[PATCH v6 05/19] mm: Remove 'page_offset' from readahead loop

Matthew Wilcox
2020-02-17T18:46:45Z

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

Eliminate the page_offset variable which was confusing with the
'offset' parameter and record the start of each consecutive run of
pages in the readahead_control.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
mm/readahead.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/mm/readahead.c b/mm/readahead.c
index 3eca59c43a45..74791b96013f 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -162,6 +162,7 @@ void __do_page_cache_readahead(struct address_space *mapping,
struct readahead_control rac = {
.mapping = mapping,
.file = filp,
+ ._start = offset,
._nr_pages = 0,
};

@@ -175,12 +176,11 @@ void __do_page_cache_readahead(struct address_space *mapping,
*/
for (page_idx = 0; page_idx < nr_to_read; page_idx++) {
struct page *page;
- pgoff_t page_offset = offset + page_idx;

- if (page_offset > end_index)
+ if (offset > end_index)
break;

- page = xa_load(&mapping->i_pages, page_offset);
+ page = xa_load(&mapping->i_pages, offset);
if (page && !xa_is_value(page)) {
/*
* Page already present? Kick off the current batch
@@ -196,16 +196,18 @@ void __do_page_cache_readahead(struct address_space *mapping,
page = __page_cache_alloc(gfp_mask);
if (!page)
break;
- page->index = page_offset;
+ page->index = offset;
list_add(&page->lru, &page_pool);
if (page_idx == nr_to_read - lookahead_size)
SetPageReadahead(page);
rac._nr_pages++;
+ offset++;
continue;
read:
if (readahead_count(&rac))
read_pages(&rac, &page_pool, gfp_mask);
rac._nr_pages = 0;
+ rac._start = ++offset;
}

/*
--
2.25.0