Merge branch 'for-4.15/block' of git://git.kernel.dk/linux-block

Pull core block layer updates from Jens Axboe:
 "This is the main pull request for block storage for 4.15-rc1.

  Nothing out of the ordinary in here, and no API changes or anything
  like that. Just various new features for drivers, core changes, etc.
  In particular, this pull request contains:

   - A patch series from Bart, closing the whole on blk/scsi-mq queue
     quescing.

   - A series from Christoph, building towards hidden gendisks (for
     multipath) and ability to move bio chains around.

   - NVMe
        - Support for native multipath for NVMe (Christoph).
        - Userspace notifications for AENs (Keith).
        - Command side-effects support (Keith).
        - SGL support (Chaitanya Kulkarni)
        - FC fixes and improvements (James Smart)
        - Lots of fixes and tweaks (Various)

   - bcache
        - New maintainer (Michael Lyle)
        - Writeback control improvements (Michael)
        - Various fixes (Coly, Elena, Eric, Liang, et al)

   - lightnvm updates, mostly centered around the pblk interface
     (Javier, Hans, and Rakesh).

   - Removal of unused bio/bvec kmap atomic interfaces (me, Christoph)

   - Writeback series that fix the much discussed hundreds of millions
     of sync-all units. This goes all the way, as discussed previously
     (me).

   - Fix for missing wakeup on writeback timer adjustments (Yafang
     Shao).

   - Fix laptop mode on blk-mq (me).

   - {mq,name} tupple lookup for IO schedulers, allowing us to have
     alias names. This means you can use 'deadline' on both !mq and on
     mq (where it's called mq-deadline). (me).

   - blktrace race fix, oopsing on sg load (me).

   - blk-mq optimizations (me).

   - Obscure waitqueue race fix for kyber (Omar).

   - NBD fixes (Josef).

   - Disable writeback throttling by default on bfq, like we do on cfq
     (Luca Miccio).

   - Series from Ming that enable us to treat flush requests on blk-mq
     like any other request. This is a really nice cleanup.

   - Series from Ming that improves merging on blk-mq with schedulers,
     getting us closer to flipping the switch on scsi-mq again.

   - BFQ updates (Paolo).

   - blk-mq atomic flags memory ordering fixes (Peter Z).

   - Loop cgroup support (Shaohua).

   - Lots of minor fixes from lots of different folks, both for core and
     driver code"

* 'for-4.15/block' of git://git.kernel.dk/linux-block: (294 commits)
  nvme: fix visibility of "uuid" ns attribute
  blk-mq: fixup some comment typos and lengths
  ide: ide-atapi: fix compile error with defining macro DEBUG
  blk-mq: improve tag waiting setup for non-shared tags
  brd: remove unused brd_mutex
  blk-mq: only run the hardware queue if IO is pending
  block: avoid null pointer dereference on null disk
  fs: guard_bio_eod() needs to consider partitions
  xtensa/simdisk: fix compile error
  nvme: expose subsys attribute to sysfs
  nvme: create 'slaves' and 'holders' entries for hidden controllers
  block: create 'slaves' and 'holders' entries for hidden gendisks
  nvme: also expose the namespace identification sysfs files for mpath nodes
  nvme: implement multipath access to nvme subsystems
  nvme: track shared namespaces
  nvme: introduce a nvme_ns_ids structure
  nvme: track subsystems
  block, nvme: Introduce blk_mq_req_flags_t
  block, scsi: Make SCSI quiesce and resume work reliably
  block: Add the QUEUE_FLAG_PREEMPT_ONLY request queue flag
  ...

4 files changed, 20 insertions, 40 deletions

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index e19606bb41a0..74b52dfd5852 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -1072,23 +1072,3 @@ out:
 	return ret;
 }
 EXPORT_SYMBOL(wait_iff_congested);
-
-int pdflush_proc_obsolete(struct ctl_table *table, int write,
-			void __user *buffer, size_t *lenp, loff_t *ppos)
-{
-	char kbuf[] = "0\n";
-
-	if (*ppos || *lenp < sizeof(kbuf)) {
-		*lenp = 0;
-		return 0;
-	}
-
-	if (copy_to_user(buffer, kbuf, sizeof(kbuf)))
-		return -EFAULT;
-	pr_warn_once("%s exported in /proc is scheduled for removal\n",
-		     table->procname);
-
-	*lenp = 2;
-	*ppos += *lenp;
-	return 2;
-}
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 0b9c5cbe8eba..c518c845f202 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1972,31 +1972,31 @@ bool wb_over_bg_thresh(struct bdi_writeback *wb)
 int dirty_writeback_centisecs_handler(struct ctl_table *table, int write,
 	void __user *buffer, size_t *length, loff_t *ppos)
 {
-	proc_dointvec(table, write, buffer, length, ppos);
-	return 0;
+	unsigned int old_interval = dirty_writeback_interval;
+	int ret;
+
+	ret = proc_dointvec(table, write, buffer, length, ppos);
+
+	/*
+	 * Writing 0 to dirty_writeback_interval will disable periodic writeback
+	 * and a different non-zero value will wakeup the writeback threads.
+	 * wb_wakeup_delayed() would be more appropriate, but it's a pain to
+	 * iterate over all bdis and wbs.
+	 * The reason we do this is to make the change take effect immediately.
+	 */
+	if (!ret && write && dirty_writeback_interval &&
+		dirty_writeback_interval != old_interval)
+		wakeup_flusher_threads(WB_REASON_PERIODIC);
+
+	return ret;
 }
 
 #ifdef CONFIG_BLOCK
 void laptop_mode_timer_fn(unsigned long data)
 {
 	struct request_queue *q = (struct request_queue *)data;
-	int nr_pages = global_node_page_state(NR_FILE_DIRTY) +
-		global_node_page_state(NR_UNSTABLE_NFS);
-	struct bdi_writeback *wb;
 
-	/*
-	 * We want to write everything out, not just down to the dirty
-	 * threshold
-	 */
-	if (!bdi_has_dirty_io(q->backing_dev_info))
-		return;
-
-	rcu_read_lock();
-	list_for_each_entry_rcu(wb, &q->backing_dev_info->wb_list, bdi_node)
-		if (wb_has_dirty_io(wb))
-			wb_start_writeback(wb, nr_pages, true,
-					   WB_REASON_LAPTOP_TIMER);
-	rcu_read_unlock();
+	wakeup_flusher_threads_bdi(q->backing_dev_info, WB_REASON_LAPTOP_TIMER);
 }
 
 /*
diff --git a/mm/page_io.c b/mm/page_io.c
index 5d882de3fbfd..cd52b9cc169b 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -408,7 +408,7 @@ int swap_readpage(struct page *page, bool do_poll)
 		if (!READ_ONCE(bio->bi_private))
 			break;
 
-		if (!blk_mq_poll(disk->queue, qc))
+		if (!blk_poll(disk->queue, qc))
 			break;
 	}
 	__set_current_state(TASK_RUNNING);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index eb2f0315b8c0..15b483ef6440 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1868,7 +1868,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 		 * also allow kswapd to start writing pages during reclaim.
 		 */
 		if (stat.nr_unqueued_dirty == nr_taken) {
-			wakeup_flusher_threads(0, WB_REASON_VMSCAN);
+			wakeup_flusher_threads(WB_REASON_VMSCAN);
 			set_bit(PGDAT_DIRTY, &pgdat->flags);
 		}