388 lines
9.0 KiB
C
388 lines
9.0 KiB
C
/*
|
|
* 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 "%s: prepare_flush_fn required\n", __func__);
|
|
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
|
|
*/
|
|
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;
|
|
}
|
|
|
|
blk_rq_init(q, rq);
|
|
rq->cmd_flags = REQ_HARDBARRIER;
|
|
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;
|
|
blk_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;
|
|
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) {
|
|
if (err == -EOPNOTSUPP)
|
|
set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
|
|
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(WRITE_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_EOPNOTSUPP))
|
|
ret = -EOPNOTSUPP;
|
|
else if (!bio_flagged(bio, BIO_UPTODATE))
|
|
ret = -EIO;
|
|
|
|
bio_put(bio);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(blkdev_issue_flush);
|
|
|
|
static void blkdev_discard_end_io(struct bio *bio, int err)
|
|
{
|
|
if (err) {
|
|
if (err == -EOPNOTSUPP)
|
|
set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
|
|
clear_bit(BIO_UPTODATE, &bio->bi_flags);
|
|
}
|
|
|
|
bio_put(bio);
|
|
}
|
|
|
|
/**
|
|
* blkdev_issue_discard - queue a discard
|
|
* @bdev: blockdev to issue discard for
|
|
* @sector: start sector
|
|
* @nr_sects: number of sectors to discard
|
|
* @gfp_mask: memory allocation flags (for bio_alloc)
|
|
*
|
|
* Description:
|
|
* Issue a discard request for the sectors in question. Does not wait.
|
|
*/
|
|
int blkdev_issue_discard(struct block_device *bdev,
|
|
sector_t sector, sector_t nr_sects, gfp_t gfp_mask)
|
|
{
|
|
struct request_queue *q;
|
|
struct bio *bio;
|
|
int ret = 0;
|
|
|
|
if (bdev->bd_disk == NULL)
|
|
return -ENXIO;
|
|
|
|
q = bdev_get_queue(bdev);
|
|
if (!q)
|
|
return -ENXIO;
|
|
|
|
if (!q->prepare_discard_fn)
|
|
return -EOPNOTSUPP;
|
|
|
|
while (nr_sects && !ret) {
|
|
bio = bio_alloc(gfp_mask, 0);
|
|
if (!bio)
|
|
return -ENOMEM;
|
|
|
|
bio->bi_end_io = blkdev_discard_end_io;
|
|
bio->bi_bdev = bdev;
|
|
|
|
bio->bi_sector = sector;
|
|
|
|
if (nr_sects > q->max_hw_sectors) {
|
|
bio->bi_size = q->max_hw_sectors << 9;
|
|
nr_sects -= q->max_hw_sectors;
|
|
sector += q->max_hw_sectors;
|
|
} else {
|
|
bio->bi_size = nr_sects << 9;
|
|
nr_sects = 0;
|
|
}
|
|
bio_get(bio);
|
|
submit_bio(DISCARD_BARRIER, bio);
|
|
|
|
/* Check if it failed immediately */
|
|
if (bio_flagged(bio, BIO_EOPNOTSUPP))
|
|
ret = -EOPNOTSUPP;
|
|
else if (!bio_flagged(bio, BIO_UPTODATE))
|
|
ret = -EIO;
|
|
bio_put(bio);
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(blkdev_issue_discard);
|