block: continue ll_rw_blk.c splitup

Adds files for barrier handling, rq execution, io context handling,
mapping data to requests, and queue settings.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

8 files changed, 1312 insertions, 1249 deletions

diff --git a/block/Makefile b/block/Makefile
index fcaae4ae6704..2002046d0a9e 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -2,8 +2,9 @@
 # Makefile for the kernel block layer
 #
 
-obj-$(CONFIG_BLOCK) := elevator.o blk-core.o blk-tag.o blk-sysfs.o ioctl.o \
-			genhd.o scsi_ioctl.o
+obj-$(CONFIG_BLOCK) := elevator.o blk-core.o blk-tag.o blk-sysfs.o \
+			blk-barrier.o blk-settings.o blk-ioc.o blk-map.o \
+			blk-exec.o ioctl.o genhd.o scsi_ioctl.o
 
 obj-$(CONFIG_BLK_DEV_BSG)	+= bsg.o
 obj-$(CONFIG_IOSCHED_NOOP)	+= noop-iosched.o
diff --git a/block/blk-barrier.c b/block/blk-barrier.c
new file mode 100644
index 000000000000..5f74fec327d5
--- /dev/null
+++ b/block/blk-barrier.c
@@ -0,0 +1,319 @@
+/*
+ * Functions related to barrier IO handling
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+
+#include "blk.h"
+
+/**
+ * blk_queue_ordered - does this queue support ordered writes
+ * @q:        the request queue
+ * @ordered:  one of QUEUE_ORDERED_*
+ * @prepare_flush_fn: rq setup helper for cache flush ordered writes
+ *
+ * Description:
+ *   For journalled file systems, doing ordered writes on a commit
+ *   block instead of explicitly doing wait_on_buffer (which is bad
+ *   for performance) can be a big win. Block drivers supporting this
+ *   feature should call this function and indicate so.
+ *
+ **/
+int blk_queue_ordered(struct request_queue *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->ordered = ordered;
+	q->next_ordered = ordered;
+	q->prepare_flush_fn = prepare_flush_fn;
+
+	return 0;
+}
+
+EXPORT_SYMBOL(blk_queue_ordered);
+
+/*
+ * Cache flushing for ordered writes handling
+ */
+inline unsigned blk_ordered_cur_seq(struct request_queue *q)
+{
+	if (!q->ordseq)
+		return 0;
+	return 1 << ffz(q->ordseq);
+}
+
+unsigned blk_ordered_req_seq(struct request *rq)
+{
+	struct request_queue *q = rq->q;
+
+	BUG_ON(q->ordseq == 0);
+
+	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;
+
+	/*
+	 * !fs requests don't need to follow barrier ordering.  Always
+	 * put them at the front.  This fixes the following deadlock.
+	 *
+	 * http://thread.gmane.org/gmane.linux.kernel/537473
+	 */
+	if (!blk_fs_request(rq))
+		return QUEUE_ORDSEQ_DRAIN;
+
+	if ((rq->cmd_flags & REQ_ORDERED_COLOR) ==
+	    (q->orig_bar_rq->cmd_flags & REQ_ORDERED_COLOR))
+		return QUEUE_ORDSEQ_DRAIN;
+	else
+		return QUEUE_ORDSEQ_DONE;
+}
+
+void blk_ordered_complete_seq(struct request_queue *q, unsigned seq, int error)
+{
+	struct request *rq;
+
+	if (error && !q->orderr)
+		q->orderr = error;
+
+	BUG_ON(q->ordseq & seq);
+	q->ordseq |= seq;
+
+	if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE)
+		return;
+
+	/*
+	 * Okay, sequence complete.
+	 */
+	q->ordseq = 0;
+	rq = q->orig_bar_rq;
+
+	if (__blk_end_request(rq, q->orderr, blk_rq_bytes(rq)))
+		BUG();
+}
+
+static void pre_flush_end_io(struct request *rq, int error)
+{
+	elv_completed_request(rq->q, rq);
+	blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_PREFLUSH, error);
+}
+
+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);
+}
+
+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);
+}
+
+static void queue_flush(struct request_queue *q, unsigned which)
+{
+	struct request *rq;
+	rq_end_io_fn *end_io;
+
+	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->cmd_flags = REQ_HARDBARRIER;
+	rq_init(q, rq);
+	rq->elevator_private = NULL;
+	rq->elevator_private2 = NULL;
+	rq->rq_disk = q->bar_rq.rq_disk;
+	rq->end_io = end_io;
+	q->prepare_flush_fn(q, rq);
+
+	elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
