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);
 
-        /*
-         * for most (all? don't know of any) queues we could
-         * skip grabbing the queue lock here. only drivers with
-         * funky private ->back_merge_fn() function could be
-         * problematic.
-         */
-        spin_lock_irq(q->queue_lock);
         if (!rq->bio)
                 blk_rq_bio_prep(q, rq, bio);
-        else if (!q->back_merge_fn(q, rq, bio)) {
+        else if (!ll_back_merge_fn(q, rq, bio)) {
                 ret = -EINVAL;
-                spin_unlock_irq(q->queue_lock);
                 goto unmap_bio;
         } else {
                 rq->biotail->bi_next = bio;
                 rq->biotail = bio;
 
-                rq->nr_sectors += bio_sectors(bio);
-                rq->hard_nr_sectors = rq->nr_sectors;
                 rq->data_len += bio->bi_size;
         }
-        spin_unlock_irq(q->queue_lock);
 
         return bio->bi_size;
 
@@ -2419,6 +2405,7 @@ int blk_rq_map_user(request_queue_t *q, struct request *rq, void __user *ubuf,
                     unsigned long len)
 {
         unsigned long bytes_read = 0;
+        struct bio *bio = NULL;
         int ret;
 
         if (len > (q->max_hw_sectors << 9))
@@ -2445,6 +2432,8 @@ int blk_rq_map_user(request_queue_t *q, struct request *rq, void __user *ubuf,
                 ret = __blk_rq_map_user(q, rq, ubuf, map_len);
                 if (ret < 0)
                         goto unmap_rq;
+                if (!bio)
+                        bio = rq->bio;
                 bytes_read += ret;
                 ubuf += ret;
         }
@@ -2452,7 +2441,7 @@ int blk_rq_map_user(request_queue_t *q, struct request *rq, void __user *ubuf,
         rq->buffer = rq->data = NULL;
         return 0;
 unmap_rq:
-        blk_rq_unmap_user(rq);
+        blk_rq_unmap_user(bio);
         return ret;
 }
 
@@ -2509,27 +2498,33 @@ EXPORT_SYMBOL(blk_rq_map_user_iov);
 
 /**
  * blk_rq_unmap_user - unmap a request with user data
- * @rq:         rq to be unmapped
+ * @bio:               start of bio list
  *
  * Description:
- *    Unmap a rq previously mapped by blk_rq_map_user().
- *    rq->bio must be set to the original head of the request.
+ *    Unmap a rq previously mapped by blk_rq_map_user(). The caller must
+ *    supply the original rq->bio from the blk_rq_map_user() return, since
+ *    the io completion may have changed rq->bio.
  */
-int blk_rq_unmap_user(struct request *rq)
+int blk_rq_unmap_user(struct bio *bio)
 {
-        struct bio *bio, *mapped_bio;
+        struct bio *mapped_bio;
+        int ret = 0, ret2;
 
-        while ((bio = rq->bio)) {
-                if (bio_flagged(bio, BIO_BOUNCED))
+        while (bio) {
+                mapped_bio = bio;
+                if (unlikely(bio_flagged(bio, BIO_BOUNCED)))
                         mapped_bio = bio->bi_private;
-                else
-                        mapped_bio = bio;
 
-                __blk_rq_unmap_user(mapped_bio);
-                rq->bio = bio->bi_next;
-                bio_put(bio);
+                ret2 = __blk_rq_unmap_user(mapped_bio);
+                if (ret2 && !ret)
+                        ret = ret2;
+
+                mapped_bio = bio;
+                bio = bio->bi_next;
+                bio_put(mapped_bio);
         }
-        return 0;
+
+        return ret;
 }
 
 EXPORT_SYMBOL(blk_rq_unmap_user);
@@ -2822,7 +2817,7 @@ static int attempt_merge(request_queue_t *q, struct request *req,
          * will have updated segment counts, update sector
          * counts here.
          */
-        if (!q->merge_requests_fn(q, req, next))
+        if (!ll_merge_requests_fn(q, req, next))
                 return 0;
 
         /*
@@ -2939,7 +2934,7 @@ static int __make_request(request_queue_t *q, struct bio *bio)
                 case ELEVATOR_BACK_MERGE:
                         BUG_ON(!rq_mergeable(req));
 
-                        if (!q->back_merge_fn(q, req, bio))
+                        if (!ll_back_merge_fn(q, req, bio))
                                 break;
 
                         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE);
@@ -2956,7 +2951,7 @@ static int __make_request(request_queue_t *q, struct bio *bio)
                 case ELEVATOR_FRONT_MERGE:
                         BUG_ON(!rq_mergeable(req));
 
-                        if (!q->front_merge_fn(q, req, bio))
+                        if (!ll_front_merge_fn(q, req, bio))
                                 break;
 
                         blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE);
diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index f322b6a441d8..2528a0c0dec8 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -333,8 +333,7 @@ static int sg_io(struct file *file, request_queue_t *q,
                         hdr->sb_len_wr = len;
         }
 
-        rq->bio = bio;
-        if (blk_rq_unmap_user(rq))
+        if (blk_rq_unmap_user(bio))
                 ret = -EFAULT;
 
