3 files changed, 143 insertions, 0 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 4daae1ee2b23..c822239bcc9d 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1157,6 +1157,7 @@ static int __make_request(struct request_queue *q, struct bio *bio)
         const unsigned short prio = bio_prio(bio);
         const int sync = bio_sync(bio);
         const int unplug = bio_unplug(bio);
+        const unsigned int ff = bio->bi_rw & REQ_FAILFAST_MASK;
         int rw_flags;
 
         if (bio_barrier(bio) && bio_has_data(bio) &&
@@ -1186,6 +1187,9 @@ static int __make_request(struct request_queue *q, struct bio *bio)
 
                 trace_block_bio_backmerge(q, bio);
 
+                if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
+                        blk_rq_set_mixed_merge(req);
+
                 req->biotail->bi_next = bio;
                 req->biotail = bio;
                 req->__data_len += bytes;
@@ -1205,6 +1209,12 @@ static int __make_request(struct request_queue *q, struct bio *bio)
 
                 trace_block_bio_frontmerge(q, bio);
 
+                if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) {
+                        blk_rq_set_mixed_merge(req);
+                        req->cmd_flags &= ~REQ_FAILFAST_MASK;
+                        req->cmd_flags |= ff;
+                }
+
                 bio->bi_next = req->bio;
                 req->bio = bio;
 
@@ -1649,6 +1659,50 @@ int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
 }
 EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
 
+/**
+ * blk_rq_err_bytes - determine number of bytes till the next failure boundary
+ * @rq: request to examine
+ *
+ * Description:
+ *     A request could be merge of IOs which require different failure
+ *     handling.  This function determines the number of bytes which
+ *     can be failed from the beginning of the request without
+ *     crossing into area which need to be retried further.
+ *
+ * Return:
+ *     The number of bytes to fail.
+ *
+ * Context:
+ *     queue_lock must be held.
+ */
+unsigned int blk_rq_err_bytes(const struct request *rq)
+{
+        unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
+        unsigned int bytes = 0;
+        struct bio *bio;
+
+        if (!(rq->cmd_flags & REQ_MIXED_MERGE))
+                return blk_rq_bytes(rq);
+
+        /*
+         * Currently the only 'mixing' which can happen is between
+         * different fastfail types.  We can safely fail portions
+         * which have all the failfast bits that the first one has -
+         * the ones which are at least as eager to fail as the first
+         * one.
+         */
+        for (bio = rq->bio; bio; bio = bio->bi_next) {
+                if ((bio->bi_rw & ff) != ff)
+                        break;
+                bytes += bio->bi_size;
+        }
+
+        /* this could lead to infinite loop */
+        BUG_ON(blk_rq_bytes(rq) && !bytes);
+        return bytes;
+}
+EXPORT_SYMBOL_GPL(blk_rq_err_bytes);
+
 static void blk_account_io_completion(struct request *req, unsigned int bytes)
 {
         if (blk_do_io_stat(req)) {
@@ -1995,6 +2049,12 @@ bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
         if (blk_fs_request(req) || blk_discard_rq(req))
                 req->__sector += total_bytes >> 9;
 
+        /* mixed attributes always follow the first bio */
+        if (req->cmd_flags & REQ_MIXED_MERGE) {
+                req->cmd_flags &= ~REQ_FAILFAST_MASK;
+                req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK;
+        }
+
         /*
          * If total number of sectors is less than the first segment
          * size, something has gone terribly wrong.
@@ -2174,6 +2234,25 @@ bool blk_end_request_cur(struct request *rq, int error)
 EXPORT_SYMBOL(blk_end_request_cur);
 
