5 files changed, 27 insertions, 39 deletions

diff --git a/include/linux/bio.h b/include/linux/bio.h
index ce33e6868a2f..a3c071c9e189 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -269,14 +269,6 @@ extern void bvec_free_bs(struct bio_set *, struct bio_vec *, unsigned int);
 extern unsigned int bvec_nr_vecs(unsigned short idx);
 
 /*
- * Allow queuer to specify a completion CPU for this bio
- */
-static inline void bio_set_completion_cpu(struct bio *bio, unsigned int cpu)
-{
-        bio->bi_comp_cpu = cpu;
-}
-
-/*
  * bio_set is used to allow other portions of the IO system to
  * allocate their own private memory pools for bio and iovec structures.
  * These memory pools in turn all allocate from the bio_slab
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 71fc53bb8f1c..4053cbd4490e 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -59,8 +59,6 @@ struct bio {
 
         unsigned int            bi_max_vecs;    /* max bvl_vecs we can hold */
 
-        unsigned int            bi_comp_cpu;    /* completion CPU */
-
         atomic_t                bi_cnt;         /* pin count */
 
         struct bio_vec          *bi_io_vec;     /* the actual vec list */
@@ -93,11 +91,10 @@ struct bio {
 #define BIO_BOUNCED     5       /* bio is a bounce bio */
 #define BIO_USER_MAPPED 6       /* contains user pages */
 #define BIO_EOPNOTSUPP  7       /* not supported */
-#define BIO_CPU_AFFINE  8       /* complete bio on same CPU as submitted */
-#define BIO_NULL_MAPPED 9       /* contains invalid user pages */
-#define BIO_FS_INTEGRITY 10     /* fs owns integrity data, not block layer */
-#define BIO_QUIET       11      /* Make BIO Quiet */
-#define BIO_MAPPED_INTEGRITY 12/* integrity metadata has been remapped */
+#define BIO_NULL_MAPPED 8       /* contains invalid user pages */
+#define BIO_FS_INTEGRITY 9      /* fs owns integrity data, not block layer */
+#define BIO_QUIET       10      /* Make BIO Quiet */
+#define BIO_MAPPED_INTEGRITY 11/* integrity metadata has been remapped */
 #define bio_flagged(bio, flag)  ((bio)->bi_flags & (1 << (flag)))
 
 /*
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 7fbaa9103344..5267cd2f20dc 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -195,7 +195,7 @@ struct request_pm_state
 #include <linux/elevator.h>
 
 typedef void (request_fn_proc) (struct request_queue *q);
-typedef int (make_request_fn) (struct request_queue *q, struct bio *bio);
+typedef void (make_request_fn) (struct request_queue *q, struct bio *bio);
 typedef int (prep_rq_fn) (struct request_queue *, struct request *);
 typedef void (unprep_rq_fn) (struct request_queue *, struct request *);
 
@@ -680,6 +680,8 @@ extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t,
 extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t,
                          struct scsi_ioctl_command __user *);
 
+extern void blk_queue_bio(struct request_queue *q, struct bio *bio);
+
 /*
  * A queue has just exitted congestion.  Note this in the global counter of
  * congested queues, and wake up anyone who was waiting for requests to be
@@ -863,16 +865,22 @@ struct request_queue *blk_alloc_queue_node(gfp_t, int);
 extern void blk_put_queue(struct request_queue *);
 
 /*
- * Note: Code in between changing the blk_plug list/cb_list or element of such
- * lists is preemptable, but such code can't do sleep (or be very careful),
- * otherwise data is corrupted. For details, please check schedule() where
- * blk_schedule_flush_plug() is called.
+ * blk_plug permits building a queue of related requests by holding the I/O
+ * fragments for a short period. This allows merging of sequential requests
+ * into single larger request. As the requests are moved from a per-task list to
+ * the device's request_queue in a batch, this results in improved scalability
+ * as the lock contention for request_queue lock is reduced.
+ *
+ * It is ok not to disable preemption when adding the request to the plug list
+ * or when attempting a merge, because blk_schedule_flush_list() will only flush
+ * the plug list when the task sleeps by itself. For details, please see
+ * schedule() where blk_schedule_flush_plug() is called.
  */
 struct blk_plug {
-        unsigned long magic;
-        struct list_head list;
-        struct list_head cb_list;
-        unsigned int should_sort;
+        unsigned long magic; /* detect uninitialized use-cases */
+        struct list_head list; /* requests */
+        struct list_head cb_list; /* md requires an unplug callback */
+        unsigned int should_sort; /* list to be sorted before flushing? */
 };
 #define BLK_MAX_REQUEST_COUNT 16
 
@@ -1189,20 +1197,6 @@ static inline uint64_t rq_io_start_time_ns(struct request *req)
 }
 #endif
 
-#ifdef CONFIG_BLK_DEV_THROTTLING
-extern int blk_throtl_init(struct request_queue *q);
-extern void blk_throtl_exit(struct request_queue *q);
-extern int blk_throtl_bio(struct request_queue *q, struct bio **bio);
-#else /* CONFIG_BLK_DEV_THROTTLING */
-static inline int blk_throtl_bio(struct request_queue *q, struct bio **bio)
-{
-        return 0;
-}
-
-static inline int blk_throtl_init(struct request_queue *q) { return 0; }
-static inline int blk_throtl_exit(struct request_queue *q) { return 0; }
-#endif /* CONFIG_BLK_DEV_THROTTLING */
-
 #define MODULE_ALIAS_BLOCKDEV(major,minor) \
         MODULE_ALIAS("block-major-" __stringify(major) "-" __stringify(minor))
 #define MODULE_ALIAS_BLOCKDEV_MAJOR(major) \
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index d800d5142184..1d0f7a2ff73b 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -38,6 +38,12 @@ struct elevator_ops
         elevator_merged_fn *elevator_merged_fn;
         elevator_merge_req_fn *elevator_merge_req_fn;
         elevator_allow_merge_fn *elevator_allow_merge_fn;
+
+        /*
+         * Used for both plugged list and elevator merging and in the
+         * former case called without queue_lock.  Read comment on top of
+         * attempt_plug_merge() for details.
+         */
         elevator_bio_merged_fn *elevator_bio_merged_fn;
 
         elevator_dispatch_fn *elevator_dispatch_fn;
diff --git a/include/linux/loop.h b/include/linux/loop.h
index 683d69890119..a06880689115 100644
--- a/include/linux/loop.h
+++ b/include/linux/loop.h
@@ -73,7 +73,6 @@ struct loop_device {
  */
 enum {
         LO_FLAGS_READ_ONLY      = 1,
-        LO_FLAGS_USE_AOPS       = 2,
         LO_FLAGS_AUTOCLEAR      = 4,
 };