[BLOCK] reimplement handling of barrier request

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>
Signed-off-by: Jens Axboe <axboe@suse.de>

2 files changed, 58 insertions, 25 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index a0ce8c585165..15db0f112d0a 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -207,6 +207,7 @@ enum rq_flag_bits {
         __REQ_SORTED,           /* elevator knows about this request */
         __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 */
@@ -230,9 +231,7 @@ 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_ORDERED_COLOR,    /* is before or after barrier */
         __REQ_NR_BITS,          /* stops here */
 };
 
@@ -241,6 +240,7 @@ enum rq_flag_bits {
 #define REQ_SORTED      (1 << __REQ_SORTED)
 #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)
@@ -260,9 +260,7 @@ 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)
+#define REQ_ORDERED_COLOR       (1 << __REQ_ORDERED_COLOR)
 
 /*
  * State information carried for REQ_PM_SUSPEND and REQ_PM_RESUME
@@ -292,8 +290,7 @@ 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,
@@ -335,7 +332,6 @@ 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;
 
         /*
          * Dispatch queue sorting
@@ -420,14 +416,11 @@ 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            ordered, next_ordered, ordseq;
+        int                     orderr, ordcolor;
+        struct request          pre_flush_rq, bar_rq, post_flush_rq;
+        struct request          *orig_bar_rq;
+        unsigned int            bi_size;
 };
 
 #define RQ_INACTIVE             (-1)
@@ -445,12 +438,51 @@ enum {
 #define QUEUE_FLAG_REENTER      6       /* Re-entrancy avoidance */
 #define QUEUE_FLAG_PLUGGED      7       /* queue is plugged */
 #define QUEUE_FLAG_ELVSWITCH    8       /* don't use elevator, just do FIFO */
-#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
+         */
+        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_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)
@@ -466,8 +498,7 @@ enum {
 
 #define blk_sorted_rq(rq)       ((rq)->flags & REQ_SORTED)
 #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)
 
@@ -665,11 +696,12 @@ extern void blk_queue_prep_rq(request_queue_t *, prep_rq_fn *pfn);
 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 *);
 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 unsigned blk_ordered_req_seq(struct request *);
+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 *);
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index a74c27e460ba..fb80fa44c4dd 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -130,6 +130,7 @@ extern int elv_try_last_merge(request_queue_t *, struct bio *);
 #define ELEVATOR_INSERT_FRONT   1
 #define ELEVATOR_INSERT_BACK    2
 #define ELEVATOR_INSERT_SORT    3
+#define ELEVATOR_INSERT_REQUEUE 4
 
 /*
  * return values from elevator_may_queue_fn