linux-kernel - [PATCH v7 52/61] shmem: Convert shmem_partial_swap

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Message-Id: <20180219194556.6575-53-willy@infradead.org>
Date:   Mon, 19 Feb 2018 11:45:47 -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
Subject: [PATCH v7 52/61] shmem: Convert shmem_partial_swap_usage to XArray

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

Simpler code because the xarray takes care of things like the limit and
dereferencing the slot.

Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
---
 mm/shmem.c | 18 +++---------------
 1 file changed, 3 insertions(+), 15 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index a7931660897d..c24c4cb76c43 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -658,29 +658,17 @@ static int shmem_free_swap(struct address_space *mapping,
 unsigned long shmem_partial_swap_usage(struct address_space *mapping,
 						pgoff_t start, pgoff_t end)
 {
-	struct radix_tree_iter iter;
-	void **slot;
+	XA_STATE(xas, &mapping->pages, start);
 	struct page *page;
 	unsigned long swapped = 0;
 
 	rcu_read_lock();
-
-	radix_tree_for_each_slot(slot, &mapping->pages, &iter, start) {
-		if (iter.index >= end)
-			break;
-
-		page = radix_tree_deref_slot(slot);
-
-		if (radix_tree_deref_retry(page)) {
-			slot = radix_tree_iter_retry(&iter);
-			continue;
-		}
-
+	xas_for_each(&xas, page, end - 1) {
 		if (xa_is_value(page))
 			swapped++;
 
 		if (need_resched()) {
-			slot = radix_tree_iter_resume(slot, &iter);
+			xas_pause(&xas);
 			cond_resched_rcu();
 		}
 	}
-- 
2.16.1