block: first step of splitting ll_rw_blk, rename it

Then we retain history in blk-core.c

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

1 files changed, 0 insertions, 4457 deletions

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
deleted file mode 100644
index 1932a56..0000000
--- a/block/ll_rw_blk.c
+++ /dev/null
@@ -1,4457 +0,0 @@
-/*
- * Copyright (C) 1991, 1992 Linus Torvalds
- * Copyright (C) 1994,      Karl Keyte: Added support for disk statistics
- * Elevator latency, (C) 2000  Andrea Arcangeli <andrea@suse.de> SuSE
- * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de>
- * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au> -  July2000
- * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
- */
-
-/*
- * This handles all read/write requests to block devices
- */
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/backing-dev.h>
-#include <linux/bio.h>
-#include <linux/blkdev.h>
-#include <linux/highmem.h>
-#include <linux/mm.h>
-#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>
-#include <linux/writeback.h>
-#include <linux/task_io_accounting_ops.h>
-#include <linux/interrupt.h>
-#include <linux/cpu.h>
-#include <linux/blktrace_api.h>
-#include <linux/fault-inject.h>
-#include <linux/scatterlist.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
- */
-static struct kmem_cache *request_cachep;
-
-/*
- * For queue allocation
- */
-static struct kmem_cache *requestq_cachep;
-
-/*
- * 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
-
-/*
- * Return the threshold (number of used requests) at which the queue is
- * considered to be congested.  It include a little hysteresis to keep the
- * context switch rate down.
- */
-static inline int queue_congestion_on_threshold(struct request_queue *q)
-{
-	return q->nr_congestion_on;
-}
-
-/*
- * The threshold at which a queue is considered to be uncongested
- */
-static inline int queue_congestion_off_threshold(struct request_queue *q)
-{
-	return q->nr_congestion_off;
-}
-
-static void blk_queue_congestion_threshold(struct request_queue *q)
-{
-	int nr;
-
-	nr = q->nr_requests - (q->nr_requests / 8) + 1;
-	if (nr > q->nr_requests)
-		nr = q->nr_requests;
-	q->nr_congestion_on = nr;
-
-	nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
-	if (nr < 1)
-		nr = 1;
-	q->nr_congestion_off = nr;
-}
-
-/**
- * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
- * @bdev:	device
- *
- * Locates the passed device's request queue and returns the address of its
- * backing_dev_info
- *
- * Will return NULL if the request queue cannot be located.
- */
-struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
-{
-	struct backing_dev_info *ret = NULL;
-	struct request_queue *q = bdev_get_queue(bdev);
-
-	if (q)
-		ret = &q->backing_dev_info;
-	return ret;
-}
-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)
-{
-	INIT_LIST_HEAD(&rq->queuelist);
-	INIT_LIST_HEAD(&rq->donelist);
-
-	rq->errors = 0;
-	rq->bio = rq->biotail = NULL;
-	INIT_HLIST_NODE(&rq->hash);
-	RB_CLEAR_NODE(&rq->rb_node);
-	rq->ioprio = 0;
-	rq->buffer = NULL;
-	rq->ref_count = 1;
-	rq->q = q;
-	rq->special = NULL;
-	rq->data_len = 0;
-	rq->data = NULL;
-	rq->nr_phys_segments = 0;
-	rq->sense = NULL;
-	rq->end_io = NULL;
-	rq->end_io_data = NULL;
-	rq->completion_data = NULL;
-	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)
-{
-	struct request_queue *q = rq->q;
-
-	if (&q->bar_rq != rq) {
-		if (error)
-			clear_bit(BIO_UPTODATE, &bio->bi_flags);
-		else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
-			error = -EIO;
-
-		if (unlikely(nbytes > bio->bi_size)) {
-			printk("%s: want %u bytes done, only %u left\n",
-			       __FUNCTION__, nbytes, bio->bi_size);
-			nbytes = bio->bi_size;
-		}
-
-		bio->bi_size -= nbytes;
-		bio->bi_sector += (nbytes >> 9);
-		if (bio->bi_size == 0)
-			bio_endio(bio, error);
-	} else {
-
-		/*
-		 * Okay, this is the barrier request in progress, just
-		 * record the error;
-		 */
-		if (error && !q->orderr)
-			q->orderr = error;
-	}
-}
-
-/**
- * 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);
-
-/**
- * blk_queue_find_tag - find a request by its tag and queue
- * @q:	 The request queue for the device
- * @tag: The tag of the request
- *
- * Notes:
- *    Should be used when a device returns a tag and you want to match
- *    it with a request.
- *
- *    no locks need be held.
- **/
-struct request *blk_queue_find_tag(struct request_queue *q, int tag)
-{
-	return blk_map_queue_find_tag(q->queue_tags, tag);
-}
-
-EXPORT_SYMBOL(blk_queue_find_tag);
-
-/**
- * __blk_free_tags - release a given set of tag maintenance info
- * @bqt:	the tag map to free
- *
- * Tries to free the specified @bqt@.  Returns true if it was
- * actually freed and false if there are still references using it
- */
-static int __blk_free_tags(struct blk_queue_tag *bqt)
-{
-	int retval;
-
-	retval = atomic_dec_and_test(&bqt->refcnt);
-	if (retval) {
-		BUG_ON(bqt->busy);
-
-		kfree(bqt->tag_index);
-		bqt->tag_index = NULL;
-
-		kfree(bqt->tag_map);
-		bqt->tag_map = NULL;
-
-		kfree(bqt);
-
-	}
-
-	return retval;
-}
-
-/**
- * __blk_queue_free_tags - release tag maintenance info
- * @q:  the request queue for the device
- *
- *  Notes:
- *    blk_cleanup_queue() will take care of calling this function, if tagging
- *    has been used. So there's no need to call this directly.
- **/
-static void __blk_queue_free_tags(struct request_queue *q)
-{
-	struct blk_queue_tag *bqt = q->queue_tags;
-
-	if (!bqt)
-		return;
-
-	__blk_free_tags(bqt);
-
-	q->queue_tags = NULL;
-	q->queue_flags &= ~(1 << QUEUE_FLAG_QUEUED);
-}
-
-
-/**
- * blk_free_tags - release a given set of tag maintenance info
- * @bqt:	the tag map to free
- *
- * For externally managed @bqt@ frees the map.  Callers of this
- * function must guarantee to have released all the queues that
- * might have been using this tag map.
- */
-void blk_free_tags(struct blk_queue_tag *bqt)
-{
-	if (unlikely(!__blk_free_tags(bqt)))
-		BUG();
-}
-EXPORT_SYMBOL(blk_free_tags);
-
-/**
- * blk_queue_free_tags - release tag maintenance info
- * @q:  the request queue for the device
- *
- *  Notes:
- *	This is used to disabled tagged queuing to a device, yet leave
- *	queue in function.
- **/
-void blk_queue_free_tags(struct request_queue *q)
-{
-	clear_bit(QUEUE_FLAG_QUEUED, &q->queue_flags);
-}
-
-EXPORT_SYMBOL(blk_queue_free_tags);
-
-static int
-init_tag_map(struct request_queue *q, struct blk_queue_tag *tags, int depth)
-{
-	struct request **tag_index;
-	unsigned long *tag_map;
-	int nr_ulongs;
-
-	if (q && depth > q->nr_requests * 2) {
-		depth = q->nr_requests * 2;
-		printk(KERN_ERR "%s: adjusted depth to %d\n",
-				__FUNCTION__, depth);
-	}
-
-	tag_index = kzalloc(depth * sizeof(struct request *), GFP_ATOMIC);
-	if (!tag_index)
-		goto fail;
-
-	nr_ulongs = ALIGN(depth, BITS_PER_LONG) / BITS_PER_LONG;
-	tag_map = kzalloc(nr_ulongs * sizeof(unsigned long), GFP_ATOMIC);
-	if (!tag_map)
-		goto fail;
-
-	tags->real_max_depth = depth;
-	tags->max_depth = depth;
-	tags->tag_index = tag_index;
-	tags->tag_map = tag_map;
-
-	return 0;
-fail:
-	kfree(tag_index);
-	return -ENOMEM;
-}
-
-static struct blk_queue_tag *__blk_queue_init_tags(struct request_queue *q,
-						   int depth)
-{
-	struct blk_queue_tag *tags;
-
-	tags = kmalloc(sizeof(struct blk_queue_tag), GFP_ATOMIC);
-	if (!tags)
-		goto fail;
-
-	if (init_tag_map(q, tags, depth))
-		goto fail;
-
-	tags->busy = 0;
-	atomic_set(&tags->refcnt, 1);
-	return tags;
-fail:
-	kfree(tags);
-	return NULL;
-}
-
-/**
- * blk_init_tags - initialize the tag info for an external tag map
- * @depth:	the maximum queue depth supported
- * @tags: the tag to use
- **/
-struct blk_queue_tag *blk_init_tags(int depth)
-{
-	return __blk_queue_init_tags(NULL, depth);
-}
-EXPORT_SYMBOL(blk_init_tags);
-
-/**
- * blk_queue_init_tags - initialize the queue tag info
- * @q:  the request queue for the device
- * @depth:  the maximum queue depth supported
- * @tags: the tag to use
- **/
-int blk_queue_init_tags(struct request_queue *q, int depth,
-			struct blk_queue_tag *tags)
-{
-	int rc;
-
-	BUG_ON(tags && q->queue_tags && tags != q->queue_tags);
-
-	if (!tags && !q->queue_tags) {
-		tags = __blk_queue_init_tags(q, depth);
-
-		if (!tags)
-			goto fail;
-	} else if (q->queue_tags) {
-		if ((rc = blk_queue_resize_tags(q, depth)))
-			return rc;
-		set_bit(QUEUE_FLAG_QUEUED, &q->queue_flags);
-		return 0;
-	} else
-		atomic_inc(&tags->refcnt);
-
-	/*
-	 * assign it, all done
-	 */
-	q->queue_tags = tags;
-	q->queue_flags |= (1 << QUEUE_FLAG_QUEUED);
-	INIT_LIST_HEAD(&q->tag_busy_list);
-	return 0;
-fail:
-	kfree(tags);
-	return -ENOMEM;
-}
-
-EXPORT_SYMBOL(blk_queue_init_tags);
-
-/**
- * blk_queue_resize_tags - change the queueing depth
- * @q:  the request queue for the device
- * @new_depth: the new max command queueing depth
- *
- *  Notes:
- *    Must be called with the queue lock held.
- **/
-int blk_queue_resize_tags(struct request_queue *q, int new_depth)
-{
-	struct blk_queue_tag *bqt = q->queue_tags;
-	struct request **tag_index;
-	unsigned long *tag_map;
-	int max_depth, nr_ulongs;
-
-	if (!bqt)
-		return -ENXIO;
-
-	/*
-	 * if we already have large enough real_max_depth.  just
-	 * adjust max_depth.  *NOTE* as requests with tag value
-	 * between new_depth and real_max_depth can be in-flight, tag
-	 * map can not be shrunk blindly here.
-	 */
-	if (new_depth <= bqt->real_max_depth) {
-		bqt->max_depth = new_depth;
-		return 0;
-	}
-
-	/*
-	 * Currently cannot replace a shared tag map with a new
-	 * one, so error out if this is the case
-	 */
-	if (atomic_read(&bqt->refcnt) != 1)
-		return -EBUSY;
-
-	/*
-	 * save the old state info, so we can copy it back
-	 */
-	tag_index = bqt->tag_index;
-	tag_map = bqt->tag_map;
-	max_depth = bqt->real_max_depth;
-
-	if (init_tag_map(q, bqt, new_depth))
-		return -ENOMEM;
-
-	memcpy(bqt->tag_index, tag_index, max_depth * sizeof(struct request *));
-	nr_ulongs = ALIGN(max_depth, BITS_PER_LONG) / BITS_PER_LONG;
-	memcpy(bqt->tag_map, tag_map, nr_ulongs * sizeof(unsigned long));
-
-	kfree(tag_index);
-	kfree(tag_map);
-	return 0;
-}
-
-EXPORT_SYMBOL(blk_queue_resize_tags);
-
-/**
- * blk_queue_end_tag - end tag operations for a request
- * @q:  the request queue for the device
- * @rq: the request that has completed
- *
- *  Description:
- *    Typically called when end_that_request_first() returns 0, meaning
- *    all transfers have been done for a request. It's important to call
- *    this function before end_that_request_last(), as that will put the
- *    request back on the free list thus corrupting the internal tag list.
- *
- *  Notes:
- *   queue lock must be held.
- **/
-void blk_queue_end_tag(struct request_queue *q, struct request *rq)
-{
-	struct blk_queue_tag *bqt = q->queue_tags;
-	int tag = rq->tag;
-
-	BUG_ON(tag == -1);
-
-	if (unlikely(tag >= bqt->real_max_depth))
-		/*
-		 * This can happen after tag depth has been reduced.
-		 * FIXME: how about a warning or info message here?
-		 */
-		return;
-
-	list_del_init(&rq->queuelist);
-	rq->cmd_flags &= ~REQ_QUEUED;
-	rq->tag = -1;
-
-	if (unlikely(bqt->tag_index[tag] == NULL))
-		printk(KERN_ERR "%s: tag %d is missing\n",
-		       __FUNCTION__, tag);
-
-	bqt->tag_index[tag] = NULL;
-
-	if (unlikely(!test_bit(tag, bqt->tag_map))) {
-		printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n",
-		       __FUNCTION__, tag);
-		return;
-	}
-	/*
-	 * The tag_map bit acts as a lock for tag_index[bit], so we need
-	 * unlock memory barrier semantics.
-	 */
-	clear_bit_unlock(tag, bqt->tag_map);
-	bqt->busy--;
-}
-
-EXPORT_SYMBOL(blk_queue_end_tag);
-
-/**
- * blk_queue_start_tag - find a free tag and assign it
- * @q:  the request queue for the device
- * @rq:  the block request that needs tagging
- *
- *  Description:
- *    This can either be used as a stand-alone helper, or possibly be
- *    assigned as the queue &prep_rq_fn (in which case &struct request
- *    automagically gets a tag assigned). Note that this function
- *    assumes that any type of request can be queued! if this is not
- *    true for your device, you must check the request type before
- *    calling this function.  The request will also be removed from
- *    the request queue, so it's the drivers responsibility to readd
- *    it if it should need to be restarted for some reason.
