You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
262 lines
6.7 KiB
262 lines
6.7 KiB
/*
|
|
* Functions to sequence FLUSH and FUA writes.
|
|
*/
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
#include <linux/bio.h>
|
|
#include <linux/blkdev.h>
|
|
#include <linux/gfp.h>
|
|
|
|
#include "blk.h"
|
|
|
|
/* FLUSH/FUA sequences */
|
|
enum {
|
|
QUEUE_FSEQ_STARTED = (1 << 0), /* flushing in progress */
|
|
QUEUE_FSEQ_PREFLUSH = (1 << 1), /* pre-flushing in progress */
|
|
QUEUE_FSEQ_DATA = (1 << 2), /* data write in progress */
|
|
QUEUE_FSEQ_POSTFLUSH = (1 << 3), /* post-flushing in progress */
|
|
QUEUE_FSEQ_DONE = (1 << 4),
|
|
};
|
|
|
|
static struct request *queue_next_fseq(struct request_queue *q);
|
|
|
|
unsigned blk_flush_cur_seq(struct request_queue *q)
|
|
{
|
|
if (!q->flush_seq)
|
|
return 0;
|
|
return 1 << ffz(q->flush_seq);
|
|
}
|
|
|
|
static struct request *blk_flush_complete_seq(struct request_queue *q,
|
|
unsigned seq, int error)
|
|
{
|
|
struct request *next_rq = NULL;
|
|
|
|
if (error && !q->flush_err)
|
|
q->flush_err = error;
|
|
|
|
BUG_ON(q->flush_seq & seq);
|
|
q->flush_seq |= seq;
|
|
|
|
if (blk_flush_cur_seq(q) != QUEUE_FSEQ_DONE) {
|
|
/* not complete yet, queue the next flush sequence */
|
|
next_rq = queue_next_fseq(q);
|
|
} else {
|
|
/* complete this flush request */
|
|
__blk_end_request_all(q->orig_flush_rq, q->flush_err);
|
|
q->orig_flush_rq = NULL;
|
|
q->flush_seq = 0;
|
|
|
|
/* dispatch the next flush if there's one */
|
|
if (!list_empty(&q->pending_flushes)) {
|
|
next_rq = list_entry_rq(q->pending_flushes.next);
|
|
list_move(&next_rq->queuelist, &q->queue_head);
|
|
}
|
|
}
|
|
return next_rq;
|
|
}
|
|
|
|
static void blk_flush_complete_seq_end_io(struct request_queue *q,
|
|
unsigned seq, int error)
|
|
{
|
|
bool was_empty = elv_queue_empty(q);
|
|
struct request *next_rq;
|
|
|
|
next_rq = blk_flush_complete_seq(q, seq, error);
|
|
|
|
/*
|
|
* Moving a request silently to empty queue_head may stall the
|
|
* queue. Kick the queue in those cases.
|
|
*/
|
|
if (was_empty && next_rq)
|
|
__blk_run_queue(q);
|
|
}
|
|
|
|
static void pre_flush_end_io(struct request *rq, int error)
|
|
{
|
|
elv_completed_request(rq->q, rq);
|
|
blk_flush_complete_seq_end_io(rq->q, QUEUE_FSEQ_PREFLUSH, error);
|
|
}
|
|
|
|
static void flush_data_end_io(struct request *rq, int error)
|
|
{
|
|
elv_completed_request(rq->q, rq);
|
|
blk_flush_complete_seq_end_io(rq->q, QUEUE_FSEQ_DATA, error);
|
|
}
|
|
|
|
static void post_flush_end_io(struct request *rq, int error)
|
|
{
|
|
elv_completed_request(rq->q, rq);
|
|
blk_flush_complete_seq_end_io(rq->q, QUEUE_FSEQ_POSTFLUSH, error);
|
|
}
|
|
|
|
static void init_flush_request(struct request *rq, struct gendisk *disk)
|
|
{
|
|
rq->cmd_type = REQ_TYPE_FS;
|
|
rq->cmd_flags = WRITE_FLUSH;
|
|
rq->rq_disk = disk;
|
|
}
|
|
|
|
static struct request *queue_next_fseq(struct request_queue *q)
|
|
{
|
|
struct request *orig_rq = q->orig_flush_rq;
|
|
struct request *rq = &q->flush_rq;
|
|
|
|
blk_rq_init(q, rq);
|
|
|
|
switch (blk_flush_cur_seq(q)) {
|
|
case QUEUE_FSEQ_PREFLUSH:
|
|
init_flush_request(rq, orig_rq->rq_disk);
|
|
rq->end_io = pre_flush_end_io;
|
|
break;
|
|
case QUEUE_FSEQ_DATA:
|
|
init_request_from_bio(rq, orig_rq->bio);
|
|
/*
|
|
* orig_rq->rq_disk may be different from
|
|
* bio->bi_bdev->bd_disk if orig_rq got here through
|
|
* remapping drivers. Make sure rq->rq_disk points
|
|
* to the same one as orig_rq.
