12 files changed, 100 insertions, 101 deletions

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 4ce34fa937d4..96f4094b706d 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -66,8 +66,6 @@ struct backing_dev_info {
         unsigned int capabilities; /* Device capabilities */
         congested_fn *congested_fn; /* Function pointer if device is md/dm */
         void *congested_data;   /* Pointer to aux data for congested func */
-        void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
-        void *unplug_io_data;
 
         char *name;
 
@@ -251,7 +249,6 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
 
 extern struct backing_dev_info default_backing_dev_info;
 extern struct backing_dev_info noop_backing_dev_info;
-void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);
 
 int writeback_in_progress(struct backing_dev_info *bdi);
 
@@ -336,17 +333,4 @@ static inline int bdi_sched_wait(void *word)
         return 0;
 }
 
-static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
-                                       struct page *page)
-{
-        if (bdi && bdi->unplug_io_fn)
-                bdi->unplug_io_fn(bdi, page);
-}
-
-static inline void blk_run_address_space(struct address_space *mapping)
-{
-        if (mapping)
-                blk_run_backing_dev(mapping->backing_dev_info, NULL);
-}
-
 #endif          /* _LINUX_BACKING_DEV_H */
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 35dcdb3589bc..ce33e6868a2f 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -304,7 +304,6 @@ struct biovec_slab {
 };
 
 extern struct bio_set *fs_bio_set;
-extern struct biovec_slab bvec_slabs[BIOVEC_NR_POOLS] __read_mostly;
 
 /*
  * a small number of entries is fine, not going to be performance critical.
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 46ad5197537a..be50d9e70a7d 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -128,7 +128,6 @@ enum rq_flag_bits {
         __REQ_NOIDLE,           /* don't anticipate more IO after this one */
 
         /* bio only flags */
-        __REQ_UNPLUG,           /* unplug the immediately after submission */
         __REQ_RAHEAD,           /* read ahead, can fail anytime */
         __REQ_THROTTLED,        /* This bio has already been subjected to
                                  * throttling rules. Don't do it again. */
@@ -148,9 +147,11 @@ enum rq_flag_bits {
         __REQ_ALLOCED,          /* request came from our alloc pool */
         __REQ_COPY_USER,        /* contains copies of user pages */
         __REQ_FLUSH,            /* request for cache flush */
+        __REQ_FLUSH_SEQ,        /* request for flush sequence */
         __REQ_IO_STAT,          /* account I/O stat */
         __REQ_MIXED_MERGE,      /* merge of different types, fail separately */
         __REQ_SECURE,           /* secure discard (used with __REQ_DISCARD) */
+        __REQ_ON_PLUG,          /* on plug list */
         __REQ_NR_BITS,          /* stops here */
 };
 
@@ -170,7 +171,6 @@ enum rq_flag_bits {
          REQ_NOIDLE | REQ_FLUSH | REQ_FUA)
 #define REQ_CLONE_MASK          REQ_COMMON_MASK
 
-#define REQ_UNPLUG              (1 << __REQ_UNPLUG)
 #define REQ_RAHEAD              (1 << __REQ_RAHEAD)
 #define REQ_THROTTLED           (1 << __REQ_THROTTLED)
 
@@ -188,8 +188,10 @@ enum rq_flag_bits {
 #define REQ_ALLOCED             (1 << __REQ_ALLOCED)
 #define REQ_COPY_USER           (1 << __REQ_COPY_USER)
 #define REQ_FLUSH               (1 << __REQ_FLUSH)
+#define REQ_FLUSH_SEQ           (1 << __REQ_FLUSH_SEQ)
 #define REQ_IO_STAT             (1 << __REQ_IO_STAT)
 #define REQ_MIXED_MERGE         (1 << __REQ_MIXED_MERGE)
 #define REQ_SECURE              (1 << __REQ_SECURE)
+#define REQ_ON_PLUG             (1 << __REQ_ON_PLUG)
 
 #endif /* __LINUX_BLK_TYPES_H */
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index d5063e1b5555..16a902f099ac 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -108,11 +108,17 @@ struct request {
 
