block: continue ll_rw_blk.c splitup

# Makefile for the kernel block layer

#

obj-$(CONFIG_BLOCK) := elevator.o blk-core.o blk-tag.o blk-sysfs.o ioctl.o \

			genhd.o scsi_ioctl.o

obj-$(CONFIG_BLOCK) := elevator.o blk-core.o blk-tag.o blk-sysfs.o \

			blk-barrier.o blk-settings.o blk-ioc.o blk-map.o \

			blk-exec.o ioctl.o genhd.o scsi_ioctl.o

obj-$(CONFIG_BLK_DEV_BSG)	+= bsg.o

obj-$(CONFIG_IOSCHED_NOOP)	+= noop-iosched.o

/*

 * Functions related to barrier IO handling

 */

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/bio.h>

#include <linux/blkdev.h>

#include "blk.h"

/**

 * blk_queue_ordered - does this queue support ordered writes

 * @q:        the request queue

 * @ordered:  one of QUEUE_ORDERED_*

 * @prepare_flush_fn: rq setup helper for cache flush ordered writes

 *

 * Description:

 *   For journalled file systems, doing ordered writes on a commit

 *   block instead of explicitly doing wait_on_buffer (which is bad

 *   for performance) can be a big win. Block drivers supporting this

 *   feature should call this function and indicate so.

 *

 **/

int blk_queue_ordered(struct request_queue *q, unsigned ordered,

		      prepare_flush_fn *prepare_flush_fn)

{

	if (ordered & (QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH) &&

	    prepare_flush_fn == NULL) {

		printk(KERN_ERR "blk_queue_ordered: prepare_flush_fn required\n");

		return -EINVAL;

	}

	if (ordered != QUEUE_ORDERED_NONE &&

	    ordered != QUEUE_ORDERED_DRAIN &&

	    ordered != QUEUE_ORDERED_DRAIN_FLUSH &&

	    ordered != QUEUE_ORDERED_DRAIN_FUA &&

	    ordered != QUEUE_ORDERED_TAG &&

	    ordered != QUEUE_ORDERED_TAG_FLUSH &&

	    ordered != QUEUE_ORDERED_TAG_FUA) {

		printk(KERN_ERR "blk_queue_ordered: bad value %d\n", ordered);

		return -EINVAL;

	}

	q->ordered = ordered;

	q->next_ordered = ordered;

	q->prepare_flush_fn = prepare_flush_fn;

	return 0;

}

EXPORT_SYMBOL(blk_queue_ordered);

/*

 * Cache flushing for ordered writes handling

 */

inline unsigned blk_ordered_cur_seq(struct request_queue *q)

{

	if (!q->ordseq)

		return 0;

	return 1 << ffz(q->ordseq);

}

unsigned blk_ordered_req_seq(struct request *rq)

{

	struct request_queue *q = rq->q;

	BUG_ON(q->ordseq == 0);

	if (rq == &q->pre_flush_rq)

		return QUEUE_ORDSEQ_PREFLUSH;

	if (rq == &q->bar_rq)

		return QUEUE_ORDSEQ_BAR;

	if (rq == &q->post_flush_rq)

		return QUEUE_ORDSEQ_POSTFLUSH;

	/*

	 * !fs requests don't need to follow barrier ordering.  Always

	 * put them at the front.  This fixes the following deadlock.

	 *

	 * http://thread.gmane.org/gmane.linux.kernel/537473

	 */

	if (!blk_fs_request(rq))

		return QUEUE_ORDSEQ_DRAIN;

	if ((rq->cmd_flags & REQ_ORDERED_COLOR) ==

	    (q->orig_bar_rq->cmd_flags & REQ_ORDERED_COLOR))

		return QUEUE_ORDSEQ_DRAIN;

	else

		return QUEUE_ORDSEQ_DONE;

}

void blk_ordered_complete_seq(struct request_queue *q, unsigned seq, int error)

{

	struct request *rq;

	if (error && !q->orderr)

		q->orderr = error;

	BUG_ON(q->ordseq & seq);

	q->ordseq |= seq;

	if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE)

		return;

	/*

	 * Okay, sequence complete.

	 */

	q->ordseq = 0;

	rq = q->orig_bar_rq;

	if (__blk_end_request(rq, q->orderr, blk_rq_bytes(rq)))

		BUG();

}

static void pre_flush_end_io(struct request *rq, int error)

{

	elv_completed_request(rq->q, rq);

	blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_PREFLUSH, error);

}

static void bar_end_io(struct request *rq, int error)

{

	elv_completed_request(rq->q, rq);

	blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_BAR, error);

}

static void post_flush_end_io(struct request *rq, int error)

{

	elv_completed_request(rq->q, rq);

	blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_POSTFLUSH, error);

}

static void queue_flush(struct request_queue *q, unsigned which)

{

	struct request *rq;

	rq_end_io_fn *end_io;

	if (which == QUEUE_ORDERED_PREFLUSH) {

		rq = &q->pre_flush_rq;

		end_io = pre_flush_end_io;

	} else {

		rq = &q->post_flush_rq;

		end_io = post_flush_end_io;

	}

	rq->cmd_flags = REQ_HARDBARRIER;

	rq_init(q, rq);

	rq->elevator_private = NULL;

	rq->elevator_private2 = NULL;

	rq->rq_disk = q->bar_rq.rq_disk;

	rq->end_io = end_io;

	q->prepare_flush_fn(q, rq);

	elv_insert(q, rq, ELEVATOR_INSERT_FRONT);

}

static inline struct request *start_ordered(struct request_queue *q,

					    struct request *rq)

{

	q->orderr = 0;

	q->ordered = q->next_ordered;

	q->ordseq |= QUEUE_ORDSEQ_STARTED;

	/*

	 * Prep proxy barrier request.

