11 files changed, 298 insertions, 152 deletions

diff --git a/block/blk-barrier.c b/block/blk-barrier.c
index 8eba4e43bb0c..f7dae57e6cab 100644
--- a/block/blk-barrier.c
+++ b/block/blk-barrier.c
@@ -302,7 +302,7 @@ static void bio_end_empty_barrier(struct bio *bio, int err)
  * Description:
  *    Issue a flush for the block device in question. Caller can supply
  *    room for storing the error offset in case of a flush error, if they
- *    wish to.  Caller must run wait_for_completion() on its own.
+ *    wish to.
  */
 int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector)
 {
diff --git a/block/blk-core.c b/block/blk-core.c
index a824e49c0d0a..29bcfac6c688 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -64,11 +64,12 @@ static struct workqueue_struct *kblockd_workqueue;
 
 static void drive_stat_acct(struct request *rq, int new_io)
 {
+        struct gendisk *disk = rq->rq_disk;
         struct hd_struct *part;
         int rw = rq_data_dir(rq);
         int cpu;
 
-        if (!blk_fs_request(rq) || !rq->rq_disk)
+        if (!blk_fs_request(rq) || !disk || !blk_do_io_stat(disk->queue))
                 return;
 
         cpu = part_stat_lock();
@@ -599,8 +600,7 @@ blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
         q->request_fn           = rfn;
         q->prep_rq_fn           = NULL;
         q->unplug_fn            = generic_unplug_device;
-        q->queue_flags          = (1 << QUEUE_FLAG_CLUSTER |
-                                   1 << QUEUE_FLAG_STACKABLE);
+        q->queue_flags          = QUEUE_FLAG_DEFAULT;
         q->queue_lock           = lock;
 
         blk_queue_segment_boundary(q, BLK_SEG_BOUNDARY_MASK);
@@ -1125,6 +1125,8 @@ void init_request_from_bio(struct request *req, struct bio *bio)
 
         if (bio_sync(bio))
                 req->cmd_flags |= REQ_RW_SYNC;
+        if (bio_unplug(bio))
+                req->cmd_flags |= REQ_UNPLUG;
         if (bio_rw_meta(bio))
                 req->cmd_flags |= REQ_RW_META;
 
@@ -1141,6 +1143,7 @@ static int __make_request(struct request_queue *q, struct bio *bio)
         int el_ret, nr_sectors;
         const unsigned short prio = bio_prio(bio);
         const int sync = bio_sync(bio);
+        const int unplug = bio_unplug(bio);
         int rw_flags;
 
         nr_sectors = bio_sectors(bio);
@@ -1244,7 +1247,7 @@ get_rq:
                 blk_plug_device(q);
         add_request(q, req);
 out:
-        if (sync || blk_queue_nonrot(q))
+        if (unplug || blk_queue_nonrot(q))
                 __generic_unplug_device(q);
         spin_unlock_irq(q->queue_lock);
         return 0;
@@ -1448,6 +1451,11 @@ static inline void __generic_make_request(struct bio *bio)
                         err = -EOPNOTSUPP;
                         goto end_io;
                 }
+                if (bio_barrier(bio) && bio_has_data(bio) &&
+                    (q->next_ordered == QUEUE_ORDERED_NONE)) {
+                        err = -EOPNOTSUPP;
+                        goto end_io;
+                }
 
                 ret = q->make_request_fn(q, bio);
         } while (ret);
@@ -1655,6 +1663,55 @@ void blkdev_dequeue_request(struct request *req)
 }
 EXPORT_SYMBOL(blkdev_dequeue_request);
 
