Re: [PATCH Linux 2.6.12-rc5-mm2 05/09] blk: reimplement handling of barrier request

Tejun Heo
2005-06-05T06:07:22Z

05_blk_ordered_reimpl.patch

Reimplement handling of barrier requests.

* Flexible handling to deal with various capabilities of
target devices.
* Retry support for falling back.
* Tagged queues which don't support ordered tag can do ordered.

Signed-off-by: Tejun Heo <htejun@gmail.com>

drivers/block/elevator.c | 79 ++++---
drivers/block/ll_rw_blk.c | 491 ++++++++++++++++++++++++++++++++--------------
include/linux/blkdev.h | 93 ++++++--
3 files changed, 469 insertions(+), 194 deletions(-)

Index: blk-fixes/drivers/block/elevator.c
===================================================================
--- blk-fixes.orig/drivers/block/elevator.c 2005-06-05 14:53:32.000000000 +0900
+++ blk-fixes/drivers/block/elevator.c 2005-06-05 14:53:34.000000000 +0900
@@ -37,9 +37,38 @@

#include <asm/uaccess.h>

+/*
+ * XXX HACK XXX Before entering elevator callbacks, we temporailiy
+ * turn off REQ_CMD of proxy barrier request so that elevators don't
+ * try to account it as a normal one. This ugliness can go away once
+ * generic dispatch queue is implemented. - tj
+ */
+#define bar_rq_hack_start(q) ((q)->bar_rq && ((q)->bar_rq->flags &= ~REQ_CMD))
+#define bar_rq_hack_end(q) ((q)->bar_rq && ((q)->bar_rq->flags |= REQ_CMD))
+
static DEFINE_SPINLOCK(elv_list_lock);
static LIST_HEAD(elv_list);

+static inline void elv_inc_inflight(request_queue_t *q)
+{
+ q->in_flight++;
+}
+
+static inline void elv_dec_inflight(request_queue_t *q)
+{
+ q->in_flight--;
+
+ /*
+ * If the queue is waiting for all accounted requests to be
+ * drained to start flush sequence and we're the last one,
+ * kick the queue in the ass to start the flush sequence.
+ */
+ if (q->in_flight == 0 && blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN) {
+ blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0);
+ q->request_fn(q);
+ }
+}
+
/*
* can we safely merge with this request?
*/
@@ -270,12 +299,15 @@ void elv_deactivate_request(request_queu
* in_flight count again
*/
if (blk_account_rq(rq))
- q->in_flight--;
+ elv_dec_inflight(q);

rq->flags &= ~REQ_STARTED;

- if (e->ops->elevator_deactivate_req_fn)
+ if (e->ops->elevator_deactivate_req_fn) {
+ bar_rq_hack_start(q);
e->ops->elevator_deactivate_req_fn(q, rq);
+ bar_rq_hack_end(q);
+ }
}

void elv_requeue_request(request_queue_t *q, struct request *rq)
@@ -283,14 +315,6 @@ void elv_requeue_request(request_queue_t
elv_deactivate_request(q, rq);

/*
- * if this is the flush, requeue the original instead and drop the flush
- */
- if (rq->flags & REQ_BAR_FLUSH) {
- clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags);
- rq = rq->end_io_data;
- }
-
- /*
* the request is prepped and may have some resources allocated.
* allowing unprepped requests to pass this one may cause resource
* deadlock. turn on softbarrier.
@@ -301,9 +325,11 @@ void elv_requeue_request(request_queue_t
* if iosched has an explicit requeue hook, then use that. otherwise
* just put the request at the front of the queue
*/
- if (q->elevator->ops->elevator_requeue_req_fn)
+ if (q->elevator->ops->elevator_requeue_req_fn) {
+ bar_rq_hack_start(q);
q->elevator->ops->elevator_requeue_req_fn(q, rq);
- else
+ bar_rq_hack_end(q);
+ } else
__elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0);
}

@@ -323,7 +349,9 @@ void __elv_add_request(request_queue_t *
rq->q = q;

if (!test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags)) {
+ bar_rq_hack_start(q);
q->elevator->ops->elevator_add_req_fn(q, rq, where);
+ bar_rq_hack_end(q);

if (blk_queue_plugged(q)) {
int nrq = q->rq.count[READ] + q->rq.count[WRITE]
@@ -353,20 +381,10 @@ void elv_add_request(request_queue_t *q,

static inline struct request *__elv_next_request(request_queue_t *q)
{
- struct request *rq = q->elevator->ops->elevator_next_req_fn(q);
-
- /*
- * if this is a barrier write and the device has to issue a
- * flush sequence to support it, check how far we are
- */
- if (rq && blk_fs_request(rq) && blk_barrier_rq(rq)) {
- BUG_ON(q->ordered == QUEUE_ORDERED_NONE);
-
- if (q->ordered == QUEUE_ORDERED_FLUSH &&
- !blk_barrier_preflush(rq))
- rq = blk_start_pre_flush(q, rq);
- }
-
+ struct request *rq;
+ while ((rq = q->elevator->ops->elevator_next_req_fn(q)))
+ if (blk_do_ordered(q, &rq))
+ break;
return rq;
}