+}
+
+static inline struct request *start_ordered(struct request_queue *q,
+					    struct request *rq)
+{
+	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->cmd_flags = 0;
+	rq_init(q, rq);
+	if (bio_data_dir(q->orig_bar_rq->bio) == WRITE)
+		rq->cmd_flags |= REQ_RW;
+	if (q->ordered & QUEUE_ORDERED_FUA)
+		rq->cmd_flags |= REQ_FUA;
+	rq->elevator_private = NULL;
+	rq->elevator_private2 = 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 this request is
+	 * an empty barrier, we don't need to do a postflush ever since
+	 * there will be no data written between the pre and post flush.
+	 * Hence a single flush will suffice.
+	 */
+	if ((q->ordered & QUEUE_ORDERED_POSTFLUSH) && !blk_empty_barrier(rq))
+		queue_flush(q, QUEUE_ORDERED_POSTFLUSH);
+	else
+		q->ordseq |= QUEUE_ORDSEQ_POSTFLUSH;
+
+	elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
+
+	if (q->ordered & QUEUE_ORDERED_PREFLUSH) {
+		queue_flush(q, QUEUE_ORDERED_PREFLUSH);
+		rq = &q->pre_flush_rq;
+	} else
+		q->ordseq |= QUEUE_ORDSEQ_PREFLUSH;
+
+	if ((q->ordered & QUEUE_ORDERED_TAG) || q->in_flight == 0)
+		q->ordseq |= QUEUE_ORDSEQ_DRAIN;
+	else
+		rq = NULL;
+
+	return rq;
+}
+
+int blk_do_ordered(struct request_queue *q, struct request **rqp)
+{
+	struct request *rq = *rqp;
+	const int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq);
+
+	if (!q->ordseq) {
+		if (!is_barrier)
+			return 1;
+
+		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);
+			if (__blk_end_request(rq, -EOPNOTSUPP,
+					      blk_rq_bytes(rq)))
+				BUG();
+			*rqp = NULL;
+			return 0;
+		}
+	}
+
+	/*
+	 * Ordered sequence in progress
+	 */
+
+	/* Special requests are not subject to ordering rules. */
+	if (!blk_fs_request(rq) &&
+	    rq != &q->pre_flush_rq && rq != &q->post_flush_rq)
+		return 1;
+
+	if (q->ordered & QUEUE_ORDERED_TAG) {
+		/* Ordered by tag.  Blocking the next barrier is enough. */
+		if (is_barrier && rq != &q->bar_rq)
+			*rqp = NULL;
+	} else {
+		/* Ordered by draining.  Wait for turn. */
+		WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q));
+		if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q))
+			*rqp = NULL;
+	}
+
+	return 1;
+}
+
+static void bio_end_empty_barrier(struct bio *bio, int err)
+{
+	if (err)
+		clear_bit(BIO_UPTODATE, &bio->bi_flags);
+
+	complete(bio->bi_private);
+}
+
+/**
+ * blkdev_issue_flush - queue a flush
+ * @bdev:	blockdev to issue flush for
+ * @error_sector:	error sector
+ *
+ * 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.
+ */
+int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector)
+{
+	DECLARE_COMPLETION_ONSTACK(wait);
+	struct request_queue *q;
+	struct bio *bio;
+	int ret;
+
+	if (bdev->bd_disk == NULL)
+		return -ENXIO;
+
+	q = bdev_get_queue(bdev);
+	if (!q)
+		return -ENXIO;
+
+	bio = bio_alloc(GFP_KERNEL, 0);
+	if (!bio)
+		return -ENOMEM;
+
+	bio->bi_end_io = bio_end_empty_barrier;
+	bio->bi_private = &wait;
+	bio->bi_bdev = bdev;
+	submit_bio(1 << BIO_RW_BARRIER, bio);
+
+	wait_for_completion(&wait);
+
+	/*
+	 * The driver must store the error location in ->bi_sector, if
+	 * it supports it. For non-stacked drivers, this should be copied
+	 * from rq->sector.
+	 */
+	if (error_sector)
+		*error_sector = bio->bi_sector;
+
+	ret = 0;
+	if (!bio_flagged(bio, BIO_UPTODATE))
+		ret = -EIO;
+
+	bio_put(bio);
+	return ret;
+}
+
+EXPORT_SYMBOL(blkdev_issue_flush);
diff --git a/block/blk-core.c b/block/blk-core.c
index 937f9d0b9bd5..2c73ed1a8131 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -20,7 +20,6 @@
 #include <linux/kernel_stat.h>
 #include <linux/string.h>
 #include <linux/init.h>
-#include <linux/bootmem.h>	/* for max_pfn/max_low_pfn */
 #include <linux/completion.h>
 #include <linux/slab.h>
 #include <linux/swap.h>
@@ -34,20 +33,9 @@
 
