEUE_ORDSEQ_POSTFLUSH;
 
-        q->end_flush_fn(q, flush_rq);
-        clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags);
-        q->request_fn(q);
+        if ((rq->flags & REQ_ORDERED_COLOR) ==
+            (q->orig_bar_rq->flags & REQ_ORDERED_COLOR))
+                return QUEUE_ORDSEQ_DRAIN;
+        else
+                return QUEUE_ORDSEQ_DONE;
 }
 
-struct request *blk_start_pre_flush(request_queue_t *q, struct request *rq)
+void blk_ordered_complete_seq(request_queue_t *q, unsigned seq, int error)
 {
-        struct request *flush_rq = q->flush_rq;
-
-        BUG_ON(!blk_barrier_rq(rq));
+        struct request *rq;
+        int uptodate;
 
-        if (test_and_set_bit(QUEUE_FLAG_FLUSH, &q->queue_flags))
-                return NULL;
+        if (error && !q->orderr)
+                q->orderr = error;
 
-        rq_init(q, flush_rq);
-        flush_rq->elevator_private = NULL;
-        flush_rq->flags = REQ_BAR_FLUSH;
-        flush_rq->rq_disk = rq->rq_disk;
-        flush_rq->rl = NULL;
+        BUG_ON(q->ordseq & seq);
+        q->ordseq |= seq;
 
-        /*
-         * prepare_flush returns 0 if no flush is needed, just mark both
-         * pre and post flush as done in that case
-         */
-        if (!q->prepare_flush_fn(q, flush_rq)) {
-                rq->flags |= REQ_BAR_PREFLUSH | REQ_BAR_POSTFLUSH;
-                clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags);
-                return rq;
-        }
+        if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE)
+                return;
 
         /*
-         * some drivers dequeue requests right away, some only after io
-         * completion. make sure the request is dequeued.
+         * Okay, sequence complete.
          */
-        if (!list_empty(&rq->queuelist))
-                blkdev_dequeue_request(rq);
+        rq = q->orig_bar_rq;
+        uptodate = q->orderr ? q->orderr : 1;
 
-        flush_rq->end_io_data = rq;
-        flush_rq->end_io = blk_pre_flush_end_io;
+        q->ordseq = 0;
 
-        __elv_add_request(q, flush_rq, ELEVATOR_INSERT_FRONT, 0);
-        return flush_rq;
+        end_that_request_first(rq, uptodate, rq->hard_nr_sectors);
+        end_that_request_last(rq, uptodate);
 }
 
-static void blk_start_post_flush(request_queue_t *q, struct request *rq)
+static void pre_flush_end_io(struct request *rq, int error)
 {
-        struct request *flush_rq = q->flush_rq;
+        elv_completed_request(rq->q, rq);
+        blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_PREFLUSH, error);
+}
 
-        BUG_ON(!blk_barrier_rq(rq));
+static void bar_end_io(struct request *rq, int error)
+{
+        elv_completed_request(rq->q, rq);
+        blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_BAR, error);
+}
 
-        rq_init(q, flush_rq);
-        flush_rq->elevator_private = NULL;
-        flush_rq->flags = REQ_BAR_FLUSH;
-        flush_rq->rq_disk = rq->rq_disk;
-        flush_rq->rl = NULL;
+static void post_flush_end_io(struct request *rq, int error)
+{
+        elv_completed_request(rq->q, rq);
+        blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_POSTFLUSH, error);
+}
 
-        if (q->prepare_flush_fn(q, flush_rq)) {
-                flush_rq->end_io_data = rq;
-                flush_rq->end_io = blk_post_flush_end_io;
+static void queue_flush(request_queue_t *q, unsigned which)
+{
+        struct request *rq;
+        rq_end_io_fn *end_io;
 
