Merge branch 'next' (accumulated 3.16 merge window patches) into master

Now that 3.15 is released, this merges the 'next' branch into 'master',
bringing us to the normal situation where my 'master' branch is the
merge window.

* accumulated work in next: (6809 commits)
  ufs: sb mutex merge + mutex_destroy
  powerpc: update comments for generic idle conversion
  cris: update comments for generic idle conversion
  idle: remove cpu_idle() forward declarations
  nbd: zero from and len fields in NBD_CMD_DISCONNECT.
  mm: convert some level-less printks to pr_*
  MAINTAINERS: adi-buildroot-devel is moderated
  MAINTAINERS: add linux-api for review of API/ABI changes
  mm/kmemleak-test.c: use pr_fmt for logging
  fs/dlm/debug_fs.c: replace seq_printf by seq_puts
  fs/dlm/lockspace.c: convert simple_str to kstr
  fs/dlm/config.c: convert simple_str to kstr
  mm: mark remap_file_pages() syscall as deprecated
  mm: memcontrol: remove unnecessary memcg argument from soft limit functions
  mm: memcontrol: clean up memcg zoneinfo lookup
  mm/memblock.c: call kmemleak directly from memblock_(alloc|free)
  mm/mempool.c: update the kmemleak stack trace for mempool allocations
  lib/radix-tree.c: update the kmemleak stack trace for radix tree allocations
  mm: introduce kmemleak_update_trace()
  mm/kmemleak.c: use %u to print ->checksum
  ...

fs/btrfs/btrfs_inode.h

@@ -279,7 +279,7 @@ static inline void btrfs_inode_block_unlocked_dio(struct inode *inode)
 
 static inline void btrfs_inode_resume_unlocked_dio(struct inode *inode)
 {
-	smp_mb__before_clear_bit();
+	smp_mb__before_atomic();
 	clear_bit(BTRFS_INODE_READDIO_NEED_LOCK,
 		  &BTRFS_I(inode)->runtime_flags);
 }

fs/btrfs/extent_io.c

@@ -3458,7 +3458,7 @@ static int lock_extent_buffer_for_io(struct extent_buffer *eb,
 static void end_extent_buffer_writeback(struct extent_buffer *eb)
 {
 	clear_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
-	smp_mb__after_clear_bit();
+	smp_mb__after_atomic();
 	wake_up_bit(&eb->bflags, EXTENT_BUFFER_WRITEBACK);
 }
 
@@ -4510,7 +4510,8 @@ static void check_buffer_tree_ref(struct extent_buffer *eb)
 	spin_unlock(&eb->refs_lock);
 }
 
-static void mark_extent_buffer_accessed(struct extent_buffer *eb)
+static void mark_extent_buffer_accessed(struct extent_buffer *eb,
+		struct page *accessed)
 {
 	unsigned long num_pages, i;
 
@@ -4519,7 +4520,8 @@ static void mark_extent_buffer_accessed(struct extent_buffer *eb)
 	num_pages = num_extent_pages(eb->start, eb->len);
 	for (i = 0; i < num_pages; i++) {
 		struct page *p = extent_buffer_page(eb, i);
-		mark_page_accessed(p);
+		if (p != accessed)
+			mark_page_accessed(p);
 	}
 }
 
@@ -4533,7 +4535,7 @@ struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info,
 			       start >> PAGE_CACHE_SHIFT);
 	if (eb && atomic_inc_not_zero(&eb->refs)) {
 		rcu_read_unlock();
-		mark_extent_buffer_accessed(eb);
+		mark_extent_buffer_accessed(eb, NULL);
 		return eb;
 	}
 	rcu_read_unlock();
@@ -4581,7 +4583,7 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
 				spin_unlock(&mapping->private_lock);
 				unlock_page(p);
 				page_cache_release(p);
-				mark_extent_buffer_accessed(exists);
+				mark_extent_buffer_accessed(exists, p);
 				goto free_eb;
 			}
 
@@ -4596,7 +4598,6 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
 		attach_extent_buffer_page(eb, p);
 		spin_unlock(&mapping->private_lock);
 		WARN_ON(PageDirty(p));
-		mark_page_accessed(p);
 		eb->pages[i] = p;
 		if (!PageUptodate(p))
 			uptodate = 0;

fs/btrfs/file.c

@@ -470,11 +470,12 @@ static void btrfs_drop_pages(struct page **pages, size_t num_pages)
 	for (i = 0; i < num_pages; i++) {
 		/* page checked is some magic around finding pages that
 		 * have been modified without going through btrfs_set_page_dirty
-		 * clear it here
+		 * clear it here. There should be no need to mark the pages
+		 * accessed as prepare_pages should have marked them accessed
+		 * in prepare_pages via find_or_create_page()
 		 */
 		ClearPageChecked(pages[i]);
 		unlock_page(pages[i]);
-		mark_page_accessed(pages[i]);
 		page_cache_release(pages[i]);
 	}
 }

fs/btrfs/inode.c

@@ -7126,7 +7126,7 @@ static void btrfs_end_dio_bio(struct bio *bio, int err)
 		 * before atomic variable goto zero, we must make sure
 		 * dip->errors is perceived to be set.
 		 */
-		smp_mb__before_atomic_dec();
+		smp_mb__before_atomic();
 	}
 
 	/* if there are more bios still pending for this dio, just exit */
@@ -7306,7 +7306,7 @@ out_err:
 	 * before atomic variable goto zero, we must
 	 * make sure dip->errors is perceived to be set.
 	 */
-	smp_mb__before_atomic_dec();
+	smp_mb__before_atomic();
 	if (atomic_dec_and_test(&dip->pending_bios))
 		bio_io_error(dip->orig_bio);
 
@@ -7449,7 +7449,7 @@ static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb,
 		return 0;
 
 	atomic_inc(&inode->i_dio_count);
-	smp_mb__after_atomic_inc();
+	smp_mb__after_atomic();
 
 	/*
 	 * The generic stuff only does filemap_write_and_wait_range, which

fs/btrfs/ioctl.c

@@ -642,7 +642,7 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir,
 		return -EINVAL;
 
 	atomic_inc(&root->will_be_snapshoted);
-	smp_mb__after_atomic_inc();
+	smp_mb__after_atomic();
 	btrfs_wait_nocow_write(root);
 
 	ret = btrfs_start_delalloc_inodes(root, 0);