@@ -433,7 +451,7 @@ void elv_remove_request(request_queue_t
* for request-request merges
*/
if (blk_account_rq(rq))
- q->in_flight++;
+ elv_inc_inflight(q);

/*
* the main clearing point for q->last_merge is on retrieval of
@@ -445,8 +463,11 @@ void elv_remove_request(request_queue_t
if (rq == q->last_merge)
q->last_merge = NULL;

- if (e->ops->elevator_remove_req_fn)
+ if (e->ops->elevator_remove_req_fn) {
+ bar_rq_hack_start(q);
e->ops->elevator_remove_req_fn(q, rq);
+ bar_rq_hack_end(q);
+ }
}

int elv_queue_empty(request_queue_t *q)
@@ -529,7 +550,7 @@ void elv_completed_request(request_queue
* request is released from the driver, io must be done
*/
if (blk_account_rq(rq))
- q->in_flight--;
+ elv_dec_inflight(q);

if (e->ops->elevator_completed_req_fn)
e->ops->elevator_completed_req_fn(q, rq);
Index: blk-fixes/drivers/block/ll_rw_blk.c
===================================================================
--- blk-fixes.orig/drivers/block/ll_rw_blk.c 2005-06-05 14:53:34.000000000 +0900
+++ blk-fixes/drivers/block/ll_rw_blk.c 2005-06-05 14:53:34.000000000 +0900
@@ -291,10 +291,112 @@ static inline void rq_init(request_queue
rq->end_io_data = NULL;
}

+static int __blk_queue_ordered(request_queue_t *q, int ordered,
+ prepare_flush_fn *prepare_flush_fn,
+ unsigned gfp_mask, int locked)
+{
+ void *rq0 = NULL, *rq1 = NULL, *rq2 = NULL;
+ unsigned long flags = 0; /* shut up, gcc */
+ unsigned ordered_flags;
+ int ret = 0;
+
+ might_sleep_if(gfp_mask & __GFP_WAIT);
+
+ ordered_flags = ordered & QUEUE_ORDERED_FLAGS;
+ ordered &= ~QUEUE_ORDERED_FLAGS;
+
+ if (ordered & (QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH) &&
+ prepare_flush_fn == NULL) {
+ printk(KERN_ERR "blk_queue_ordered: prepare_flush_fn required\n");
+ ret = -EINVAL;
+ goto out_unlocked;
+ }
+
+ if (!locked)
+ spin_lock_irqsave(q->queue_lock, flags);
+
+ if (q->ordseq) {
+ /* Queue flushing in progress, defer changing q->ordered. */
+ q->next_ordered = ordered;
+ q->next_prepare_flush_fn = prepare_flush_fn;
+ ret = -EINPROGRESS;
+ goto out;
+ }
+
+ switch (ordered) {
+ case QUEUE_ORDERED_NONE:
+ ordered_flags = 0; /* for '== QUEUE_ORDERED_NONE' tests */
+ if (!q->pre_flush_rq) {
+ rq0 = q->pre_flush_rq;
+ rq1 = q->bar_rq;
+ rq2 = q->post_flush_rq;
+ q->pre_flush_rq = NULL;
+ q->bar_rq = NULL;
+ q->post_flush_rq = NULL;
+ }
+ break;
+
+ case QUEUE_ORDERED_DRAIN:
+ case QUEUE_ORDERED_DRAIN_FLUSH:
+ case QUEUE_ORDERED_DRAIN_FUA:
+ case QUEUE_ORDERED_TAG:
+ case QUEUE_ORDERED_TAG_FLUSH:
+ case QUEUE_ORDERED_TAG_FUA:
+ if (q->pre_flush_rq)
+ break;
+
+ if (!locked)
+ spin_unlock_irqrestore(q->queue_lock, flags);
+ if (!(rq0 = kmem_cache_alloc(request_cachep, gfp_mask)) ||
+ !(rq1 = kmem_cache_alloc(request_cachep, gfp_mask)) ||
+ !(rq2 = kmem_cache_alloc(request_cachep, gfp_mask))) {
+ printk(KERN_ERR "blk_queue_ordered: failed to "
+ "switch to 0x%x (out of memory)\n", ordered);
+ ret = -ENOMEM;
+ goto out_unlocked;
+ }
+ if (!locked)
+ spin_lock_irqsave(q->queue_lock, flags);
+
+ if (!q->pre_flush_rq) {
+ q->pre_flush_rq = rq0;
+ q->bar_rq = rq1;
+ q->post_flush_rq = rq2;
+ rq0 = NULL;
+ rq1 = NULL;
+ rq2 = NULL;
+ }
+ break;
+
+ default:
+ printk(KERN_ERR "blk_queue_ordered: bad value %d\n", ordered);
+ ret = -EINVAL;
+ goto out;
+ }
+
+ q->ordered = ordered | ordered_flags;
+ q->next_ordered = q->ordered;
+ q->prepare_flush_fn = prepare_flush_fn;
+
+ out:
+ if (!locked)
+ spin_unlock_irqrestore(q->queue_lock, flags);
+ out_unlocked:
+ if (rq0)
+ kmem_cache_free(request_cachep, rq0);
+ if (rq1)
+ kmem_cache_free(request_cachep, rq1);
+ if (rq2)
+ kmem_cache_free(request_cachep, rq2);
+
+ return ret;
+}
+
/**
* blk_queue_ordered - does this queue support ordered writes
- * @q: the request queue
- * @flag: see below
+ * @q: the request queue
+ * @ordered: one of QUEUE_ORDERED_*
+ * @gfp_mask: allocation mask
*
* Description:
* For journalled file systems, doing ordered writes on a commit
@@ -303,32 +405,24 @@ static inline void rq_init(request_queue
* feature should call this function and indicate so.
*
**/
-void blk_queue_ordered(request_queue_t *q, int flag)
+extern int blk_queue_ordered(request_queue_t *q, unsigned ordered,
+ prepare_flush_fn *prepare_flush_fn,
+ unsigned gfp_mask)
{
- switch (flag) {
- case QUEUE_ORDERED_NONE:
- if (q->flush_rq)
- kmem_cache_free(request_cachep, q->flush_rq);
- q->flush_rq = NULL;
- q->ordered = flag;
- break;
- case QUEUE_ORDERED_TAG:
- q->ordered = flag;
- break;
- case QUEUE_ORDERED_FLUSH:
- q->ordered = flag;
- if (!q->flush_rq)
- q->flush_rq = kmem_cache_alloc(request_cachep,
- GFP_KERNEL);
- break;
- default:
- printk("blk_queue_ordered: bad value %d\n", flag);
- break;
- }
+ return __blk_queue_ordered(q, ordered, prepare_flush_fn, gfp_mask, 0);
}