-                __elv_add_request(q, flush_rq, ELEVATOR_INSERT_FRONT, 0);
-                q->request_fn(q);
+        if (which == QUEUE_ORDERED_PREFLUSH) {
+                rq = &q->pre_flush_rq;
+                end_io = pre_flush_end_io;
+        } else {
+                rq = &q->post_flush_rq;
+                end_io = post_flush_end_io;
         }
+
+        rq_init(q, rq);
+        rq->flags = REQ_HARDBARRIER;
+        rq->elevator_private = NULL;
+        rq->rq_disk = q->bar_rq.rq_disk;
+        rq->rl = NULL;
+        rq->end_io = end_io;
+        q->prepare_flush_fn(q, rq);
+
+        __elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0);
 }
 
-static inline int blk_check_end_barrier(request_queue_t *q, struct request *rq,
-                                        int sectors)
+static inline struct request *start_ordered(request_queue_t *q,
+                                            struct request *rq)
 {
-        if (sectors > rq->nr_sectors)
-                sectors = rq->nr_sectors;
+        q->bi_size = 0;
+        q->orderr = 0;
+        q->ordered = q->next_ordered;
+        q->ordseq |= QUEUE_ORDSEQ_STARTED;
+
+        /*
+         * Prep proxy barrier request.
+         */
+        blkdev_dequeue_request(rq);
+        q->orig_bar_rq = rq;
+        rq = &q->bar_rq;
+        rq_init(q, rq);
+        rq->flags = bio_data_dir(q->orig_bar_rq->bio);
+        rq->flags |= q->ordered & QUEUE_ORDERED_FUA ? REQ_FUA : 0;
+        rq->elevator_private = NULL;
+        rq->rl = NULL;
+        init_request_from_bio(rq, q->orig_bar_rq->bio);
+        rq->end_io = bar_end_io;
+
+        /*
+         * Queue ordered sequence.  As we stack them at the head, we
+         * need to queue in reverse order.  Note that we rely on that
+         * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs
+         * request gets inbetween ordered sequence.
+         */
+        if (q->ordered & QUEUE_ORDERED_POSTFLUSH)
+                queue_flush(q, QUEUE_ORDERED_POSTFLUSH);
+        else
+                q->ordseq |= QUEUE_ORDSEQ_POSTFLUSH;
+
+        __elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0);
+
+        if (q->ordered & QUEUE_ORDERED_PREFLUSH) {
+                queue_flush(q, QUEUE_ORDERED_PREFLUSH);
+                rq = &q->pre_flush_rq;
+        } else
+                q->ordseq |= QUEUE_ORDSEQ_PREFLUSH;
 
-        rq->nr_sectors -= sectors;
-        return rq->nr_sectors;
+        if ((q->ordered & QUEUE_ORDERED_TAG) || q->in_flight == 0)
+                q->ordseq |= QUEUE_ORDSEQ_DRAIN;
+        else
+                rq = NULL;
+
+        return rq;
 }
 
-static int __blk_complete_barrier_rq(request_queue_t *q, struct request *rq,
-                                     int sectors, int queue_locked)
+int blk_do_ordered(request_queue_t *q, struct request **rqp)
 {
-        if (q->ordered != QUEUE_ORDERED_FLUSH)
-                return 0;
-        if (!blk_fs_request(rq) || !blk_barrier_rq(rq))
-                return 0;
-        if (blk_barrier_postflush(rq))
-                return 0;
+        struct request *rq = *rqp, *allowed_rq;
+        int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq);
 
-        if (!blk_check_end_barrier(q, rq, sectors)) {
-                unsigned long flags = 0;
+        if (!q->ordseq) {
+                if (!is_barrier)
+                        return 1;
 
-                if (!queue_locked)
-                        spin_lock_irqsave(q->queue_lock, flags);
+                if (q->next_ordered != QUEUE_ORDERED_NONE) {
+                        *rqp = start_ordered(q, rq);
+                        return 1;
+                } else {
+                        /*
+                         * This can happen when the queue switches to
+                         * ORDERED_NONE while this request is on it.
+                         */
+                        blkdev_dequeue_request(rq);
+                        end_that_request_first(rq, -EOPNOTSUPP,
+                                               rq->hard_nr_sectors);
+                        end_that_request_last(rq, -EOPNOTSUPP);
+                        *rqp = NULL;
+                        return 0;
+                }
+        }
 
