Received-SPF: pass (google.com: domain of linux-kernel+bounces-102175-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
From: "Pankaj Raghav (Samsung)" <kernel@pankajraghav.com>
To: willy@infradead.org,
	linux-xfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
Cc: gost.dev@samsung.com,
	chandan.babu@oracle.com,
	hare@suse.de,
	mcgrof@kernel.org,
	djwong@kernel.org,
	linux-mm@kvack.org,
	linux-kernel@vger.kernel.org,
	david@fromorbit.com,
	akpm@linux-foundation.org,
	Pankaj Raghav <p.raghav@samsung.com>
Subject: [PATCH v3 04/11] readahead: rework loop in page_cache_ra_unbounded()
Date: Wed, 13 Mar 2024 18:02:46 +0100
Message-ID: <20240313170253.2324812-5-kernel@pankajraghav.com>
In-Reply-To: <20240313170253.2324812-1-kernel@pankajraghav.com>
References: <20240313170253.2324812-1-kernel@pankajraghav.com>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

From: Hannes Reinecke <hare@suse.de>

Rework the loop in page_cache_ra_unbounded() to advance with
the number of pages in a folio instead of just one page at a time.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Co-developed-by: Pankaj Raghav <p.raghav@samsung.com>
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
Acked-by: Darrick J. Wong <djwong@kernel.org>
---
 mm/readahead.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/mm/readahead.c b/mm/readahead.c
index 369c70e2be42..37b938f4b54f 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -208,7 +208,7 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
 	struct address_space *mapping = ractl->mapping;
 	unsigned long index = readahead_index(ractl);
 	gfp_t gfp_mask = readahead_gfp_mask(mapping);
-	unsigned long i;
+	unsigned long i = 0;
 
 	/*
 	 * Partway through the readahead operation, we will have added
@@ -226,7 +226,7 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
 	/*
 	 * Preallocate as many pages as we will need.
 	 */
-	for (i = 0; i < nr_to_read; i++) {
+	while (i < nr_to_read) {
 		struct folio *folio = xa_load(&mapping->i_pages, index + i);
 
 		if (folio && !xa_is_value(folio)) {
@@ -239,8 +239,8 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
 			 * not worth getting one just for that.
 			 */
 			read_pages(ractl);
-			ractl->_index++;
-			i = ractl->_index + ractl->_nr_pages - index - 1;
+			ractl->_index += folio_nr_pages(folio);
+			i = ractl->_index + ractl->_nr_pages - index;
 			continue;
 		}
 
@@ -252,13 +252,14 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
 			folio_put(folio);
 			read_pages(ractl);
 			ractl->_index++;
-			i = ractl->_index + ractl->_nr_pages - index - 1;
+			i = ractl->_index + ractl->_nr_pages - index;
 			continue;
 		}
 		if (i == nr_to_read - lookahead_size)
 			folio_set_readahead(folio);
 		ractl->_workingset |= folio_test_workingset(folio);
-		ractl->_nr_pages++;
+		ractl->_nr_pages += folio_nr_pages(folio);
+		i += folio_nr_pages(folio);
 	}
 
 	/*
-- 
2.43.0