 #include "blk.h"
 
-/*
- * for max sense size
- */
-#include <scsi/scsi_cmnd.h>
-
-static void blk_unplug_work(struct work_struct *work);
-static void blk_unplug_timeout(unsigned long data);
 static void drive_stat_acct(struct request *rq, int new_io);
-static void init_request_from_bio(struct request *req, struct bio *bio);
 static int __make_request(struct request_queue *q, struct bio *bio);
-static struct io_context *current_io_context(gfp_t gfp_flags, int node);
 static void blk_recalc_rq_segments(struct request *rq);
-static void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
-			    struct bio *bio);
 
 /*
  * For the allocated request tables
@@ -60,28 +48,12 @@ struct kmem_cache *request_cachep;
 struct kmem_cache *blk_requestq_cachep = NULL;
 
 /*
- * For io context allocations
- */
-static struct kmem_cache *iocontext_cachep;
-
-/*
  * Controlling structure to kblockd
  */
 static struct workqueue_struct *kblockd_workqueue;
 
-unsigned long blk_max_low_pfn, blk_max_pfn;
-
-EXPORT_SYMBOL(blk_max_low_pfn);
-EXPORT_SYMBOL(blk_max_pfn);
-
 static DEFINE_PER_CPU(struct list_head, blk_cpu_done);
 
-/* Amount of time in which a process may batch requests */
-#define BLK_BATCH_TIME	(HZ/50UL)
-
-/* Number of requests a "batching" process may submit */
-#define BLK_BATCH_REQ	32
-
 void blk_queue_congestion_threshold(struct request_queue *q)
 {
 	int nr;
@@ -117,113 +89,7 @@ struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
 }
 EXPORT_SYMBOL(blk_get_backing_dev_info);
 