-                blk_start_post_flush(q, rq);
+        if (q->ordered & QUEUE_ORDERED_TAG) {
+                if (is_barrier && rq != &q->bar_rq)
+                        *rqp = NULL;
+                return 1;
+        }
 
-                if (!queue_locked)
-                        spin_unlock_irqrestore(q->queue_lock, flags);
+        switch (blk_ordered_cur_seq(q)) {
+        case QUEUE_ORDSEQ_PREFLUSH:
+                allowed_rq = &q->pre_flush_rq;
+                break;
+        case QUEUE_ORDSEQ_BAR:
+                allowed_rq = &q->bar_rq;
+                break;
+        case QUEUE_ORDSEQ_POSTFLUSH:
+                allowed_rq = &q->post_flush_rq;
+                break;
+        default:
+                allowed_rq = NULL;
+                break;
         }
 
+        if (rq != allowed_rq &&
+            (blk_fs_request(rq) || rq == &q->pre_flush_rq ||
+             rq == &q->post_flush_rq))
+                *rqp = NULL;
+
         return 1;
 }
 
-/**
- * blk_complete_barrier_rq - complete possible barrier request
- * @q:  the request queue for the device
- * @rq:  the request
- * @sectors:  number of sectors to complete
- *
- * Description:
- *   Used in driver end_io handling to determine whether to postpone
- *   completion of a barrier request until a post flush has been done. This
- *   is the unlocked variant, used if the caller doesn't already hold the
- *   queue lock.
- **/
-int blk_complete_barrier_rq(request_queue_t *q, struct request *rq, int sectors)
+static int flush_dry_bio_endio(struct bio *bio, unsigned int bytes, int error)
 {
-        return __blk_complete_barrier_rq(q, rq, sectors, 0);
+        request_queue_t *q = bio->bi_private;
+        struct bio_vec *bvec;
+        int i;
+
+        /*
+         * This is dry run, restore bio_sector and size.  We'll finish
+         * this request again with the original bi_end_io after an
+         * error occurs or post flush is complete.
+         */
+        q->bi_size += bytes;
+
+        if (bio->bi_size)
+                return 1;
+
+        /* Rewind bvec's */
+        bio->bi_idx = 0;
+        bio_for_each_segment(bvec, bio, i) {
+                bvec->bv_len += bvec->bv_offset;
+                bvec->bv_offset = 0;
+        }
+
+        /* Reset bio */
+        set_bit(BIO_UPTODATE, &bio->bi_flags);
+        bio->bi_size = q->bi_size;
+        bio->bi_sector -= (q->bi_size >> 9);
+        q->bi_size = 0;
+
+        return 0;
 }
-EXPORT_SYMBOL(blk_complete_barrier_rq);
 
-/**
- * blk_complete_barrier_rq_locked - complete possible barrier request
- * @q:  the request queue for the device
- * @rq:  the request
- * @sectors:  number of sectors to complete
- *
- * Description:
- *   See blk_complete_barrier_rq(). This variant must be used if the caller
- *   holds the queue lock.
- **/
-int blk_complete_barrier_rq_locked(request_queue_t *q, struct request *rq,
-                                   int sectors)
+static inline int ordered_bio_endio(struct request *rq, struct bio *bio,
+                                    unsigned int nbytes, int error)
 {
-        return __blk_complete_barrier_rq(q, rq, sectors, 1);
+        request_queue_t *q = rq->q;
+        bio_end_io_t *endio;
+        void *private;
+
+        if (&q->bar_rq != rq)
+                return 0;
+
+        /*
+         * Okay, this is the barrier request in progress, dry finish it.
+         */
+        if (error && !q->orderr)
+                q->orderr = error;
+
+        endio = bio->bi_end_io;
+        private = bio->bi_private;
+        bio->bi_end_io = flush_dry_bio_endio;
+        bio->bi_private = q;
+
+        bio_endio(bio, nbytes, error);
+
+        bio->bi_end_io = endio;
+        bio->bi_private = private;
+
+        return 1;
 }
-EXPORT_SYMBOL(blk_complete_barrier_rq_locked);
 
