#include "blk.h"
+static struct request *queue_next_ordseq(struct request_queue *q);
+
/*
* Cache flushing for ordered writes handling
*/
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 (rq->cmd_type != REQ_TYPE_FS)
- 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;
-}
-
-bool blk_ordered_complete_seq(struct request_queue *q, unsigned seq, int error)
+static struct request *blk_ordered_complete_seq(struct request_queue *q,
+ unsigned seq, int error)
{
- struct request *rq;
+ struct request *next_rq = NULL;
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 false;
-
- /*
- * Okay, sequence complete.
- */
- q->ordseq = 0;
- rq = q->orig_bar_rq;
- __blk_end_request_all(rq, q->orderr);
- return true;
+ if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE) {
+ /* not complete yet, queue the next ordered sequence */
+ next_rq = queue_next_ordseq(q);
+ } else {
+ /* complete this barrier request */
+ __blk_end_request_all(q->orig_bar_rq, q->orderr);
+ q->orig_bar_rq = NULL;
+ q->ordseq = 0;
+
+ /* dispatch the next barrier if there's one */
+ if (!list_empty(&q->pending_barriers)) {
+ next_rq = list_entry_rq(q->pending_barriers.next);
+ list_move(&next_rq->queuelist, &q->queue_head);
+ }
+ }
+ return next_rq;
}
static void pre_flush_end_io(struct request *rq, int error)
blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_POSTFLUSH, error);
}
-static void queue_flush(struct request_queue *q, unsigned which)
+static void queue_flush(struct request_queue *q, struct request *rq,
+ rq_end_io_fn *end_io)
{
- struct request *rq;
- rq_end_io_fn *end_io;
-
- if (which == QUEUE_ORDERED_DO_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_type = REQ_TYPE_FS;
- rq->cmd_flags = REQ_HARDBARRIER | REQ_FLUSH;
+ rq->cmd_flags = REQ_FLUSH;
rq->rq_disk = q->orig_bar_rq->rq_disk;
rq->end_io = end_io;
elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
}
-static inline struct request *start_ordered(struct request_queue *q,
- struct request *rq)
+static struct request *queue_next_ordseq(struct request_queue *q)
{
- unsigned skip = 0;
-
- q->orderr = 0;
- q->ordered = q->next_ordered;
- q->ordseq |= QUEUE_ORDSEQ_STARTED;
-
- /*
- * For an empty barrier, there's no actual BAR request, which
- * in turn makes POSTFLUSH unnecessary. Mask them off.
- */
- if (!blk_rq_sectors(rq))
- q->ordered &= ~(QUEUE_ORDERED_DO_BAR |
- QUEUE_ORDERED_DO_POSTFLUSH);
-
- /* stash away the original request */
- blk_dequeue_request(rq);
- q->orig_bar_rq = rq;
- rq = NULL;
-
- /*
- * 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_DO_POSTFLUSH) {
- queue_flush(q, QUEUE_ORDERED_DO_POSTFLUSH);
- rq = &q->post_flush_rq;
- } else
- skip |= QUEUE_ORDSEQ_POSTFLUSH;
+ struct request *rq = &q->bar_rq;
- if (q->ordered & QUEUE_ORDERED_DO_BAR) {
- rq = &q->bar_rq;
+ switch (blk_ordered_cur_seq(q)) {
+ case QUEUE_ORDSEQ_PREFLUSH:
+ queue_flush(q, rq, pre_flush_end_io);
+ break;
+ case QUEUE_ORDSEQ_BAR:
/* initialize proxy request and queue it */
blk_rq_init(q, rq);
init_request_from_bio(rq, q->orig_bar_rq->bio);
+ rq->cmd_flags &= ~REQ_HARDBARRIER;
if (q->ordered & QUEUE_ORDERED_DO_FUA)
rq->cmd_flags |= REQ_FUA;
rq->end_io = bar_end_io;
elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
- } else
- skip |= QUEUE_ORDSEQ_BAR;
+ break;
- if (q->ordered & QUEUE_ORDERED_DO_PREFLUSH) {
- queue_flush(q, QUEUE_ORDERED_DO_PREFLUSH);
- rq = &q->pre_flush_rq;
- } else
- skip |= QUEUE_ORDSEQ_PREFLUSH;
+ case QUEUE_ORDSEQ_POSTFLUSH:
+ queue_flush(q, rq, post_flush_end_io);
+ break;
- if (queue_in_flight(q))
- rq = NULL;
- else
- skip |= QUEUE_ORDSEQ_DRAIN;
-
- /*
- * Complete skipped sequences. If whole sequence is complete,
- * return %NULL to tell elevator that this request is gone.
