Merge branch 'for-linus' of git://brick.kernel.dk/data/git/linux-2.6-block

* 'for-linus' of git://brick.kernel.dk/data/git/linux-2.6-block:
  [PATCH] block: document io scheduler allow_merge_fn hook
  [PATCH] cfq-iosched: don't allow sync merges across queues
  [PATCH] Fixup blk_rq_unmap_user() API
  [PATCH] __blk_rq_unmap_user() fails to return error
  [PATCH] __blk_rq_map_user() doesn't need to grab the queue_lock
  [PATCH] Remove queue merging hooks
  [PATCH] ->nr_sectors and ->hard_nr_sectors are not used for BLOCK_PC requests
  [PATCH] cciss: fix XFER_READ/XFER_WRITE in do_cciss_request
  [PATCH] cciss: set default raid level when reading geometry fails

10 files changed, 107 insertions, 56 deletions

diff --git a/Documentation/block/biodoc.txt b/Documentation/block/biodoc.txt
index c6c9a9c10d7f..3adaace328a6 100644
--- a/Documentation/block/biodoc.txt
+++ b/Documentation/block/biodoc.txt
@@ -946,6 +946,13 @@ elevator_merged_fn		called when a request in the scheduler has been
                                 scheduler for example, to reposition the request
                                 if its sorting order has changed.
 
+elevator_allow_merge_fn         called whenever the block layer determines
+                                that a bio can be merged into an existing
+                                request safely. The io scheduler may still
+                                want to stop a merge at this point if it
+                                results in some sort of conflict internally,
+                                this hook allows it to do that.
+
 elevator_dispatch_fn            fills the dispatch queue with ready requests.
                                 I/O schedulers are free to postpone requests by
                                 not filling the dispatch queue unless @force
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 533a2938ffd6..9fc5eafa6c0e 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -568,6 +568,38 @@ cfq_merged_requests(request_queue_t *q, struct request *rq,
         cfq_remove_request(next);
 }
 
+static int cfq_allow_merge(request_queue_t *q, struct request *rq,
+                           struct bio *bio)
+{
+        struct cfq_data *cfqd = q->elevator->elevator_data;
+        const int rw = bio_data_dir(bio);
+        struct cfq_queue *cfqq;
+        pid_t key;
+
+        /*
+         * If bio is async or a write, always allow merge
+         */
+        if (!bio_sync(bio) || rw == WRITE)
+                return 1;
+
+        /*
+         * bio is sync. if request is not, disallow.
+         */
+        if (!rq_is_sync(rq))
+                return 0;
+
+        /*
+         * Ok, both bio and request are sync. Allow merge if they are
+         * from the same queue.
+         */
+        key = cfq_queue_pid(current, rw, 1);
+        cfqq = cfq_find_cfq_hash(cfqd, key, current->ioprio);
+        if (cfqq != RQ_CFQQ(rq))
+                return 0;
+
+        return 1;
+}
+
 static inline void
 __cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
@@ -2125,6 +2157,7 @@ static struct elevator_type iosched_cfq = {
                 .elevator_merge_fn =            cfq_merge,
                 .elevator_merged_fn =           cfq_merged_request,
                 .elevator_merge_req_fn =        cfq_merged_requests,
+                .elevator_allow_merge_fn =      cfq_allow_merge,
                 .elevator_dispatch_fn =         cfq_dispatch_requests,
                 .elevator_add_req_fn =          cfq_insert_request,
                 .elevator_activate_req_fn =     cfq_activate_request,
diff --git a/block/elevator.c b/block/elevator.c
index c0063f345c5d..62c7a3069d3a 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -51,6 +51,21 @@ static const int elv_hash_shift = 6;
 #define ELV_ON_HASH(rq)         (!hlist_unhashed(&(rq)->hash))
 
 /*
+ * Query io scheduler to see if the current process issuing bio may be
+ * merged with rq.
+ */
+static int elv_iosched_allow_merge(struct request *rq, struct bio *bio)
+{
+        request_queue_t *q = rq->q;
+        elevator_t *e = q->elevator;
+
+        if (e->ops->elevator_allow_merge_fn)
+                return e->ops->elevator_allow_merge_fn(q, rq, bio);
+
+        return 1;
+}
+
+/*
  * can we safely merge with this request?
  */
 inline int elv_rq_merge_ok(struct request *rq, struct bio *bio)
@@ -65,12 +80,15 @@ inline int elv_rq_merge_ok(struct request *rq, struct bio *bio)
                 return 0;
 
         /*
-         * same device and no special stuff set, merge is ok
+         * must be same device and not a special request
          */
-        if (rq->rq_disk == bio->bi_bdev->bd_disk && !rq->special)
-                return 1;
+        if (rq->rq_disk != bio->bi_bdev->bd_disk || !rq->special)
+                return 0;
 
-        return 0;
+        if (!elv_iosched_allow_merge(rq, bio))
+                return 0;
+
+        return 1;
 }
 EXPORT_SYMBOL(elv_rq_merge_ok);
 
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 79807dbc306e..e07c079e07e6 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -1405,8 +1405,7 @@ static inline int ll_new_hw_segment(request_queue_t *q,
         return 1;
 }
 
-static int ll_back_merge_fn(request_queue_t *q, struct request *req, 
-                            struct bio *bio)
+int ll_back_merge_fn(request_queue_t *q, struct request *req, struct bio *bio)
 {
         unsigned short max_sectors;
         int len;
@@ -1442,6 +1441,7 @@ static int ll_back_merge_fn(request_queue_t *q, struct request *req,
 
         return ll_new_hw_segment(q, req, bio);
 }
+EXPORT_SYMBOL(ll_back_merge_fn);
 
 static int ll_front_merge_fn(request_queue_t *q, struct request *req, 
                              struct bio *bio)
@@ -1912,9 +1912,6 @@ blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
         }
 
         q->request_fn           = rfn;
-        q->back_merge_fn        = ll_back_merge_fn;
-        q->front_merge_fn       = ll_front_merge_fn;
-        q->merge_requests_fn    = ll_merge_requests_fn;
         q->prep_rq_fn           = NULL;
         q->unplug_fn            = generic_unplug_device;
         q->queue_flags          = (1 << QUEUE_FLAG_CLUSTER);
@@ -2350,40 +2347,29 @@ static int __blk_rq_map_user(request_queue_t *q, struct request *rq,
         else
                 bio = bio_copy_user(q, uaddr, len, reading);
 
-        if (IS_ERR(bio)) {
+        if (IS_ERR(bio))
                 return PTR_ERR(bio);
-        }
 
         orig_bio = bio;
         blk_queue_bounce(q, &bio);
+
         /*
          * We link the bounce buffer in and could have to traverse it
          * later so we have to get a ref to prevent it from being freed
          */
         bio_get(bio);