[PATCH v9 06/25] mm: Use readahead_control to pass arguments

Matthew Wilcox
2020-03-20T14:25:14Z

In this patch, only between __do_page_cache_readahead() and read_pages(),
but it will be extended in upcoming patches. The read_pages() function
becomes aops centric, as this makes the most sense by the end of the
patchset.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
---
mm/readahead.c | 33 +++++++++++++++++++--------------
1 file changed, 19 insertions(+), 14 deletions(-)

diff --git a/mm/readahead.c b/mm/readahead.c
index 9fcd4e32b62d..9d9aa4ffc7d4 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -113,29 +113,32 @@ int read_cache_pages(struct address_space *mapping, struct list_head *pages,

EXPORT_SYMBOL(read_cache_pages);

-static void read_pages(struct address_space *mapping, struct file *filp,
- struct list_head *pages, unsigned int nr_pages, gfp_t gfp)
+static void read_pages(struct readahead_control *rac, struct list_head *pages,
+ gfp_t gfp)
{
+ const struct address_space_operations *aops = rac->mapping->a_ops;
struct blk_plug plug;
unsigned page_idx;

- if (!nr_pages)
+ if (!readahead_count(rac))
return;

blk_start_plug(&plug);

- if (mapping->a_ops->readpages) {
- mapping->a_ops->readpages(filp, mapping, pages, nr_pages);
+ if (aops->readpages) {
+ aops->readpages(rac->file, rac->mapping, pages,
+ readahead_count(rac));
/* Clean up the remaining pages */
put_pages_list(pages);
goto out;
}

- for (page_idx = 0; page_idx < nr_pages; page_idx++) {
+ for (page_idx = 0; page_idx < readahead_count(rac); page_idx++) {
struct page *page = lru_to_page(pages);
list_del(&page->lru);
- if (!add_to_page_cache_lru(page, mapping, page->index, gfp))
- mapping->a_ops->readpage(filp, page);
+ if (!add_to_page_cache_lru(page, rac->mapping, page->index,
+ gfp))
+ aops->readpage(rac->file, page);
put_page(page);
}

@@ -143,6 +146,7 @@ static void read_pages(struct address_space *mapping, struct file *filp,
blk_finish_plug(&plug);

BUG_ON(!list_empty(pages));
+ rac->_nr_pages = 0;
}

/*
@@ -160,9 +164,12 @@ void __do_page_cache_readahead(struct address_space *mapping,
unsigned long end_index; /* The last page we want to read */
LIST_HEAD(page_pool);
int page_idx;
- unsigned int nr_pages = 0;
loff_t isize = i_size_read(inode);
gfp_t gfp_mask = readahead_gfp_mask(mapping);
+ struct readahead_control rac = {
+ .mapping = mapping,
+ .file = filp,
+ };

if (isize == 0)
return;
@@ -185,9 +192,7 @@ void __do_page_cache_readahead(struct address_space *mapping,
* contiguous pages before continuing with the next
* batch.
*/
- read_pages(mapping, filp, &page_pool, nr_pages,
- gfp_mask);
- nr_pages = 0;
+ read_pages(&rac, &page_pool, gfp_mask);
continue;
}

@@ -198,7 +203,7 @@ void __do_page_cache_readahead(struct address_space *mapping,
list_add(&page->lru, &page_pool);
if (page_idx == nr_to_read - lookahead_size)
SetPageReadahead(page);
- nr_pages++;
+ rac._nr_pages++;
}

/*
@@ -206,7 +211,7 @@ void __do_page_cache_readahead(struct address_space *mapping,
* uptodate then the caller will launch readpage again, and
* will then handle the error.
*/
- read_pages(mapping, filp, &page_pool, nr_pages, gfp_mask);
+ read_pages(&rac, &page_pool, gfp_mask);
}

/*
--
2.25.1