 /**
  * blk_queue_bounce_limit - set bounce buffer limit for queue
@@ -1039,12 +1141,13 @@ void blk_queue_invalidate_tags(request_queue_t *q)
 
 EXPORT_SYMBOL(blk_queue_invalidate_tags);
 
-static char *rq_flags[] = {
+static const char * const rq_flags[] = {
         "REQ_RW",
         "REQ_FAILFAST",
         "REQ_SORTED",
         "REQ_SOFTBARRIER",
         "REQ_HARDBARRIER",
+        "REQ_FUA",
         "REQ_CMD",
         "REQ_NOMERGE",
         "REQ_STARTED",
@@ -1064,6 +1167,7 @@ static char *rq_flags[] = {
         "REQ_PM_SUSPEND",
         "REQ_PM_RESUME",
         "REQ_PM_SHUTDOWN",
+        "REQ_ORDERED_COLOR",
 };
 
 void blk_dump_rq_flags(struct request *rq, char *msg)
@@ -1641,8 +1745,6 @@ void blk_cleanup_queue(request_queue_t * q)
         if (q->queue_tags)
                 __blk_queue_free_tags(q);
 
-        blk_queue_ordered(q, QUEUE_ORDERED_NONE);
-
         kmem_cache_free(requestq_cachep, q);
 }
 
@@ -1667,8 +1769,6 @@ static int blk_init_free_list(request_queue_t *q)
         return 0;
 }
 
-static int __make_request(request_queue_t *, struct bio *);
-
 request_queue_t *blk_alloc_queue(gfp_t gfp_mask)
 {
         return blk_alloc_queue_node(gfp_mask, -1);
@@ -1908,40 +2008,40 @@ static struct request *get_request(request_queue_t *q, int rw, struct bio *bio,
 {
         struct request *rq = NULL;
         struct request_list *rl = &q->rq;
-        struct io_context *ioc = current_io_context(GFP_ATOMIC);
-        int priv;
+        struct io_context *ioc = NULL;
+        int may_queue, priv;
 
-        if (rl->count[rw]+1 >= q->nr_requests) {
-                /*
-                 * The queue will fill after this allocation, so set it as
-                 * full, and mark this process as "batching". This process
-                 * will be allowed to complete a batch of requests, others
-                 * will be blocked.
-                 */
-                if (!blk_queue_full(q, rw)) {
-                        ioc_set_batching(q, ioc);
-                        blk_set_queue_full(q, rw);
-                }
-        }
+        may_queue = elv_may_queue(q, rw, bio);
+        if (may_queue == ELV_MQUEUE_NO)
+                goto rq_starved;
 
-        switch (elv_may_queue(q, rw, bio)) {
-                case ELV_MQUEUE_NO:
-                        goto rq_starved;
-                case ELV_MQUEUE_MAY:
-                        break;
-                case ELV_MQUEUE_MUST:
-                        goto get_rq;
-        }
-
-        if (blk_queue_full(q, rw) && !ioc_batching(q, ioc)) {
-                /*
-                 * The queue is full and the allocating process is not a
-                 * "batcher", and not exempted by the IO scheduler
-                 */
-                goto out;
+        if (rl->count[rw]+1 >= queue_congestion_on_threshold(q)) {
+                if (rl->count[rw]+1 >= q->nr_requests) {
+                        ioc = current_io_context(GFP_ATOMIC);
+                        /*
+                         * The queue will fill after this allocation, so set
+                         * it as full, and mark this process as "batching".
+                         * This process will be allowed to complete a batch of
+                         * requests, others will be blocked.
+                         */
+                        if (!blk_queue_full(q, rw)) {
+                                ioc_set_batching(q, ioc);
+                                blk_set_queue_full(q, rw);
+                        } else {
+                                if (may_queue != ELV_MQUEUE_MUST
+                                                && !ioc_batching(q, ioc)) {
+                                        /*
+                                         * The queue is full and the allocating
+                                         * process is not a "batcher", and not
+                                         * exempted by the IO scheduler
+                                         */
+                                        goto out;
+                                }
+                        }
+                }
+                set_queue_congested(q, rw);
         }
 
