[PATCH v4 10/16] mm: Add an 'end' parameter to find_get_entries

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

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@infradead.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
---
 include/linux/pagemap.h |  4 ++--
 mm/filemap.c            |  9 +++++----
 mm/shmem.c              | 10 ++--------
 mm/swap.c               |  2 +-
 4 files changed, 10 insertions(+), 15 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 9f1f4ab9612a..c7c26a902743 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -449,8 +449,8 @@ static inline struct page *find_subpage(struct page *head, pgoff_t index)
 }
 
 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 f18c5074865d..b3b89a62ab1a 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1870,6 +1870,7 @@ static inline struct page *find_get_entry(struct xa_state *xas, pgoff_t max,
  * find_get_entries - gang pagecache lookup
  * @mapping:	The address_space to search
  * @start:	The starting page cache index
+ * @end:	The final page index (inclusive).
  * @nr_entries:	The maximum number of entries
  * @entries:	Where the resulting entries are placed
  * @indices:	The cache indices corresponding to the entries in @entries
@@ -1893,9 +1894,9 @@ static inline struct page *find_get_entry(struct xa_state *xas, pgoff_t max,
  *
  * 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;
@@ -1905,7 +1906,7 @@ unsigned find_get_entries(struct address_space *mapping,
 		return 0;
 
 	rcu_read_lock();
-	while ((page = find_get_entry(&xas, ULONG_MAX, XA_PRESENT))) {
+	while ((page = find_get_entry(&xas, end, XA_PRESENT))) {
 		/*
 		 * Terminate early on finding a THP, to allow the caller to
 		 * handle it all at once; but continue if this is hugetlbfs.
diff --git a/mm/shmem.c b/mm/shmem.c
index a4aa762a55f8..7a62dc967d7d 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -913,8 +913,6 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 			struct page *page = pvec.pages[i];
 
 			index = indices[i];
-			if (index >= end)
-				break;
 
 			if (xa_is_value(page)) {
 				if (unfalloc)
@@ -967,9 +965,8 @@ 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)
@@ -982,9 +979,6 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 			struct page *page = pvec.pages[i];
 
 			index = indices[i];
-			if (index >= end)
-				break;
-
 			if (xa_is_value(page)) {
 				if (unfalloc)
 					continue;
diff --git a/mm/swap.c b/mm/swap.c
index 29220174433b..39be55635ebd 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -1102,7 +1102,7 @@ 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