- *
- *  Notes:
- *   queue lock must be held.
- **/
-int blk_queue_start_tag(struct request_queue *q, struct request *rq)
-{
-	struct blk_queue_tag *bqt = q->queue_tags;
-	int tag;
-
-	if (unlikely((rq->cmd_flags & REQ_QUEUED))) {
-		printk(KERN_ERR 
-		       "%s: request %p for device [%s] already tagged %d",
-		       __FUNCTION__, rq,
-		       rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->tag);
-		BUG();
-	}
-
-	/*
-	 * Protect against shared tag maps, as we may not have exclusive
-	 * access to the tag map.
-	 */
-	do {
-		tag = find_first_zero_bit(bqt->tag_map, bqt->max_depth);
-		if (tag >= bqt->max_depth)
-			return 1;
-
-	} while (test_and_set_bit_lock(tag, bqt->tag_map));
-	/*
-	 * We need lock ordering semantics given by test_and_set_bit_lock.
-	 * See blk_queue_end_tag for details.
-	 */
-
-	rq->cmd_flags |= REQ_QUEUED;
-	rq->tag = tag;
-	bqt->tag_index[tag] = rq;
-	blkdev_dequeue_request(rq);
-	list_add(&rq->queuelist, &q->tag_busy_list);
-	bqt->busy++;
-	return 0;
-}
-
-EXPORT_SYMBOL(blk_queue_start_tag);
-
-/**
- * blk_queue_invalidate_tags - invalidate all pending tags
- * @q:  the request queue for the device
- *
- *  Description:
- *   Hardware conditions may dictate a need to stop all pending requests.
- *   In this case, we will safely clear the block side of the tag queue and
- *   readd all requests to the request queue in the right order.
- *
- *  Notes:
- *   queue lock must be held.
- **/
-void blk_queue_invalidate_tags(struct request_queue *q)
-{
-	struct list_head *tmp, *n;
-
-	list_for_each_safe(tmp, n, &q->tag_busy_list)
-		blk_requeue_request(q, list_entry_rq(tmp));
-}
-
-EXPORT_SYMBOL(blk_queue_invalidate_tags);
-
-void blk_dump_rq_flags(struct request *rq, char *msg)
-{
-	int bit;
-
-	printk("%s: dev %s: type=%x, flags=%x\n", msg,
-		rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type,
-		rq->cmd_flags);
-
-	printk("\nsector %llu, nr/cnr %lu/%u\n", (unsigned long long)rq->sector,
-						       rq->nr_sectors,
-						       rq->current_nr_sectors);
-	printk("bio %p, biotail %p, buffer %p, data %p, len %u\n", rq->bio, rq->biotail, rq->buffer, rq->data, rq->data_len);
-
-	if (blk_pc_request(rq)) {
-		printk("cdb: ");
-		for (bit = 0; bit < sizeof(rq->cmd); bit++)
-			printk("%02x ", rq->cmd[bit]);
-		printk("\n");
-	}
-}
-
-EXPORT_SYMBOL(blk_dump_rq_flags);
-
-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_next = nxt;
-	bio->bi_phys_segments = rq.nr_phys_segments;
-	bio->bi_hw_segments = rq.nr_hw_segments;
-	bio->bi_flags |= (1 << BIO_SEG_VALID);
-}
-EXPORT_SYMBOL(blk_recount_segments);
-
-static void blk_recalc_rq_segments(struct request *rq)
-{
-	int nr_phys_segs;
-	int nr_hw_segs;
-	unsigned int phys_size;
-	unsigned int hw_size;
-	struct bio_vec *bv, *bvprv = NULL;
-	int seg_size;
-	int hw_seg_size;
-	int cluster;
-	struct req_iterator iter;
-	int high, highprv = 1;
-	struct request_queue *q = rq->q;
-
-	if (!rq->bio)
-		return;
-
-	cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
-	hw_seg_size = seg_size = 0;
-	phys_size = hw_size = nr_phys_segs = nr_hw_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_hw_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;
-			if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len))
-				goto new_hw_segment;
-
-			seg_size += bv->bv_len;
-			hw_seg_size += bv->bv_len;
-			bvprv = bv;
-			continue;
-		}
-new_segment:
-		if (BIOVEC_VIRT_MERGEABLE(bvprv, bv) &&
-		    !BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len))
-			hw_seg_size += bv->bv_len;
-		else {
-new_hw_segment:
-			if (nr_hw_segs == 1 &&
-			    hw_seg_size > rq->bio->bi_hw_front_size)
-				rq->bio->bi_hw_front_size = hw_seg_size;
-			hw_seg_size = BIOVEC_VIRT_START_SIZE(bv) + bv->bv_len;
-			nr_hw_segs++;
-		}
-
-		nr_phys_segs++;
-		bvprv = bv;
-		seg_size = bv->bv_len;
-		highprv = high;
-	}
-
-	if (nr_hw_segs == 1 &&
-	    hw_seg_size > rq->bio->bi_hw_front_size)
-		rq->bio->bi_hw_front_size = hw_seg_size;
-	if (hw_seg_size > rq->biotail->bi_hw_back_size)
-		rq->biotail->bi_hw_back_size = hw_seg_size;
-	rq->nr_phys_segments = nr_phys_segs;
-	rq->nr_hw_segments = nr_hw_segs;
-}
-
-static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
-				   struct bio *nxt)
-{
-	if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER)))
-		return 0;
-
-	if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)))
-		return 0;
-	if (bio->bi_size + nxt->bi_size > q->max_segment_size)
-		return 0;
-
-	/*
-	 * bio and nxt are contigous in memory, check if the queue allows
-	 * these two to be merged into one
-	 */
-	if (BIO_SEG_BOUNDARY(q, bio, nxt))
-		return 1;
-
-	return 0;
-}
-
-static int blk_hw_contig_segment(struct request_queue *q, struct bio *bio,
-				 struct bio *nxt)
-{
-	if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
-		blk_recount_segments(q, bio);
-	if (unlikely(!bio_flagged(nxt, BIO_SEG_VALID)))
-		blk_recount_segments(q, nxt);
-	if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)) ||
-	    BIOVEC_VIRT_OVERSIZE(bio->bi_hw_back_size + nxt->bi_hw_front_size))
-		return 0;
-	if (bio->bi_hw_back_size + nxt->bi_hw_front_size > q->max_segment_size)
-		return 0;
-
-	return 1;
-}
-
-/*
- * map a request to scatterlist, return number of sg entries setup. Caller
- * must make sure sg can hold rq->nr_phys_segments entries
- */
-int blk_rq_map_sg(struct request_queue *q, struct request *rq,
-		  struct scatterlist *sglist)
-{
-	struct bio_vec *bvec, *bvprv;
-	struct req_iterator iter;
-	struct scatterlist *sg;
-	int nsegs, cluster;
-
-	nsegs = 0;
-	cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
-
-	/*
-	 * for each bio in rq
-	 */
-	bvprv = NULL;
-	sg = NULL;
-	rq_for_each_segment(bvec, rq, iter) {
-		int nbytes = bvec->bv_len;
-
-		if (bvprv && cluster) {
-			if (sg->length + nbytes > q->max_segment_size)
-				goto new_segment;
-
-			if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec))
-				goto new_segment;
-			if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec))
-				goto new_segment;
-
-			sg->length += nbytes;
-		} else {
-new_segment:
-			if (!sg)
-				sg = sglist;
-			else {
-				/*
-				 * If the driver previously mapped a shorter
-				 * list, we could see a termination bit
-				 * prematurely unless it fully inits the sg
-				 * table on each mapping. We KNOW that there
-				 * must be more entries here or the driver
-				 * would be buggy, so force clear the
-				 * termination bit to avoid doing a full
-				 * sg_init_table() in drivers for each command.
-				 */
-				sg->page_link &= ~0x02;
-				sg = sg_next(sg);
-			}
-
-			sg_set_page(sg, bvec->bv_page, nbytes, bvec->bv_offset);
-			nsegs++;
-		}
-		bvprv = bvec;
-	} /* segments in rq */
-
-	if (q->dma_drain_size) {
-		sg->page_link &= ~0x02;
-		sg = sg_next(sg);
-		sg_set_page(sg, virt_to_page(q->dma_drain_buffer),
-			    q->dma_drain_size,
-			    ((unsigned long)q->dma_drain_buffer) &
-			    (PAGE_SIZE - 1));
-		nsegs++;
-	}
-
-	if (sg)
-		sg_mark_end(sg);
-
-	return nsegs;
-}
-
-EXPORT_SYMBOL(blk_rq_map_sg);
-
-/*
- * the standard queue merge functions, can be overridden with device
- * specific ones if so desired
- */
-
-static inline int ll_new_mergeable(struct request_queue *q,
-				   struct request *req,
-				   struct bio *bio)
-{
-	int nr_phys_segs = bio_phys_segments(q, bio);
-
-	if (req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) {
-		req->cmd_flags |= REQ_NOMERGE;
-		if (req == q->last_merge)
-			q->last_merge = NULL;
-		return 0;
-	}
-
-	/*
-	 * A hw segment is just getting larger, bump just the phys
-	 * counter.
-	 */
-	req->nr_phys_segments += nr_phys_segs;
-	return 1;
-}
-
-static inline int ll_new_hw_segment(struct request_queue *q,
-				    struct request *req,
-				    struct bio *bio)
-{
-	int nr_hw_segs = bio_hw_segments(q, bio);
-	int nr_phys_segs = bio_phys_segments(q, bio);
-
-	if (req->nr_hw_segments + nr_hw_segs > q->max_hw_segments
-	    || req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) {
-		req->cmd_flags |= REQ_NOMERGE;
-		if (req == q->last_merge)
-			q->last_merge = NULL;
-		return 0;
-	}
-
-	/*
-	 * This will form the start of a new hw segment.  Bump both
-	 * counters.
-	 */
-	req->nr_hw_segments += nr_hw_segs;
-	req->nr_phys_segments += nr_phys_segs;
-	return 1;
-}
-
-static int ll_back_merge_fn(struct request_queue *q, struct request *req,
-			    struct bio *bio)
-{
-	unsigned short max_sectors;
-	int len;
-
-	if (unlikely(blk_pc_request(req)))
-		max_sectors = q->max_hw_sectors;
-	else
-		max_sectors = q->max_sectors;
-
-	if (req->nr_sectors + bio_sectors(bio) > max_sectors) {
-		req->cmd_flags |= REQ_NOMERGE;
-		if (req == q->last_merge)
-			q->last_merge = NULL;
-		return 0;
-	}
-	if (unlikely(!bio_flagged(req->biotail, BIO_SEG_VALID)))
-		blk_recount_segments(q, req->biotail);
-	if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
-		blk_recount_segments(q, bio);
-	len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size;
-	if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio)) &&
-	    !BIOVEC_VIRT_OVERSIZE(len)) {
-		int mergeable =  ll_new_mergeable(q, req, bio);
-
-		if (mergeable) {
-			if (req->nr_hw_segments == 1)
-				req->bio->bi_hw_front_size = len;
-			if (bio->bi_hw_segments == 1)
-				bio->bi_hw_back_size = len;
-		}
-		return mergeable;
-	}
-
-	return ll_new_hw_segment(q, req, bio);
-}
-
-static int ll_front_merge_fn(struct request_queue *q, struct request *req, 
-			     struct bio *bio)
-{
-	unsigned short max_sectors;
-	int len;
-
-	if (unlikely(blk_pc_request(req)))
-		max_sectors = q->max_hw_sectors;
-	else
-		max_sectors = q->max_sectors;
-
-
-	if (req->nr_sectors + bio_sectors(bio) > max_sectors) {
-		req->cmd_flags |= REQ_NOMERGE;
-		if (req == q->last_merge)
-			q->last_merge = NULL;
-		return 0;
-	}
-	len = bio->bi_hw_back_size + req->bio->bi_hw_front_size;
-	if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
-		blk_recount_segments(q, bio);
-	if (unlikely(!bio_flagged(req->bio, BIO_SEG_VALID)))
-		blk_recount_segments(q, req->bio);
-	if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) &&
-	    !BIOVEC_VIRT_OVERSIZE(len)) {
-		int mergeable =  ll_new_mergeable(q, req, bio);
-
-		if (mergeable) {
-			if (bio->bi_hw_segments == 1)
-				bio->bi_hw_front_size = len;
-			if (req->nr_hw_segments == 1)
-				req->biotail->bi_hw_back_size = len;
-		}
-		return mergeable;
-	}
-
-	return ll_new_hw_segment(q, req, bio);
-}
-
-static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
-				struct request *next)
-{
-	int total_phys_segments;
-	int total_hw_segments;
-
-	/*
-	 * First check if the either of the requests are re-queued
-	 * requests.  Can't merge them if they are.
-	 */
-	if (req->special || next->special)
-		return 0;
-
-	/*
-	 * Will it become too large?
-	 */
-	if ((req->nr_sectors + next->nr_sectors) > q->max_sectors)
-		return 0;
-
-	total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
-	if (blk_phys_contig_segment(q, req->biotail, next->bio))
-		total_phys_segments--;
-
-	if (total_phys_segments > q->max_phys_segments)
-		return 0;
-
-	total_hw_segments = req->nr_hw_segments + next->nr_hw_segments;
-	if (blk_hw_contig_segment(q, req->biotail, next->bio)) {
-		int len = req->biotail->bi_hw_back_size + next->bio->bi_hw_front_size;
-		/*
-		 * propagate the combined length to the end of the requests
-		 */
-		if (req->nr_hw_segments == 1)
-			req->bio->bi_hw_front_size = len;
-		if (next->nr_hw_segments == 1)
-			next->biotail->bi_hw_back_size = len;
-		total_hw_segments--;
-	}
-
-	if (total_hw_segments > q->max_hw_segments)
-		return 0;
-
-	/* Merge is OK... */
-	req->nr_phys_segments = total_phys_segments;
-	req->nr_hw_segments = total_hw_segments;
-	return 1;
-}
-
-/*
- * "plug" the device if there are no outstanding requests: this will
- * force the transfer to start only after we have put all the requests
- * on the list.