+static void blk_account_io_completion(struct request *req, unsigned int bytes)
+{
+        struct gendisk *disk = req->rq_disk;
+
+        if (!disk || !blk_do_io_stat(disk->queue))
+                return;
+
+        if (blk_fs_request(req)) {
+                const int rw = rq_data_dir(req);
+                struct hd_struct *part;
+                int cpu;
+
+                cpu = part_stat_lock();
+                part = disk_map_sector_rcu(req->rq_disk, req->sector);
+                part_stat_add(cpu, part, sectors[rw], bytes >> 9);
+                part_stat_unlock();
+        }
+}
+
+static void blk_account_io_done(struct request *req)
+{
+        struct gendisk *disk = req->rq_disk;
+
+        if (!disk || !blk_do_io_stat(disk->queue))
+                return;
+
+        /*
+         * Account IO completion.  bar_rq isn't accounted as a normal
+         * IO on queueing nor completion.  Accounting the containing
+         * request is enough.
+         */
+        if (blk_fs_request(req) && req != &req->q->bar_rq) {
+                unsigned long duration = jiffies - req->start_time;
+                const int rw = rq_data_dir(req);
+                struct hd_struct *part;
+                int cpu;
+
+                cpu = part_stat_lock();
+                part = disk_map_sector_rcu(disk, req->sector);
+
+                part_stat_inc(cpu, part, ios[rw]);
+                part_stat_add(cpu, part, ticks[rw], duration);
+                part_round_stats(cpu, part);
+                part_dec_in_flight(part);
+
+                part_stat_unlock();
+        }
+}
+
 /**
  * __end_that_request_first - end I/O on a request
  * @req:      the request being processed
@@ -1690,16 +1747,7 @@ static int __end_that_request_first(struct request *req, int error,
                                 (unsigned long long)req->sector);
         }
 
-        if (blk_fs_request(req) && req->rq_disk) {
-                const int rw = rq_data_dir(req);
-                struct hd_struct *part;
-                int cpu;
-
-                cpu = part_stat_lock();
-                part = disk_map_sector_rcu(req->rq_disk, req->sector);
-                part_stat_add(cpu, part, sectors[rw], nr_bytes >> 9);
-                part_stat_unlock();
-        }
+        blk_account_io_completion(req, nr_bytes);
 
         total_bytes = bio_nbytes = 0;
         while ((bio = req->bio) != NULL) {
@@ -1779,8 +1827,6 @@ static int __end_that_request_first(struct request *req, int error,
  */
 static void end_that_request_last(struct request *req, int error)
 {
-        struct gendisk *disk = req->rq_disk;
-
         if (blk_rq_tagged(req))
                 blk_queue_end_tag(req->q, req);
 
@@ -1792,27 +1838,7 @@ static void end_that_request_last(struct request *req, int error)
 
         blk_delete_timer(req);
 
-        /*
-         * Account IO completion.  bar_rq isn't accounted as a normal
-         * IO on queueing nor completion.  Accounting the containing
-         * request is enough.
-         */
-        if (disk && blk_fs_request(req) && req != &req->q->bar_rq) {
-                unsigned long duration = jiffies - req->start_time;
-                const int rw = rq_data_dir(req);
-                struct hd_struct *part;
-                int cpu;
-
-                cpu = part_stat_lock();
-                part = disk_map_sector_rcu(disk, req->sector);
-
-                part_stat_inc(cpu, part, ios[rw]);
-                part_stat_add(cpu, part, ticks[rw], duration);
-                part_round_stats(cpu, part);
-                part_dec_in_flight(part);
-
-                part_stat_unlock();
-        }
+        blk_account_io_done(req);
 
         if (req->end_io)
                 req->end_io(req, error);
diff --git a/block/blk-integrity.c b/block/blk-integrity.c
index 61a8e2f8fdd0..91fa8e06b6a5 100644
--- a/block/blk-integrity.c
+++ b/block/blk-integrity.c
@@ -309,24 +309,24 @@ static struct kobj_type integrity_ktype = {
 /**
  * blk_integrity_register - Register a gendisk as being integrity-capable
  * @disk:       struct gendisk pointer to make integrity-aware
- * @template:   integrity profile
+ * @template:   optional integrity profile to register
  *
  * Description: When a device needs to advertise itself as being able
  * to send/receive integrity metadata it must use this function to
  * register the capability with the block layer.  The template is a
  * blk_integrity struct with values appropriate for the underlying
- * hardware.  See Documentation/block/data-integrity.txt.
+ * hardware.  If template is NULL the new profile is allocated but
+ * not filled out. See Documentation/block/data-integrity.txt.
  */
 int blk_integrity_register(struct gendisk *disk, struct blk_integrity *template)
 {
         struct blk_integrity *bi;
 
