Re: [PATCH v10 2/3] cachestat: implement cachestat syscall
From: Matthew Wilcox <willy@infradead.org>
Date: 2023-02-19 12:21:44
Also in:
linux-mm, lkml
On Sat, Feb 18, 2023 at 11:33:17PM -0800, Nhat Pham wrote:
quoted hunk ↗ jump to hunk
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?
quoted hunk ↗ jump to hunk
@@ -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/