EXPORT_SYMBOL(blk_queue_ordered);

+extern int blk_queue_ordered_locked(request_queue_t *q, unsigned ordered,
+ prepare_flush_fn *prepare_flush_fn,
+ unsigned gfp_mask)
+{
+ return __blk_queue_ordered(q, ordered, prepare_flush_fn, gfp_mask, 1);
+}
+
+EXPORT_SYMBOL(blk_queue_ordered_locked);
+
/**
* blk_queue_issue_flush_fn - set function for issuing a flush
* @q: the request queue
@@ -349,165 +443,281 @@ EXPORT_SYMBOL(blk_queue_issue_flush_fn);
/*
* Cache flushing for ordered writes handling
*/
-static void blk_pre_flush_end_io(struct request *flush_rq, int error)
+inline unsigned blk_ordered_cur_seq(request_queue_t *q)
{
- struct request *rq = flush_rq->end_io_data;
- request_queue_t *q = rq->q;
-
- rq->flags |= REQ_BAR_PREFLUSH;
-
- if (!flush_rq->errors)
- elv_requeue_request(q, rq);
- else {
- q->end_flush_fn(q, flush_rq);
- clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags);
- q->request_fn(q);
- }
+ if (!q->ordseq)
+ return 0;
+ return 1 << ffz(q->ordseq);
}

-static void blk_post_flush_end_io(struct request *flush_rq, int error)
+static void ordered_set_error(request_queue_t *q, unsigned seq, int error)
{
- struct request *rq = flush_rq->end_io_data;
- request_queue_t *q = rq->q;
+ unsigned ordered;

- rq->flags |= REQ_BAR_POSTFLUSH;
+ q->orderr = error;