- *
- * This is called with interrupts off and no requests on the queue and
- * with the queue lock held.
- */
-void blk_plug_device(struct request_queue *q)
-{
-	WARN_ON(!irqs_disabled());
-
-	/*
-	 * don't plug a stopped queue, it must be paired with blk_start_queue()
-	 * which will restart the queueing
-	 */
-	if (blk_queue_stopped(q))
-		return;
-
-	if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) {
-		mod_timer(&q->unplug_timer, jiffies + q->unplug_delay);
-		blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG);
-	}
-}
-
-EXPORT_SYMBOL(blk_plug_device);
-
-/*
- * remove the queue from the plugged list, if present. called with
- * queue lock held and interrupts disabled.
- */
-int blk_remove_plug(struct request_queue *q)
-{
-	WARN_ON(!irqs_disabled());
-
-	if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags))
-		return 0;
-
-	del_timer(&q->unplug_timer);
-	return 1;
-}
-
-EXPORT_SYMBOL(blk_remove_plug);
-
-/*
- * remove the plug and let it rip..
- */
-void __generic_unplug_device(struct request_queue *q)
-{
-	if (unlikely(blk_queue_stopped(q)))
-		return;
-
-	if (!blk_remove_plug(q))
-		return;
-
-	q->request_fn(q);
-}
-EXPORT_SYMBOL(__generic_unplug_device);
-
-/**
- * generic_unplug_device - fire a request queue
- * @q:    The &struct request_queue in question
- *
- * Description:
- *   Linux uses plugging to build bigger requests queues before letting
- *   the device have at them. If a queue is plugged, the I/O scheduler
- *   is still adding and merging requests on the queue. Once the queue
- *   gets unplugged, the request_fn defined for the queue is invoked and
- *   transfers started.
- **/
-void generic_unplug_device(struct request_queue *q)
-{
-	spin_lock_irq(q->queue_lock);
-	__generic_unplug_device(q);
-	spin_unlock_irq(q->queue_lock);
-}
-EXPORT_SYMBOL(generic_unplug_device);
-
-static void blk_backing_dev_unplug(struct backing_dev_info *bdi,
-				   struct page *page)
-{
-	struct request_queue *q = bdi->unplug_io_data;
-
-	blk_unplug(q);
-}
-
-static void blk_unplug_work(struct work_struct *work)
-{
-	struct request_queue *q =
-		container_of(work, struct request_queue, unplug_work);
-
-	blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL,
-				q->rq.count[READ] + q->rq.count[WRITE]);
-
-	q->unplug_fn(q);
-}
-
-static void blk_unplug_timeout(unsigned long data)
-{
-	struct request_queue *q = (struct request_queue *)data;
-
-	blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_TIMER, NULL,
-				q->rq.count[READ] + q->rq.count[WRITE]);
-
-	kblockd_schedule_work(&q->unplug_work);
-}
-
-void blk_unplug(struct request_queue *q)
-{
-	/*
-	 * devices don't necessarily have an ->unplug_fn defined
-	 */
-	if (q->unplug_fn) {
-		blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL,
-					q->rq.count[READ] + q->rq.count[WRITE]);
-
-		q->unplug_fn(q);
-	}
-}
-EXPORT_SYMBOL(blk_unplug);
-
-/**
- * blk_start_queue - restart a previously stopped queue
- * @q:    The &struct request_queue in question
- *
- * Description:
- *   blk_start_queue() will clear the stop flag on the queue, and call
- *   the request_fn for the queue if it was in a stopped state when
- *   entered. Also see blk_stop_queue(). Queue lock must be held.
- **/
-void blk_start_queue(struct request_queue *q)
-{
-	WARN_ON(!irqs_disabled());
-
-	clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
-
-	/*
-	 * one level of recursion is ok and is much faster than kicking
-	 * the unplug handling
-	 */
-	if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
-		q->request_fn(q);
-		clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags);
-	} else {
-		blk_plug_device(q);
-		kblockd_schedule_work(&q->unplug_work);
-	}
-}
-
-EXPORT_SYMBOL(blk_start_queue);
-
-/**
- * blk_stop_queue - stop a queue
- * @q:    The &struct request_queue in question
- *
- * Description:
- *   The Linux block layer assumes that a block driver will consume all
- *   entries on the request queue when the request_fn strategy is called.
- *   Often this will not happen, because of hardware limitations (queue
- *   depth settings). If a device driver gets a 'queue full' response,
- *   or if it simply chooses not to queue more I/O at one point, it can
- *   call this function to prevent the request_fn from being called until
- *   the driver has signalled it's ready to go again. This happens by calling
- *   blk_start_queue() to restart queue operations. Queue lock must be held.
- **/
-void blk_stop_queue(struct request_queue *q)
-{
-	blk_remove_plug(q);
-	set_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
-}
-EXPORT_SYMBOL(blk_stop_queue);
-
-/**
- * blk_sync_queue - cancel any pending callbacks on a queue
- * @q: the queue
- *
- * Description:
- *     The block layer may perform asynchronous callback activity
- *     on a queue, such as calling the unplug function after a timeout.
- *     A block device may call blk_sync_queue to ensure that any
- *     such activity is cancelled, thus allowing it to release resources
- *     that the callbacks might use. The caller must already have made sure
- *     that its ->make_request_fn will not re-add plugging prior to calling
- *     this function.
- *
- */
-void blk_sync_queue(struct request_queue *q)
-{
-	del_timer_sync(&q->unplug_timer);
-	kblockd_flush_work(&q->unplug_work);
-}
-EXPORT_SYMBOL(blk_sync_queue);
-
-/**
- * blk_run_queue - run a single device queue
- * @q:	The queue to run
- */
-void blk_run_queue(struct request_queue *q)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(q->queue_lock, flags);
-	blk_remove_plug(q);
-
-	/*
-	 * Only recurse once to avoid overrunning the stack, let the unplug
-	 * handling reinvoke the handler shortly if we already got there.
-	 */
-	if (!elv_queue_empty(q)) {
-		if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
-			q->request_fn(q);
-			clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags);
-		} else {
-			blk_plug_device(q);
-			kblockd_schedule_work(&q->unplug_work);
-		}
-	}
-
-	spin_unlock_irqrestore(q->queue_lock, flags);
-}
-EXPORT_SYMBOL(blk_run_queue);
-
-/**
- * blk_cleanup_queue: - release a &struct request_queue when it is no longer needed
- * @kobj:    the kobj belonging of the request queue to be released
- *
- * Description:
- *     blk_cleanup_queue is the pair to blk_init_queue() or
- *     blk_queue_make_request().  It should be called when a request queue is
- *     being released; typically when a block device is being de-registered.
- *     Currently, its primary task it to free all the &struct request
- *     structures that were allocated to the queue and the queue itself.
- *
- * Caveat:
- *     Hopefully the low level driver will have finished any
- *     outstanding requests first...
- **/
-static void blk_release_queue(struct kobject *kobj)
-{
-	struct request_queue *q =
-		container_of(kobj, struct request_queue, kobj);
-	struct request_list *rl = &q->rq;
-
-	blk_sync_queue(q);
-
-	if (rl->rq_pool)
-		mempool_destroy(rl->rq_pool);
-
-	if (q->queue_tags)
-		__blk_queue_free_tags(q);
-
-	blk_trace_shutdown(q);
-
-	bdi_destroy(&q->backing_dev_info);
-	kmem_cache_free(requestq_cachep, q);
-}
-
-void blk_put_queue(struct request_queue *q)
-{
-	kobject_put(&q->kobj);
-}
-EXPORT_SYMBOL(blk_put_queue);
-
-void blk_cleanup_queue(struct request_queue * q)
-{
-	mutex_lock(&q->sysfs_lock);
-	set_bit(QUEUE_FLAG_DEAD, &q->queue_flags);
-	mutex_unlock(&q->sysfs_lock);
-
-	if (q->elevator)
-		elevator_exit(q->elevator);
-
-	blk_put_queue(q);
-}
-
-EXPORT_SYMBOL(blk_cleanup_queue);
-
-static int blk_init_free_list(struct request_queue *q)
-{
-	struct request_list *rl = &q->rq;
-
-	rl->count[READ] = rl->count[WRITE] = 0;
-	rl->starved[READ] = rl->starved[WRITE] = 0;
-	rl->elvpriv = 0;
-	init_waitqueue_head(&rl->wait[READ]);
-	init_waitqueue_head(&rl->wait[WRITE]);
-
-	rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
-				mempool_free_slab, request_cachep, q->node);
-
-	if (!rl->rq_pool)
-		return -ENOMEM;
-
-	return 0;
-}
-
-struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
-{
-	return blk_alloc_queue_node(gfp_mask, -1);
-}
-EXPORT_SYMBOL(blk_alloc_queue);
-
-static struct kobj_type queue_ktype;
-
-struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
-{
-	struct request_queue *q;
-	int err;
-
-	q = kmem_cache_alloc_node(requestq_cachep,
-				gfp_mask | __GFP_ZERO, node_id);
-	if (!q)
-		return NULL;
-
-	q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug;
-	q->backing_dev_info.unplug_io_data = q;
-	err = bdi_init(&q->backing_dev_info);
-	if (err) {
-		kmem_cache_free(requestq_cachep, q);
-		return NULL;
-	}
-
-	init_timer(&q->unplug_timer);
-
-	kobject_init(&q->kobj, &queue_ktype);
-
-	mutex_init(&q->sysfs_lock);
-
-	return q;
-}
-EXPORT_SYMBOL(blk_alloc_queue_node);
-
-/**
- * blk_init_queue  - prepare a request queue for use with a block device
- * @rfn:  The function to be called to process requests that have been
- *        placed on the queue.
- * @lock: Request queue spin lock
- *
- * Description:
- *    If a block device wishes to use the standard request handling procedures,
- *    which sorts requests and coalesces adjacent requests, then it must
- *    call blk_init_queue().  The function @rfn will be called when there
- *    are requests on the queue that need to be processed.  If the device
- *    supports plugging, then @rfn may not be called immediately when requests
- *    are available on the queue, but may be called at some time later instead.
- *    Plugged queues are generally unplugged when a buffer belonging to one
- *    of the requests on the queue is needed, or due to memory pressure.
- *
- *    @rfn is not required, or even expected, to remove all requests off the
- *    queue, but only as many as it can handle at a time.  If it does leave
- *    requests on the queue, it is responsible for arranging that the requests
- *    get dealt with eventually.
- *
- *    The queue spin lock must be held while manipulating the requests on the
- *    request queue; this lock will be taken also from interrupt context, so irq
- *    disabling is needed for it.
- *
- *    Function returns a pointer to the initialized request queue, or NULL if
- *    it didn't succeed.
- *
- * Note:
- *    blk_init_queue() must be paired with a blk_cleanup_queue() call
- *    when the block device is deactivated (such as at module unload).
- **/
-
-struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
-{
-	return blk_init_queue_node(rfn, lock, -1);
-}
-EXPORT_SYMBOL(blk_init_queue);
-
-struct request_queue *
-blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
-{
-	struct request_queue *q = blk_alloc_queue_node(GFP_KERNEL, node_id);
-
-	if (!q)
-		return NULL;
-
-	q->node = node_id;
-	if (blk_init_free_list(q)) {
-		kmem_cache_free(requestq_cachep, q);
-		return NULL;
-	}
-
-	/*
-	 * if caller didn't supply a lock, they get per-queue locking with
-	 * our embedded lock
-	 */
-	if (!lock) {
-		spin_lock_init(&q->__queue_lock);
-		lock = &q->__queue_lock;
-	}
-
-	q->request_fn		= rfn;
-	q->prep_rq_fn		= NULL;
-	q->unplug_fn		= generic_unplug_device;
-	q->queue_flags		= (1 << QUEUE_FLAG_CLUSTER);
-	q->queue_lock		= lock;
-
-	blk_queue_segment_boundary(q, 0xffffffff);
-
-	blk_queue_make_request(q, __make_request);
-	blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE);
-
-	blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
-	blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
-
-	q->sg_reserved_size = INT_MAX;
-
-	/*
-	 * all done
-	 */
-	if (!elevator_init(q, NULL)) {
-		blk_queue_congestion_threshold(q);
-		return q;
-	}
-
-	blk_put_queue(q);
-	return NULL;
-}
-EXPORT_SYMBOL(blk_init_queue_node);
-
-int blk_get_queue(struct request_queue *q)
-{
-	if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
-		kobject_get(&q->kobj);
-		return 0;
-	}
-
-	return 1;
-}
-
-EXPORT_SYMBOL(blk_get_queue);
-
-static inline void blk_free_request(struct request_queue *q, struct request *rq)
-{
-	if (rq->cmd_flags & REQ_ELVPRIV)
-		elv_put_request(q, rq);
-	mempool_free(rq, q->rq.rq_pool);
-}
-
-static struct request *
-blk_alloc_request(struct request_queue *q, int rw, int priv, gfp_t gfp_mask)
-{
-	struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask);
-
-	if (!rq)
-		return NULL;
-
-	/*
-	 * first three bits are identical in rq->cmd_flags and bio->bi_rw,
-	 * see bio.h and blkdev.h
-	 */
-	rq->cmd_flags = rw | REQ_ALLOCED;
-
-	if (priv) {
-		if (unlikely(elv_set_request(q, rq, gfp_mask))) {
-			mempool_free(rq, q->rq.rq_pool);
-			return NULL;
-		}
-		rq->cmd_flags |= REQ_ELVPRIV;
-	}
-
-	return rq;
-}
-
-/*
- * ioc_batching returns true if the ioc is a valid batching request and
- * should be given priority access to a request.