- */
- if (blk_ordered_complete_seq(q, skip, 0))
- rq = NULL;
+ default:
+ BUG();
+ }
return rq;
}
struct request *blk_do_ordered(struct request_queue *q, struct request *rq)
{
- const int is_barrier = rq->cmd_type == REQ_TYPE_FS &&
- (rq->cmd_flags & REQ_HARDBARRIER);
-
- if (!q->ordseq) {
- if (!is_barrier)
- return rq;
-
- if (q->next_ordered != QUEUE_ORDERED_NONE)
- return start_ordered(q, rq);
- else {
- /*
- * Queue ordering not supported. Terminate
- * with prejudice.
- */
- blk_dequeue_request(rq);
- __blk_end_request_all(rq, -EOPNOTSUPP);
- return NULL;
- }
+ unsigned skip = 0;
+
+ if (!(rq->cmd_flags & REQ_HARDBARRIER))
+ return rq;
+
+ if (q->ordseq) {
+ /*
+ * Barrier is already in progress and they can't be
+ * processed in parallel. Queue for later processing.
+ */
+ list_move_tail(&rq->queuelist, &q->pending_barriers);
+ return NULL;
+ }
+
+ if (unlikely(q->next_ordered == QUEUE_ORDERED_NONE)) {
+ /*
+ * Queue ordering not supported. Terminate
+ * with prejudice.
+ */
+ blk_dequeue_request(rq);
+ __blk_end_request_all(rq, -EOPNOTSUPP);
+ return NULL;
}
/*
- * Ordered sequence in progress
+ * Start a new ordered sequence
*/
+ q->orderr = 0;
+ q->ordered = q->next_ordered;
+ q->ordseq |= QUEUE_ORDSEQ_STARTED;
- /* Special requests are not subject to ordering rules. */
- if (rq->cmd_type != REQ_TYPE_FS &&
- rq != &q->pre_flush_rq && rq != &q->post_flush_rq)
- return rq;
+ /*
+ * For an empty barrier, there's no actual BAR request, which
+ * in turn makes POSTFLUSH unnecessary. Mask them off.
+ */
+ if (!blk_rq_sectors(rq))
+ q->ordered &= ~(QUEUE_ORDERED_DO_BAR |
+ QUEUE_ORDERED_DO_POSTFLUSH);
- /* 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))
- rq = ERR_PTR(-EAGAIN);
+ /* stash away the original request */
+ blk_dequeue_request(rq);
+ q->orig_bar_rq = rq;
- return rq;
+ if (!(q->ordered & QUEUE_ORDERED_DO_PREFLUSH))
+ skip |= QUEUE_ORDSEQ_PREFLUSH;
+
+ if (!(q->ordered & QUEUE_ORDERED_DO_BAR))
+ skip |= QUEUE_ORDSEQ_BAR;
+
+ if (!(q->ordered & QUEUE_ORDERED_DO_POSTFLUSH))
+ skip |= QUEUE_ORDSEQ_POSTFLUSH;
+
+ /* complete skipped sequences and return the first sequence */
+ return blk_ordered_complete_seq(q, skip, 0);
}
static void bio_end_empty_barrier(struct bio *bio, int err)
void elv_insert(struct request_queue *q, struct request *rq, int where)
{
- struct list_head *pos;
- unsigned ordseq;
int unplug_it = 1;
trace_block_rq_insert(q, rq);
rq->q = q;
switch (where) {
+ case ELEVATOR_INSERT_REQUEUE:
+ /*
+ * Most requeues happen because of a busy condition,
+ * don't force unplug of the queue for that case.
+ * Clear unplug_it and fall through.