- q->end_flush_fn(q, flush_rq);
- clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags);
- q->request_fn(q);
+ if (q->ordered & QUEUE_ORDERED_NOFALLBACK ||
+ q->ordered != q->next_ordered)
+ return;
+
+ switch (seq) {
+ case QUEUE_ORDSEQ_PREFLUSH:
+ if (q->ordered & QUEUE_ORDERED_TAG)
+ ordered = (q->ordered & ~QUEUE_ORDERED_TAG) |
+ QUEUE_ORDERED_DRAIN;
+ else
+ ordered = QUEUE_ORDERED_NONE;
+ break;
+ case QUEUE_ORDSEQ_BAR:
+ ordered = (q->ordered & ~QUEUE_ORDERED_FUA) |
+ QUEUE_ORDERED_POSTFLUSH;
+ break;
+ default:
+ return;
+ }
+
+ blk_queue_ordered_locked(q, ordered, q->prepare_flush_fn, GFP_ATOMIC);
}

-struct request *blk_start_pre_flush(request_queue_t *q, struct request *rq)
+void blk_ordered_complete_seq(request_queue_t *q, unsigned seq, int error)
{
- struct request *flush_rq = q->flush_rq;
+ struct request *rq;
+ int uptodate, changed = 0;

- BUG_ON(!blk_barrier_rq(rq));
+ if (error && !q->orderr)
+ ordered_set_error(q, seq, error);

- if (test_and_set_bit(QUEUE_FLAG_FLUSH, &q->queue_flags))
- return NULL;
+ BUG_ON(q->ordseq & seq);
+ q->ordseq |= seq;

- rq_init(q, flush_rq);
- flush_rq->elevator_private = NULL;
- flush_rq->flags = REQ_BAR_FLUSH;
- flush_rq->rq_disk = rq->rq_disk;
- flush_rq->rl = NULL;
+ if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE)
+ return;

/*
- * prepare_flush returns 0 if no flush is needed, just mark both
- * pre and post flush as done in that case
- */
- if (!q->prepare_flush_fn(q, flush_rq)) {
- rq->flags |= REQ_BAR_PREFLUSH | REQ_BAR_POSTFLUSH;
- clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags);
- return rq;
- }
+ * Okay, sequence complete.
+ */
+ rq = q->orig_bar_rq;
+ uptodate = q->orderr ? q->orderr : 1;
+
+ q->ordseq = 0;

/*
- * some drivers dequeue requests right away, some only after io
- * completion. make sure the request is dequeued.
+ * We give a failed barrier request second chance if ordered
+ * has changed since it has started.
*/
- if (!list_empty(&rq->queuelist))
- blkdev_dequeue_request(rq);
+ if (q->next_ordered != q->ordered)
+ changed = !blk_queue_ordered_locked(q, q->next_ordered,
+ q->next_prepare_flush_fn,
+ GFP_ATOMIC);

- elv_deactivate_request(q, rq);
+ if (!q->orderr || !changed || q->ordered == QUEUE_ORDERED_NONE) {
+ end_that_request_first(rq, uptodate, rq->hard_nr_sectors);
+ end_that_request_last(rq, uptodate);
+ } else
+ blk_requeue_request(q, rq);
+}

- flush_rq->end_io_data = rq;
- flush_rq->end_io = blk_pre_flush_end_io;
+static void pre_flush_end_io(struct request *rq, int error)
+{
+ blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_PREFLUSH, error);
+}

- __elv_add_request(q, flush_rq, ELEVATOR_INSERT_FRONT, 0);
- return flush_rq;
+static void bar_end_io(struct request *rq, int error)
+{
+ blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_BAR, error);
}

-static void blk_start_post_flush(request_queue_t *q, struct request *rq)
+static void post_flush_end_io(struct request *rq, int error)
{
- struct request *flush_rq = q->flush_rq;
+ blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_POSTFLUSH, error);
+}

- BUG_ON(!blk_barrier_rq(rq));
+static void queue_flush(request_queue_t *q, unsigned which)
+{
+ struct request *rq;
+ rq_end_io_fn *end_io;

- rq_init(q, flush_rq);
- flush_rq->elevator_private = NULL;
- flush_rq->flags = REQ_BAR_FLUSH;
- flush_rq->rq_disk = rq->rq_disk;
- flush_rq->rl = NULL;
+ 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;
+ }

- if (q->prepare_flush_fn(q, flush_rq)) {
- flush_rq->end_io_data = rq;
- flush_rq->end_io = blk_post_flush_end_io;
+ rq_init(q, rq);
+ rq->flags = REQ_HARDBARRIER;
+ rq->elevator_private = NULL;
+ rq->rq_disk = q->bar_rq->rq_disk;
+ rq->rl = NULL;
+ rq->end_io = end_io;
+ q->prepare_flush_fn(q, rq);

- __elv_add_request(q, flush_rq, ELEVATOR_INSERT_FRONT, 0);
- q->request_fn(q);
- }
+ __elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0);
}

