[PATCH] filemap: call filemap_get_folios_tag() from filemap_get_folios()

[PATCH] filemap: call filemap_get_folios_tag() from filemap_get_folios()

[Pankaj Raghav]

From: Pankaj Raghav <p.raghav@samsung.com>

filemap_get_folios() is filemap_get_folios_tag() with XA_PRESENT as the
tag that is being matched. Return filemap_get_folios_tag() with
XA_PRESENT as the tag instead of duplicating the code in
filemap_get_folios().

No functional changes.

Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
---
 mm/filemap.c | 45 ++++++++-------------------------------------
 1 file changed, 8 insertions(+), 37 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 695cf0e643da..525b8d68b4b1 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2120,48 +2120,13 @@ unsigned find_lock_entries(struct address_space *mapping, pgoff_t *start,
  * index @start and up to index @end (inclusive).  The folios are returned
  * in @fbatch with an elevated reference count.
  *
- * The first folio may start before @start; if it does, it will contain
- * @start.  The final folio may extend beyond @end; if it does, it will
- * contain @end.  The folios have ascending indices.  There may be gaps
- * between the folios if there are indices which have no folio in the
- * page cache.  If folios are added to or removed from the page cache
- * while this is running, they may or may not be found by this call.
- *
  * Return: The number of folios which were found.
  * We also update @start to index the next folio for the traversal.
  */
 unsigned filemap_get_folios(struct address_space *mapping, pgoff_t *start,
 		pgoff_t end, struct folio_batch *fbatch)
 {
-	XA_STATE(xas, &mapping->i_pages, *start);
-	struct folio *folio;
-
-	rcu_read_lock();
-	while ((folio = find_get_entry(&xas, end, XA_PRESENT)) != NULL) {
-		/* Skip over shadow, swap and DAX entries */
-		if (xa_is_value(folio))
-			continue;
-		if (!folio_batch_add(fbatch, folio)) {
-			unsigned long nr = folio_nr_pages(folio);
-			*start = folio->index + nr;
-			goto out;
-		}
-	}
-
-	/*
-	 * We come here when there is no page beyond @end. We take care to not
-	 * overflow the index @start as it confuses some of the callers. This
-	 * breaks the iteration when there is a page at index -1 but that is
-	 * already broken anyway.
-	 */
-	if (end == (pgoff_t)-1)
-		*start = (pgoff_t)-1;
-	else
-		*start = end + 1;
-out:
-	rcu_read_unlock();
-
-	return folio_batch_count(fbatch);
+	return filemap_get_folios_tag(mapping, start, end, XA_PRESENT, fbatch);
 }
 EXPORT_SYMBOL(filemap_get_folios);
 
@@ -2240,7 +2205,13 @@ EXPORT_SYMBOL(filemap_get_folios_contig);
  * @tag:        The tag index
  * @fbatch:     The batch to fill
  *
- * Same as filemap_get_folios(), but only returning folios tagged with @tag.
+ * The first folio may start before @start; if it does, it will contain
+ * @start.  The final folio may extend beyond @end; if it does, it will
+ * contain @end.  The folios have ascending indices.  There may be gaps
+ * between the folios if there are indices which have no folio in the
+ * page cache.  If folios are added to or removed from the page cache
+ * while this is running, they may or may not be found by this call.
+ * Only returns folios that are tagged with @tag.
  *
  * Return: The number of folios found.
  * Also update @start to index the next folio for traversal.
-- 
2.40.1

Re: [PATCH] filemap: call filemap_get_folios_tag() from filemap_get_folios()

[Matthew Wilcox]

On Fri, Oct 06, 2023 at 01:01:20PM +0200, Pankaj Raghav wrote:
> From: Pankaj Raghav <p.raghav@samsung.com>
> 
> filemap_get_folios() is filemap_get_folios_tag() with XA_PRESENT as the
> tag that is being matched. Return filemap_get_folios_tag() with
> XA_PRESENT as the tag instead of duplicating the code in
> filemap_get_folios().

Yes, I think this makes sense.  I was consciously trying to make them
as similar to each other as possible.  I hadn't realised I'd succeeded
to such an extent.

Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>