         BUG_ON(disk == NULL);
-        BUG_ON(template == NULL);
 
         if (disk->integrity == NULL) {
                 bi = kmem_cache_alloc(integrity_cachep,
-                                                GFP_KERNEL | __GFP_ZERO);
+                                      GFP_KERNEL | __GFP_ZERO);
                 if (!bi)
                         return -1;
 
@@ -346,13 +346,16 @@ int blk_integrity_register(struct gendisk *disk, struct blk_integrity *template)
                 bi = disk->integrity;
 
         /* Use the provided profile as template */
-        bi->name = template->name;
-        bi->generate_fn = template->generate_fn;
-        bi->verify_fn = template->verify_fn;
-        bi->tuple_size = template->tuple_size;
-        bi->set_tag_fn = template->set_tag_fn;
-        bi->get_tag_fn = template->get_tag_fn;
-        bi->tag_size = template->tag_size;
+        if (template != NULL) {
+                bi->name = template->name;
+                bi->generate_fn = template->generate_fn;
+                bi->verify_fn = template->verify_fn;
+                bi->tuple_size = template->tuple_size;
+                bi->set_tag_fn = template->set_tag_fn;
+                bi->get_tag_fn = template->get_tag_fn;
+                bi->tag_size = template->tag_size;
+        } else
+                bi->name = "unsupported";
 
         return 0;
 }
diff --git a/block/blk-merge.c b/block/blk-merge.c
index b92f5b0866b0..a104593e70c3 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -38,72 +38,84 @@ void blk_recalc_rq_sectors(struct request *rq, int nsect)
         }
 }
 
-void blk_recalc_rq_segments(struct request *rq)
+static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
+                                             struct bio *bio,
+                                             unsigned int *seg_size_ptr)
 {
-        int nr_phys_segs;
         unsigned int phys_size;
         struct bio_vec *bv, *bvprv = NULL;
-        int seg_size;
-        int cluster;
-        struct req_iterator iter;
-        int high, highprv = 1;
-        struct request_queue *q = rq->q;
+        int cluster, i, high, highprv = 1;
+        unsigned int seg_size, nr_phys_segs;
+        struct bio *fbio;
 
-        if (!rq->bio)
-                return;
+        if (!bio)
+                return 0;
 
+        fbio = bio;
         cluster = test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
         seg_size = 0;
         phys_size = nr_phys_segs = 0;
-        rq_for_each_segment(bv, rq, iter) {
-                /*
-                 * the trick here is making sure that a high page is never
-                 * considered part of another segment, since that might
-                 * change with the bounce page.
-                 */
-                high = page_to_pfn(bv->bv_page) > q->bounce_pfn;
-                if (high || highprv)
-                        goto new_segment;
-                if (cluster) {
-                        if (seg_size + bv->bv_len > q->max_segment_size)
-                                goto new_segment;
-                        if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv))
-                                goto new_segment;
-                        if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
+        for_each_bio(bio) {
+                bio_for_each_segment(bv, bio, i) {
+                        /*
+                         * the trick here is making sure that a high page is
+                         * never considered part of another segment, since that
+                         * might change with the bounce page.
+                         */
+                        high = page_to_pfn(bv->bv_page) > q->bounce_pfn;
+                        if (high || highprv)
                                 goto new_segment;
+                        if (cluster) {
+                                if (seg_size + bv->bv_len > q->max_segment_size)
+                                        goto new_segment;
+                                if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv))
+                                        goto new_segment;
+                                if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
+                                        goto new_segment;
+
+                                seg_size += bv->bv_len;
+                                bvprv = bv;
+                                continue;
+                        }
+new_segment:
+                        if (nr_phys_segs == 1 && seg_size >
+                            fbio->bi_seg_front_size)
+                                fbio->bi_seg_front_size = seg_size;
 
-                        seg_size += bv->bv_len;
+                        nr_phys_segs++;
                         bvprv = bv;
-                        continue;
+                        seg_size = bv->bv_len;
+                        highprv = high;
                 }
-new_segment:
-                if (nr_phys_segs == 1 && seg_size > rq->bio->bi_seg_front_size)
-                        rq->bio->bi_seg_front_size = seg_size;
-
-                nr_phys_segs++;
-                bvprv = bv;
-                seg_size = bv->bv_len;
-                highprv = high;
         }
 