         /*
          * Three pointers are available for the IO schedulers, if they need
-         * more they have to dynamically allocate it.
+         * more they have to dynamically allocate it.  Flush requests are
+         * never put on the IO scheduler. So let the flush fields share
+         * space with the three elevator_private pointers.
          */
-        void *elevator_private;
-        void *elevator_private2;
-        void *elevator_private3;
+        union {
+                void *elevator_private[3];
+                struct {
+                        unsigned int            seq;
+                        struct list_head        list;
+                } flush;
+        };
 
         struct gendisk *rq_disk;
         struct hd_struct *part;
@@ -190,7 +196,6 @@ typedef void (request_fn_proc) (struct request_queue *q);
 typedef int (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 *);
-typedef void (unplug_fn) (struct request_queue *);
 
 struct bio_vec;
 struct bvec_merge_data {
@@ -273,7 +278,6 @@ struct request_queue
         make_request_fn         *make_request_fn;
         prep_rq_fn              *prep_rq_fn;
         unprep_rq_fn            *unprep_rq_fn;
-        unplug_fn               *unplug_fn;
         merge_bvec_fn           *merge_bvec_fn;
         softirq_done_fn         *softirq_done_fn;
         rq_timed_out_fn         *rq_timed_out_fn;
@@ -287,12 +291,9 @@ struct request_queue
         struct request          *boundary_rq;
 
         /*
-         * Auto-unplugging state
+         * Delayed queue handling
          */
-        struct timer_list       unplug_timer;
-        int                     unplug_thresh;  /* After this many requests */
-        unsigned long           unplug_delay;   /* After this many jiffies */
-        struct work_struct      unplug_work;
+        struct delayed_work     delay_work;
 
         struct backing_dev_info backing_dev_info;
 
@@ -363,11 +364,12 @@ struct request_queue
          * for flush operations
          */
         unsigned int            flush_flags;
-        unsigned int            flush_seq;
-        int                     flush_err;
+        unsigned int            flush_pending_idx:1;
+        unsigned int            flush_running_idx:1;
+        unsigned long           flush_pending_since;
+        struct list_head        flush_queue[2];
+        struct list_head        flush_data_in_flight;
         struct request          flush_rq;
-        struct request          *orig_flush_rq;
-        struct list_head        pending_flushes;
 
         struct mutex            sysfs_lock;
 
@@ -387,14 +389,13 @@ struct request_queue
 #define QUEUE_FLAG_ASYNCFULL    4       /* write queue has been filled */
 #define QUEUE_FLAG_DEAD         5       /* queue being torn down */
 #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_BIDI         9       /* queue supports bidi requests */
-#define QUEUE_FLAG_NOMERGES    10       /* disable merge attempts */
-#define QUEUE_FLAG_SAME_COMP   11       /* force complete on same CPU */
-#define QUEUE_FLAG_FAIL_IO     12       /* fake timeout */
-#define QUEUE_FLAG_STACKABLE   13       /* supports request stacking */
-#define QUEUE_FLAG_NONROT      14       /* non-rotational device (SSD) */
+#define QUEUE_FLAG_ELVSWITCH    7       /* don't use elevator, just do FIFO */
+#define QUEUE_FLAG_BIDI         8       /* queue supports bidi requests */
+#define QUEUE_FLAG_NOMERGES     9       /* disable merge attempts */
+#define QUEUE_FLAG_SAME_COMP   10       /* force complete on same CPU */
+#define QUEUE_FLAG_FAIL_IO     11       /* fake timeout */
+#define QUEUE_FLAG_STACKABLE   12       /* supports request stacking */
+#define QUEUE_FLAG_NONROT      13       /* non-rotational device (SSD) */
 #define QUEUE_FLAG_VIRT        QUEUE_FLAG_NONROT /* paravirt device */
 #define QUEUE_FLAG_IO_STAT     15       /* do IO stats */
 #define QUEUE_FLAG_DISCARD     16       /* supports DISCARD */
@@ -472,7 +473,6 @@ static inline void queue_flag_clear(unsigned int flag, struct request_queue *q)
         __clear_bit(flag, &q->queue_flags);
 }
 
