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-rw-r--r--block/blk-flush.c85
1 files changed, 46 insertions, 39 deletions
diff --git a/block/blk-flush.c b/block/blk-flush.c
index dd873225da97..452c552e9ead 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -1,5 +1,5 @@
/*
- * Functions related to barrier IO handling
+ * Functions to sequence FLUSH and FUA writes.
*/
#include <linux/kernel.h>
#include <linux/module.h>
@@ -9,6 +9,15 @@
#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)
@@ -79,6 +88,7 @@ static void queue_flush(struct request_queue *q, struct request *rq,
static struct request *queue_next_fseq(struct request_queue *q)
{
+ struct request *orig_rq = q->orig_flush_rq;
struct request *rq = &q->flush_rq;
switch (blk_flush_cur_seq(q)) {
@@ -87,12 +97,11 @@ static struct request *queue_next_fseq(struct request_queue *q)
break;
case QUEUE_FSEQ_DATA:
- /* initialize proxy request and queue it */
+ /* initialize proxy request, inherit FLUSH/FUA and queue it */
blk_rq_init(q, rq);
- init_request_from_bio(rq, q->orig_flush_rq->bio);
- rq->cmd_flags &= ~REQ_HARDBARRIER;
- if (q->ordered & QUEUE_ORDERED_DO_FUA)
- rq->cmd_flags |= REQ_FUA;
+ init_request_from_bio(rq, orig_rq->bio);
+ 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;
elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
@@ -110,60 +119,58 @@ static struct request *queue_next_fseq(struct request_queue *q)
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;
- if (!(rq->cmd_flags & REQ_HARDBARRIER))
+ /*
+ * 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) {
- /*
- * Sequenced flush is already in progress and they
- * can't be processed in parallel. Queue for later
- * processing.
- */
list_move_tail(&rq->queuelist, &q->pending_flushes);
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;
- }
-
/*
* Start a new flush sequence
*/
q->flush_err = 0;
- q->ordered = q->next_ordered;
q->flush_seq |= QUEUE_FSEQ_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 */
+ /* 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;
- if (!(q->ordered & QUEUE_ORDERED_DO_PREFLUSH))
+ /* skip unneded sequences and return the first one */
+ if (!do_preflush)
skip |= QUEUE_FSEQ_PREFLUSH;
-
- if (!(q->ordered & QUEUE_ORDERED_DO_BAR))
+ if (!blk_rq_sectors(rq))
skip |= QUEUE_FSEQ_DATA;
-
- if (!(q->ordered & QUEUE_ORDERED_DO_POSTFLUSH))
+ if (!do_postflush)
skip |= QUEUE_FSEQ_POSTFLUSH;
-
- /* complete skipped sequences and return the first sequence */
return blk_flush_complete_seq(q, skip, 0);
}