-/**
- * blk_queue_prep_rq - set a prepare_request function for queue
- * @q:		queue
- * @pfn:	prepare_request function
- *
- * It's possible for a queue to register a prepare_request callback which
- * is invoked before the request is handed to the request_fn. The goal of
- * the function is to prepare a request for I/O, it can be used to build a
- * cdb from the request data for instance.
- *
- */
-void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn)
-{
-	q->prep_rq_fn = pfn;
-}
-
-EXPORT_SYMBOL(blk_queue_prep_rq);
-
-/**
- * blk_queue_merge_bvec - set a merge_bvec function for queue
- * @q:		queue
- * @mbfn:	merge_bvec_fn
- *
- * Usually queues have static limitations on the max sectors or segments that
- * we can put in a request. Stacking drivers may have some settings that
- * are dynamic, and thus we have to query the queue whether it is ok to
- * add a new bio_vec to a bio at a given offset or not. If the block device
- * has such limitations, it needs to register a merge_bvec_fn to control
- * the size of bio's sent to it. Note that a block device *must* allow a
- * single page to be added to an empty bio. The block device driver may want
- * to use the bio_split() function to deal with these bio's. By default
- * no merge_bvec_fn is defined for a queue, and only the fixed limits are
- * honored.
- */
-void blk_queue_merge_bvec(struct request_queue *q, merge_bvec_fn *mbfn)
-{
-	q->merge_bvec_fn = mbfn;
-}
-
-EXPORT_SYMBOL(blk_queue_merge_bvec);
-
-void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn)
-{
-	q->softirq_done_fn = fn;
-}
-
-EXPORT_SYMBOL(blk_queue_softirq_done);
-
-/**
- * blk_queue_make_request - define an alternate make_request function for a device
- * @q:  the request queue for the device to be affected
- * @mfn: the alternate make_request function
- *
- * Description:
- *    The normal way for &struct bios to be passed to a device
- *    driver is for them to be collected into requests on a request
- *    queue, and then to allow the device driver to select requests
- *    off that queue when it is ready.  This works well for many block
- *    devices. However some block devices (typically virtual devices
- *    such as md or lvm) do not benefit from the processing on the
- *    request queue, and are served best by having the requests passed
- *    directly to them.  This can be achieved by providing a function
- *    to blk_queue_make_request().
- *
- * Caveat:
- *    The driver that does this *must* be able to deal appropriately
- *    with buffers in "highmemory". This can be accomplished by either calling
- *    __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
- *    blk_queue_bounce() to create a buffer in normal memory.
- **/
-void blk_queue_make_request(struct request_queue * q, make_request_fn * mfn)
-{
-	/*
-	 * set defaults
-	 */
-	q->nr_requests = BLKDEV_MAX_RQ;
-	blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
-	blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
-	q->make_request_fn = mfn;
-	q->backing_dev_info.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
-	q->backing_dev_info.state = 0;
-	q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY;
-	blk_queue_max_sectors(q, SAFE_MAX_SECTORS);
-	blk_queue_hardsect_size(q, 512);
-	blk_queue_dma_alignment(q, 511);
-	blk_queue_congestion_threshold(q);
-	q->nr_batching = BLK_BATCH_REQ;
-
-	q->unplug_thresh = 4;		/* hmm */
-	q->unplug_delay = (3 * HZ) / 1000;	/* 3 milliseconds */
-	if (q->unplug_delay == 0)
-		q->unplug_delay = 1;
-
-	INIT_WORK(&q->unplug_work, blk_unplug_work);
-
-	q->unplug_timer.function = blk_unplug_timeout;
-	q->unplug_timer.data = (unsigned long)q;
-
-	/*
-	 * by default assume old behaviour and bounce for any highmem page
-	 */
-	blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
-}
-
-EXPORT_SYMBOL(blk_queue_make_request);
-
-static void rq_init(struct request_queue *q, struct request *rq)
+void rq_init(struct request_queue *q, struct request *rq)
 {
 	INIT_LIST_HEAD(&rq->queuelist);
 	INIT_LIST_HEAD(&rq->donelist);
@@ -247,255 +113,6 @@ static void rq_init(struct request_queue *q, struct request *rq)
 	rq->next_rq = NULL;
 }
 
