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);

/*

 * Functions related to setting various queue properties from drivers

 */

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/bio.h>

#include <linux/blkdev.h>

#include "blk.h"

/*

 * for max sense size

 */

#include <scsi/scsi_cmnd.h>

/**

 * 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);

/**

 * 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);

/*

 * Functions related to io context handling

 */

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/init.h>

#include <linux/bio.h>

#include <linux/blkdev.h>

#include <linux/bootmem.h>	/* for max_pfn/max_low_pfn */

#include "blk.h"

/*

 * For io context allocations

 */

static struct kmem_cache *iocontext_cachep;

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.

 */

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);

int __init blk_ioc_init(void)

{

	iocontext_cachep = kmem_cache_create("blkdev_ioc",

			sizeof(struct io_context), 0, SLAB_PANIC, NULL);

	return 0;

}

subsys_initcall(blk_ioc_init);