linux-kernel - [PATCH 33/62] page cache: Convert page_cache_next

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Date:   Wed, 22 Nov 2017 13:07:10 -0800
From:   Matthew Wilcox <willy@...radead.org>
To:     linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     Matthew Wilcox <mawilcox@...rosoft.com>
Subject: [PATCH 33/62] page cache: Convert page_cache_next_hole to XArray

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

Use xas_find_any() to scan the entries instead of doing a lookup from
the top of the tree each time.

Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
---
 mm/filemap.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 1c03b0ea105e..accc350f9544 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1349,20 +1349,15 @@ int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
 pgoff_t page_cache_next_hole(struct address_space *mapping,
 			     pgoff_t index, unsigned long max_scan)
 {
-	unsigned long i;
-
-	for (i = 0; i < max_scan; i++) {
-		struct page *page;
+	XA_STATE(xas, index);
 
-		page = radix_tree_lookup(&mapping->pages, index);
-		if (!page || xa_is_value(page))
-			break;
-		index++;
-		if (index == 0)
+	while (max_scan--) {
+		void *entry = xas_find_any(&mapping->pages, &xas);
+		if (!entry || xa_is_value(entry))
 			break;
 	}
 
-	return index;
+	return xas.xa_index;
 }
 EXPORT_SYMBOL(page_cache_next_hole);
 
-- 
2.15.0