-get_rq:
         /*
          * Only allow batching queuers to allocate up to 50% over the defined
          * limit of requests, otherwise we could have thousands of requests
@@ -1952,8 +2052,6 @@ get_rq:
 
         rl->count[rw]++;
         rl->starved[rw] = 0;
-        if (rl->count[rw] >= queue_congestion_on_threshold(q))
-                set_queue_congested(q, rw);
 
         priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
         if (priv)
@@ -1962,7 +2060,7 @@ get_rq:
         spin_unlock_irq(q->queue_lock);
 
         rq = blk_alloc_request(q, rw, bio, priv, gfp_mask);
-        if (!rq) {
+        if (unlikely(!rq)) {
                 /*
                  * Allocation failed presumably due to memory. Undo anything
                  * we might have messed up.
@@ -1987,6 +2085,12 @@ rq_starved:
                 goto out;
         }
 
+        /*
+         * ioc may be NULL here, and ioc_batching will be false. That's
+         * OK, if the queue is under the request limit then requests need
+         * not count toward the nr_batch_requests limit. There will always
+         * be some limit enforced by BLK_BATCH_TIME.
+         */
         if (ioc_batching(q, ioc))
                 ioc->nr_batch_requests--;
         
@@ -2313,7 +2417,7 @@ EXPORT_SYMBOL(blk_rq_map_kern);
  */
 void blk_execute_rq_nowait(request_queue_t *q, struct gendisk *bd_disk,
                            struct request *rq, int at_head,
-                           void (*done)(struct request *))
+                           rq_end_io_fn *done)
 {
         int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
 
@@ -2517,7 +2621,7 @@ EXPORT_SYMBOL(blk_put_request);
  * blk_end_sync_rq - executes a completion event on a request
  * @rq: request to complete
  */
-void blk_end_sync_rq(struct request *rq)
+void blk_end_sync_rq(struct request *rq, int error)
 {
         struct completion *waiting = rq->waiting;
 
@@ -2655,6 +2759,36 @@ void blk_attempt_remerge(request_queue_t *q, struct request *rq)
 
 EXPORT_SYMBOL(blk_attempt_remerge);
 
+static void init_request_from_bio(struct request *req, struct bio *bio)
+{
+        req->flags |= REQ_CMD;
+
+        /*
+         * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST)
+         */
+        if (bio_rw_ahead(bio) || bio_failfast(bio))
+                req->flags |= REQ_FAILFAST;
+
+        /*
+         * REQ_BARRIER implies no merging, but lets make it explicit
+         */
+        if (unlikely(bio_barrier(bio)))
+                req->flags |= (REQ_HARDBARRIER | REQ_NOMERGE);
+
+        req->errors = 0;
+        req->hard_sector = req->sector = bio->bi_sector;
+        req->hard_nr_sectors = req->nr_sectors = bio_sectors(bio);
+        req->current_nr_sectors = req->hard_cur_sectors = bio_cur_sectors(bio);
+        req->nr_phys_segments = bio_phys_segments(req->q, bio);
+        req->nr_hw_segments = bio_hw_segments(req->q, bio);
+        req->buffer = bio_data(bio);    /* see ->buffer comment above */
+        req->waiting = NULL;
+        req->bio = req->biotail = bio;
+        req->ioprio = bio_prio(bio);
+        req->rq_disk = bio->bi_bdev->bd_disk;
+        req->start_time = jiffies;
+}
+
 static int __make_request(request_queue_t *q, struct bio *bio)
 {
         struct request *req;
@@ -2680,7 +2814,7 @@ static int __make_request(request_queue_t *q, struct bio *bio)
         spin_lock_prefetch(q->queue_lock);
 