-        if (nr_phys_segs == 1 && seg_size > rq->bio->bi_seg_front_size)
+        if (seg_size_ptr)
+                *seg_size_ptr = seg_size;
+
+        return nr_phys_segs;
+}
+
+void blk_recalc_rq_segments(struct request *rq)
+{
+        unsigned int seg_size = 0, phys_segs;
+
+        phys_segs = __blk_recalc_rq_segments(rq->q, rq->bio, &seg_size);
+
+        if (phys_segs == 1 && seg_size > rq->bio->bi_seg_front_size)
                 rq->bio->bi_seg_front_size = seg_size;
         if (seg_size > rq->biotail->bi_seg_back_size)
                 rq->biotail->bi_seg_back_size = seg_size;
 
-        rq->nr_phys_segments = nr_phys_segs;
+        rq->nr_phys_segments = phys_segs;
 }
 
 void blk_recount_segments(struct request_queue *q, struct bio *bio)
 {
-        struct request rq;
         struct bio *nxt = bio->bi_next;
-        rq.q = q;
-        rq.bio = rq.biotail = bio;
+
         bio->bi_next = NULL;
-        blk_recalc_rq_segments(&rq);
+        bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, NULL);
         bio->bi_next = nxt;
-        bio->bi_phys_segments = rq.nr_phys_segments;
         bio->bi_flags |= (1 << BIO_SEG_VALID);
 }
 EXPORT_SYMBOL(blk_recount_segments);
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index a29cb788e408..e29ddfc73cf4 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -130,6 +130,27 @@ static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
         return queue_var_show(max_hw_sectors_kb, (page));
 }
 
+static ssize_t queue_nonrot_show(struct request_queue *q, char *page)
+{
+        return queue_var_show(!blk_queue_nonrot(q), page);
+}
+
+static ssize_t queue_nonrot_store(struct request_queue *q, const char *page,
+                                  size_t count)
+{
+        unsigned long nm;
+        ssize_t ret = queue_var_store(&nm, page, count);
+
+        spin_lock_irq(q->queue_lock);
+        if (nm)
+                queue_flag_clear(QUEUE_FLAG_NONROT, q);
+        else
+                queue_flag_set(QUEUE_FLAG_NONROT, q);
+        spin_unlock_irq(q->queue_lock);
+
+        return ret;
+}
+
 static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
 {
         return queue_var_show(blk_queue_nomerges(q), page);
@@ -146,8 +167,8 @@ static ssize_t queue_nomerges_store(struct request_queue *q, const char *page,
                 queue_flag_set(QUEUE_FLAG_NOMERGES, q);
         else
                 queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
-
         spin_unlock_irq(q->queue_lock);
+
         return ret;
 }
 
@@ -176,6 +197,27 @@ queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
         return ret;
 }
 
+static ssize_t queue_iostats_show(struct request_queue *q, char *page)
+{
+        return queue_var_show(blk_queue_io_stat(q), page);
+}
+
+static ssize_t queue_iostats_store(struct request_queue *q, const char *page,
+                                   size_t count)
+{
+        unsigned long stats;
+        ssize_t ret = queue_var_store(&stats, page, count);
+
+        spin_lock_irq(q->queue_lock);
+        if (stats)
+                queue_flag_set(QUEUE_FLAG_IO_STAT, q);
+        else
+                queue_flag_clear(QUEUE_FLAG_IO_STAT, q);
+        spin_unlock_irq(q->queue_lock);
+
+        return ret;
+}
+
 static struct queue_sysfs_entry queue_requests_entry = {
         .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
         .show = queue_requests_show,
@@ -210,6 +252,12 @@ static struct queue_sysfs_entry queue_hw_sector_size_entry = {
         .show = queue_hw_sector_size_show,
 };
 
+static struct queue_sysfs_entry queue_nonrot_entry = {
+        .attr = {.name = "rotational", .mode = S_IRUGO | S_IWUSR },
+        .show = queue_nonrot_show,
+        .store = queue_nonrot_store,
+};
+
 static struct queue_sysfs_entry queue_nomerges_entry = {
         .attr = {.name = "nomerges", .mode = S_IRUGO | S_IWUSR },
         .show = queue_nomerges_show,
@@ -222,6 +270,12 @@ static struct queue_sysfs_entry queue_rq_affinity_entry = {
         .store = queue_rq_affinity_store,
 };
 