- */
-static inline int ioc_batching(struct request_queue *q, struct io_context *ioc)
-{
-	if (!ioc)
-		return 0;
-
-	/*
-	 * Make sure the process is able to allocate at least 1 request
-	 * even if the batch times out, otherwise we could theoretically
-	 * lose wakeups.
-	 */
-	return ioc->nr_batch_requests == q->nr_batching ||
-		(ioc->nr_batch_requests > 0
-		&& time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
-}
-
-/*
- * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
- * will cause the process to be a "batcher" on all queues in the system. This
- * is the behaviour we want though - once it gets a wakeup it should be given
- * a nice run.
- */
-static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
-{
-	if (!ioc || ioc_batching(q, ioc))
-		return;
-
-	ioc->nr_batch_requests = q->nr_batching;
-	ioc->last_waited = jiffies;
-}
-
-static void __freed_request(struct request_queue *q, int rw)
-{
-	struct request_list *rl = &q->rq;
-
-	if (rl->count[rw] < queue_congestion_off_threshold(q))
-		blk_clear_queue_congested(q, rw);
-
-	if (rl->count[rw] + 1 <= q->nr_requests) {
-		if (waitqueue_active(&rl->wait[rw]))
-			wake_up(&rl->wait[rw]);
-
-		blk_clear_queue_full(q, rw);
-	}
-}
-
-/*
- * A request has just been released.  Account for it, update the full and
- * congestion status, wake up any waiters.   Called under q->queue_lock.
- */
-static void freed_request(struct request_queue *q, int rw, int priv)
-{
-	struct request_list *rl = &q->rq;
-
-	rl->count[rw]--;
-	if (priv)
-		rl->elvpriv--;
-
-	__freed_request(q, rw);
-
-	if (unlikely(rl->starved[rw ^ 1]))
-		__freed_request(q, rw ^ 1);
-}
-
-#define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist)
-/*
- * Get a free request, queue_lock must be held.
- * Returns NULL on failure, with queue_lock held.
- * Returns !NULL on success, with queue_lock *not held*.
- */
-static struct request *get_request(struct request_queue *q, int rw_flags,
-				   struct bio *bio, gfp_t gfp_mask)
-{
-	struct request *rq = NULL;
-	struct request_list *rl = &q->rq;
-	struct io_context *ioc = NULL;
-	const int rw = rw_flags & 0x01;
-	int may_queue, priv;
-
-	may_queue = elv_may_queue(q, rw_flags);
-	if (may_queue == ELV_MQUEUE_NO)
-		goto rq_starved;
-
-	if (rl->count[rw]+1 >= queue_congestion_on_threshold(q)) {
-		if (rl->count[rw]+1 >= q->nr_requests) {
-			ioc = current_io_context(GFP_ATOMIC, q->node);
-			/*
-			 * 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;
-				}
-			}
-		}
-		blk_set_queue_congested(q, rw);
-	}
-
-	/*
-	 * Only allow batching queuers to allocate up to 50% over the defined
-	 * limit of requests, otherwise we could have thousands of requests
-	 * allocated with any setting of ->nr_requests
-	 */
-	if (rl->count[rw] >= (3 * q->nr_requests / 2))
-		goto out;
-
-	rl->count[rw]++;
-	rl->starved[rw] = 0;
-
-	priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
-	if (priv)
-		rl->elvpriv++;
-
-	spin_unlock_irq(q->queue_lock);
-
-	rq = blk_alloc_request(q, rw_flags, priv, gfp_mask);
-	if (unlikely(!rq)) {
-		/*
-		 * Allocation failed presumably due to memory. Undo anything
-		 * we might have messed up.
-		 *
-		 * Allocating task should really be put onto the front of the
-		 * wait queue, but this is pretty rare.
-		 */
-		spin_lock_irq(q->queue_lock);
-		freed_request(q, rw, priv);
-
-		/*
-		 * in the very unlikely event that allocation failed and no
-		 * requests for this direction was pending, mark us starved
-		 * so that freeing of a request in the other direction will
-		 * notice us. another possible fix would be to split the
-		 * rq mempool into READ and WRITE
-		 */
-rq_starved:
-		if (unlikely(rl->count[rw] == 0))
-			rl->starved[rw] = 1;
-
-		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--;
-	
-	rq_init(q, rq);
-
-	blk_add_trace_generic(q, bio, rw, BLK_TA_GETRQ);
-out:
-	return rq;
-}
-
-/*
- * No available requests for this queue, unplug the device and wait for some
- * requests to become available.
- *
- * Called with q->queue_lock held, and returns with it unlocked.
- */
-static struct request *get_request_wait(struct request_queue *q, int rw_flags,
-					struct bio *bio)
-{
-	const int rw = rw_flags & 0x01;
-	struct request *rq;
-
-	rq = get_request(q, rw_flags, bio, GFP_NOIO);
-	while (!rq) {
-		DEFINE_WAIT(wait);
-		struct request_list *rl = &q->rq;
-
-		prepare_to_wait_exclusive(&rl->wait[rw], &wait,
-				TASK_UNINTERRUPTIBLE);
-
-		rq = get_request(q, rw_flags, bio, GFP_NOIO);
-
-		if (!rq) {
-			struct io_context *ioc;
-
-			blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ);
-
-			__generic_unplug_device(q);
-			spin_unlock_irq(q->queue_lock);
-			io_schedule();
-
-			/*
-			 * After sleeping, we become a "batching" process and
-			 * will be able to allocate at least one request, and
-			 * up to a big batch of them for a small period time.
-			 * See ioc_batching, ioc_set_batching
-			 */
-			ioc = current_io_context(GFP_NOIO, q->node);
-			ioc_set_batching(q, ioc);
-
-			spin_lock_irq(q->queue_lock);
-		}
-		finish_wait(&rl->wait[rw], &wait);
-	}
-
-	return rq;
-}
-
-struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
-{
-	struct request *rq;
-
-	BUG_ON(rw != READ && rw != WRITE);
-
-	spin_lock_irq(q->queue_lock);
-	if (gfp_mask & __GFP_WAIT) {
-		rq = get_request_wait(q, rw, NULL);
-	} else {
-		rq = get_request(q, rw, NULL, gfp_mask);
-		if (!rq)
-			spin_unlock_irq(q->queue_lock);
-	}
-	/* q->queue_lock is unlocked at this point */
-
-	return rq;
-}
-EXPORT_SYMBOL(blk_get_request);
-
-/**
- * blk_start_queueing - initiate dispatch of requests to device
- * @q:		request queue to kick into gear
- *
- * This is basically a helper to remove the need to know whether a queue
- * is plugged or not if someone just wants to initiate dispatch of requests
- * for this queue.
- *
- * The queue lock must be held with interrupts disabled.
- */
-void blk_start_queueing(struct request_queue *q)
-{
-	if (!blk_queue_plugged(q))
-		q->request_fn(q);
-	else
-		__generic_unplug_device(q);
-}
-EXPORT_SYMBOL(blk_start_queueing);
-
-/**
- * blk_requeue_request - put a request back on queue
- * @q:		request queue where request should be inserted
- * @rq:		request to be inserted
- *
- * Description:
- *    Drivers often keep queueing requests until the hardware cannot accept
- *    more, when that condition happens we need to put the request back
- *    on the queue. Must be called with queue lock held.
- */
-void blk_requeue_request(struct request_queue *q, struct request *rq)
-{
-	blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
-
-	if (blk_rq_tagged(rq))
-		blk_queue_end_tag(q, rq);
-
-	elv_requeue_request(q, rq);
-}
-
-EXPORT_SYMBOL(blk_requeue_request);
-
-/**
- * blk_insert_request - insert a special request in to a request queue
- * @q:		request queue where request should be inserted
- * @rq:		request to be inserted
- * @at_head:	insert request at head or tail of queue
- * @data:	private data
- *
- * Description:
- *    Many block devices need to execute commands asynchronously, so they don't
- *    block the whole kernel from preemption during request execution.  This is
- *    accomplished normally by inserting aritficial requests tagged as
- *    REQ_SPECIAL in to the corresponding request queue, and letting them be
- *    scheduled for actual execution by the request queue.
- *
- *    We have the option of inserting the head or the tail of the queue.
- *    Typically we use the tail for new ioctls and so forth.  We use the head
- *    of the queue for things like a QUEUE_FULL message from a device, or a
- *    host that is unable to accept a particular command.
- */
-void blk_insert_request(struct request_queue *q, struct request *rq,
-			int at_head, void *data)
-{
-	int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
-	unsigned long flags;
-
-	/*
-	 * tell I/O scheduler that this isn't a regular read/write (ie it
-	 * must not attempt merges on this) and that it acts as a soft
-	 * barrier
-	 */
-	rq->cmd_type = REQ_TYPE_SPECIAL;
-	rq->cmd_flags |= REQ_SOFTBARRIER;
-
-	rq->special = data;
-
-	spin_lock_irqsave(q->queue_lock, flags);
-
-	/*
-	 * If command is tagged, release the tag
-	 */
-	if (blk_rq_tagged(rq))
-		blk_queue_end_tag(q, rq);
-
-	drive_stat_acct(rq, 1);
-	__elv_add_request(q, rq, where, 0);
-	blk_start_queueing(q);
-	spin_unlock_irqrestore(q->queue_lock, flags);
-}
-
-EXPORT_SYMBOL(blk_insert_request);
-
-static int __blk_rq_unmap_user(struct bio *bio)
-{
-	int ret = 0;
-
-	if (bio) {
-		if (bio_flagged(bio, BIO_USER_MAPPED))
-			bio_unmap_user(bio);
-		else
-			ret = bio_uncopy_user(bio);
-	}
-
-	return ret;
-}
-
-int blk_rq_append_bio(struct request_queue *q, struct request *rq,
-		      struct bio *bio)
-{
-	if (!rq->bio)
-		blk_rq_bio_prep(q, rq, bio);
-	else if (!ll_back_merge_fn(q, rq, bio))
-		return -EINVAL;
-	else {
-		rq->biotail->bi_next = bio;
-		rq->biotail = bio;
-
-		rq->data_len += bio->bi_size;
-	}
-	return 0;
-}
-EXPORT_SYMBOL(blk_rq_append_bio);
-
-static int __blk_rq_map_user(struct request_queue *q, struct request *rq,
-			     void __user *ubuf, unsigned int len)
-{
-	unsigned long uaddr;
-	struct bio *bio, *orig_bio;
-	int reading, ret;
-
-	reading = rq_data_dir(rq) == READ;
-
-	/*
-	 * if alignment requirement is satisfied, map in user pages for
-	 * direct dma. else, set up kernel bounce buffers
-	 */
-	uaddr = (unsigned long) ubuf;
-	if (!(uaddr & queue_dma_alignment(q)) && !(len & queue_dma_alignment(q)))
-		bio = bio_map_user(q, NULL, uaddr, len, reading);
-	else
-		bio = bio_copy_user(q, uaddr, len, reading);
-
-	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);
-
-	ret = blk_rq_append_bio(q, rq, bio);
-	if (!ret)
-		return bio->bi_size;
-
-	/* if it was boucned we must call the end io function */
-	bio_endio(bio, 0);
-	__blk_rq_unmap_user(orig_bio);
-	bio_put(bio);
-	return ret;
-}
-
-/**
- * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage
- * @q:		request queue where request should be inserted
- * @rq:		request structure to fill
- * @ubuf:	the user buffer
- * @len:	length of user data
- *
- * Description:
- *    Data will be mapped directly for zero copy io, if possible. Otherwise
- *    a kernel bounce buffer is used.
- *
- *    A matching blk_rq_unmap_user() must be issued at the end of io, while
- *    still in process context.
- *
- *    Note: The mapped bio may need to be bounced through blk_queue_bounce()
- *    before being submitted to the device, as pages mapped may be out of
- *    reach. It's the callers responsibility to make sure this happens. The
- *    original bio must be passed back in to blk_rq_unmap_user() for proper
- *    unmapping.
- */
-int blk_rq_map_user(struct request_queue *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))
-		return -EINVAL;
-	if (!len || !ubuf)
-		return -EINVAL;
-
-	while (bytes_read != len) {
-		unsigned long map_len, end, start;
-
-		map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE);
-		end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1)
-								>> PAGE_SHIFT;
-		start = (unsigned long)ubuf >> PAGE_SHIFT;
-
-		/*
-		 * A bad offset could cause us to require BIO_MAX_PAGES + 1
-		 * pages. If this happens we just lower the requested
-		 * mapping len by a page so that we can fit
-		 */
-		if (end - start > BIO_MAX_PAGES)
-			map_len -= PAGE_SIZE;
-
-		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;
-	}
-
-	rq->buffer = rq->data = NULL;
-	return 0;
-unmap_rq:
-	blk_rq_unmap_user(bio);
-	return ret;
-}
-
-EXPORT_SYMBOL(blk_rq_map_user);
-
-/**
- * blk_rq_map_user_iov - map user data to a request, for REQ_BLOCK_PC usage
- * @q:		request queue where request should be inserted
- * @rq:		request to map data to
- * @iov:	pointer to the iovec
- * @iov_count:	number of elements in the iovec
- * @len:	I/O byte count
- *
- * Description:
- *    Data will be mapped directly for zero copy io, if possible. Otherwise
- *    a kernel bounce buffer is used.
- *
- *    A matching blk_rq_unmap_user() must be issued at the end of io, while
- *    still in process context.
- *
- *    Note: The mapped bio may need to be bounced through blk_queue_bounce()
- *    before being submitted to the device, as pages mapped may be out of
- *    reach. It's the callers responsibility to make sure this happens. The
- *    original bio must be passed back in to blk_rq_unmap_user() for proper
- *    unmapping.