-static inline int blk_check_end_barrier(request_queue_t *q, struct request *rq,
- int sectors)
+static inline struct request *start_ordered(request_queue_t *q,
+ struct request *rq)
{
- if (sectors > rq->nr_sectors)
- sectors = rq->nr_sectors;
+ q->bi_size = 0;
+ q->orderr = 0;
+ q->ordseq |= QUEUE_ORDSEQ_STARTED;

- rq->nr_sectors -= sectors;
- return rq->nr_sectors;
-}
+ /*
+ * Prep proxy barrier request.
+ */
+ blkdev_dequeue_request(rq);
+ q->orig_bar_rq = rq;
+ rq = q->bar_rq;
+ rq_init(q, rq);
+ rq->flags = bio_data_dir(q->orig_bar_rq->bio);
+ rq->flags |= q->ordered & QUEUE_ORDERED_FUA ? REQ_FUA : 0;
+ rq->elevator_private = NULL;
+ rq->rl = NULL;
+ init_request_from_bio(rq, q->orig_bar_rq->bio);
+ rq->end_io = bar_end_io;

-static int __blk_complete_barrier_rq(request_queue_t *q, struct request *rq,
- int sectors, int queue_locked)
-{
- if (q->ordered != QUEUE_ORDERED_FLUSH)
- return 0;
- if (!blk_fs_request(rq) || !blk_barrier_rq(rq))
- return 0;
- if (blk_barrier_postflush(rq))
- return 0;
+ /*
+ * 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 (q->ordered & QUEUE_ORDERED_POSTFLUSH)
+ queue_flush(q, QUEUE_ORDERED_POSTFLUSH);
+ else
+ q->ordseq |= QUEUE_ORDSEQ_POSTFLUSH;

- if (!blk_check_end_barrier(q, rq, sectors)) {
- unsigned long flags = 0;
+ __elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0);

- if (!queue_locked)
- spin_lock_irqsave(q->queue_lock, flags);
+ if (q->ordered & QUEUE_ORDERED_PREFLUSH) {
+ queue_flush(q, QUEUE_ORDERED_PREFLUSH);
+ rq = q->pre_flush_rq;
+ } else
+ q->ordseq |= QUEUE_ORDSEQ_PREFLUSH;

- blk_start_post_flush(q, rq);
+ if ((q->ordered & QUEUE_ORDERED_TAG) || q->in_flight == 0)
+ q->ordseq |= QUEUE_ORDSEQ_DRAIN;
+ else
+ rq = NULL;

- if (!queue_locked)
- spin_unlock_irqrestore(q->queue_lock, flags);
+ return rq;
+}
+
+int blk_do_ordered(request_queue_t *q, struct request **rqp)
+{
+ struct request *rq = *rqp, *allowed_rq;
+ int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq);
+
+ if (!q->ordseq) {
+ if (!is_barrier)
+ return 1;
+
+ if (q->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);
+ end_that_request_first(rq, -EOPNOTSUPP,
+ rq->hard_nr_sectors);
+ end_that_request_last(rq, -EOPNOTSUPP);
+ *rqp = NULL;
+ return 0;
+ }
+ }
+
+ if (q->ordered & QUEUE_ORDERED_TAG) {
+ if (blk_fs_request(rq) && rq != q->bar_rq)
+ *rqp = NULL;
+ return 1;
}

+ switch (blk_ordered_cur_seq(q)) {
+ case QUEUE_ORDSEQ_PREFLUSH:
+ allowed_rq = q->pre_flush_rq;
+ break;
+ case QUEUE_ORDSEQ_BAR:
+ allowed_rq = q->bar_rq;
+ break;
+ case QUEUE_ORDSEQ_POSTFLUSH:
+ allowed_rq = q->post_flush_rq;
+ break;
+ default:
+ allowed_rq = NULL;
+ break;
+ }
+
+ if (rq != allowed_rq && (blk_fs_request(rq) || rq == q->pre_flush_rq ||
+ rq == q->post_flush_rq))
+ *rqp = NULL;
+
return 1;
}