         /* may not have succeeded, but output values written to control
diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
index d719a5d8f435..9d2ddb209343 100644
--- a/drivers/block/cciss.c
+++ b/drivers/block/cciss.c
@@ -1907,6 +1907,7 @@ static void cciss_geometry_inquiry(int ctlr, int logvol,
                                "does not support reading geometry\n");
                         drv->heads = 255;
                         drv->sectors = 32;      // Sectors per track
+                        drv->raid_level = RAID_UNKNOWN;
                 } else {
                         drv->heads = inq_buff->data_byte[6];
                         drv->sectors = inq_buff->data_byte[7];
@@ -2491,7 +2492,7 @@ static void do_cciss_request(request_queue_t *q)
         c->Request.Type.Type = TYPE_CMD;        // It is a command.
         c->Request.Type.Attribute = ATTR_SIMPLE;
         c->Request.Type.Direction =
-            (rq_data_dir(creq) == READ) ? h->cciss_read : h->cciss_write;
+            (rq_data_dir(creq) == READ) ? XFER_READ : XFER_WRITE;
         c->Request.Timeout = 0; // Don't time out
         c->Request.CDB[0] =
             (rq_data_dir(creq) == READ) ? h->cciss_read : h->cciss_write;
diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index e4a2f8f3a1d7..66d028d30439 100644
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -2139,8 +2139,7 @@ static int cdrom_read_cdda_bpc(struct cdrom_device_info *cdi, __u8 __user *ubuf,
                         cdi->last_sense = s->sense_key;
                 }
 
-                rq->bio = bio;
-                if (blk_rq_unmap_user(rq))
+                if (blk_rq_unmap_user(bio))
                         ret = -EFAULT;
 
                 if (ret)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 1748e27501cd..f02f48a882a9 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -265,13 +265,11 @@ static int scsi_merge_bio(struct request *rq, struct bio *bio)
 
         if (!rq->bio)
                 blk_rq_bio_prep(q, rq, bio);
-        else if (!q->back_merge_fn(q, rq, bio))
+        else if (!ll_back_merge_fn(q, rq, bio))
                 return -EINVAL;
         else {
                 rq->biotail->bi_next = bio;
                 rq->biotail = bio;
-                rq->hard_nr_sectors += bio_sectors(bio);
-                rq->nr_sectors = rq->hard_nr_sectors;
         }
 
         return 0;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index ea330d7b46c0..36a6eacefe20 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -331,10 +331,6 @@ struct request_pm_state
 
 #include <linux/elevator.h>
 
-typedef int (merge_request_fn) (request_queue_t *, struct request *,
-                                struct bio *);
-typedef int (merge_requests_fn) (request_queue_t *, struct request *,
-                                 struct request *);
 typedef void (request_fn_proc) (request_queue_t *q);
 typedef int (make_request_fn) (request_queue_t *q, struct bio *bio);
 typedef int (prep_rq_fn) (request_queue_t *, struct request *);
@@ -376,9 +372,6 @@ struct request_queue
         struct request_list     rq;
 
         request_fn_proc         *request_fn;
-        merge_request_fn        *back_merge_fn;
-        merge_request_fn        *front_merge_fn;
-        merge_requests_fn       *merge_requests_fn;
         make_request_fn         *make_request_fn;
         prep_rq_fn              *prep_rq_fn;
         unplug_fn               *unplug_fn;
@@ -649,6 +642,11 @@ extern int sg_scsi_ioctl(struct file *, struct request_queue *,
                 struct gendisk *, struct scsi_ioctl_command __user *);
 
 /*
+ * Temporary export, until SCSI gets fixed up.
+ */
+extern int ll_back_merge_fn(request_queue_t *, struct request *, struct bio *);
+
+/*
  * A queue has just exitted congestion.  Note this in the global counter of
  * congested queues, and wake up anyone who was waiting for requests to be
  * put back.
@@ -674,7 +672,7 @@ extern void __blk_stop_queue(request_queue_t *q);
 extern void blk_run_queue(request_queue_t *);
 extern void blk_start_queueing(request_queue_t *);
 extern int blk_rq_map_user(request_queue_t *, struct request *, void __user *, unsigned long);
-extern int blk_rq_unmap_user(struct request *);
+extern int blk_rq_unmap_user(struct bio *);
 extern int blk_rq_map_kern(request_queue_t *, struct request *, void *, unsigned int, gfp_t);
 extern int blk_rq_map_user_iov(request_queue_t *, struct request *,
                                struct sg_iovec *, int, unsigned int);
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index a24931d24404..e88fcbc77f8f 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -12,6 +12,8 @@ typedef void (elevator_merge_req_fn) (request_queue_t *, struct request *, struc
 
 typedef void (elevator_merged_fn) (request_queue_t *, struct request *, int);
 
+typedef int (elevator_allow_merge_fn) (request_queue_t *, struct request *, struct bio *);
+
 typedef int (elevator_dispatch_fn) (request_queue_t *, int);
 
 typedef void (elevator_add_req_fn) (request_queue_t *, struct request *);
@@ -33,6 +35,7 @@ struct elevator_ops
         elevator_merge_fn *elevator_merge_fn;
         elevator_merged_fn *elevator_merged_fn;
         elevator_merge_req_fn *elevator_merge_req_fn;
+        elevator_allow_merge_fn *elevator_allow_merge_fn;
 
         elevator_dispatch_fn *elevator_dispatch_fn;
         elevator_add_req_fn *elevator_add_req_fn;