+ */
+ unplug_it = 0;
+
case ELEVATOR_INSERT_FRONT:
rq->cmd_flags |= REQ_SOFTBARRIER;
-
list_add(&rq->queuelist, &q->queue_head);
break;
q->elevator->ops->elevator_add_req_fn(q, rq);
break;
- case ELEVATOR_INSERT_REQUEUE:
- /*
- * If ordered flush isn't in progress, we do front
- * insertion; otherwise, requests should be requeued
- * in ordseq order.
- */
- rq->cmd_flags |= REQ_SOFTBARRIER;
-
- /*
- * Most requeues happen because of a busy condition,
- * don't force unplug of the queue for that case.
- */
- unplug_it = 0;
-
- if (q->ordseq == 0) {
- list_add(&rq->queuelist, &q->queue_head);
- break;
- }
-
- ordseq = blk_ordered_req_seq(rq);
-
- list_for_each(pos, &q->queue_head) {
- struct request *pos_rq = list_entry_rq(pos);
- if (ordseq <= blk_ordered_req_seq(pos_rq))
- break;
- }
-
- list_add_tail(&rq->queuelist, pos);
- break;
-
default:
printk(KERN_ERR "%s: bad insertion point %d\n",
__func__, where);
void __elv_add_request(struct request_queue *q, struct request *rq, int where,
int plug)
{
- if (q->ordcolor)
- rq->cmd_flags |= REQ_ORDERED_COLOR;
-
if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) {
- /*
- * toggle ordered color
- */
- if (rq->cmd_flags & REQ_HARDBARRIER)
- q->ordcolor ^= 1;
-
- /*
- * barriers implicitly indicate back insertion
- */
- if (where == ELEVATOR_INSERT_SORT)
- where = ELEVATOR_INSERT_BACK;
-
- /*
- * this request is scheduling boundary, update
- * end_sector
- */
+ /* barriers are scheduling boundary, update end_sector */
if (rq->cmd_type == REQ_TYPE_FS ||
(rq->cmd_flags & REQ_DISCARD)) {
q->end_sector = rq_end_sector(rq);
e->ops->elevator_completed_req_fn)
e->ops->elevator_completed_req_fn(q, rq);
}
-
- /*
- * Check if the queue is waiting for fs requests to be
- * drained for flush sequence.
- */
- if (unlikely(q->ordseq)) {
- struct request *next = NULL;
-
- if (!list_empty(&q->queue_head))
- next = list_entry_rq(q->queue_head.next);
-
- if (!queue_in_flight(q) &&
- blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN &&
- (!next || blk_ordered_req_seq(next) > QUEUE_ORDSEQ_DRAIN)) {
- blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0);
- __blk_run_queue(q);
- }
- }
}
#define to_elv(atr) container_of((atr), struct elv_fs_entry, attr)
unsigned int flush_flags;
unsigned int ordered, next_ordered, ordseq;
- int orderr, ordcolor;
- struct request pre_flush_rq, bar_rq, post_flush_rq;
+ int orderr;
+ struct request bar_rq;
struct request *orig_bar_rq;
+ struct list_head pending_barriers;
struct mutex sysfs_lock;
/*
* 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,
+ QUEUE_ORDSEQ_STARTED = (1 << 0), /* flushing in progress */
+ QUEUE_ORDSEQ_PREFLUSH = (1 << 1), /* pre-flushing in progress */
+ QUEUE_ORDSEQ_BAR = (1 << 2), /* barrier write in progress */
+ QUEUE_ORDSEQ_POSTFLUSH = (1 << 3), /* post-flushing in progress */
+ QUEUE_ORDSEQ_DONE = (1 << 4),
};
#define blk_queue_plugged(q) test_bit(QUEUE_FLAG_PLUGGED, &(q)->queue_flags)
extern void blk_queue_rq_timeout(struct request_queue *, unsigned int);
extern void blk_queue_flush(struct request_queue *q, unsigned int flush);
extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);
-extern unsigned blk_ordered_cur_seq(struct request_queue *);
-extern unsigned blk_ordered_req_seq(struct request *);
-extern bool blk_ordered_complete_seq(struct request_queue *, unsigned, int);
extern int blk_rq_map_sg(struct request_queue *, struct request *, struct scatterlist *);
extern void blk_dump_rq_flags(struct request *, char *);
projects / users / willy / pagecache.git / commitdiff