7 files changed, 67 insertions, 84 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 8870ae40179d..18455c4f618a 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1204,7 +1204,7 @@ static int __make_request(struct request_queue *q, struct bio *bio)
 
         spin_lock_irq(q->queue_lock);
 
-        if (bio->bi_rw & REQ_HARDBARRIER) {
+        if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) {
                 where = ELEVATOR_INSERT_FRONT;
                 goto get_rq;
         }
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);
 }
 
diff --git a/block/blk.h b/block/blk.h
index 24b92bd78f37..a09c18b19116 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -60,6 +60,9 @@ static inline struct request *__elv_next_request(struct request_queue *q)
         while (1) {
                 while (!list_empty(&q->queue_head)) {
                         rq = list_entry_rq(q->queue_head.next);
+                        if (!(rq->cmd_flags & (REQ_FLUSH | REQ_FUA)) ||
+                            rq == &q->flush_rq)
+                                return rq;
                         rq = blk_do_flush(q, rq);
                         if (rq)
                                 return rq;
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 9192282b4259..179799479e6f 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -167,7 +167,7 @@ enum rq_flag_bits {
         (REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER)
 #define REQ_COMMON_MASK \
         (REQ_WRITE | REQ_FAILFAST_MASK | REQ_HARDBARRIER | REQ_SYNC | \
-         REQ_META| REQ_DISCARD | REQ_NOIDLE)
+         REQ_META | REQ_DISCARD | REQ_NOIDLE | REQ_FLUSH | REQ_FUA)
 
 #define REQ_UNPLUG              (1 << __REQ_UNPLUG)
 #define REQ_RAHEAD              (1 << __REQ_RAHEAD)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 1cd83ec077db..8ef705f800ab 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -357,7 +357,6 @@ struct request_queue
         /*
          * for flush operations
          */
-        unsigned int            ordered, next_ordered;
         unsigned int            flush_flags;
         unsigned int            flush_seq;
         int                     flush_err;
@@ -465,40 +464,6 @@ static inline void queue_flag_clear(unsigned int flag, struct request_queue *q)
         __clear_bit(flag, &q->queue_flags);
 }
 
-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
-         */
-        QUEUE_ORDERED_DO_PREFLUSH       = 0x10,
-        QUEUE_ORDERED_DO_BAR            = 0x20,
-        QUEUE_ORDERED_DO_POSTFLUSH      = 0x40,
-        QUEUE_ORDERED_DO_FUA            = 0x80,
-
-        QUEUE_ORDERED_NONE              = 0x00,
-
-        QUEUE_ORDERED_DRAIN             = QUEUE_ORDERED_DO_BAR,
-        QUEUE_ORDERED_DRAIN_FLUSH       = QUEUE_ORDERED_DRAIN |
-                                          QUEUE_ORDERED_DO_PREFLUSH |
-                                          QUEUE_ORDERED_DO_POSTFLUSH,
-        QUEUE_ORDERED_DRAIN_FUA         = QUEUE_ORDERED_DRAIN |
-                                          QUEUE_ORDERED_DO_PREFLUSH |
-                                          QUEUE_ORDERED_DO_FUA,
-
-        /*
-         * FLUSH/FUA sequences.
-         */
-        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),
-};
-
 #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)
@@ -578,7 +543,8 @@ static inline void blk_clear_queue_full(struct request_queue *q, int sync)
  * it already be started by driver.
  */
 #define RQ_NOMERGE_FLAGS        \
-        (REQ_NOMERGE | REQ_STARTED | REQ_HARDBARRIER | REQ_SOFTBARRIER)
+        (REQ_NOMERGE | REQ_STARTED | REQ_HARDBARRIER | REQ_SOFTBARRIER | \
+         REQ_FLUSH | REQ_FUA)
 #define rq_mergeable(rq)        \
         (!((rq)->cmd_flags & RQ_NOMERGE_FLAGS) && \
          (((rq)->cmd_flags & REQ_DISCARD) || \
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index ec94c12f21da..fc999f583fda 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -32,7 +32,7 @@ enum bh_state_bits {
         BH_Delay,       /* Buffer is not yet allocated on disk */
         BH_Boundary,    /* Block is followed by a discontiguity */
         BH_Write_EIO,   /* I/O error on write */
-        BH_Eopnotsupp,  /* operation not supported (barrier) */
+        BH_Eopnotsupp,  /* DEPRECATED: operation not supported (barrier) */
         BH_Unwritten,   /* Buffer is allocated on disk but not written */
         BH_Quiet,       /* Buffer Error Prinks to be quiet */
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 76041b614758..352c48627381 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -135,12 +135,13 @@ struct inodes_stat_t {
  *                      immediately after submission. The write equivalent
  *                      of READ_SYNC.
  * WRITE_ODIRECT_PLUG   Special case write for O_DIRECT only.
- * WRITE_BARRIER        Like WRITE_SYNC, but tells the block layer that all
- *                      previously submitted writes must be safely on storage
- *                      before this one is started. Also guarantees that when
- *                      this write is complete, it itself is also safely on
- *                      storage. Prevents reordering of writes on both sides
- *                      of this IO.
+ * WRITE_BARRIER        DEPRECATED. Always fails. Use FLUSH/FUA instead.
+ * WRITE_FLUSH          Like WRITE_SYNC but with preceding cache flush.
+ * WRITE_FUA            Like WRITE_SYNC but data is guaranteed to be on
+ *                      non-volatile media on completion.
+ * WRITE_FLUSH_FUA      Combination of WRITE_FLUSH and FUA. The IO is preceded
+ *                      by a cache flush and data is guaranteed to be on
+ *                      non-volatile media on completion.
  *
  */
 #define RW_MASK                 REQ_WRITE
@@ -158,6 +159,12 @@ struct inodes_stat_t {
 #define WRITE_META              (WRITE | REQ_META)
 #define WRITE_BARRIER           (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_UNPLUG | \
                                  REQ_HARDBARRIER)
+#define WRITE_FLUSH             (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_UNPLUG | \
+                                 REQ_FLUSH)
+#define WRITE_FUA               (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_UNPLUG | \
+                                 REQ_FUA)
+#define WRITE_FLUSH_FUA         (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_UNPLUG | \
+                                 REQ_FLUSH | REQ_FUA)
 
 /*
  * These aren't really reads or writes, they pass down information about