+static struct queue_sysfs_entry queue_iostats_entry = {
+        .attr = {.name = "iostats", .mode = S_IRUGO | S_IWUSR },
+        .show = queue_iostats_show,
+        .store = queue_iostats_store,
+};
+
 static struct attribute *default_attrs[] = {
         &queue_requests_entry.attr,
         &queue_ra_entry.attr,
@@ -229,8 +283,10 @@ static struct attribute *default_attrs[] = {
         &queue_max_sectors_entry.attr,
         &queue_iosched_entry.attr,
         &queue_hw_sector_size_entry.attr,
+        &queue_nonrot_entry.attr,
         &queue_nomerges_entry.attr,
         &queue_rq_affinity_entry.attr,
+        &queue_iostats_entry.attr,
         NULL,
 };
 
diff --git a/block/blk-timeout.c b/block/blk-timeout.c
index a09535377a94..bbbdc4b8ccf2 100644
--- a/block/blk-timeout.c
+++ b/block/blk-timeout.c
@@ -209,12 +209,19 @@ void blk_abort_queue(struct request_queue *q)
 {
         unsigned long flags;
         struct request *rq, *tmp;
+        LIST_HEAD(list);
 
         spin_lock_irqsave(q->queue_lock, flags);
 
         elv_abort_queue(q);
 
-        list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)
+        /*
+         * Splice entries to local list, to avoid deadlocking if entries
+         * get readded to the timeout list by error handling
+         */
+        list_splice_init(&q->timeout_list, &list);
+
+        list_for_each_entry_safe(rq, tmp, &list, timeout_list)
                 blk_abort_request(rq);
 
         spin_unlock_irqrestore(q->queue_lock, flags);
diff --git a/block/blk.h b/block/blk.h
index 6e1ed40534e9..0dce92c37496 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -108,4 +108,12 @@ static inline int blk_cpu_to_group(int cpu)
 #endif
 }
 
+static inline int blk_do_io_stat(struct request_queue *q)
+{
+        if (q)
+                return blk_queue_io_stat(q);
+
+        return 0;
+}
+
 #endif
diff --git a/block/blktrace.c b/block/blktrace.c
index b0a2cae886db..7cf9d1ff45a0 100644
--- a/block/blktrace.c
+++ b/block/blktrace.c
@@ -142,7 +142,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 
         what |= ddir_act[rw & WRITE];
         what |= MASK_TC_BIT(rw, BARRIER);
-        what |= MASK_TC_BIT(rw, SYNC);
+        what |= MASK_TC_BIT(rw, SYNCIO);
         what |= MASK_TC_BIT(rw, AHEAD);
         what |= MASK_TC_BIT(rw, META);
         what |= MASK_TC_BIT(rw, DISCARD);
@@ -187,59 +187,12 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 
 static struct dentry *blk_tree_root;
 static DEFINE_MUTEX(blk_tree_mutex);
-static unsigned int root_users;
-
-static inline void blk_remove_root(void)
-{
-        if (blk_tree_root) {
-                debugfs_remove(blk_tree_root);
-                blk_tree_root = NULL;
-        }
-}
-
-static void blk_remove_tree(struct dentry *dir)
-{
-        mutex_lock(&blk_tree_mutex);
-        debugfs_remove(dir);
-        if (--root_users == 0)
-                blk_remove_root();
-        mutex_unlock(&blk_tree_mutex);
-}
-
-static struct dentry *blk_create_tree(const char *blk_name)
-{
-        struct dentry *dir = NULL;
-        int created = 0;
-
-        mutex_lock(&blk_tree_mutex);
-
-        if (!blk_tree_root) {
-                blk_tree_root = debugfs_create_dir("block", NULL);
-                if (!blk_tree_root)
-                        goto err;
-                created = 1;
-        }
-
-        dir = debugfs_create_dir(blk_name, blk_tree_root);
-        if (dir)
-                root_users++;
-        else {
-                /* Delete root only if we created it */
-                if (created)
-                        blk_remove_root();
-        }
-
-err:
-        mutex_unlock(&blk_tree_mutex);
-        return dir;
-}
 