- */
-int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
-			struct sg_iovec *iov, int iov_count, unsigned int len)
-{
-	struct bio *bio;
-
-	if (!iov || iov_count <= 0)
-		return -EINVAL;
-
-	/* we don't allow misaligned data like bio_map_user() does.  If the
-	 * user is using sg, they're expected to know the alignment constraints
-	 * and respect them accordingly */
-	bio = bio_map_user_iov(q, NULL, iov, iov_count, rq_data_dir(rq)== READ);
-	if (IS_ERR(bio))
-		return PTR_ERR(bio);
-
-	if (bio->bi_size != len) {
-		bio_endio(bio, 0);
-		bio_unmap_user(bio);
-		return -EINVAL;
-	}
-
-	bio_get(bio);
-	blk_rq_bio_prep(q, rq, bio);
-	rq->buffer = rq->data = NULL;
-	return 0;
-}
-
-EXPORT_SYMBOL(blk_rq_map_user_iov);
-
-/**
- * blk_rq_unmap_user - unmap a request with user data
- * @bio:	       start of bio list
- *
- * Description:
- *    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 bio *bio)
-{
-	struct bio *mapped_bio;
-	int ret = 0, ret2;
-
-	while (bio) {
-		mapped_bio = bio;
-		if (unlikely(bio_flagged(bio, BIO_BOUNCED)))
-			mapped_bio = bio->bi_private;
-
-		ret2 = __blk_rq_unmap_user(mapped_bio);
-		if (ret2 && !ret)
-			ret = ret2;
-
-		mapped_bio = bio;
-		bio = bio->bi_next;
-		bio_put(mapped_bio);
-	}
-
-	return ret;
-}
-
-EXPORT_SYMBOL(blk_rq_unmap_user);
-
-/**
- * blk_rq_map_kern - map kernel data to a request, for REQ_BLOCK_PC usage
- * @q:		request queue where request should be inserted
- * @rq:		request to fill
- * @kbuf:	the kernel buffer
- * @len:	length of user data
- * @gfp_mask:	memory allocation flags
- */
-int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
-		    unsigned int len, gfp_t gfp_mask)
-{
-	struct bio *bio;
-
-	if (len > (q->max_hw_sectors << 9))
-		return -EINVAL;
-	if (!len || !kbuf)
-		return -EINVAL;
-
-	bio = bio_map_kern(q, kbuf, len, gfp_mask);
-	if (IS_ERR(bio))
-		return PTR_ERR(bio);
-
-	if (rq_data_dir(rq) == WRITE)
-		bio->bi_rw |= (1 << BIO_RW);
-
-	blk_rq_bio_prep(q, rq, bio);
-	blk_queue_bounce(q, &rq->bio);
-	rq->buffer = rq->data = NULL;
-	return 0;
-}
-
-EXPORT_SYMBOL(blk_rq_map_kern);
-
-/**
- * blk_execute_rq_nowait - insert a request into queue for execution
- * @q:		queue to insert the request in
- * @bd_disk:	matching gendisk
- * @rq:		request to insert
- * @at_head:    insert request at head or tail of queue
- * @done:	I/O completion handler
- *
- * Description:
- *    Insert a fully prepared request at the back of the io scheduler queue
- *    for execution.  Don't wait for completion.
- */
-void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
-			   struct request *rq, int at_head,
-			   rq_end_io_fn *done)
-{
-	int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
-
-	rq->rq_disk = bd_disk;
-	rq->cmd_flags |= REQ_NOMERGE;
-	rq->end_io = done;
-	WARN_ON(irqs_disabled());
-	spin_lock_irq(q->queue_lock);
-	__elv_add_request(q, rq, where, 1);
-	__generic_unplug_device(q);
-	spin_unlock_irq(q->queue_lock);
-}
-EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
-
-/**
- * blk_execute_rq - insert a request into queue for execution
- * @q:		queue to insert the request in
- * @bd_disk:	matching gendisk
- * @rq:		request to insert
- * @at_head:    insert request at head or tail of queue
- *
- * Description:
- *    Insert a fully prepared request at the back of the io scheduler queue
- *    for execution and wait for completion.
- */
-int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
-		   struct request *rq, int at_head)
-{
-	DECLARE_COMPLETION_ONSTACK(wait);
-	char sense[SCSI_SENSE_BUFFERSIZE];
-	int err = 0;
-
-	/*
-	 * we need an extra reference to the request, so we can look at
-	 * it after io completion
-	 */
-	rq->ref_count++;
-
-	if (!rq->sense) {
-		memset(sense, 0, sizeof(sense));
-		rq->sense = sense;
-		rq->sense_len = 0;
-	}
-
-	rq->end_io_data = &wait;
-	blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
-	wait_for_completion(&wait);
-
-	if (rq->errors)
-		err = -EIO;
-
-	return err;
-}
-
-EXPORT_SYMBOL(blk_execute_rq);
-
-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);
-
-static void drive_stat_acct(struct request *rq, int new_io)
-{
-	int rw = rq_data_dir(rq);
-
-	if (!blk_fs_request(rq) || !rq->rq_disk)
-		return;
-
-	if (!new_io) {
-		__disk_stat_inc(rq->rq_disk, merges[rw]);
-	} else {
-		disk_round_stats(rq->rq_disk);
-		rq->rq_disk->in_flight++;
-	}
-}
-
-/*
- * add-request adds a request to the linked list.
- * queue lock is held and interrupts disabled, as we muck with the
- * request queue list.
- */
-static inline void add_request(struct request_queue * q, struct request * req)
-{
-	drive_stat_acct(req, 1);
-
-	/*
-	 * elevator indicated where it wants this request to be
-	 * inserted at elevator_merge time
-	 */
-	__elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0);
-}
- 
-/*
- * disk_round_stats()	- Round off the performance stats on a struct
- * disk_stats.
- *
- * The average IO queue length and utilisation statistics are maintained
- * by observing the current state of the queue length and the amount of
- * time it has been in this state for.
- *
- * Normally, that accounting is done on IO completion, but that can result
- * in more than a second's worth of IO being accounted for within any one
- * second, leading to >100% utilisation.  To deal with that, we call this
- * function to do a round-off before returning the results when reading
- * /proc/diskstats.  This accounts immediately for all queue usage up to
- * the current jiffies and restarts the counters again.
- */
-void disk_round_stats(struct gendisk *disk)
-{
-	unsigned long now = jiffies;
-
-	if (now == disk->stamp)
-		return;
-
-	if (disk->in_flight) {
-		__disk_stat_add(disk, time_in_queue,
-				disk->in_flight * (now - disk->stamp));
-		__disk_stat_add(disk, io_ticks, (now - disk->stamp));
-	}
-	disk->stamp = now;
-}
-
-EXPORT_SYMBOL_GPL(disk_round_stats);
-
-/*
- * queue lock must be held
- */
-void __blk_put_request(struct request_queue *q, struct request *req)
-{
-	if (unlikely(!q))
-		return;
-	if (unlikely(--req->ref_count))
-		return;
-
-	elv_completed_request(q, req);
-
-	/*
-	 * Request may not have originated from ll_rw_blk. if not,
-	 * it didn't come out of our reserved rq pools
-	 */
-	if (req->cmd_flags & REQ_ALLOCED) {
-		int rw = rq_data_dir(req);
-		int priv = req->cmd_flags & REQ_ELVPRIV;
-
-		BUG_ON(!list_empty(&req->queuelist));
-		BUG_ON(!hlist_unhashed(&req->hash));
-
-		blk_free_request(q, req);
-		freed_request(q, rw, priv);
-	}
-}
-
-EXPORT_SYMBOL_GPL(__blk_put_request);
-
-void blk_put_request(struct request *req)
-{
-	unsigned long flags;
-	struct request_queue *q = req->q;
-
-	/*
-	 * Gee, IDE calls in w/ NULL q.  Fix IDE and remove the
-	 * following if (q) test.
-	 */
-	if (q) {
-		spin_lock_irqsave(q->queue_lock, flags);
-		__blk_put_request(q, req);
-		spin_unlock_irqrestore(q->queue_lock, flags);
-	}
-}
-
-EXPORT_SYMBOL(blk_put_request);
-
-/**
- * blk_end_sync_rq - executes a completion event on a request
- * @rq: request to complete
- * @error: end io status of the request
- */
-void blk_end_sync_rq(struct request *rq, int error)
-{
-	struct completion *waiting = rq->end_io_data;
-
-	rq->end_io_data = NULL;
-	__blk_put_request(rq->q, rq);
-
-	/*
-	 * complete last, if this is a stack request the process (and thus
-	 * the rq pointer) could be invalid right after this complete()
-	 */
-	complete(waiting);
-}
-EXPORT_SYMBOL(blk_end_sync_rq);
-
-/*
- * Has to be called with the request spinlock acquired
- */
-static int attempt_merge(struct request_queue *q, struct request *req,
-			  struct request *next)
-{
-	if (!rq_mergeable(req) || !rq_mergeable(next))
-		return 0;
-
-	/*
-	 * not contiguous
-	 */
-	if (req->sector + req->nr_sectors != next->sector)
-		return 0;
-
-	if (rq_data_dir(req) != rq_data_dir(next)
-	    || req->rq_disk != next->rq_disk
-	    || next->special)
-		return 0;
-
-	/*
-	 * If we are allowed to merge, then append bio list
-	 * from next to rq and release next. merge_requests_fn
-	 * will have updated segment counts, update sector
-	 * counts here.
-	 */
-	if (!ll_merge_requests_fn(q, req, next))
-		return 0;
-
-	/*
-	 * At this point we have either done a back merge
-	 * or front merge. We need the smaller start_time of
-	 * the merged requests to be the current request
-	 * for accounting purposes.
-	 */
-	if (time_after(req->start_time, next->start_time))
-		req->start_time = next->start_time;
-
-	req->biotail->bi_next = next->bio;
-	req->biotail = next->biotail;
-
-	req->nr_sectors = req->hard_nr_sectors += next->hard_nr_sectors;
-
-	elv_merge_requests(q, req, next);
-
-	if (req->rq_disk) {
-		disk_round_stats(req->rq_disk);
-		req->rq_disk->in_flight--;
-	}
-
-	req->ioprio = ioprio_best(req->ioprio, next->ioprio);
-
-	__blk_put_request(q, next);
-	return 1;
-}
-
-static inline int attempt_back_merge(struct request_queue *q,
-				     struct request *rq)
-{
-	struct request *next = elv_latter_request(q, rq);
-
-	if (next)
-		return attempt_merge(q, rq, next);
-
-	return 0;
-}
-
-static inline int attempt_front_merge(struct request_queue *q,
-				      struct request *rq)
-{
-	struct request *prev = elv_former_request(q, rq);
-
-	if (prev)
-		return attempt_merge(q, prev, rq);
-
-	return 0;
-}
-
-static void init_request_from_bio(struct request *req, struct bio *bio)
-{
-	req->cmd_type = REQ_TYPE_FS;
-
-	/*
-	 * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST)
-	 */
-	if (bio_rw_ahead(bio) || bio_failfast(bio))
-		req->cmd_flags |= REQ_FAILFAST;
-
-	/*
-	 * REQ_BARRIER implies no merging, but lets make it explicit
-	 */
-	if (unlikely(bio_barrier(bio)))
-		req->cmd_flags |= (REQ_HARDBARRIER | REQ_NOMERGE);
-
-	if (bio_sync(bio))
-		req->cmd_flags |= REQ_RW_SYNC;
-	if (bio_rw_meta(bio))
-		req->cmd_flags |= REQ_RW_META;
-
-	req->errors = 0;
-	req->hard_sector = req->sector = bio->bi_sector;
-	req->ioprio = bio_prio(bio);
-	req->start_time = jiffies;
-	blk_rq_bio_prep(req->q, req, bio);
-}
-
-static int __make_request(struct request_queue *q, struct bio *bio)
-{
-	struct request *req;
-	int el_ret, nr_sectors, barrier, err;
-	const unsigned short prio = bio_prio(bio);
-	const int sync = bio_sync(bio);
-	int rw_flags;
-
-	nr_sectors = bio_sectors(bio);
-
-	/*
-	 * low level driver can indicate that it wants pages above a
-	 * certain limit bounced to low memory (ie for highmem, or even
-	 * ISA dma in theory)
-	 */
-	blk_queue_bounce(q, &bio);
-
-	barrier = bio_barrier(bio);
-	if (unlikely(barrier) && (q->next_ordered == QUEUE_ORDERED_NONE)) {
-		err = -EOPNOTSUPP;
-		goto end_io;
-	}
-
-	spin_lock_irq(q->queue_lock);
-
-	if (unlikely(barrier) || elv_queue_empty(q))
-		goto get_rq;
-
-	el_ret = elv_merge(q, &req, bio);
-	switch (el_ret) {
-		case ELEVATOR_BACK_MERGE:
-			BUG_ON(!rq_mergeable(req));
-
-			if (!ll_back_merge_fn(q, req, bio))
-				break;
-
-			blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE);
-
-			req->biotail->bi_next = bio;
-			req->biotail = bio;
-			req->nr_sectors = req->hard_nr_sectors += nr_sectors;
-			req->ioprio = ioprio_best(req->ioprio, prio);
-			drive_stat_acct(req, 0);
-			if (!attempt_back_merge(q, req))
-				elv_merged_request(q, req, el_ret);
-			goto out;
-
-		case ELEVATOR_FRONT_MERGE:
-			BUG_ON(!rq_mergeable(req));
-
-			if (!ll_front_merge_fn(q, req, bio))
-				break;
-
-			blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE);
-
-			bio->bi_next = req->bio;
-			req->bio = bio;
-
-			/*
-			 * may not be valid. if the low level driver said
-			 * it didn't need a bounce buffer then it better
-			 * not touch req->buffer either...
-			 */
-			req->buffer = bio_data(bio);
-			req->current_nr_sectors = bio_cur_sectors(bio);
-			req->hard_cur_sectors = req->current_nr_sectors;
-			req->sector = req->hard_sector = bio->bi_sector;
-			req->nr_sectors = req->hard_nr_sectors += nr_sectors;
-			req->ioprio = ioprio_best(req->ioprio, prio);
-			drive_stat_acct(req, 0);
-			if (!attempt_front_merge(q, req))
-				elv_merged_request(q, req, el_ret);
-			goto out;
-
-		/* ELV_NO_MERGE: elevator says don't/can't merge. */
-		default:
-			;
-	}
-
-get_rq:
-	/*
-	 * This sync check and mask will be re-done in init_request_from_bio(),
-	 * but we need to set it earlier to expose the sync flag to the
-	 * rq allocator and io schedulers.