-/**
- * blk_complete_barrier_rq - complete possible barrier request
- * @q: the request queue for the device
- * @rq: the request
- * @sectors: number of sectors to complete
- *
- * Description:
- * Used in driver end_io handling to determine whether to postpone
- * completion of a barrier request until a post flush has been done. This
- * is the unlocked variant, used if the caller doesn't already hold the
- * queue lock.
- **/
-int blk_complete_barrier_rq(request_queue_t *q, struct request *rq, int sectors)
+static int flush_dry_bio_endio(struct bio *bio, unsigned int bytes, int error)
{
- return __blk_complete_barrier_rq(q, rq, sectors, 0);
+ request_queue_t *q = bio->bi_private;
+ struct bio_vec *bvec;
+ int i;
+
+ /*
+ * This is dry run, restore bio_sector and size. We'll finish
+ * this request again with the original bi_end_io after an
+ * error occurs or post flush is complete.
+ */
+ q->bi_size += bytes;
+
+ if (bio->bi_size)
+ return 1;
+
+ /* Rewind bvec's */
+ bio->bi_idx = 0;
+ bio_for_each_segment(bvec, bio, i) {
+ bvec->bv_len += bvec->bv_offset;
+ bvec->bv_offset = 0;
+ }
+
+ /* Reset bio */
+ set_bit(BIO_UPTODATE, &bio->bi_flags);
+ bio->bi_size = q->bi_size;
+ bio->bi_sector -= (q->bi_size >> 9);
+ q->bi_size = 0;
+
+ return 0;
}
-EXPORT_SYMBOL(blk_complete_barrier_rq);

-/**
- * blk_complete_barrier_rq_locked - complete possible barrier request
- * @q: the request queue for the device
- * @rq: the request
- * @sectors: number of sectors to complete
- *
- * Description:
- * See blk_complete_barrier_rq(). This variant must be used if the caller
- * holds the queue lock.
- **/
-int blk_complete_barrier_rq_locked(request_queue_t *q, struct request *rq,
- int sectors)
+static inline int ordered_bio_endio(struct request *rq, struct bio *bio,
+ unsigned int nbytes, int error)
{
- return __blk_complete_barrier_rq(q, rq, sectors, 1);
+ request_queue_t *q = rq->q;
+ bio_end_io_t *endio;
+ void *private;
+
+ if (q->bar_rq != rq)
+ return 0;
+
+ /*
+ * Okay, this is the barrier request in progress, dry finish it.
+ */
+ if (error && !q->orderr)
+ ordered_set_error(q, QUEUE_ORDSEQ_BAR, error);
+
+ endio = bio->bi_end_io;
+ private = bio->bi_private;
+ bio->bi_end_io = flush_dry_bio_endio;
+ bio->bi_private = q;
+
+ bio_endio(bio, nbytes, error);
+
+ bio->bi_end_io = endio;
+ bio->bi_private = private;
+
+ return 1;
}
-EXPORT_SYMBOL(blk_complete_barrier_rq_locked);

/**
* blk_queue_bounce_limit - set bounce buffer limit for queue
@@ -1031,6 +1241,7 @@ static char *rq_flags[] = {
"REQ_FAILFAST",
"REQ_SOFTBARRIER",
"REQ_HARDBARRIER",
+ "REQ_FUA",
"REQ_CMD",
"REQ_NOMERGE",
"REQ_STARTED",
@@ -1614,7 +1825,7 @@ void blk_cleanup_queue(request_queue_t *
if (q->queue_tags)
__blk_queue_free_tags(q);

- blk_queue_ordered(q, QUEUE_ORDERED_NONE);
+ blk_queue_ordered(q, QUEUE_ORDERED_NONE, NULL, 0);

kmem_cache_free(requestq_cachep, q);
}
@@ -3034,7 +3245,8 @@ static int __end_that_request_first(stru
if (nr_bytes >= bio->bi_size) {
req->bio = bio->bi_next;
nbytes = bio->bi_size;
- bio_endio(bio, nbytes, error);
+ if (!ordered_bio_endio(req, bio, nbytes, error))
+ bio_endio(bio, nbytes, error);
next_idx = 0;
bio_nbytes = 0;
} else {
@@ -3089,7 +3301,8 @@ static int __end_that_request_first(stru
* if the request wasn't completed, update state
*/
if (bio_nbytes) {
- bio_endio(bio, bio_nbytes, error);
+ if (!ordered_bio_endio(req, bio, bio_nbytes, error))
+ bio_endio(bio, bio_nbytes, error);
bio->bi_idx += next_idx;
bio_iovec(bio)->bv_offset += nr_bytes;
bio_iovec(bio)->bv_len -= nr_bytes;
Index: blk-fixes/include/linux/blkdev.h
===================================================================
--- blk-fixes.orig/include/linux/blkdev.h 2005-06-05 14:53:32.000000000 +0900
+++ blk-fixes/include/linux/blkdev.h 2005-06-05 14:53:34.000000000 +0900
@@ -205,6 +205,7 @@ enum rq_flag_bits {
__REQ_FAILFAST, /* no low level driver retries */
__REQ_SOFTBARRIER, /* may not be passed by ioscheduler */
__REQ_HARDBARRIER, /* may not be passed by drive either */
+ __REQ_FUA, /* forced unit access */
__REQ_CMD, /* is a regular fs rw request */
__REQ_NOMERGE, /* don't touch this for merging */
__REQ_STARTED, /* drive already may have started this one */
@@ -227,9 +228,6 @@ enum rq_flag_bits {
__REQ_PM_SUSPEND, /* suspend request */
__REQ_PM_RESUME, /* resume request */
__REQ_PM_SHUTDOWN, /* shutdown request */
- __REQ_BAR_PREFLUSH, /* barrier pre-flush done */
- __REQ_BAR_POSTFLUSH, /* barrier post-flush */
- __REQ_BAR_FLUSH, /* rq is the flush request */
__REQ_NR_BITS, /* stops here */
};