         barrier = bio_barrier(bio);
-        if (unlikely(barrier) && (q->ordered == QUEUE_ORDERED_NONE)) {
+        if (unlikely(barrier) && (q->next_ordered == QUEUE_ORDERED_NONE)) {
                 err = -EOPNOTSUPP;
                 goto end_io;
         }
@@ -2750,33 +2884,7 @@ get_rq:
          * We don't worry about that case for efficiency. It won't happen
          * often, and the elevators are able to handle it.
          */
-
-        req->flags |= REQ_CMD;
-
-        /*
-         * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST)
-         */
-        if (bio_rw_ahead(bio) || bio_failfast(bio))
-                req->flags |= REQ_FAILFAST;
-
-        /*
-         * REQ_BARRIER implies no merging, but lets make it explicit
-         */
-        if (unlikely(barrier))
-                req->flags |= (REQ_HARDBARRIER | REQ_NOMERGE);
-
-        req->errors = 0;
-        req->hard_sector = req->sector = sector;
-        req->hard_nr_sectors = req->nr_sectors = nr_sectors;
-        req->current_nr_sectors = req->hard_cur_sectors = cur_nr_sectors;
-        req->nr_phys_segments = bio_phys_segments(q, bio);
-        req->nr_hw_segments = bio_hw_segments(q, bio);
-        req->buffer = bio_data(bio);    /* see ->buffer comment above */
-        req->waiting = NULL;
-        req->bio = req->biotail = bio;
-        req->ioprio = prio;
-        req->rq_disk = bio->bi_bdev->bd_disk;
-        req->start_time = jiffies;
+        init_request_from_bio(req, bio);
 
         spin_lock_irq(q->queue_lock);
         if (elv_queue_empty(q))
@@ -3067,7 +3175,8 @@ static int __end_that_request_first(struct request *req, int uptodate,
                 if (nr_bytes >= bio->bi_size) {
                         req->bio = bio->bi_next;
                         nbytes = bio->bi_size;
-                        bio_endio(bio, nbytes, error);
+                        if (!ordered_bio_endio(req, bio, nbytes, error))
+                                bio_endio(bio, nbytes, error);
                         next_idx = 0;
                         bio_nbytes = 0;
                 } else {
@@ -3122,7 +3231,8 @@ static int __end_that_request_first(struct request *req, int uptodate,
          * if the request wasn't completed, update state
          */
         if (bio_nbytes) {
-                bio_endio(bio, bio_nbytes, error);
+                if (!ordered_bio_endio(req, bio, bio_nbytes, error))
+                        bio_endio(bio, bio_nbytes, error);
                 bio->bi_idx += next_idx;
                 bio_iovec(bio)->bv_offset += nr_bytes;
                 bio_iovec(bio)->bv_len -= nr_bytes;
@@ -3179,9 +3289,17 @@ EXPORT_SYMBOL(end_that_request_chunk);
 /*
  * queue lock must be held
  */
-void end_that_request_last(struct request *req)
+void end_that_request_last(struct request *req, int uptodate)
 {
         struct gendisk *disk = req->rq_disk;
+        int error;
+
+        /*
+         * extend uptodate bool to allow < 0 value to be direct io error
+         */
+        error = 0;
+        if (end_io_error(uptodate))
+                error = !uptodate ? -EIO : uptodate;
 
         if (unlikely(laptop_mode) && blk_fs_request(req))
                 laptop_io_completion();
@@ -3196,7 +3314,7 @@ void end_that_request_last(struct request *req)
                 disk->in_flight--;
         }
         if (req->end_io)
-                req->end_io(req);
+                req->end_io(req, error);
         else
                 __blk_put_request(req->q, req);
 }
@@ -3208,7 +3326,7 @@ void end_request(struct request *req, int uptodate)
         if (!end_that_request_first(req, uptodate, req->hard_cur_sectors)) {
                 add_disk_randomness(req->rq_disk);
                 blkdev_dequeue_request(req);
-                end_that_request_last(req);
+                end_that_request_last(req, uptodate);
         }
 }
 
diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index 1d8852f7bbff..c2ac36dfe4f3 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -46,7 +46,7 @@ EXPORT_SYMBOL(scsi_command_size);
 
 static int sg_get_version(int __user *p)
 {
-        static int sg_version_num = 30527;
+        static const int sg_version_num = 30527;
         return put_user(sg_version_num, p);
 }