-	 */
-	rw_flags = bio_data_dir(bio);
-	if (sync)
-		rw_flags |= REQ_RW_SYNC;
-
-	/*
-	 * Grab a free request. This is might sleep but can not fail.
-	 * Returns with the queue unlocked.
-	 */
-	req = get_request_wait(q, rw_flags, bio);
-
-	/*
-	 * After dropping the lock and possibly sleeping here, our request
-	 * may now be mergeable after it had proven unmergeable (above).
-	 * We don't worry about that case for efficiency. It won't happen
-	 * often, and the elevators are able to handle it.
-	 */
-	init_request_from_bio(req, bio);
-
-	spin_lock_irq(q->queue_lock);
-	if (elv_queue_empty(q))
-		blk_plug_device(q);
-	add_request(q, req);
-out:
-	if (sync)
-		__generic_unplug_device(q);
-
-	spin_unlock_irq(q->queue_lock);
-	return 0;
-
-end_io:
-	bio_endio(bio, err);
-	return 0;
-}
-
-/*
- * If bio->bi_dev is a partition, remap the location
- */
-static inline void blk_partition_remap(struct bio *bio)
-{
-	struct block_device *bdev = bio->bi_bdev;
-
-	if (bio_sectors(bio) && bdev != bdev->bd_contains) {
-		struct hd_struct *p = bdev->bd_part;
-		const int rw = bio_data_dir(bio);
-
-		p->sectors[rw] += bio_sectors(bio);
-		p->ios[rw]++;
-
-		bio->bi_sector += p->start_sect;
-		bio->bi_bdev = bdev->bd_contains;
-
-		blk_add_trace_remap(bdev_get_queue(bio->bi_bdev), bio,
-				    bdev->bd_dev, bio->bi_sector,
-				    bio->bi_sector - p->start_sect);
-	}
-}
-
-static void handle_bad_sector(struct bio *bio)
-{
-	char b[BDEVNAME_SIZE];
-
-	printk(KERN_INFO "attempt to access beyond end of device\n");
-	printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
-			bdevname(bio->bi_bdev, b),
-			bio->bi_rw,
-			(unsigned long long)bio->bi_sector + bio_sectors(bio),
-			(long long)(bio->bi_bdev->bd_inode->i_size >> 9));
-
-	set_bit(BIO_EOF, &bio->bi_flags);
-}
-
-#ifdef CONFIG_FAIL_MAKE_REQUEST
-
-static DECLARE_FAULT_ATTR(fail_make_request);
-
-static int __init setup_fail_make_request(char *str)
-{
-	return setup_fault_attr(&fail_make_request, str);
-}
-__setup("fail_make_request=", setup_fail_make_request);
-
-static int should_fail_request(struct bio *bio)
-{
-	if ((bio->bi_bdev->bd_disk->flags & GENHD_FL_FAIL) ||
-	    (bio->bi_bdev->bd_part && bio->bi_bdev->bd_part->make_it_fail))
-		return should_fail(&fail_make_request, bio->bi_size);
-
-	return 0;
-}
-
-static int __init fail_make_request_debugfs(void)
-{
-	return init_fault_attr_dentries(&fail_make_request,
-					"fail_make_request");
-}
-
-late_initcall(fail_make_request_debugfs);
-
-#else /* CONFIG_FAIL_MAKE_REQUEST */
-
-static inline int should_fail_request(struct bio *bio)
-{
-	return 0;
-}
-
-#endif /* CONFIG_FAIL_MAKE_REQUEST */
-
-/*
- * Check whether this bio extends beyond the end of the device.
- */
-static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
-{
-	sector_t maxsector;
-
-	if (!nr_sectors)
-		return 0;
-
-	/* Test device or partition size, when known. */
-	maxsector = bio->bi_bdev->bd_inode->i_size >> 9;
-	if (maxsector) {
-		sector_t sector = bio->bi_sector;
-
-		if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
-			/*
-			 * This may well happen - the kernel calls bread()
-			 * without checking the size of the device, e.g., when
-			 * mounting a device.
-			 */
-			handle_bad_sector(bio);
-			return 1;
-		}
-	}
-
-	return 0;
-}
-
-/**
- * generic_make_request: hand a buffer to its device driver for I/O
- * @bio:  The bio describing the location in memory and on the device.
- *
- * generic_make_request() is used to make I/O requests of block
- * devices. It is passed a &struct bio, which describes the I/O that needs
- * to be done.
- *
- * generic_make_request() does not return any status.  The
- * success/failure status of the request, along with notification of
- * completion, is delivered asynchronously through the bio->bi_end_io
- * function described (one day) else where.
- *
- * The caller of generic_make_request must make sure that bi_io_vec
- * are set to describe the memory buffer, and that bi_dev and bi_sector are
- * set to describe the device address, and the
- * bi_end_io and optionally bi_private are set to describe how
- * completion notification should be signaled.
- *
- * generic_make_request and the drivers it calls may use bi_next if this
- * bio happens to be merged with someone else, and may change bi_dev and
- * bi_sector for remaps as it sees fit.  So the values of these fields
- * should NOT be depended on after the call to generic_make_request.
- */
-static inline void __generic_make_request(struct bio *bio)
-{
-	struct request_queue *q;
-	sector_t old_sector;
-	int ret, nr_sectors = bio_sectors(bio);
-	dev_t old_dev;
-	int err = -EIO;
-
-	might_sleep();
-
-	if (bio_check_eod(bio, nr_sectors))
-		goto end_io;
-
-	/*
-	 * Resolve the mapping until finished. (drivers are
-	 * still free to implement/resolve their own stacking
-	 * by explicitly returning 0)
-	 *
-	 * NOTE: we don't repeat the blk_size check for each new device.
-	 * Stacking drivers are expected to know what they are doing.
-	 */
-	old_sector = -1;
-	old_dev = 0;
-	do {
-		char b[BDEVNAME_SIZE];
-
-		q = bdev_get_queue(bio->bi_bdev);
-		if (!q) {
-			printk(KERN_ERR
-			       "generic_make_request: Trying to access "
-				"nonexistent block-device %s (%Lu)\n",
-				bdevname(bio->bi_bdev, b),
-				(long long) bio->bi_sector);
-end_io:
-			bio_endio(bio, err);
-			break;
-		}
-
-		if (unlikely(nr_sectors > q->max_hw_sectors)) {
-			printk("bio too big device %s (%u > %u)\n", 
-				bdevname(bio->bi_bdev, b),
-				bio_sectors(bio),
-				q->max_hw_sectors);
-			goto end_io;
-		}
-
-		if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
-			goto end_io;
-
-		if (should_fail_request(bio))
-			goto end_io;
-
-		/*
-		 * If this device has partitions, remap block n
-		 * of partition p to block n+start(p) of the disk.
-		 */
-		blk_partition_remap(bio);
-
-		if (old_sector != -1)
-			blk_add_trace_remap(q, bio, old_dev, bio->bi_sector,
-					    old_sector);
-
-		blk_add_trace_bio(q, bio, BLK_TA_QUEUE);
-
-		old_sector = bio->bi_sector;
-		old_dev = bio->bi_bdev->bd_dev;
-
-		if (bio_check_eod(bio, nr_sectors))
-			goto end_io;
-		if (bio_empty_barrier(bio) && !q->prepare_flush_fn) {
-			err = -EOPNOTSUPP;
-			goto end_io;
-		}
-
-		ret = q->make_request_fn(q, bio);
-	} while (ret);
-}
-
-/*
- * We only want one ->make_request_fn to be active at a time,
- * else stack usage with stacked devices could be a problem.
- * So use current->bio_{list,tail} to keep a list of requests
- * submited by a make_request_fn function.
- * current->bio_tail is also used as a flag to say if
- * generic_make_request is currently active in this task or not.
- * If it is NULL, then no make_request is active.  If it is non-NULL,
- * then a make_request is active, and new requests should be added
- * at the tail
- */
-void generic_make_request(struct bio *bio)
-{
-	if (current->bio_tail) {
-		/* make_request is active */
-		*(current->bio_tail) = bio;
-		bio->bi_next = NULL;
-		current->bio_tail = &bio->bi_next;
-		return;
-	}
-	/* following loop may be a bit non-obvious, and so deserves some
-	 * explanation.
-	 * Before entering the loop, bio->bi_next is NULL (as all callers
-	 * ensure that) so we have a list with a single bio.
-	 * We pretend that we have just taken it off a longer list, so
-	 * we assign bio_list to the next (which is NULL) and bio_tail
-	 * to &bio_list, thus initialising the bio_list of new bios to be
-	 * added.  __generic_make_request may indeed add some more bios
-	 * through a recursive call to generic_make_request.  If it
-	 * did, we find a non-NULL value in bio_list and re-enter the loop
-	 * from the top.  In this case we really did just take the bio
-	 * of the top of the list (no pretending) and so fixup bio_list and
-	 * bio_tail or bi_next, and call into __generic_make_request again.
-	 *
-	 * The loop was structured like this to make only one call to
-	 * __generic_make_request (which is important as it is large and
-	 * inlined) and to keep the structure simple.
-	 */
-	BUG_ON(bio->bi_next);
-	do {
-		current->bio_list = bio->bi_next;
-		if (bio->bi_next == NULL)
-			current->bio_tail = &current->bio_list;
-		else
-			bio->bi_next = NULL;
-		__generic_make_request(bio);
-		bio = current->bio_list;
-	} while (bio);
-	current->bio_tail = NULL; /* deactivate */
-}
-
-EXPORT_SYMBOL(generic_make_request);
-
-/**
- * submit_bio: submit a bio to the block device layer for I/O
- * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
- * @bio: The &struct bio which describes the I/O
- *
- * submit_bio() is very similar in purpose to generic_make_request(), and
- * uses that function to do most of the work. Both are fairly rough
- * interfaces, @bio must be presetup and ready for I/O.
- *
- */
-void submit_bio(int rw, struct bio *bio)
-{
-	int count = bio_sectors(bio);
-
-	bio->bi_rw |= rw;
-
-	/*
-	 * If it's a regular read/write or a barrier with data attached,
-	 * go through the normal accounting stuff before submission.
-	 */
-	if (!bio_empty_barrier(bio)) {
-
-		BIO_BUG_ON(!bio->bi_size);
-		BIO_BUG_ON(!bio->bi_io_vec);
-
-		if (rw & WRITE) {
-			count_vm_events(PGPGOUT, count);
-		} else {
-			task_io_account_read(bio->bi_size);
-			count_vm_events(PGPGIN, count);
-		}
-
-		if (unlikely(block_dump)) {
-			char b[BDEVNAME_SIZE];
-			printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n",
-			current->comm, task_pid_nr(current),
-				(rw & WRITE) ? "WRITE" : "READ",
-				(unsigned long long)bio->bi_sector,
-				bdevname(bio->bi_bdev,b));
-		}
-	}
-
-	generic_make_request(bio);
-}
-
-EXPORT_SYMBOL(submit_bio);
-
-static void blk_recalc_rq_sectors(struct request *rq, int nsect)
-{
-	if (blk_fs_request(rq)) {
-		rq->hard_sector += nsect;
-		rq->hard_nr_sectors -= nsect;
-
-		/*
-		 * Move the I/O submission pointers ahead if required.
-		 */
-		if ((rq->nr_sectors >= rq->hard_nr_sectors) &&
-		    (rq->sector <= rq->hard_sector)) {
-			rq->sector = rq->hard_sector;
-			rq->nr_sectors = rq->hard_nr_sectors;
-			rq->hard_cur_sectors = bio_cur_sectors(rq->bio);
-			rq->current_nr_sectors = rq->hard_cur_sectors;
-			rq->buffer = bio_data(rq->bio);
-		}
-
-		/*
-		 * if total number of sectors is less than the first segment
-		 * size, something has gone terribly wrong
-		 */
-		if (rq->nr_sectors < rq->current_nr_sectors) {
-			printk("blk: request botched\n");
-			rq->nr_sectors = rq->current_nr_sectors;
-		}
-	}
-}
-
-/**
- * __end_that_request_first - end I/O on a request
- * @req:      the request being processed
- * @error:    0 for success, < 0 for error
- * @nr_bytes: number of bytes to complete
- *
- * Description:
- *     Ends I/O on a number of bytes attached to @req, and sets it up
- *     for the next range of segments (if any) in the cluster.
- *
- * Return:
- *     0 - we are done with this request, call end_that_request_last()
- *     1 - still buffers pending for this request
- **/
-static int __end_that_request_first(struct request *req, int error,
-				    int nr_bytes)
-{
-	int total_bytes, bio_nbytes, next_idx = 0;
-	struct bio *bio;
-
-	blk_add_trace_rq(req->q, req, BLK_TA_COMPLETE);
-
-	/*
-	 * for a REQ_BLOCK_PC request, we want to carry any eventual
-	 * sense key with us all the way through
-	 */
-	if (!blk_pc_request(req))
-		req->errors = 0;
-
-	if (error) {
-		if (blk_fs_request(req) && !(req->cmd_flags & REQ_QUIET))
-			printk("end_request: I/O error, dev %s, sector %llu\n",
-				req->rq_disk ? req->rq_disk->disk_name : "?",
-				(unsigned long long)req->sector);
-	}
-
-	if (blk_fs_request(req) && req->rq_disk) {
-		const int rw = rq_data_dir(req);
-
-		disk_stat_add(req->rq_disk, sectors[rw], nr_bytes >> 9);
-	}
-
-	total_bytes = bio_nbytes = 0;
-	while ((bio = req->bio) != NULL) {
-		int nbytes;
-
-		/*
-		 * For an empty barrier request, the low level driver must
-		 * store a potential error location in ->sector. We pass
-		 * that back up in ->bi_sector.