@@ -237,6 +235,7 @@ enum rq_flag_bits {
#define REQ_FAILFAST (1 << __REQ_FAILFAST)
#define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER)
#define REQ_HARDBARRIER (1 << __REQ_HARDBARRIER)
+#define REQ_FUA (1 << __REQ_FUA)
#define REQ_CMD (1 << __REQ_CMD)
#define REQ_NOMERGE (1 << __REQ_NOMERGE)
#define REQ_STARTED (1 << __REQ_STARTED)
@@ -255,9 +254,6 @@ enum rq_flag_bits {
#define REQ_PM_SUSPEND (1 << __REQ_PM_SUSPEND)
#define REQ_PM_RESUME (1 << __REQ_PM_RESUME)
#define REQ_PM_SHUTDOWN (1 << __REQ_PM_SHUTDOWN)
-#define REQ_BAR_PREFLUSH (1 << __REQ_BAR_PREFLUSH)
-#define REQ_BAR_POSTFLUSH (1 << __REQ_BAR_POSTFLUSH)
-#define REQ_BAR_FLUSH (1 << __REQ_BAR_FLUSH)

/*
* State information carried for REQ_PM_SUSPEND and REQ_PM_RESUME
@@ -287,8 +283,7 @@ struct bio_vec;
typedef int (merge_bvec_fn) (request_queue_t *, struct bio *, struct bio_vec *);
typedef void (activity_fn) (void *data, int rw);
typedef int (issue_flush_fn) (request_queue_t *, struct gendisk *, sector_t *);
-typedef int (prepare_flush_fn) (request_queue_t *, struct request *);
-typedef void (end_flush_fn) (request_queue_t *, struct request *);
+typedef void (prepare_flush_fn) (request_queue_t *, struct request *);

enum blk_queue_state {
Queue_down,
@@ -329,7 +324,6 @@ struct request_queue
activity_fn *activity_fn;
issue_flush_fn *issue_flush_fn;
prepare_flush_fn *prepare_flush_fn;
- end_flush_fn *end_flush_fn;

/*
* Auto-unplugging state
@@ -409,14 +403,13 @@ struct request_queue
/*
* reserved for flush operations
*/
- struct request *flush_rq;
- unsigned char ordered;
-};
-
-enum {
- QUEUE_ORDERED_NONE,
- QUEUE_ORDERED_TAG,
- QUEUE_ORDERED_FLUSH,
+ unsigned int ordseq;
+ int orderr;
+ struct request *pre_flush_rq, *bar_rq, *post_flush_rq;
+ struct request *orig_bar_rq;
+ unsigned int bi_size;
+ unsigned int ordered, next_ordered;
+ prepare_flush_fn *next_prepare_flush_fn;
};