|
|
*/
|
|
rq->rq_disk = orig_rq->rq_disk;
|
|
rq->cmd_flags &= ~(REQ_FLUSH | REQ_FUA);
|
|
rq->cmd_flags |= orig_rq->cmd_flags & (REQ_FLUSH | REQ_FUA);
|
|
rq->end_io = flush_data_end_io;
|
|
break;
|
|
case QUEUE_FSEQ_POSTFLUSH:
|
|
init_flush_request(rq, orig_rq->rq_disk);
|
|
rq->end_io = post_flush_end_io;
|
|
break;
|
|
default:
|
|
BUG();
|
|
}
|
|
|
|
elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
|
|
return rq;
|
|
}
|
|
|
|
struct request *blk_do_flush(struct request_queue *q, struct request *rq)
|
|
{
|
|
unsigned int fflags = q->flush_flags; /* may change, cache it */
|
|
bool has_flush = fflags & REQ_FLUSH, has_fua = fflags & REQ_FUA;
|
|
bool do_preflush = has_flush && (rq->cmd_flags & REQ_FLUSH);
|
|
bool do_postflush = has_flush && !has_fua && (rq->cmd_flags & REQ_FUA);
|
|
unsigned skip = 0;
|
|
|
|
/*
|
|
* Special case. If there's data but flush is not necessary,
|
|
* the request can be issued directly.
|
|
*
|
|
* Flush w/o data should be able to be issued directly too but
|
|
* currently some drivers assume that rq->bio contains
|
|
* non-zero data if it isn't NULL and empty FLUSH requests
|
|
* getting here usually have bio's without data.
|
|
*/
|
|
if (blk_rq_sectors(rq) && !do_preflush && !do_postflush) {
|
|
rq->cmd_flags &= ~REQ_FLUSH;
|
|
if (!has_fua)
|
|
rq->cmd_flags &= ~REQ_FUA;
|
|
return rq;
|
|
}
|
|
|
|
/*
|
|
* Sequenced flushes can't be processed in parallel. If
|
|
* another one is already in progress, queue for later
|
|
* processing.
|
|
*/
|
|
if (q->flush_seq) {
|
|
list_move_tail(&rq->queuelist, &q->pending_flushes);
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Start a new flush sequence
|
|
*/
|
|
q->flush_err = 0;
|
|
q->flush_seq |= QUEUE_FSEQ_STARTED;
|
|
|
|
/* adjust FLUSH/FUA of the original request and stash it away */
|
|
rq->cmd_flags &= ~REQ_FLUSH;
|
|
if (!has_fua)
|
|
rq->cmd_flags &= ~REQ_FUA;
|
|
blk_dequeue_request(rq);
|
|
q->orig_flush_rq = rq;
|
|
|
|
/* skip unneded sequences and return the first one */
|
|
if (!do_preflush)
|
|
skip |= QUEUE_FSEQ_PREFLUSH;
|
|
if (!blk_rq_sectors(rq))
|
|
skip |= QUEUE_FSEQ_DATA;
|
|
if (!do_postflush)
|
|
skip |= QUEUE_FSEQ_POSTFLUSH;
|
|
return blk_flush_complete_seq(q, skip, 0);
|
|
}
|
|
|
|
static void bio_end_flush(struct bio *bio, int err)
|
|
{
|
|
if (err)
|
|
clear_bit(BIO_UPTODATE, &bio->bi_flags);
|
|
if (bio->bi_private)
|
|
complete(bio->bi_private);
|
|
bio_put(bio);
|
|
}
|
|
|
|
/**
|
|
* blkdev_issue_flush - queue a flush
|
|
* @bdev: blockdev to issue flush for
|
|
* @gfp_mask: memory allocation flags (for bio_alloc)
|
|
* @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. If WAIT flag is not passed then caller may check only what
|
|
* request was pushed in some internal queue for later handling.
|
|
*/
|
|
int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
|
|
sector_t *error_sector)
|
|
{
|
|
DECLARE_COMPLETION_ONSTACK(wait);
|
|
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;
|
|
|
|
/*
|
|
* some block devices may not have their queue correctly set up here
|
|
* (e.g. loop device without a backing file) and so issuing a flush
|
|
* here will panic. Ensure there is a request function before issuing
|
|
* the flush.
|
|
*/
|
|
if (!q->make_request_fn)
|
|
return -ENXIO;
|
|
|
|
bio = bio_alloc(gfp_mask, 0);
|
|
bio->bi_end_io = bio_end_flush;
|
|
bio->bi_bdev = bdev;
|
|
bio->bi_private = &wait;
|
|
|
|
bio_get(bio);
|
|
submit_bio(WRITE_FLUSH, 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 blk_rq_pos(rq).
|
|
*/
|
|
if (error_sector)
|
|
*error_sector = bio->bi_sector;
|
|
|
|
if (!bio_flagged(bio, BIO_UPTODATE))
|
|
ret = -EIO;
|
|
|
|
bio_put(bio);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(blkdev_issue_flush);
|
|
|