-		 */
-		if (blk_empty_barrier(req))
-			bio->bi_sector = req->sector;
-
-		if (nr_bytes >= bio->bi_size) {
-			req->bio = bio->bi_next;
-			nbytes = bio->bi_size;
-			req_bio_endio(req, bio, nbytes, error);
-			next_idx = 0;
-			bio_nbytes = 0;
-		} else {
-			int idx = bio->bi_idx + next_idx;
-
-			if (unlikely(bio->bi_idx >= bio->bi_vcnt)) {
-				blk_dump_rq_flags(req, "__end_that");
-				printk("%s: bio idx %d >= vcnt %d\n",
-						__FUNCTION__,
-						bio->bi_idx, bio->bi_vcnt);
-				break;
-			}
-
-			nbytes = bio_iovec_idx(bio, idx)->bv_len;
-			BIO_BUG_ON(nbytes > bio->bi_size);
-
-			/*
-			 * not a complete bvec done
-			 */
-			if (unlikely(nbytes > nr_bytes)) {
-				bio_nbytes += nr_bytes;
-				total_bytes += nr_bytes;
-				break;
-			}
-
-			/*
-			 * advance to the next vector
-			 */
-			next_idx++;
-			bio_nbytes += nbytes;
-		}
-
-		total_bytes += nbytes;
-		nr_bytes -= nbytes;
-
-		if ((bio = req->bio)) {
-			/*
-			 * end more in this run, or just return 'not-done'
-			 */
-			if (unlikely(nr_bytes <= 0))
-				break;
-		}
-	}
-
-	/*
-	 * completely done
-	 */
-	if (!req->bio)
-		return 0;
-
-	/*
-	 * if the request wasn't completed, update state
-	 */
-	if (bio_nbytes) {
-		req_bio_endio(req, bio, bio_nbytes, error);
-		bio->bi_idx += next_idx;
-		bio_iovec(bio)->bv_offset += nr_bytes;
-		bio_iovec(bio)->bv_len -= nr_bytes;
-	}
-
-	blk_recalc_rq_sectors(req, total_bytes >> 9);
-	blk_recalc_rq_segments(req);
-	return 1;
-}
-
-/*
- * splice the completion data to a local structure and hand off to
- * process_completion_queue() to complete the requests
- */
-static void blk_done_softirq(struct softirq_action *h)
-{
-	struct list_head *cpu_list, local_list;
-
-	local_irq_disable();
-	cpu_list = &__get_cpu_var(blk_cpu_done);
-	list_replace_init(cpu_list, &local_list);
-	local_irq_enable();
-
-	while (!list_empty(&local_list)) {
-		struct request *rq = list_entry(local_list.next, struct request, donelist);
-
-		list_del_init(&rq->donelist);
-		rq->q->softirq_done_fn(rq);
-	}
-}
-
-static int __cpuinit blk_cpu_notify(struct notifier_block *self, unsigned long action,
-			  void *hcpu)
-{
-	/*
-	 * If a CPU goes away, splice its entries to the current CPU
-	 * and trigger a run of the softirq
-	 */
-	if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
-		int cpu = (unsigned long) hcpu;
-
-		local_irq_disable();
-		list_splice_init(&per_cpu(blk_cpu_done, cpu),
-				 &__get_cpu_var(blk_cpu_done));
-		raise_softirq_irqoff(BLOCK_SOFTIRQ);
-		local_irq_enable();
-	}
-
-	return NOTIFY_OK;
-}
-
-
-static struct notifier_block blk_cpu_notifier __cpuinitdata = {
-	.notifier_call	= blk_cpu_notify,
-};
-
-/**
- * blk_complete_request - end I/O on a request
- * @req:      the request being processed
- *
- * Description:
- *     Ends all I/O on a request. It does not handle partial completions,
- *     unless the driver actually implements this in its completion callback
- *     through requeueing. The actual completion happens out-of-order,
- *     through a softirq handler. The user must have registered a completion
- *     callback through blk_queue_softirq_done().
- **/
-
-void blk_complete_request(struct request *req)
-{
-	struct list_head *cpu_list;
-	unsigned long flags;
-
-	BUG_ON(!req->q->softirq_done_fn);
-		
-	local_irq_save(flags);
-
-	cpu_list = &__get_cpu_var(blk_cpu_done);
-	list_add_tail(&req->donelist, cpu_list);
-	raise_softirq_irqoff(BLOCK_SOFTIRQ);
-
-	local_irq_restore(flags);
-}
-
-EXPORT_SYMBOL(blk_complete_request);
-	
-/*
- * queue lock must be held
- */
-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);
-
-	if (blk_queued_rq(req))
-		blkdev_dequeue_request(req);
-
-	if (unlikely(laptop_mode) && blk_fs_request(req))
-		laptop_io_completion();
-
-	/*
-	 * 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);
-
-		__disk_stat_inc(disk, ios[rw]);
-		__disk_stat_add(disk, ticks[rw], duration);
-		disk_round_stats(disk);
-		disk->in_flight--;
-	}
-
-	if (req->end_io)
-		req->end_io(req, error);
-	else {
-		if (blk_bidi_rq(req))
-			__blk_put_request(req->next_rq->q, req->next_rq);
-
-		__blk_put_request(req->q, req);
-	}
-}
-
-static inline void __end_request(struct request *rq, int uptodate,
-				 unsigned int nr_bytes)
-{
-	int error = 0;
-
-	if (uptodate <= 0)
-		error = uptodate ? uptodate : -EIO;
-
-	__blk_end_request(rq, error, nr_bytes);
-}
-
-/**
- * blk_rq_bytes - Returns bytes left to complete in the entire request
- **/
-unsigned int blk_rq_bytes(struct request *rq)
-{
-	if (blk_fs_request(rq))
-		return rq->hard_nr_sectors << 9;
-
-	return rq->data_len;
-}
-EXPORT_SYMBOL_GPL(blk_rq_bytes);
-
-/**
- * blk_rq_cur_bytes - Returns bytes left to complete in the current segment
- **/
-unsigned int blk_rq_cur_bytes(struct request *rq)
-{
-	if (blk_fs_request(rq))
-		return rq->current_nr_sectors << 9;
-
-	if (rq->bio)
-		return rq->bio->bi_size;
-
-	return rq->data_len;
-}
-EXPORT_SYMBOL_GPL(blk_rq_cur_bytes);
-
-/**
- * end_queued_request - end all I/O on a queued request
- * @rq:		the request being processed
- * @uptodate:	error value or 0/1 uptodate flag
- *
- * Description:
- *     Ends all I/O on a request, and removes it from the block layer queues.
- *     Not suitable for normal IO completion, unless the driver still has
- *     the request attached to the block layer.
- *
- **/
-void end_queued_request(struct request *rq, int uptodate)
-{
-	__end_request(rq, uptodate, blk_rq_bytes(rq));
-}
-EXPORT_SYMBOL(end_queued_request);
-
-/**
- * end_dequeued_request - end all I/O on a dequeued request
- * @rq:		the request being processed
- * @uptodate:	error value or 0/1 uptodate flag
- *
- * Description:
- *     Ends all I/O on a request. The request must already have been
- *     dequeued using blkdev_dequeue_request(), as is normally the case
- *     for most drivers.
- *
- **/
-void end_dequeued_request(struct request *rq, int uptodate)
-{
-	__end_request(rq, uptodate, blk_rq_bytes(rq));
-}
-EXPORT_SYMBOL(end_dequeued_request);
-
-
-/**
- * end_request - end I/O on the current segment of the request
- * @req:	the request being processed
- * @uptodate:	error value or 0/1 uptodate flag
- *
- * Description:
- *     Ends I/O on the current segment of a request. If that is the only
- *     remaining segment, the request is also completed and freed.
- *
- *     This is a remnant of how older block drivers handled IO completions.
- *     Modern drivers typically end IO on the full request in one go, unless
- *     they have a residual value to account for. For that case this function
- *     isn't really useful, unless the residual just happens to be the
- *     full current segment. In other words, don't use this function in new
- *     code. Either use end_request_completely(), or the
- *     end_that_request_chunk() (along with end_that_request_last()) for
- *     partial completions.
- *
- **/
-void end_request(struct request *req, int uptodate)
-{
-	__end_request(req, uptodate, req->hard_cur_sectors << 9);
-}
-EXPORT_SYMBOL(end_request);
-
-/**
- * blk_end_io - Generic end_io function to complete a request.
- * @rq:           the request being processed
- * @error:        0 for success, < 0 for error
- * @nr_bytes:     number of bytes to complete @rq
- * @bidi_bytes:   number of bytes to complete @rq->next_rq
- * @drv_callback: function called between completion of bios in the request
- *                and completion of the request.
- *                If the callback returns non 0, this helper returns without
- *                completion of the request.
- *
- * Description:
- *     Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
- *     If @rq has leftover, sets it up for the next range of segments.
- *
- * Return:
- *     0 - we are done with this request
- *     1 - this request is not freed yet, it still has pending buffers.
- **/
-static int blk_end_io(struct request *rq, int error, int nr_bytes,
-		      int bidi_bytes, int (drv_callback)(struct request *))
-{
-	struct request_queue *q = rq->q;
-	unsigned long flags = 0UL;
-
-	if (blk_fs_request(rq) || blk_pc_request(rq)) {
-		if (__end_that_request_first(rq, error, nr_bytes))
-			return 1;
-
-		/* Bidi request must be completed as a whole */
-		if (blk_bidi_rq(rq) &&
-		    __end_that_request_first(rq->next_rq, error, bidi_bytes))
-			return 1;
-	}
-
-	/* Special feature for tricky drivers */
-	if (drv_callback && drv_callback(rq))
-		return 1;
-
-	add_disk_randomness(rq->rq_disk);
-
-	spin_lock_irqsave(q->queue_lock, flags);
-	end_that_request_last(rq, error);
-	spin_unlock_irqrestore(q->queue_lock, flags);
-
-	return 0;
-}
-
-/**
- * blk_end_request - Helper function for drivers to complete the request.
- * @rq:       the request being processed
- * @error:    0 for success, < 0 for error
- * @nr_bytes: number of bytes to complete
- *
- * Description:
- *     Ends I/O on a number of bytes attached to @rq.
- *     If @rq has leftover, sets it up for the next range of segments.
- *
- * Return:
- *     0 - we are done with this request
- *     1 - still buffers pending for this request
- **/
-int blk_end_request(struct request *rq, int error, int nr_bytes)
-{
-	return blk_end_io(rq, error, nr_bytes, 0, NULL);
-}
-EXPORT_SYMBOL_GPL(blk_end_request);
-
-/**
- * __blk_end_request - Helper function for drivers to complete the request.
- * @rq:       the request being processed
- * @error:    0 for success, < 0 for error
- * @nr_bytes: number of bytes to complete
- *
- * Description:
- *     Must be called with queue lock held unlike blk_end_request().
- *
- * Return:
- *     0 - we are done with this request
- *     1 - still buffers pending for this request
- **/
-int __blk_end_request(struct request *rq, int error, int nr_bytes)
-{
-	if (blk_fs_request(rq) || blk_pc_request(rq)) {
-		if (__end_that_request_first(rq, error, nr_bytes))
-			return 1;
-	}
-
-	add_disk_randomness(rq->rq_disk);
-
-	end_that_request_last(rq, error);
-
-	return 0;
-}
-EXPORT_SYMBOL_GPL(__blk_end_request);
-
-/**
- * blk_end_bidi_request - Helper function for drivers to complete bidi request.
- * @rq:         the bidi request being processed
- * @error:      0 for success, < 0 for error
- * @nr_bytes:   number of bytes to complete @rq
- * @bidi_bytes: number of bytes to complete @rq->next_rq
- *
- * Description:
- *     Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
- *
- * Return:
- *     0 - we are done with this request
- *     1 - still buffers pending for this request
- **/
-int blk_end_bidi_request(struct request *rq, int error, int nr_bytes,
-			 int bidi_bytes)
-{
-	return blk_end_io(rq, error, nr_bytes, bidi_bytes, NULL);
-}
-EXPORT_SYMBOL_GPL(blk_end_bidi_request);
-
-/**
- * blk_end_request_callback - Special helper function for tricky drivers
- * @rq:           the request being processed
- * @error:        0 for success, < 0 for error
- * @nr_bytes:     number of bytes to complete
- * @drv_callback: function called between completion of bios in the request
- *                and completion of the request.
- *                If the callback returns non 0, this helper returns without
- *                completion of the request.
- *
- * Description:
- *     Ends I/O on a number of bytes attached to @rq.
- *     If @rq has leftover, sets it up for the next range of segments.
- *
- *     This special helper function is used only for existing tricky drivers.
- *     (e.g. cdrom_newpc_intr() of ide-cd)
- *     This interface will be removed when such drivers are rewritten.
- *     Don't use this interface in other places anymore.
- *
- * Return:
- *     0 - we are done with this request
- *     1 - this request is not freed yet.
- *         this request still has pending buffers or
- *         the driver doesn't want to finish this request yet.
