btrfs: rename PagePrivate2 to PageOrdered inside btrfs

Inside btrfs we use Private2 page status to indicate we have an ordered
extent with pending IO for the sector.

But the page status name, Private2, tells us nothing about the bit
itself, so this patch will rename it to Ordered.
And with extra comment about the bit added, so reader who is still
uncertain about the page Ordered status, will find the comment pretty
easily.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 26 insertions, 24 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index f036b6e992df..412abf923136 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -170,7 +170,7 @@ static inline void btrfs_cleanup_ordered_extents(struct btrfs_inode *inode,
 		index++;
 		if (!page)
 			continue;
-		ClearPagePrivate2(page);
+		ClearPageOrdered(page);
 		put_page(page);
 	}
 
@@ -1151,15 +1151,16 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
 
 		btrfs_dec_block_group_reservations(fs_info, ins.objectid);
 
-		/* we're not doing compressed IO, don't unlock the first
-		 * page (which the caller expects to stay locked), don't
-		 * clear any dirty bits and don't set any writeback bits
+		/*
+		 * We're not doing compressed IO, don't unlock the first page
+		 * (which the caller expects to stay locked), don't clear any
+		 * dirty bits and don't set any writeback bits
 		 *
-		 * Do set the Private2 bit so we know this page was properly
-		 * setup for writepage
+		 * Do set the Ordered (Private2) bit so we know this page was
+		 * properly setup for writepage.
 		 */
 		page_ops = unlock ? PAGE_UNLOCK : 0;
-		page_ops |= PAGE_SET_PRIVATE2;
+		page_ops |= PAGE_SET_ORDERED;
 
 		extent_clear_unlock_delalloc(inode, start, start + ram_size - 1,
 					     locked_page,
@@ -1823,7 +1824,7 @@ out_check:
 					     locked_page, EXTENT_LOCKED |
 					     EXTENT_DELALLOC |
 					     EXTENT_CLEAR_DATA_RESV,
-					     PAGE_UNLOCK | PAGE_SET_PRIVATE2);
+					     PAGE_UNLOCK | PAGE_SET_ORDERED);
 
 		cur_offset = extent_end;
 
@@ -2571,7 +2572,7 @@ again:
 	lock_extent_bits(&inode->io_tree, page_start, page_end, &cached_state);
 
 	/* already ordered? We're done */
-	if (PagePrivate2(page))
+	if (PageOrdered(page))
 		goto out_reserved;
 
 	ordered = btrfs_lookup_ordered_range(inode, page_start, PAGE_SIZE);
@@ -2646,8 +2647,8 @@ int btrfs_writepage_cow_fixup(struct page *page, u64 start, u64 end)
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	struct btrfs_writepage_fixup *fixup;
 
-	/* this page is properly in the ordered list */
-	if (PagePrivate2(page))
+	/* This page has ordered extent covering it already */
+	if (PageOrdered(page))
 		return 0;
 
 	/*
@@ -8300,9 +8301,9 @@ static int btrfs_migratepage(struct address_space *mapping,
 	if (page_has_private(page))
 		attach_page_private(newpage, detach_page_private(page));
 
-	if (PagePrivate2(page)) {
-		ClearPagePrivate2(page);
-		SetPagePrivate2(newpage);
+	if (PageOrdered(page)) {
+		ClearPageOrdered(page);
+		SetPageOrdered(newpage);
 	}
 
 	if (mode != MIGRATE_SYNC_NO_COPY)
@@ -8329,9 +8330,10 @@ static void btrfs_invalidatepage(struct page *page, unsigned int offset,
 	 * page, nor bio can be submitted for this page.
 	 *
 	 * But already submitted bio can still be finished on this page.
-	 * Furthermore, endio function won't skip page which has Private2
-	 * already cleared, so it's possible for endio and invalidatepage to do
-	 * the same ordered extent accounting twice on one page.
+	 * Furthermore, endio function won't skip page which has Ordered
+	 * (Private2) already cleared, so it's possible for endio and
+	 * invalidatepage to do the same ordered extent accounting twice
+	 * on one page.
 	 *
 	 * So here we wait for any submitted bios to finish, so that we won't
 	 * do double ordered extent accounting on the same page.
@@ -8377,17 +8379,17 @@ static void btrfs_invalidatepage(struct page *page, unsigned int offset,
 
 		range_end = min(ordered->file_offset + ordered->num_bytes - 1,
 				page_end);
-		if (!PagePrivate2(page)) {
+		if (!PageOrdered(page)) {
 			/*
-			 * If Private2 is cleared, it means endio has already
-			 * been executed for the range.
+			 * If Ordered (Private2) is cleared, it means endio has
+			 * already been executed for the range.
 			 * We can't delete the extent states as
 			 * btrfs_finish_ordered_io() may still use some of them.
 			 */
 			delete_states = false;
 			goto next;
 		}
-		ClearPagePrivate2(page);
+		ClearPageOrdered(page);
 
 		/*
 		 * IO on this page will never be started, so we need to account
@@ -8454,10 +8456,10 @@ next:
 	}
 	/*
 	 * We have iterated through all ordered extents of the page, the page
-	 * should not have Private2 anymore, or the above iteration does
-	 * something wrong.
+	 * should not have Ordered (Private2) anymore, or the above iteration
+	 * did something wrong.
 	 */
-	ASSERT(!PagePrivate2(page));
+	ASSERT(!PageOrdered(page));
 	if (!inode_evicting)
 		__btrfs_releasepage(page, GFP_NOFS);
 	ClearPageChecked(page);