-/**
- * blk_queue_ordered - does this queue support ordered writes
- * @q:        the request queue
- * @ordered:  one of QUEUE_ORDERED_*
- * @prepare_flush_fn: rq setup helper for cache flush ordered writes
- *
- * Description:
- *   For journalled file systems, doing ordered writes on a commit
- *   block instead of explicitly doing wait_on_buffer (which is bad
- *   for performance) can be a big win. Block drivers supporting this
- *   feature should call this function and indicate so.
- *
- **/
-int blk_queue_ordered(struct request_queue *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->ordered = ordered;
-	q->next_ordered = ordered;
-	q->prepare_flush_fn = prepare_flush_fn;
-
-	return 0;
-}
-
-EXPORT_SYMBOL(blk_queue_ordered);
-
-/*
- * Cache flushing for ordered writes handling
- */
-inline unsigned blk_ordered_cur_seq(struct request_queue *q)
-{
-	if (!q->ordseq)
-		return 0;
-	return 1 << ffz(q->ordseq);
-}
-
-unsigned blk_ordered_req_seq(struct request *rq)
-{
-	struct request_queue *q = rq->q;
-
-	BUG_ON(q->ordseq == 0);
-
-	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;
-
-	/*
-	 * !fs requests don't need to follow barrier ordering.  Always
-	 * put them at the front.  This fixes the following deadlock.
-	 *
-	 * http://thread.gmane.org/gmane.linux.kernel/537473
-	 */
-	if (!blk_fs_request(rq))
-		return QUEUE_ORDSEQ_DRAIN;
-
-	if ((rq->cmd_flags & REQ_ORDERED_COLOR) ==
-	    (q->orig_bar_rq->cmd_flags & REQ_ORDERED_COLOR))
-		return QUEUE_ORDSEQ_DRAIN;
-	else
-		return QUEUE_ORDSEQ_DONE;
-}
-
-void blk_ordered_complete_seq(struct request_queue *q, unsigned seq, int error)
-{
-	struct request *rq;
-
-	if (error && !q->orderr)
-		q->orderr = error;
-
-	BUG_ON(q->ordseq & seq);
-	q->ordseq |= seq;
-
-	if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE)
-		return;
-
-	/*
-	 * Okay, sequence complete.
-	 */
-	q->ordseq = 0;
-	rq = q->orig_bar_rq;
-
-	if (__blk_end_request(rq, q->orderr, blk_rq_bytes(rq)))
-		BUG();
-}
-
-static void pre_flush_end_io(struct request *rq, int error)
-{
-	elv_completed_request(rq->q, rq);
-	blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_PREFLUSH, error);
-}
-
-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);
-}
-
-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);
-}
-
-static void queue_flush(struct request_queue *q, unsigned which)
-{
-	struct request *rq;
-	rq_end_io_fn *end_io;
-
-	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->cmd_flags = REQ_HARDBARRIER;
-	rq_init(q, rq);
-	rq->elevator_private = NULL;
-	rq->elevator_private2 = NULL;
-	rq->rq_disk = q->bar_rq.rq_disk;
-	rq->end_io = end_io;
-	q->prepare_flush_fn(q, rq);
-
-	elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
-}
-
-static inline struct request *start_ordered(struct request_queue *q,
-					    struct request *rq)
-{
-	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->cmd_flags = 0;
-	rq_init(q, rq);
-	if (bio_data_dir(q->orig_bar_rq->bio) == WRITE)
-		rq->cmd_flags |= REQ_RW;
-	if (q->ordered & QUEUE_ORDERED_FUA)
-		rq->cmd_flags |= REQ_FUA;
-	rq->elevator_private = NULL;
-	rq->elevator_private2 = 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 this request is
-	 * an empty barrier, we don't need to do a postflush ever since
-	 * there will be no data written between the pre and post flush.
-	 * Hence a single flush will suffice.
-	 */
-	if ((q->ordered & QUEUE_ORDERED_POSTFLUSH) && !blk_empty_barrier(rq))
-		queue_flush(q, QUEUE_ORDERED_POSTFLUSH);
-	else
-		q->ordseq |= QUEUE_ORDSEQ_POSTFLUSH;
-
-	elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
-
-	if (q->ordered & QUEUE_ORDERED_PREFLUSH) {
-		queue_flush(q, QUEUE_ORDERED_PREFLUSH);
-		rq = &q->pre_flush_rq;
-	} else
-		q->ordseq |= QUEUE_ORDSEQ_PREFLUSH;
-
-	if ((q->ordered & QUEUE_ORDERED_TAG) || q->in_flight == 0)
-		q->ordseq |= QUEUE_ORDSEQ_DRAIN;
-	else
-		rq = NULL;
-
-	return rq;
-}
-
-int blk_do_ordered(struct request_queue *q, struct request **rqp)
-{
-	struct request *rq = *rqp;
-	const int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq);
-
-	if (!q->ordseq) {
-		if (!is_barrier)
-			return 1;
-
-		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);
-			if (__blk_end_request(rq, -EOPNOTSUPP,
-					      blk_rq_bytes(rq)))
-				BUG();
-			*rqp = NULL;
-			return 0;
-		}
-	}
-
-	/*
-	 * Ordered sequence in progress
-	 */
-
-	/* Special requests are not subject to ordering rules. */
-	if (!blk_fs_request(rq) &&
-	    rq != &q->pre_flush_rq && rq != &q->post_flush_rq)
-		return 1;
-
-	if (q->ordered & QUEUE_ORDERED_TAG) {
-		/* Ordered by tag.  Blocking the next barrier is enough. */
-		if (is_barrier && rq != &q->bar_rq)
-			*rqp = NULL;
-	} else {
-		/* Ordered by draining.  Wait for turn. */
-		WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q));
-		if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q))
-			*rqp = NULL;
-	}
-
-	return 1;
-}
-
 static void req_bio_endio(struct request *rq, struct bio *bio,
 			  unsigned int nbytes, int error)
 {
@@ -528,279 +145,6 @@ static void req_bio_endio(struct request *rq, struct bio *bio,
 	}
 }
 