 static void blk_trace_cleanup(struct blk_trace *bt)
 {
-        relay_close(bt->rchan);
         debugfs_remove(bt->msg_file);
         debugfs_remove(bt->dropped_file);
-        blk_remove_tree(bt->dir);
+        relay_close(bt->rchan);
         free_percpu(bt->sequence);
         free_percpu(bt->msg_data);
         kfree(bt);
@@ -346,7 +299,18 @@ static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
 
 static int blk_remove_buf_file_callback(struct dentry *dentry)
 {
+        struct dentry *parent = dentry->d_parent;
         debugfs_remove(dentry);
+
+        /*
+        * this will fail for all but the last file, but that is ok. what we
+        * care about is the top level buts->name directory going away, when
+        * the last trace file is gone. Then we don't have to rmdir() that
+        * manually on trace stop, so it nicely solves the issue with
+        * force killing of running traces.
+        */
+
+        debugfs_remove(parent);
         return 0;
 }
 
@@ -404,7 +368,15 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
                 goto err;
 
         ret = -ENOENT;
-        dir = blk_create_tree(buts->name);
+
+        if (!blk_tree_root) {
+                blk_tree_root = debugfs_create_dir("block", NULL);
+                if (!blk_tree_root)
+                        return -ENOMEM;
+        }
+
+        dir = debugfs_create_dir(buts->name, blk_tree_root);
+
         if (!dir)
                 goto err;
 
@@ -458,8 +430,6 @@ probe_err:
         atomic_dec(&blk_probes_ref);
         mutex_unlock(&blk_probe_mutex);
 err:
-        if (dir)
-                blk_remove_tree(dir);
         if (bt) {
                 if (bt->msg_file)
                         debugfs_remove(bt->msg_file);
diff --git a/block/bsg.c b/block/bsg.c
index d414bb5607e8..0ce8806dd0c1 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -244,7 +244,8 @@ bsg_validate_sgv4_hdr(struct request_queue *q, struct sg_io_v4 *hdr, int *rw)
  * map sg_io_v4 to a request.
  */
 static struct request *
-bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm)
+bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm,
+            u8 *sense)
 {
         struct request_queue *q = bd->queue;
         struct request *rq, *next_rq = NULL;
@@ -306,6 +307,10 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm)
                 if (ret)
                         goto out;
         }
+
+        rq->sense = sense;
+        rq->sense_len = 0;
+
         return rq;
 out:
         if (rq->cmd != rq->__cmd)
@@ -348,9 +353,6 @@ static void bsg_rq_end_io(struct request *rq, int uptodate)
 static void bsg_add_command(struct bsg_device *bd, struct request_queue *q,
                             struct bsg_command *bc, struct request *rq)
 {
-        rq->sense = bc->sense;
-        rq->sense_len = 0;
-
         /*
          * add bc command to busy queue and submit rq for io
          */
@@ -419,7 +421,7 @@ static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
 {
         int ret = 0;
 
-        dprintk("rq %p bio %p %u\n", rq, bio, rq->errors);
+        dprintk("rq %p bio %p 0x%x\n", rq, bio, rq->errors);
         /*
          * fill in all the output members
          */
@@ -635,7 +637,7 @@ static int __bsg_write(struct bsg_device *bd, const char __user *buf,
                 /*
                  * get a request, fill in the blanks, and add to request queue
                  */
-                rq = bsg_map_hdr(bd, &bc->hdr, has_write_perm);
+                rq = bsg_map_hdr(bd, &bc->hdr, has_write_perm, bc->sense);
                 if (IS_ERR(rq)) {
                         ret = PTR_ERR(rq);
                         rq = NULL;
@@ -922,11 +924,12 @@ static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                 struct request *rq;
                 struct bio *bio, *bidi_bio = NULL;
                 struct sg_io_v4 hdr;
+                u8 sense[SCSI_SENSE_BUFFERSIZE];
 
                 if (copy_from_user(&hdr, uarg, sizeof(hdr)))
                         return -EFAULT;
 
-                rq = bsg_map_hdr(bd, &hdr, file->f_mode & FMODE_WRITE);
+                rq = bsg_map_hdr(bd, &hdr, file->f_mode & FMODE_WRITE, sense);
                 if (IS_ERR(rq))
                         return PTR_ERR(rq);
 