-#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_nomerges(q)   test_bit(QUEUE_FLAG_NOMERGES, &(q)->queue_flags)
@@ -667,9 +667,7 @@ extern int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
 extern void blk_rq_unprep_clone(struct request *rq);
 extern int blk_insert_cloned_request(struct request_queue *q,
                                      struct request *rq);
-extern void blk_plug_device(struct request_queue *);
-extern void blk_plug_device_unlocked(struct request_queue *);
-extern int blk_remove_plug(struct request_queue *);
+extern void blk_delay_queue(struct request_queue *, unsigned long);
 extern void blk_recount_segments(struct request_queue *, struct bio *);
 extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t,
                           unsigned int, void __user *);
@@ -713,7 +711,6 @@ extern int blk_execute_rq(struct request_queue *, struct gendisk *,
                           struct request *, int);
 extern void blk_execute_rq_nowait(struct request_queue *, struct gendisk *,
                                   struct request *, int, rq_end_io_fn *);
-extern void blk_unplug(struct request_queue *q);
 
 static inline struct request_queue *bdev_get_queue(struct block_device *bdev)
 {
@@ -850,7 +847,6 @@ extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bd
 
 extern int blk_rq_map_sg(struct request_queue *, struct request *, struct scatterlist *);
 extern void blk_dump_rq_flags(struct request *, char *);
-extern void generic_unplug_device(struct request_queue *);
 extern long nr_blockdev_pages(void);
 
 int blk_get_queue(struct request_queue *);
@@ -858,6 +854,31 @@ struct request_queue *blk_alloc_queue(gfp_t);
 struct request_queue *blk_alloc_queue_node(gfp_t, int);
 extern void blk_put_queue(struct request_queue *);
 
+struct blk_plug {
+        unsigned long magic;
+        struct list_head list;
+        unsigned int should_sort;
+};
+
+extern void blk_start_plug(struct blk_plug *);
+extern void blk_finish_plug(struct blk_plug *);
+extern void __blk_flush_plug(struct task_struct *, struct blk_plug *);
+
+static inline void blk_flush_plug(struct task_struct *tsk)
+{
+        struct blk_plug *plug = tsk->plug;
+
+        if (unlikely(plug))
+                __blk_flush_plug(tsk, plug);
+}
+
+static inline bool blk_needs_flush_plug(struct task_struct *tsk)
+{
+        struct blk_plug *plug = tsk->plug;
+
+        return plug && !list_empty(&plug->list);
+}
+
 /*
  * tag stuff
  */
@@ -1135,7 +1156,6 @@ static inline uint64_t rq_io_start_time_ns(struct request *req)
 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);
-extern void throtl_shutdown_timer_wq(struct request_queue *q);
 #else /* CONFIG_BLK_DEV_THROTTLING */
 static inline int blk_throtl_bio(struct request_queue *q, struct bio **bio)
 {
@@ -1144,7 +1164,6 @@ static inline int blk_throtl_bio(struct request_queue *q, struct bio **bio)
 
 static inline int blk_throtl_init(struct request_queue *q) { return 0; }
 static inline int blk_throtl_exit(struct request_queue *q) { return 0; }
-static inline void throtl_shutdown_timer_wq(struct request_queue *q) {}
 #endif /* CONFIG_BLK_DEV_THROTTLING */
 
 #define MODULE_ALIAS_BLOCKDEV(major,minor) \
@@ -1278,6 +1297,26 @@ static inline long nr_blockdev_pages(void)
         return 0;
 }
 
+struct blk_plug {
+};
+
+static inline void blk_start_plug(struct blk_plug *plug)
+{
+}
+
+static inline void blk_finish_plug(struct blk_plug *plug)
+{
+}
+
+static inline void blk_flush_plug(struct task_struct *task)
+{
+}
+
+static inline bool blk_needs_flush_plug(struct task_struct *tsk)
+{
+        return false;
+}
+
 #endif /* CONFIG_BLOCK */
 
 #endif
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 68d1fe7b877c..f5df23561b96 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -219,7 +219,6 @@ int generic_cont_expand_simple(struct inode *inode, loff_t size);
 int block_commit_write(struct page *page, unsigned from, unsigned to);
 int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
                                 get_block_t get_block);
-void block_sync_page(struct page *);
 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
 int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 272496d1fae4..e2768834f397 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -286,11 +286,6 @@ void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callback
 int dm_table_complete(struct dm_table *t);
 
