The patch titled
Subject: mm/filemap: add helper for finding pages
has been added to the -mm tree. Its filename is
mm-filemap-add-helper-for-finding-pages.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-filemap-add-helper-for-finding-pages.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-filemap-add-helper-for-finding-pages.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm/filemap: add helper for finding pages
There is a lot of common code in find_get_entries(),
find_get_pages_range() and find_get_pages_range_tag(). Factor out
find_get_entry() which simplifies all three functions.
Link: https://lkml.kernel.org/r/20201112212641.27837-7-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Reviewed-by: William Kucharski <william.kucharski@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Dave Chinner <dchinner@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/filemap.c | 98 +++++++++++++++++++++----------------------------
1 file changed, 43 insertions(+), 55 deletions(-)
--- a/mm/filemap.c~mm-filemap-add-helper-for-finding-pages
+++ a/mm/filemap.c
@@ -1829,6 +1829,43 @@ no_page:
}
EXPORT_SYMBOL(pagecache_get_page);
+static inline struct page *find_get_entry(struct xa_state *xas, pgoff_t max,
+ xa_mark_t mark)
+{
+ struct page *page;
+
+retry:
+ if (mark == XA_PRESENT)
+ page = xas_find(xas, max);
+ else
+ page = xas_find_marked(xas, max, mark);
+
+ if (xas_retry(xas, page))
+ goto retry;
+ /*
+ * A shadow entry of a recently evicted page, a swap
+ * entry from shmem/tmpfs or a DAX entry. Return it
+ * without attempting to raise page count.
+ */
+ if (!page || xa_is_value(page))
+ return page;
+
+ if (!page_cache_get_speculative(page))
+ goto reset;
+
+ /* Has the page moved or been split? */
+ if (unlikely(page != xas_reload(xas))) {
+ put_page(page);
+ goto reset;
+ }
+ VM_BUG_ON_PAGE(!thp_contains(page, xas->xa_index), page);
+
+ return page;
+reset:
+ xas_reset(xas);
+ goto retry;
+}
+
/**
* find_get_entries - gang pagecache lookup
* @mapping: The address_space to search
@@ -1868,42 +1905,21 @@ unsigned find_get_entries(struct address
return 0;
rcu_read_lock();
- xas_for_each(&xas, page, ULONG_MAX) {
- if (xas_retry(&xas, page))
- continue;
- /*
- * A shadow entry of a recently evicted page, a swap
- * entry from shmem/tmpfs or a DAX entry. Return it
- * without attempting to raise page count.
- */
- if (xa_is_value(page))
- goto export;
-
- if (!page_cache_get_speculative(page))
- goto retry;
-
- /* Has the page moved or been split? */
- if (unlikely(page != xas_reload(&xas)))
- goto put_page;
-
+ while ((page = find_get_entry(&xas, ULONG_MAX, XA_PRESENT))) {
/*
* Terminate early on finding a THP, to allow the caller to
* handle it all at once; but continue if this is hugetlbfs.
*/
- if (PageTransHuge(page) && !PageHuge(page)) {
+ if (!xa_is_value(page) && PageTransHuge(page) &&
+ !PageHuge(page)) {
page = find_subpage(page, xas.xa_index);
nr_entries = ret + 1;
}
-export:
+
indices[ret] = xas.xa_index;
entries[ret] = page;
if (++ret == nr_entries)
break;
- continue;
-put_page:
- put_page(page);
-retry:
- xas_reset(&xas);
}
rcu_read_unlock();
return ret;
@@ -1942,30 +1958,16 @@ unsigned find_get_pages_range(struct add
return 0;
rcu_read_lock();
- xas_for_each(&xas, page, end) {
- if (xas_retry(&xas, page))
- continue;
+ while ((page = find_get_entry(&xas, end, XA_PRESENT))) {
/* Skip over shadow, swap and DAX entries */
if (xa_is_value(page))
continue;
- if (!page_cache_get_speculative(page))
- goto retry;
-
- /* Has the page moved or been split? */
- if (unlikely(page != xas_reload(&xas)))
- goto put_page;
-
pages[ret] = find_subpage(page, xas.xa_index);
if (++ret == nr_pages) {
*start = xas.xa_index + 1;
goto out;
}
- continue;
-put_page:
- put_page(page);
-retry:
- xas_reset(&xas);
}
/*
@@ -2065,9 +2067,7 @@ unsigned find_get_pages_range_tag(struct
return 0;
rcu_read_lock();
- xas_for_each_marked(&xas, page, end, tag) {
- if (xas_retry(&xas, page))
- continue;
+ while ((page = find_get_entry(&xas, end, tag))) {
/*
* Shadow entries should never be tagged, but this iteration
* is lockless so there is a window for page reclaim to evict
@@ -2076,23 +2076,11 @@ unsigned find_get_pages_range_tag(struct
if (xa_is_value(page))
continue;
- if (!page_cache_get_speculative(page))
- goto retry;
-
- /* Has the page moved or been split? */
- if (unlikely(page != xas_reload(&xas)))
- goto put_page;
-
pages[ret] = page;
if (++ret == nr_pages) {
*index = page->index + thp_nr_pages(page);
goto out;
}
- continue;
-put_page:
- put_page(page);
-retry:
- xas_reset(&xas);
}
/*
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
mm-fix-readahead_page_batch-for-retry-entries.patch
mm-fix-madvise-willneed-performance-problem.patch
mm-page-flags-fix-comment.patch
mm-page_alloc-add-__free_pages-documentation.patch
mm-make-pagecache-tagged-lookups-return-only-head-pages.patch
mm-shmem-use-pagevec_lookup-in-shmem_unlock_mapping.patch
mm-swap-optimise-get_shadow_from_swap_cache.patch
mm-add-fgp_entry.patch
mm-filemap-rename-find_get_entry-to-mapping_get_entry.patch
mm-filemap-add-helper-for-finding-pages.patch
mm-filemap-add-mapping_seek_hole_data.patch
iomap-use-mapping_seek_hole_data.patch
mm-add-and-use-find_lock_entries.patch
mm-add-an-end-parameter-to-find_get_entries.patch
mm-add-an-end-parameter-to-pagevec_lookup_entries.patch
mm-remove-nr_entries-parameter-from-pagevec_lookup_entries.patch
mm-pass-pvec-directly-to-find_get_entries.patch
mm-remove-pagevec_lookup_entries.patch
mm-truncateshmem-handle-truncates-that-split-thps.patch
mm-filemap-return-only-head-pages-from-find_get_entries.patch
mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix.patch