#define RQ_INACTIVE (-1)
@@ -434,19 +427,67 @@ enum {
#define QUEUE_FLAG_REENTER 6 /* Re-entrancy avoidance */
#define QUEUE_FLAG_PLUGGED 7 /* queue is plugged */
#define QUEUE_FLAG_DRAIN 8 /* draining queue for sched switch */
-#define QUEUE_FLAG_FLUSH 9 /* doing barrier flush sequence */
+
+enum {
+ /*
+ * Hardbarrier is supported with one of the following methods.
+ *
+ * NONE : hardbarrier unsupported
+ * DRAIN : ordering by draining is enough
+ * DRAIN_FLUSH : ordering by draining w/ pre and post flushes
+ * DRAIN_FUA : ordering by draining w/ pre flush and FUA write
+ * TAG : ordering by tag is enough
+ * TAG_FLUSH : ordering by tag w/ pre and post flushes
+ * TAG_FUA : ordering by tag w/ pre flush and FUA write
+ *
+ * The following flags can be or'd.
+ *
+ * NOFALLBACK : disable auto-fallback
+ */
+ QUEUE_ORDERED_NONE = 0x00,
+ QUEUE_ORDERED_DRAIN = 0x01,
+ QUEUE_ORDERED_TAG = 0x02,
+
+ QUEUE_ORDERED_PREFLUSH = 0x10,
+ QUEUE_ORDERED_POSTFLUSH = 0x20,
+ QUEUE_ORDERED_FUA = 0x40,
+
+ QUEUE_ORDERED_NOFALLBACK = 0x80,
+
+ QUEUE_ORDERED_FLAGS = QUEUE_ORDERED_NOFALLBACK,
+
+ QUEUE_ORDERED_DRAIN_FLUSH = QUEUE_ORDERED_DRAIN |
+ QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH,
+ QUEUE_ORDERED_DRAIN_FUA = QUEUE_ORDERED_DRAIN |
+ QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_FUA,
+ QUEUE_ORDERED_TAG_FLUSH = QUEUE_ORDERED_TAG |
+ QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH,
+ QUEUE_ORDERED_TAG_FUA = QUEUE_ORDERED_TAG |
+ QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_FUA,
+
+ /*
+ * Ordered operation sequence
+ */
+ QUEUE_ORDSEQ_STARTED = 0x01, /* flushing in progress */
+ QUEUE_ORDSEQ_DRAIN = 0x02, /* waiting for the queue to be drained */
+ QUEUE_ORDSEQ_PREFLUSH = 0x04, /* pre-flushing in progress */
+ QUEUE_ORDSEQ_BAR = 0x08, /* original barrier req in progress */
+ QUEUE_ORDSEQ_POSTFLUSH = 0x10, /* post-flushing in progress */
+ QUEUE_ORDSEQ_DONE = 0x20,
+};

#define blk_queue_plugged(q) test_bit(QUEUE_FLAG_PLUGGED, &(q)->queue_flags)
#define blk_queue_tagged(q) test_bit(QUEUE_FLAG_QUEUED, &(q)->queue_flags)
#define blk_queue_stopped(q) test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
-#define blk_queue_flushing(q) test_bit(QUEUE_FLAG_FLUSH, &(q)->queue_flags)
+#define blk_queue_flushing(q) ((q)->ordseq)

#define blk_fs_request(rq) ((rq)->flags & REQ_CMD)
#define blk_pc_request(rq) ((rq)->flags & REQ_BLOCK_PC)
#define blk_noretry_request(rq) ((rq)->flags & REQ_FAILFAST)
#define blk_rq_started(rq) ((rq)->flags & REQ_STARTED)

-#define blk_account_rq(rq) (blk_rq_started(rq) && blk_fs_request(rq))
+#define blk_account_rq(rq) \
+ (blk_rq_started(rq) && blk_fs_request(rq) && rq != rq->q->bar_rq)

#define blk_pm_suspend_request(rq) ((rq)->flags & REQ_PM_SUSPEND)
#define blk_pm_resume_request(rq) ((rq)->flags & REQ_PM_RESUME)
@@ -454,8 +495,7 @@ enum {
((rq)->flags & (REQ_PM_SUSPEND | REQ_PM_RESUME))

#define blk_barrier_rq(rq) ((rq)->flags & REQ_HARDBARRIER)
-#define blk_barrier_preflush(rq) ((rq)->flags & REQ_BAR_PREFLUSH)
-#define blk_barrier_postflush(rq) ((rq)->flags & REQ_BAR_POSTFLUSH)
+#define blk_fua_rq(rq) ((rq)->flags & REQ_FUA)

#define list_entry_rq(ptr) list_entry((ptr), struct request, queuelist)

@@ -636,11 +676,12 @@ extern void blk_queue_prep_rq(request_qu
extern void blk_queue_merge_bvec(request_queue_t *, merge_bvec_fn *);
extern void blk_queue_dma_alignment(request_queue_t *, int);
extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);
-extern void blk_queue_ordered(request_queue_t *, int);
+extern int blk_queue_ordered(request_queue_t *, unsigned, prepare_flush_fn *, unsigned);
+extern int blk_queue_ordered_locked(request_queue_t *, unsigned, prepare_flush_fn *, unsigned);
extern void blk_queue_issue_flush_fn(request_queue_t *, issue_flush_fn *);
-extern struct request *blk_start_pre_flush(request_queue_t *,struct request *);
-extern int blk_complete_barrier_rq(request_queue_t *, struct request *, int);
-extern int blk_complete_barrier_rq_locked(request_queue_t *, struct request *, int);
+extern int blk_do_ordered(request_queue_t *, struct request **);
+extern unsigned blk_ordered_cur_seq(request_queue_t *);
+extern void blk_ordered_complete_seq(request_queue_t *, unsigned, int);

extern int blk_rq_map_sg(request_queue_t *, struct request *, struct scatterlist *);
extern void blk_dump_rq_flags(struct request *, char *);