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index e8525fa72823..664ebfd092ec 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -84,6 +84,11 @@ struct cfq_data {
          */
         struct cfq_rb_root service_tree;
         unsigned int busy_queues;
+        /*
+         * Used to track any pending rt requests so we can pre-empt current
+         * non-RT cfqq in service when this value is non-zero.
+         */
+        unsigned int busy_rt_queues;
 
         int rq_in_driver;
         int sync_flight;
@@ -562,6 +567,8 @@ static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
         BUG_ON(cfq_cfqq_on_rr(cfqq));
         cfq_mark_cfqq_on_rr(cfqq);
         cfqd->busy_queues++;
+        if (cfq_class_rt(cfqq))
+                cfqd->busy_rt_queues++;
 
         cfq_resort_rr_list(cfqd, cfqq);
 }
@@ -581,6 +588,8 @@ static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 
         BUG_ON(!cfqd->busy_queues);
         cfqd->busy_queues--;
+        if (cfq_class_rt(cfqq))
+                cfqd->busy_rt_queues--;
 }
 
 /*
@@ -1005,6 +1014,20 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
                 goto expire;
 
         /*
+         * If we have a RT cfqq waiting, then we pre-empt the current non-rt
+         * cfqq.
+         */
+        if (!cfq_class_rt(cfqq) && cfqd->busy_rt_queues) {
+                /*
+                 * We simulate this as cfqq timed out so that it gets to bank
+                 * the remaining of its time slice.
+                 */
+                cfq_log_cfqq(cfqd, cfqq, "preempt");
+                cfq_slice_expired(cfqd, 1);
+                goto new_queue;
+        }
+
+        /*
          * The active queue has requests and isn't expired, allow it to
          * dispatch.
          */
@@ -1067,6 +1090,13 @@ __cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                 if (RB_EMPTY_ROOT(&cfqq->sort_list))
                         break;
 
+                /*
+                 * If there is a non-empty RT cfqq waiting for current
+                 * cfqq's timeslice to complete, pre-empt this cfqq
+                 */
+                if (!cfq_class_rt(cfqq) && cfqd->busy_rt_queues)
+                        break;
+
         } while (dispatched < max_dispatch);
 
         /*
@@ -1801,6 +1831,12 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
         if (rq_is_meta(rq) && !cfqq->meta_pending)
                 return 1;
 
+        /*
+         * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
+         */
+        if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
+                return 1;
+
         if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
                 return 0;
 
@@ -1870,7 +1906,8 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                 /*
                  * not the active queue - expire current slice if it is
                  * idle and has expired it's mean thinktime or this new queue
-                 * has some old slice time left and is of higher priority
+                 * has some old slice time left and is of higher priority or
+                 * this new queue is RT and the current one is BE
                  */
                 cfq_preempt_queue(cfqd, cfqq);
                 cfq_mark_cfqq_must_dispatch(cfqq);
diff --git a/block/genhd.c b/block/genhd.c
index 397960cf26af..a9ec910974c1 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -256,6 +256,22 @@ void blkdev_show(struct seq_file *seqf, off_t offset)
 }
 #endif /* CONFIG_PROC_FS */
 
+/**
+ * register_blkdev - register a new block device
+ *
+ * @major: the requested major device number [1..255]. If @major=0, try to
+ *         allocate any unused major number.
+ * @name: the name of the new block device as a zero terminated string
+ *
+ * The @name must be unique within the system.
+ *
+ * The return value depends on the @major input parameter.
+ *  - if a major device number was requested in range [1..255] then the
+ *    function returns zero on success, or a negative error code
+ *  - if any unused major number was requested with @major=0 parameter
+ *    then the return value is the allocated major number in range
+ *    [1..255] or a negative error code otherwise
+ */
 int register_blkdev(unsigned int major, const char *name)
 {
         struct blk_major_name **n, *p;
@@ -1087,6 +1103,14 @@ dev_t blk_lookup_devt(const char *name, int partno)
                 if (strcmp(dev_name(dev), name))
                         continue;
 
+                if (partno < disk->minors) {
+                        /* We need to return the right devno, even
+                         * if the partition doesn't exist yet.
+                         */
+                        devt = MKDEV(MAJOR(dev->devt),
+                                     MINOR(dev->devt) + partno);
+                        break;
+                }
                 part = disk_get_part(disk, partno);
                 if (part) {
                         devt = part_devt(part);