 /*
- * Unplug all devices in a table.
- */
-void dm_table_unplug_all(struct dm_table *t);
-
-/*
  * Table reference counting.
  */
 struct dm_table *dm_get_live_table(struct mapped_device *md);
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index 4d857973d2c9..d93efcc44570 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -20,7 +20,6 @@ typedef void (elevator_bio_merged_fn) (struct request_queue *,
 typedef int (elevator_dispatch_fn) (struct request_queue *, int);
 
 typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
-typedef int (elevator_queue_empty_fn) (struct request_queue *);
 typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
 typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
 typedef int (elevator_may_queue_fn) (struct request_queue *, int);
@@ -46,7 +45,6 @@ struct elevator_ops
         elevator_activate_req_fn *elevator_activate_req_fn;
         elevator_deactivate_req_fn *elevator_deactivate_req_fn;
 
-        elevator_queue_empty_fn *elevator_queue_empty_fn;
         elevator_completed_req_fn *elevator_completed_req_fn;
 
         elevator_request_list_fn *elevator_former_req_fn;
@@ -101,17 +99,17 @@ struct elevator_queue
  */
 extern void elv_dispatch_sort(struct request_queue *, struct request *);
 extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
-extern void elv_add_request(struct request_queue *, struct request *, int, int);
-extern void __elv_add_request(struct request_queue *, struct request *, int, int);
+extern void elv_add_request(struct request_queue *, struct request *, int);
+extern void __elv_add_request(struct request_queue *, struct request *, int);
 extern void elv_insert(struct request_queue *, struct request *, int);
 extern int elv_merge(struct request_queue *, struct request **, struct bio *);
+extern int elv_try_merge(struct request *, struct bio *);
 extern void elv_merge_requests(struct request_queue *, struct request *,
                                struct request *);
 extern void elv_merged_request(struct request_queue *, struct request *, int);
 extern void elv_bio_merged(struct request_queue *q, struct request *,
                                 struct bio *);
 extern void elv_requeue_request(struct request_queue *, struct request *);
-extern int elv_queue_empty(struct request_queue *);
 extern struct request *elv_former_request(struct request_queue *, struct request *);
 extern struct request *elv_latter_request(struct request_queue *, struct request *);
 extern int elv_register_queue(struct request_queue *q);
@@ -167,6 +165,8 @@ extern struct request *elv_rb_find(struct rb_root *, sector_t);
 #define ELEVATOR_INSERT_BACK    2
 #define ELEVATOR_INSERT_SORT    3
 #define ELEVATOR_INSERT_REQUEUE 4
+#define ELEVATOR_INSERT_FLUSH   5
+#define ELEVATOR_INSERT_SORT_MERGE      6
 
 /*
  * return values from elevator_may_queue_fn
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 4dda076c24a1..ce7e18555197 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -138,16 +138,10 @@ struct inodes_stat_t {
  *                      block layer could (in theory) choose to ignore this
  *                      request if it runs into resource problems.
  * WRITE                A normal async write. Device will be plugged.
- * WRITE_SYNC_PLUG      Synchronous write. Identical to WRITE, but passes down
+ * WRITE_SYNC           Synchronous write. Identical to WRITE, but passes down
  *                      the hint that someone will be waiting on this IO
- *                      shortly. The device must still be unplugged explicitly,
- *                      WRITE_SYNC_PLUG does not do this as we could be
- *                      submitting more writes before we actually wait on any
- *                      of them.
- * WRITE_SYNC           Like WRITE_SYNC_PLUG, but also unplugs the device
- *                      immediately after submission. The write equivalent
- *                      of READ_SYNC.
- * WRITE_ODIRECT_PLUG   Special case write for O_DIRECT only.
+ *                      shortly. The write equivalent of READ_SYNC.
+ * WRITE_ODIRECT        Special case write for O_DIRECT only.
  * 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.
@@ -163,18 +157,14 @@ struct inodes_stat_t {
 #define WRITE                   RW_MASK
 #define READA                   RWA_MASK
 