	 */

	blkdev_dequeue_request(rq);

	q->orig_bar_rq = rq;

	rq = &q->bar_rq;

	rq->cmd_flags = 0;

	rq_init(q, rq);

	if (bio_data_dir(q->orig_bar_rq->bio) == WRITE)

		rq->cmd_flags |= REQ_RW;

	if (q->ordered & QUEUE_ORDERED_FUA)

		rq->cmd_flags |= REQ_FUA;

	rq->elevator_private = NULL;

	rq->elevator_private2 = NULL;

	init_request_from_bio(rq, q->orig_bar_rq->bio);

	rq->end_io = bar_end_io;

	/*

	 * Queue ordered sequence.  As we stack them at the head, we

	 * need to queue in reverse order.  Note that we rely on that

	 * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs

	 * request gets inbetween ordered sequence. If this request is

	 * an empty barrier, we don't need to do a postflush ever since

	 * there will be no data written between the pre and post flush.

	 * Hence a single flush will suffice.

	 */

	if ((q->ordered & QUEUE_ORDERED_POSTFLUSH) && !blk_empty_barrier(rq))

		queue_flush(q, QUEUE_ORDERED_POSTFLUSH);

	else

		q->ordseq |= QUEUE_ORDSEQ_POSTFLUSH;

	elv_insert(q, rq, ELEVATOR_INSERT_FRONT);

	if (q->ordered & QUEUE_ORDERED_PREFLUSH) {

		queue_flush(q, QUEUE_ORDERED_PREFLUSH);

		rq = &q->pre_flush_rq;

	} else

		q->ordseq |= QUEUE_ORDSEQ_PREFLUSH;

	if ((q->ordered & QUEUE_ORDERED_TAG) || q->in_flight == 0)

		q->ordseq |= QUEUE_ORDSEQ_DRAIN;

	else

		rq = NULL;

	return rq;

}

int blk_do_ordered(struct request_queue *q, struct request **rqp)

{

	struct request *rq = *rqp;

	const int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq);

	if (!q->ordseq) {

		if (!is_barrier)

			return 1;

		if (q->next_ordered != QUEUE_ORDERED_NONE) {

			*rqp = start_ordered(q, rq);

			return 1;

		} else {

			/*

			 * This can happen when the queue switches to

			 * ORDERED_NONE while this request is on it.

			 */

			blkdev_dequeue_request(rq);

			if (__blk_end_request(rq, -EOPNOTSUPP,

					      blk_rq_bytes(rq)))

				BUG();

			*rqp = NULL;

			return 0;

		}

	}

	/*

	 * Ordered sequence in progress

	 */

	/* Special requests are not subject to ordering rules. */

	if (!blk_fs_request(rq) &&

	    rq != &q->pre_flush_rq && rq != &q->post_flush_rq)

		return 1;

	if (q->ordered & QUEUE_ORDERED_TAG) {

		/* Ordered by tag.  Blocking the next barrier is enough. */

		if (is_barrier && rq != &q->bar_rq)

			*rqp = NULL;

	} else {

		/* Ordered by draining.  Wait for turn. */

		WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q));

		if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q))

			*rqp = NULL;

	}

	return 1;

}

static void bio_end_empty_barrier(struct bio *bio, int err)

{

	if (err)

		clear_bit(BIO_UPTODATE, &bio->bi_flags);

	complete(bio->bi_private);

}

/**

 * blkdev_issue_flush - queue a flush

 * @bdev:	blockdev to issue flush for

 * @error_sector:	error sector

 *

 * Description:

 *    Issue a flush for the block device in question. Caller can supply

 *    room for storing the error offset in case of a flush error, if they

 *    wish to.  Caller must run wait_for_completion() on its own.

 */

int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector)

{

	DECLARE_COMPLETION_ONSTACK(wait);

	struct request_queue *q;

	struct bio *bio;

	int ret;

	if (bdev->bd_disk == NULL)

		return -ENXIO;

	q = bdev_get_queue(bdev);

	if (!q)

		return -ENXIO;

	bio = bio_alloc(GFP_KERNEL, 0);

	if (!bio)

		return -ENOMEM;

	bio->bi_end_io = bio_end_empty_barrier;

	bio->bi_private = &wait;

	bio->bi_bdev = bdev;

	submit_bio(1 << BIO_RW_BARRIER, bio);

	wait_for_completion(&wait);

	/*

	 * The driver must store the error location in ->bi_sector, if

	 * it supports it. For non-stacked drivers, this should be copied

	 * from rq->sector.

	 */

	if (error_sector)

		*error_sector = bio->bi_sector;

	ret = 0;

	if (!bio_flagged(bio, BIO_UPTODATE))

		ret = -EIO;

	bio_put(bio);

	return ret;

}

EXPORT_SYMBOL(blkdev_issue_flush);