-/**
- * blk_queue_bounce_limit - set bounce buffer limit for queue
- * @q:  the request queue for the device
- * @dma_addr:   bus address limit
- *
- * Description:
- *    Different hardware can have different requirements as to what pages
- *    it can do I/O directly to. A low level driver can call
- *    blk_queue_bounce_limit to have lower memory pages allocated as bounce
- *    buffers for doing I/O to pages residing above @page.
- **/
-void blk_queue_bounce_limit(struct request_queue *q, u64 dma_addr)
-{
-	unsigned long bounce_pfn = dma_addr >> PAGE_SHIFT;
-	int dma = 0;
-
-	q->bounce_gfp = GFP_NOIO;
-#if BITS_PER_LONG == 64
-	/* Assume anything <= 4GB can be handled by IOMMU.
-	   Actually some IOMMUs can handle everything, but I don't
-	   know of a way to test this here. */
-	if (bounce_pfn < (min_t(u64,0xffffffff,BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
-		dma = 1;
-	q->bounce_pfn = max_low_pfn;
-#else
-	if (bounce_pfn < blk_max_low_pfn)
-		dma = 1;
-	q->bounce_pfn = bounce_pfn;
-#endif
-	if (dma) {
-		init_emergency_isa_pool();
-		q->bounce_gfp = GFP_NOIO | GFP_DMA;
-		q->bounce_pfn = bounce_pfn;
-	}
-}
-
-EXPORT_SYMBOL(blk_queue_bounce_limit);
-
-/**
- * blk_queue_max_sectors - set max sectors for a request for this queue
- * @q:  the request queue for the device
- * @max_sectors:  max sectors in the usual 512b unit
- *
- * Description:
- *    Enables a low level driver to set an upper limit on the size of
- *    received requests.
- **/
-void blk_queue_max_sectors(struct request_queue *q, unsigned int max_sectors)
-{
-	if ((max_sectors << 9) < PAGE_CACHE_SIZE) {
-		max_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
-		printk("%s: set to minimum %d\n", __FUNCTION__, max_sectors);
-	}
-
-	if (BLK_DEF_MAX_SECTORS > max_sectors)
-		q->max_hw_sectors = q->max_sectors = max_sectors;
- 	else {
-		q->max_sectors = BLK_DEF_MAX_SECTORS;
-		q->max_hw_sectors = max_sectors;
-	}
-}
-
-EXPORT_SYMBOL(blk_queue_max_sectors);
-
-/**
- * blk_queue_max_phys_segments - set max phys segments for a request for this queue
- * @q:  the request queue for the device
- * @max_segments:  max number of segments
- *
- * Description:
- *    Enables a low level driver to set an upper limit on the number of
- *    physical data segments in a request.  This would be the largest sized
- *    scatter list the driver could handle.
- **/
-void blk_queue_max_phys_segments(struct request_queue *q,
-				 unsigned short max_segments)
-{
-	if (!max_segments) {
-		max_segments = 1;
-		printk("%s: set to minimum %d\n", __FUNCTION__, max_segments);
-	}
-
-	q->max_phys_segments = max_segments;
-}
-
-EXPORT_SYMBOL(blk_queue_max_phys_segments);
-
-/**
- * blk_queue_max_hw_segments - set max hw segments for a request for this queue
- * @q:  the request queue for the device
- * @max_segments:  max number of segments
- *
- * Description:
- *    Enables a low level driver to set an upper limit on the number of
- *    hw data segments in a request.  This would be the largest number of
- *    address/length pairs the host adapter can actually give as once
