linux-kernel - [PATCH 3/7] mm: Add an 'end' parameter to find_get

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Date:   Wed, 19 Aug 2020 16:05:51 +0100
From:   "Matthew Wilcox (Oracle)" <willy@...radead.org>
To:     linux-mm@...ck.org
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Hugh Dickins <hughd@...gle.com>,
        William Kucharski <william.kucharski@...cle.com>,
        Johannes Weiner <hannes@...xchg.org>, Jan Kara <jack@...e.cz>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 3/7] mm: Add an 'end' parameter to find_get_entries

This simplifies the callers and leads to a more efficient implementation
since the XArray has this functionality already.

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
---
 include/linux/pagemap.h |  4 ++--
 mm/filemap.c            |  9 +++++----
 mm/shmem.c              | 10 ++++------
 mm/swap.c               |  2 +-
 4 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 7de11dcd534d..3f0dc8d00f2a 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -387,8 +387,8 @@ static inline struct page *find_subpage(struct page *head, pgoff_t index)
 struct page *find_get_entry(struct address_space *mapping, pgoff_t offset);
 struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset);
 unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
-			  unsigned int nr_entries, struct page **entries,
-			  pgoff_t *indices);
+		pgoff_t end, unsigned int nr_entries, struct page **entries,
+		pgoff_t *indices);
 unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
 			pgoff_t end, unsigned int nr_pages,
 			struct page **pages);
diff --git a/mm/filemap.c b/mm/filemap.c
index 1aaea26556cc..159cf3d6f1ae 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1742,6 +1742,7 @@ EXPORT_SYMBOL(pagecache_get_page);
  * find_get_entries - gang pagecache lookup
  * @mapping:	The address_space to search
  * @start:	The starting page cache index
+ * @end:	The highest page cache index to return.
  * @nr_entries:	The maximum number of entries
  * @entries:	Where the resulting entries are placed
  * @indices:	The cache indices corresponding to the entries in @entries
@@ -1765,9 +1766,9 @@ EXPORT_SYMBOL(pagecache_get_page);
  *
  * Return: the number of pages and shadow entries which were found.
  */
-unsigned find_get_entries(struct address_space *mapping,
-			  pgoff_t start, unsigned int nr_entries,
-			  struct page **entries, pgoff_t *indices)
+unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
+		pgoff_t end, unsigned int nr_entries, struct page **entries,
+		pgoff_t *indices)
 {
 	XA_STATE(xas, &mapping->i_pages, start);
 	struct page *page;
@@ -1777,7 +1778,7 @@ unsigned find_get_entries(struct address_space *mapping,
 		return 0;
 
 	rcu_read_lock();
-	xas_for_each(&xas, page, ULONG_MAX) {
+	xas_for_each(&xas, page, end) {
 		if (xas_retry(&xas, page))
 			continue;
 		/*
diff --git a/mm/shmem.c b/mm/shmem.c
index 0f9f149f4b5e..abdbe61a1aa7 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -906,9 +906,8 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 	pagevec_init(&pvec);
 	index = start;
 	while (index < end) {
-		pvec.nr = find_get_entries(mapping, index,
-			min(end - index, (pgoff_t)PAGEVEC_SIZE),
-			pvec.pages, indices);
+		pvec.nr = find_get_entries(mapping, index, end - 1,
+				PAGEVEC_SIZE, pvec.pages, indices);
 		if (!pvec.nr)
 			break;
 		for (i = 0; i < pagevec_count(&pvec); i++) {
@@ -977,9 +976,8 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 	while (index < end) {
 		cond_resched();
 
-		pvec.nr = find_get_entries(mapping, index,
-				min(end - index, (pgoff_t)PAGEVEC_SIZE),
-				pvec.pages, indices);
+		pvec.nr = find_get_entries(mapping, index, end - 1,
+				PAGEVEC_SIZE, pvec.pages, indices);
 		if (!pvec.nr) {
 			/* If all gone or hole-punch or unfalloc, we're done */
 			if (index == start || end != -1)
diff --git a/mm/swap.c b/mm/swap.c
index d16d65d9b4e0..fcf6ccb94b09 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -1060,7 +1060,7 @@ unsigned pagevec_lookup_entries(struct pagevec *pvec,
 				pgoff_t start, unsigned nr_entries,
 				pgoff_t *indices)
 {
-	pvec->nr = find_get_entries(mapping, start, nr_entries,
+	pvec->nr = find_get_entries(mapping, start, ULONG_MAX, nr_entries,
 				    pvec->pages, indices);
 	return pagevec_count(pvec);
 }
-- 
2.28.0