-#define READ_SYNC               (READ | REQ_SYNC | REQ_UNPLUG)
+#define READ_SYNC               (READ | REQ_SYNC)
 #define READ_META               (READ | REQ_META)
-#define WRITE_SYNC_PLUG         (WRITE | REQ_SYNC | REQ_NOIDLE)
-#define WRITE_SYNC              (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_UNPLUG)
-#define WRITE_ODIRECT_PLUG      (WRITE | REQ_SYNC)
+#define WRITE_SYNC              (WRITE | REQ_SYNC | REQ_NOIDLE)
+#define WRITE_ODIRECT           (WRITE | REQ_SYNC)
 #define WRITE_META              (WRITE | REQ_META)
-#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)
+#define WRITE_FLUSH             (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_FLUSH)
+#define WRITE_FUA               (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_FUA)
+#define WRITE_FLUSH_FUA         (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_FLUSH | REQ_FUA)
 
 #define SEL_IN          1
 #define SEL_OUT         2
@@ -586,7 +576,6 @@ typedef int (*read_actor_t)(read_descriptor_t *, struct page *,
 struct address_space_operations {
         int (*writepage)(struct page *page, struct writeback_control *wbc);
         int (*readpage)(struct file *, struct page *);
-        void (*sync_page)(struct page *);
 
         /* Write back some dirty pages from this mapping. */
         int (*writepages)(struct address_space *, struct writeback_control *);
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index c0d5f6945c1e..d764a426e9fd 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -109,7 +109,7 @@ struct hd_struct {
         int make_it_fail;
 #endif
         unsigned long stamp;
-        int in_flight[2];
+        atomic_t in_flight[2];
 #ifdef  CONFIG_SMP
         struct disk_stats __percpu *dkstats;
 #else
@@ -370,21 +370,21 @@ static inline void free_part_stats(struct hd_struct *part)
 
 static inline void part_inc_in_flight(struct hd_struct *part, int rw)
 {
-        part->in_flight[rw]++;
+        atomic_inc(&part->in_flight[rw]);
         if (part->partno)
-                part_to_disk(part)->part0.in_flight[rw]++;
+                atomic_inc(&part_to_disk(part)->part0.in_flight[rw]);
 }
 
 static inline void part_dec_in_flight(struct hd_struct *part, int rw)
 {
-        part->in_flight[rw]--;
+        atomic_dec(&part->in_flight[rw]);
         if (part->partno)
-                part_to_disk(part)->part0.in_flight[rw]--;
+                atomic_dec(&part_to_disk(part)->part0.in_flight[rw]);
 }
 
 static inline int part_in_flight(struct hd_struct *part)
 {
-        return part->in_flight[0] + part->in_flight[1];
+        return atomic_read(&part->in_flight[0]) + atomic_read(&part->in_flight[1]);
 }
 
 static inline struct partition_meta_info *alloc_part_info(struct gendisk *disk)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 29ebba54c238..c11950652646 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -298,7 +298,6 @@ static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
 
 extern void __lock_page(struct page *page);
 extern int __lock_page_killable(struct page *page);
-extern void __lock_page_nosync(struct page *page);
 extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
                                 unsigned int flags);
 extern void unlock_page(struct page *page);
@@ -342,17 +341,6 @@ static inline int lock_page_killable(struct page *page)
 }
 
 /*
- * lock_page_nosync should only be used if we can't pin the page's inode.
- * Doesn't play quite so well with block device plugging.
- */
-static inline void lock_page_nosync(struct page *page)
-{
-        might_sleep();
-        if (!trylock_page(page))
-                __lock_page_nosync(page);
-}
-        
-/*
  * lock_page_or_retry - Lock the page, unless this would block and the
  * caller indicated that it can handle a retry.
  */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 98fc7ed4b191..b8369d522bf8 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -99,6 +99,7 @@ struct robust_list_head;
 struct bio_list;
 struct fs_struct;
 struct perf_event_context;
+struct blk_plug;
 
 /*
  * List of flags we want to share for kernel threads,
@@ -1428,6 +1429,11 @@ struct task_struct {
 /* stacked block device info */
         struct bio_list *bio_list;
 
+#ifdef CONFIG_BLOCK
+/* stack plugging */
+        struct blk_plug *plug;
+#endif
+
 /* VM state */
         struct reclaim_state *reclaim_state;
 
diff --git a/include/linux/swap.h b/include/linux/swap.h
index ed6ebe690f4a..a5c6da5d8df8 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -309,8 +309,6 @@ extern void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
                                         struct page **pagep, swp_entry_t *ent);
 #endif
 
-extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
-
 #ifdef CONFIG_SWAP
 /* linux/mm/page_io.c */
 extern int swap_readpage(struct page *);