- *    to the device.
- **/
-void blk_queue_max_hw_segments(struct request_queue *q,
-			       unsigned short max_segments)
-{
-	if (!max_segments) {
-		max_segments = 1;
-		printk("%s: set to minimum %d\n", __FUNCTION__, max_segments);
-	}
-
-	q->max_hw_segments = max_segments;
-}
-
-EXPORT_SYMBOL(blk_queue_max_hw_segments);
-
-/**
- * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
- * @q:  the request queue for the device
- * @max_size:  max size of segment in bytes
- *
- * Description:
- *    Enables a low level driver to set an upper limit on the size of a
- *    coalesced segment
- **/
-void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size)
-{
-	if (max_size < PAGE_CACHE_SIZE) {
-		max_size = PAGE_CACHE_SIZE;
-		printk("%s: set to minimum %d\n", __FUNCTION__, max_size);
-	}
-
-	q->max_segment_size = max_size;
-}
-
-EXPORT_SYMBOL(blk_queue_max_segment_size);
-
-/**
- * blk_queue_hardsect_size - set hardware sector size for the queue
- * @q:  the request queue for the device
- * @size:  the hardware sector size, in bytes
- *
- * Description:
- *   This should typically be set to the lowest possible sector size
- *   that the hardware can operate on (possible without reverting to
- *   even internal read-modify-write operations). Usually the default
- *   of 512 covers most hardware.
- **/
-void blk_queue_hardsect_size(struct request_queue *q, unsigned short size)
-{
-	q->hardsect_size = size;
-}
-
-EXPORT_SYMBOL(blk_queue_hardsect_size);
-
-/*
- * Returns the minimum that is _not_ zero, unless both are zero.
- */
-#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
-
-/**
- * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
- * @t:	the stacking driver (top)
- * @b:  the underlying device (bottom)
- **/
-void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b)
-{
-	/* zero is "infinity" */
-	t->max_sectors = min_not_zero(t->max_sectors,b->max_sectors);
-	t->max_hw_sectors = min_not_zero(t->max_hw_sectors,b->max_hw_sectors);
-
-	t->max_phys_segments = min(t->max_phys_segments,b->max_phys_segments);
-	t->max_hw_segments = min(t->max_hw_segments,b->max_hw_segments);
-	t->max_segment_size = min(t->max_segment_size,b->max_segment_size);
-	t->hardsect_size = max(t->hardsect_size,b->hardsect_size);
-	if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags))
-		clear_bit(QUEUE_FLAG_CLUSTER, &t->queue_flags);
-}
-
-EXPORT_SYMBOL(blk_queue_stack_limits);
-
-/**
- * blk_queue_dma_drain - Set up a drain buffer for excess dma.
- *
- * @q:  the request queue for the device
- * @buf:	physically contiguous buffer
- * @size:	size of the buffer in bytes
- *
- * Some devices have excess DMA problems and can't simply discard (or
- * zero fill) the unwanted piece of the transfer.  They have to have a
- * real area of memory to transfer it into.  The use case for this is
- * ATAPI devices in DMA mode.  If the packet command causes a transfer
- * bigger than the transfer size some HBAs will lock up if there
- * aren't DMA elements to contain the excess transfer.  What this API
