linux-kernel - [PATCH v8 57/63] fs: Convert writeback to XArray

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Message-Id: <20180306192413.5499-58-willy@infradead.org>
Date:   Tue,  6 Mar 2018 11:24:07 -0800
From:   Matthew Wilcox <willy@...radead.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Matthew Wilcox <mawilcox@...rosoft.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org,
        Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>,
        linux-nilfs@...r.kernel.org, linux-btrfs@...r.kernel.org
Subject: [PATCH v8 57/63] fs: Convert writeback to XArray

From: Matthew Wilcox <mawilcox@...rosoft.com>

A couple of short loops.

Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
---
 fs/fs-writeback.c | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 091577edc497..98e5e08274a2 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -339,9 +339,9 @@ static void inode_switch_wbs_work_fn(struct work_struct *work)
 	struct address_space *mapping = inode->i_mapping;
 	struct bdi_writeback *old_wb = inode->i_wb;
 	struct bdi_writeback *new_wb = isw->new_wb;
-	struct radix_tree_iter iter;
+	XA_STATE(xas, &mapping->i_pages, 0);
+	struct page *page;
 	bool switched = false;
-	void **slot;
 
 	/*
 	 * By the time control reaches here, RCU grace period has passed
@@ -375,25 +375,18 @@ static void inode_switch_wbs_work_fn(struct work_struct *work)
 	 * to possibly dirty pages while PAGECACHE_TAG_WRITEBACK points to
 	 * pages actually under writeback.
 	 */
-	radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter, 0,
-				   PAGECACHE_TAG_DIRTY) {
-		struct page *page = radix_tree_deref_slot_protected(slot,
-						&mapping->i_pages.xa_lock);
-		if (likely(page) && PageDirty(page)) {
+	xas_for_each_tag(&xas, page, ULONG_MAX, PAGECACHE_TAG_DIRTY) {
+		if (PageDirty(page)) {
 			dec_wb_stat(old_wb, WB_RECLAIMABLE);
 			inc_wb_stat(new_wb, WB_RECLAIMABLE);
 		}
 	}
 
-	radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter, 0,
-				   PAGECACHE_TAG_WRITEBACK) {
-		struct page *page = radix_tree_deref_slot_protected(slot,
-						&mapping->i_pages.xa_lock);
-		if (likely(page)) {
-			WARN_ON_ONCE(!PageWriteback(page));
-			dec_wb_stat(old_wb, WB_WRITEBACK);
-			inc_wb_stat(new_wb, WB_WRITEBACK);
-		}
+	xas_set(&xas, 0);
+	xas_for_each_tag(&xas, page, ULONG_MAX, PAGECACHE_TAG_WRITEBACK) {
+		WARN_ON_ONCE(!PageWriteback(page));
+		dec_wb_stat(old_wb, WB_WRITEBACK);
+		inc_wb_stat(new_wb, WB_WRITEBACK);
 	}
 
 	wb_get(new_wb);
-- 
2.16.1