- **/
-int blk_end_request_callback(struct request *rq, int error, int nr_bytes,
-			     int (drv_callback)(struct request *))
-{
-	return blk_end_io(rq, error, nr_bytes, 0, drv_callback);
-}
-EXPORT_SYMBOL_GPL(blk_end_request_callback);
-
-static void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
-			    struct bio *bio)
-{
-	/* first two bits are identical in rq->cmd_flags and bio->bi_rw */
-	rq->cmd_flags |= (bio->bi_rw & 3);
-
-	rq->nr_phys_segments = bio_phys_segments(q, bio);
-	rq->nr_hw_segments = bio_hw_segments(q, bio);
-	rq->current_nr_sectors = bio_cur_sectors(bio);
-	rq->hard_cur_sectors = rq->current_nr_sectors;
-	rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio);
-	rq->buffer = bio_data(bio);
-	rq->data_len = bio->bi_size;
-
-	rq->bio = rq->biotail = bio;
-
-	if (bio->bi_bdev)
-		rq->rq_disk = bio->bi_bdev->bd_disk;
-}
-
-int kblockd_schedule_work(struct work_struct *work)
-{
-	return queue_work(kblockd_workqueue, work);
-}
-
-EXPORT_SYMBOL(kblockd_schedule_work);
-
-void kblockd_flush_work(struct work_struct *work)
-{
-	cancel_work_sync(work);
-}
-EXPORT_SYMBOL(kblockd_flush_work);
-
-int __init blk_dev_init(void)
-{
-	int i;
-
-	kblockd_workqueue = create_workqueue("kblockd");
-	if (!kblockd_workqueue)
-		panic("Failed to create kblockd\n");
-
-	request_cachep = kmem_cache_create("blkdev_requests",
-			sizeof(struct request), 0, SLAB_PANIC, NULL);
-
-	requestq_cachep = kmem_cache_create("blkdev_queue",
-			sizeof(struct request_queue), 0, SLAB_PANIC, NULL);
-
-	iocontext_cachep = kmem_cache_create("blkdev_ioc",
-			sizeof(struct io_context), 0, SLAB_PANIC, NULL);
-
-	for_each_possible_cpu(i)
-		INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i));
-
-	open_softirq(BLOCK_SOFTIRQ, blk_done_softirq, NULL);
-	register_hotcpu_notifier(&blk_cpu_notifier);
-
-	blk_max_low_pfn = max_low_pfn - 1;
-	blk_max_pfn = max_pfn - 1;
-
-	return 0;
-}
-
-static void cfq_dtor(struct io_context *ioc)
-{
-	struct cfq_io_context *cic[1];
-	int r;
-
-	/*
-	 * We don't have a specific key to lookup with, so use the gang
-	 * lookup to just retrieve the first item stored. The cfq exit
-	 * function will iterate the full tree, so any member will do.
-	 */
-	r = radix_tree_gang_lookup(&ioc->radix_root, (void **) cic, 0, 1);
-	if (r > 0)
-		cic[0]->dtor(ioc);
-}
-
-/*
- * IO Context helper functions. put_io_context() returns 1 if there are no
- * more users of this io context, 0 otherwise.
- */
-int put_io_context(struct io_context *ioc)
-{
-	if (ioc == NULL)
-		return 1;
-
-	BUG_ON(atomic_read(&ioc->refcount) == 0);
-
-	if (atomic_dec_and_test(&ioc->refcount)) {
-		rcu_read_lock();
-		if (ioc->aic && ioc->aic->dtor)
-			ioc->aic->dtor(ioc->aic);
-		rcu_read_unlock();
-		cfq_dtor(ioc);
-
-		kmem_cache_free(iocontext_cachep, ioc);
-		return 1;
-	}
-	return 0;
-}
-EXPORT_SYMBOL(put_io_context);
-
-static void cfq_exit(struct io_context *ioc)
-{
-	struct cfq_io_context *cic[1];
-	int r;
-
-	rcu_read_lock();
-	/*
-	 * See comment for cfq_dtor()
-	 */
-	r = radix_tree_gang_lookup(&ioc->radix_root, (void **) cic, 0, 1);
-	rcu_read_unlock();
-
-	if (r > 0)
-		cic[0]->exit(ioc);
-}
-
-/* Called by the exitting task */
-void exit_io_context(void)
-{
-	struct io_context *ioc;
-
-	task_lock(current);
-	ioc = current->io_context;
-	current->io_context = NULL;
-	task_unlock(current);
-
-	if (atomic_dec_and_test(&ioc->nr_tasks)) {
-		if (ioc->aic && ioc->aic->exit)
-			ioc->aic->exit(ioc->aic);
-		cfq_exit(ioc);
-
-		put_io_context(ioc);
-	}
-}
-
-struct io_context *alloc_io_context(gfp_t gfp_flags, int node)
-{
-	struct io_context *ret;
-
-	ret = kmem_cache_alloc_node(iocontext_cachep, gfp_flags, node);
-	if (ret) {
-		atomic_set(&ret->refcount, 1);
-		atomic_set(&ret->nr_tasks, 1);
-		spin_lock_init(&ret->lock);
-		ret->ioprio_changed = 0;
-		ret->ioprio = 0;
-		ret->last_waited = jiffies; /* doesn't matter... */
-		ret->nr_batch_requests = 0; /* because this is 0 */
-		ret->aic = NULL;
-		INIT_RADIX_TREE(&ret->radix_root, GFP_ATOMIC | __GFP_HIGH);
-		ret->ioc_data = NULL;
-	}
-
-	return ret;
-}
-
-/*
- * If the current task has no IO context then create one and initialise it.
- * Otherwise, return its existing IO context.
- *
- * This returned IO context doesn't have a specifically elevated refcount,
- * but since the current task itself holds a reference, the context can be
- * used in general code, so long as it stays within `current` context.
- */
-static struct io_context *current_io_context(gfp_t gfp_flags, int node)
-{
-	struct task_struct *tsk = current;
-	struct io_context *ret;
-
-	ret = tsk->io_context;
-	if (likely(ret))
-		return ret;
-
-	ret = alloc_io_context(gfp_flags, node);
-	if (ret) {
-		/* make sure set_task_ioprio() sees the settings above */
-		smp_wmb();
-		tsk->io_context = ret;
-	}
-
-	return ret;
-}
-
-/*
- * If the current task has no IO context then create one and initialise it.
- * If it does have a context, take a ref on it.
- *
- * This is always called in the context of the task which submitted the I/O.
- */
-struct io_context *get_io_context(gfp_t gfp_flags, int node)
-{
-	struct io_context *ret = NULL;
-
-	/*
-	 * Check for unlikely race with exiting task. ioc ref count is
-	 * zero when ioc is being detached.
-	 */
-	do {
-		ret = current_io_context(gfp_flags, node);
-		if (unlikely(!ret))
-			break;
-	} while (!atomic_inc_not_zero(&ret->refcount));
-
-	return ret;
-}
-EXPORT_SYMBOL(get_io_context);
-
-void copy_io_context(struct io_context **pdst, struct io_context **psrc)
-{
-	struct io_context *src = *psrc;
-	struct io_context *dst = *pdst;
-
-	if (src) {
-		BUG_ON(atomic_read(&src->refcount) == 0);
-		atomic_inc(&src->refcount);
-		put_io_context(dst);
-		*pdst = src;
-	}
-}
-EXPORT_SYMBOL(copy_io_context);
-
-void swap_io_context(struct io_context **ioc1, struct io_context **ioc2)
-{
-	struct io_context *temp;
-	temp = *ioc1;
-	*ioc1 = *ioc2;
-	*ioc2 = temp;
-}
-EXPORT_SYMBOL(swap_io_context);
-
-/*
- * sysfs parts below
- */
-struct queue_sysfs_entry {
-	struct attribute attr;
-	ssize_t (*show)(struct request_queue *, char *);
-	ssize_t (*store)(struct request_queue *, const char *, size_t);
-};
-
-static ssize_t
-queue_var_show(unsigned int var, char *page)
-{
-	return sprintf(page, "%d\n", var);
-}
-
-static ssize_t
-queue_var_store(unsigned long *var, const char *page, size_t count)
-{
-	char *p = (char *) page;
-
-	*var = simple_strtoul(p, &p, 10);
-	return count;
-}
-
-static ssize_t queue_requests_show(struct request_queue *q, char *page)
-{
-	return queue_var_show(q->nr_requests, (page));
-}
-
-static ssize_t
-queue_requests_store(struct request_queue *q, const char *page, size_t count)
-{
-	struct request_list *rl = &q->rq;
-	unsigned long nr;
-	int ret = queue_var_store(&nr, page, count);
-	if (nr < BLKDEV_MIN_RQ)
-		nr = BLKDEV_MIN_RQ;
-
-	spin_lock_irq(q->queue_lock);
-	q->nr_requests = nr;
-	blk_queue_congestion_threshold(q);
-
-	if (rl->count[READ] >= queue_congestion_on_threshold(q))
-		blk_set_queue_congested(q, READ);
-	else if (rl->count[READ] < queue_congestion_off_threshold(q))
-		blk_clear_queue_congested(q, READ);
-
-	if (rl->count[WRITE] >= queue_congestion_on_threshold(q))
-		blk_set_queue_congested(q, WRITE);
-	else if (rl->count[WRITE] < queue_congestion_off_threshold(q))
-		blk_clear_queue_congested(q, WRITE);
-
-	if (rl->count[READ] >= q->nr_requests) {
-		blk_set_queue_full(q, READ);
-	} else if (rl->count[READ]+1 <= q->nr_requests) {
-		blk_clear_queue_full(q, READ);
-		wake_up(&rl->wait[READ]);
-	}
-
-	if (rl->count[WRITE] >= q->nr_requests) {
-		blk_set_queue_full(q, WRITE);
-	} else if (rl->count[WRITE]+1 <= q->nr_requests) {
-		blk_clear_queue_full(q, WRITE);
-		wake_up(&rl->wait[WRITE]);
-	}
-	spin_unlock_irq(q->queue_lock);
-	return ret;
-}
-
-static ssize_t queue_ra_show(struct request_queue *q, char *page)
-{
-	int ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10);
-
-	return queue_var_show(ra_kb, (page));
-}
-
-static ssize_t
-queue_ra_store(struct request_queue *q, const char *page, size_t count)
-{
-	unsigned long ra_kb;
-	ssize_t ret = queue_var_store(&ra_kb, page, count);
-
-	spin_lock_irq(q->queue_lock);
-	q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10);
-	spin_unlock_irq(q->queue_lock);
-
-	return ret;
-}
-
-static ssize_t queue_max_sectors_show(struct request_queue *q, char *page)
-{
-	int max_sectors_kb = q->max_sectors >> 1;
-
-	return queue_var_show(max_sectors_kb, (page));
-}
-
-static ssize_t
-queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
-{
-	unsigned long max_sectors_kb,
-			max_hw_sectors_kb = q->max_hw_sectors >> 1,
-			page_kb = 1 << (PAGE_CACHE_SHIFT - 10);
-	ssize_t ret = queue_var_store(&max_sectors_kb, page, count);
-
-	if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
-		return -EINVAL;
-	/*
-	 * Take the queue lock to update the readahead and max_sectors
-	 * values synchronously:
-	 */
-	spin_lock_irq(q->queue_lock);
-	q->max_sectors = max_sectors_kb << 1;
-	spin_unlock_irq(q->queue_lock);
-
-	return ret;
-}
-
-static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
-{
-	int max_hw_sectors_kb = q->max_hw_sectors >> 1;
-
-	return queue_var_show(max_hw_sectors_kb, (page));
-}
-
-
-static struct queue_sysfs_entry queue_requests_entry = {
-	.attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
-	.show = queue_requests_show,
-	.store = queue_requests_store,
-};
-
-static struct queue_sysfs_entry queue_ra_entry = {
-	.attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
-	.show = queue_ra_show,
-	.store = queue_ra_store,
-};
-
-static struct queue_sysfs_entry queue_max_sectors_entry = {
-	.attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
-	.show = queue_max_sectors_show,
-	.store = queue_max_sectors_store,
-};
-
-static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
-	.attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
-	.show = queue_max_hw_sectors_show,
-};
-
-static struct queue_sysfs_entry queue_iosched_entry = {
-	.attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
-	.show = elv_iosched_show,
-	.store = elv_iosched_store,
-};
-
-static struct attribute *default_attrs[] = {
-	&queue_requests_entry.attr,
-	&queue_ra_entry.attr,
-	&queue_max_hw_sectors_entry.attr,
-	&queue_max_sectors_entry.attr,
-	&queue_iosched_entry.attr,
-	NULL,
-};
-
-#define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
-
-static ssize_t
-queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
-{
-	struct queue_sysfs_entry *entry = to_queue(attr);
-	struct request_queue *q =
-		container_of(kobj, struct request_queue, kobj);
-	ssize_t res;
-
-	if (!entry->show)
-		return -EIO;
-	mutex_lock(&q->sysfs_lock);
-	if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
-		mutex_unlock(&q->sysfs_lock);
-		return -ENOENT;
-	}
-	res = entry->show(q, page);
-	mutex_unlock(&q->sysfs_lock);
-	return res;
-}
-
-static ssize_t
-queue_attr_store(struct kobject *kobj, struct attribute *attr,
-		    const char *page, size_t length)
-{
-	struct queue_sysfs_entry *entry = to_queue(attr);
-	struct request_queue *q = container_of(kobj, struct request_queue, kobj);
-
-	ssize_t res;
-
-	if (!entry->store)
-		return -EIO;
-	mutex_lock(&q->sysfs_lock);
-	if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
-		mutex_unlock(&q->sysfs_lock);
-		return -ENOENT;
-	}
-	res = entry->store(q, page, length);
-	mutex_unlock(&q->sysfs_lock);
-	return res;
-}
-
-static struct sysfs_ops queue_sysfs_ops = {
-	.show	= queue_attr_show,
-	.store	= queue_attr_store,
-};
-
-static struct kobj_type queue_ktype = {
-	.sysfs_ops	= &queue_sysfs_ops,
-	.default_attrs	= default_attrs,
-	.release	= blk_release_queue,
-};
-
-int blk_register_queue(struct gendisk *disk)
-{
-	int ret;
-
-	struct request_queue *q = disk->queue;
-
-	if (!q || !q->request_fn)
-		return -ENXIO;
-
-	ret = kobject_add(&q->kobj, kobject_get(&disk->dev.kobj),
-			  "%s", "queue");
-	if (ret < 0)
-		return ret;
-
-	kobject_uevent(&q->kobj, KOBJ_ADD);
-
-	ret = elv_register_queue(q);
-	if (ret) {
-		kobject_uevent(&q->kobj, KOBJ_REMOVE);
-		kobject_del(&q->kobj);
-		return ret;
-	}
-
-	return 0;
-}
-
-void blk_unregister_queue(struct gendisk *disk)
-{
-	struct request_queue *q = disk->queue;
-
-	if (q && q->request_fn) {
-		elv_unregister_queue(q);
-
-		kobject_uevent(&q->kobj, KOBJ_REMOVE);
-		kobject_del(&q->kobj);
-		kobject_put(&disk->dev.kobj);
-	}
-}