- * does is adjust the queue so that the buf is always appended
- * silently to the scatterlist.
- *
- * Note: This routine adjusts max_hw_segments to make room for
- * appending the drain buffer.  If you call
- * blk_queue_max_hw_segments() or blk_queue_max_phys_segments() after
- * calling this routine, you must set the limit to one fewer than your
- * device can support otherwise there won't be room for the drain
- * buffer.
- */
-int blk_queue_dma_drain(struct request_queue *q, void *buf,
-				unsigned int size)
-{
-	if (q->max_hw_segments < 2 || q->max_phys_segments < 2)
-		return -EINVAL;
-	/* make room for appending the drain */
-	--q->max_hw_segments;
-	--q->max_phys_segments;
-	q->dma_drain_buffer = buf;
-	q->dma_drain_size = size;
-
-	return 0;
-}
-
-EXPORT_SYMBOL_GPL(blk_queue_dma_drain);
-
-/**
- * blk_queue_segment_boundary - set boundary rules for segment merging
- * @q:  the request queue for the device
- * @mask:  the memory boundary mask
- **/
-void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask)
-{
-	if (mask < PAGE_CACHE_SIZE - 1) {
-		mask = PAGE_CACHE_SIZE - 1;
-		printk("%s: set to minimum %lx\n", __FUNCTION__, mask);
-	}
-
-	q->seg_boundary_mask = mask;
-}
-
-EXPORT_SYMBOL(blk_queue_segment_boundary);
-
-/**
- * blk_queue_dma_alignment - set dma length and memory alignment
- * @q:     the request queue for the device
- * @mask:  alignment mask
- *
- * description:
- *    set required memory and length aligment for direct dma transactions.
- *    this is used when buiding direct io requests for the queue.
- *
- **/
-void blk_queue_dma_alignment(struct request_queue *q, int mask)
-{
-	q->dma_alignment = mask;
-}
-
-EXPORT_SYMBOL(blk_queue_dma_alignment);
-
-/**
- * blk_queue_update_dma_alignment - update dma length and memory alignment
- * @q:     the request queue for the device
- * @mask:  alignment mask
- *
- * description:
- *    update required memory and length aligment for direct dma transactions.
- *    If the requested alignment is larger than the current alignment, then
- *    the current queue alignment is updated to the new value, otherwise it
- *    is left alone.  The design of this is to allow multiple objects
- *    (driver, device, transport etc) to set their respective
- *    alignments without having them interfere.
- *
- **/
-void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
-{
-	BUG_ON(mask > PAGE_SIZE);
-
-	if (mask > q->dma_alignment)
-		q->dma_alignment = mask;
-}
-
-EXPORT_SYMBOL(blk_queue_update_dma_alignment);
-
 void blk_dump_rq_flags(struct request *rq, char *msg)
 {
 	int bit;
@@ -1074,8 +418,8 @@ static inline int ll_new_hw_segment(struct request_queue *q,
 	return 1;
 }
 
-static int ll_back_merge_fn(struct request_queue *q, struct request *req,
-			    struct bio *bio)
+int ll_back_merge_fn(struct request_queue *q, struct request *req,
+		     struct bio *bio)
 {
 	unsigned short max_sectors;
 	int len;
@@ -1285,7 +629,7 @@ static void blk_backing_dev_unplug(struct backing_dev_info *bdi,
 	blk_unplug(q);
 }
 
-static void blk_unplug_work(struct work_struct *w