+ mm-truncate-reset-xa_has_values-flag-on-each-iteration.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/truncate: reset xa_has_values flag on each iteration
has been added to the -mm mm-unstable branch.  Its filename is
     mm-truncate-reset-xa_has_values-flag-on-each-iteration.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-truncate-reset-xa_has_values-flag-on-each-iteration.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Shakeel Butt <shakeel.butt@linux.dev>
Subject: mm/truncate: reset xa_has_values flag on each iteration
Date: Wed, 2 Oct 2024 15:51:50 -0700

Currently mapping_try_invalidate() and invalidate_inode_pages2_range()
traverses the xarray in batches and then for each batch, maintains and
sets the flag named xa_has_values if the batch has a shadow entry to clear
the entries at the end of the iteration.

However they forgot to reset the flag at the end of the iteration which
causes them to always try to clear the shadow entries in the subsequent
iterations where there might not be any shadow entries.

Fix this inefficiency.

Link: https://lkml.kernel.org/r/20241002225150.2334504-1-shakeel.butt@linux.dev
Fixes: 61c663e020d2 ("mm/truncate: batch-clear shadow entries")
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/truncate.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/mm/truncate.c~mm-truncate-reset-xa_has_values-flag-on-each-iteration
+++ a/mm/truncate.c
@@ -463,10 +463,10 @@ unsigned long mapping_try_invalidate(str
 	unsigned long ret;
 	unsigned long count = 0;
 	int i;
-	bool xa_has_values = false;
 
 	folio_batch_init(&fbatch);
 	while (find_lock_entries(mapping, &index, end, &fbatch, indices)) {
+		bool xa_has_values = false;
 		int nr = folio_batch_count(&fbatch);
 
 		for (i = 0; i < nr; i++) {
@@ -592,7 +592,6 @@ int invalidate_inode_pages2_range(struct
 	int ret = 0;
 	int ret2 = 0;
 	int did_range_unmap = 0;
-	bool xa_has_values = false;
 
 	if (mapping_empty(mapping))
 		return 0;
@@ -600,6 +599,7 @@ int invalidate_inode_pages2_range(struct
 	folio_batch_init(&fbatch);
 	index = start;
 	while (find_get_entries(mapping, &index, end, &fbatch, indices)) {
+		bool xa_has_values = false;
 		int nr = folio_batch_count(&fbatch);
 
 		for (i = 0; i < nr; i++) {
_

Patches currently in -mm which might be from shakeel.butt@linux.dev are

mm-optimize-truncation-of-shadow-entries.patch
mm-optimize-invalidation-of-shadow-entries.patch
mm-truncate-reset-xa_has_values-flag-on-each-iteration.patch