On Sat, Feb 18, 2023 at 11:33:17PM -0800, Nhat Pham wrote:
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index e654435f1651..83300f1491e7 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -75,6 +75,7 @@ struct fs_context;
> struct fs_parameter_spec;
> struct fileattr;
> struct iomap_ops;
> +struct cachestat;
>
> extern void __init inode_init(void);
> extern void __init inode_init_early(void);
> @@ -830,6 +831,8 @@ void filemap_invalidate_lock_two(struct address_space *mapping1,
> struct address_space *mapping2);
> void filemap_invalidate_unlock_two(struct address_space *mapping1,
> struct address_space *mapping2);
> +void filemap_cachestat(struct address_space *mapping, pgoff_t first_index,
> + pgoff_t last_index, struct cachestat *cs);
1. Why is this in fs.h instead of pagemap.h?
2. Why is it not static, since it's only used by the syscall,
which is also in filemap.c?
> @@ -55,6 +56,9 @@
> #include <linux/buffer_head.h> /* for try_to_free_buffers */
>
> #include <asm/mman.h>
> +#include <uapi/linux/mman.h>
I think this hunk should be:
-#include <asm/mman.h>
+#include <linux/mman.h>
(linux/mman.h includes uapi/linux/mman.h, which includes asm/mman.h)
> +/**
> + * filemap_cachestat() - compute the page cache statistics of a mapping
> + * @mapping: The mapping to compute the statistics for.
> + * @first_index: The starting page cache index.
> + * @last_index: The final page index (inclusive).
> + * @cs: the cachestat struct to write the result to.
> + *
> + * This will query the page cache statistics of a mapping in the
> + * page range of [first_index, last_index] (inclusive). The statistics
> + * queried include: number of dirty pages, number of pages marked for
> + * writeback, and the number of (recently) evicted pages.
> + */
Do we care that this isn't going to work for hugetlbfs?
> + rcu_read_lock();
> + xas_for_each(&xas, folio, last_index) {
> + unsigned long nr_pages;
> + pgoff_t folio_first_index, folio_last_index;
> +
> + if (xas_retry(&xas, folio))
> + continue;
> +
> + nr_pages = folio_nr_pages(folio);
> + folio_first_index = folio_pgoff(folio);
> + folio_last_index = folio_first_index + nr_pages - 1;
> +
> + /* Folios might straddle the range boundaries, only count covered subpages */
s/subpages/pages/