 /**
+ * blk_end_request_err - Finish a request till the next failure boundary.
+ * @rq: the request to finish till the next failure boundary for
+ * @error: must be negative errno
+ *
+ * Description:
+ *     Complete @rq till the next failure boundary.
+ *
+ * Return:
+ *     %false - we are done with this request
+ *     %true  - still buffers pending for this request
+ */
+bool blk_end_request_err(struct request *rq, int error)
+{
+        WARN_ON(error >= 0);
+        return blk_end_request(rq, error, blk_rq_err_bytes(rq));
+}
+EXPORT_SYMBOL_GPL(blk_end_request_err);
+
+/**
  * __blk_end_request - Helper function for drivers to complete the request.
  * @rq:       the request being processed
  * @error:    %0 for success, < %0 for error
@@ -2232,6 +2311,26 @@ bool __blk_end_request_cur(struct request *rq, int error)
 }
 EXPORT_SYMBOL(__blk_end_request_cur);
 
+/**
+ * __blk_end_request_err - Finish a request till the next failure boundary.
+ * @rq: the request to finish till the next failure boundary for
+ * @error: must be negative errno
+ *
+ * Description:
+ *     Complete @rq till the next failure boundary.  Must be called
+ *     with queue lock held.
+ *
+ * Return:
+ *     %false - we are done with this request
+ *     %true  - still buffers pending for this request
+ */
+bool __blk_end_request_err(struct request *rq, int error)
+{
+        WARN_ON(error >= 0);
+        return __blk_end_request(rq, error, blk_rq_err_bytes(rq));
+}
+EXPORT_SYMBOL_GPL(__blk_end_request_err);
+
 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
                      struct bio *bio)
 {
diff --git a/block/blk-merge.c b/block/blk-merge.c
index e1999679a4d5..7c9ca01baa45 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -311,6 +311,36 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
         return 1;
 }
 
+/**
+ * blk_rq_set_mixed_merge - mark a request as mixed merge
+ * @rq: request to mark as mixed merge
+ *
+ * Description:
+ *     @rq is about to be mixed merged.  Make sure the attributes
+ *     which can be mixed are set in each bio and mark @rq as mixed
+ *     merged.
+ */
+void blk_rq_set_mixed_merge(struct request *rq)
+{
+        unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
+        struct bio *bio;
+
+        if (rq->cmd_flags & REQ_MIXED_MERGE)
+                return;
+
+        /*
+         * @rq will no longer represent mixable attributes for all the
+         * contained bios.  It will just track those of the first one.
+         * Distributes the attributs to each bio.
+         */
+        for (bio = rq->bio; bio; bio = bio->bi_next) {
+                WARN_ON_ONCE((bio->bi_rw & REQ_FAILFAST_MASK) &&
+                             (bio->bi_rw & REQ_FAILFAST_MASK) != ff);
+                bio->bi_rw |= ff;
+        }
+        rq->cmd_flags |= REQ_MIXED_MERGE;
+}
+
 static void blk_account_io_merge(struct request *req)
 {
         if (blk_do_io_stat(req)) {
@@ -366,6 +396,19 @@ static int attempt_merge(struct request_queue *q, struct request *req,
                 return 0;
 
         /*
+         * If failfast settings disagree or any of the two is already
+         * a mixed merge, mark both as mixed before proceeding.  This
+         * makes sure that all involved bios have mixable attributes
+         * set properly.
+         */
+        if ((req->cmd_flags | next->cmd_flags) & REQ_MIXED_MERGE ||
+            (req->cmd_flags & REQ_FAILFAST_MASK) !=
+            (next->cmd_flags & REQ_FAILFAST_MASK)) {
+                blk_rq_set_mixed_merge(req);
+                blk_rq_set_mixed_merge(next);
+        }
+
+        /*
          * At this point we have either done a back merge
          * or front merge. We need the smaller start_time of
          * the merged requests to be the current request
diff --git a/block/blk.h b/block/blk.h
index 3fae6add5430..5ee3d7e72feb 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -104,6 +104,7 @@ int ll_front_merge_fn(struct request_queue *q, struct request *req,
 int attempt_back_merge(struct request_queue *q, struct request *rq);
 int attempt_front_merge(struct request_queue *q, struct request *rq);
 void blk_recalc_rq_segments(struct request *rq);
+void blk_rq_set_mixed_merge(struct request *rq);
 
 void blk_queue_congestion_threshold(struct request_queue *q);