[PATCH v14 111/138] mm/filemap: Convert find_get_entry to return a folio

Matthew Wilcox (Oracle)
2021-07-15T05:08:31Z

Convert callers to cope. Saves 580 bytes of kernel text; all five
callers are reduced in size.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
mm/filemap.c | 129 +++++++++++++++++++++++++--------------------------
1 file changed, 64 insertions(+), 65 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 4a81eaff363e..c4190c0a6d86 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1907,37 +1907,36 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
}
EXPORT_SYMBOL(__filemap_get_folio);

-static inline struct page *find_get_entry(struct xa_state *xas, pgoff_t max,
+static inline struct folio *find_get_entry(struct xa_state *xas, pgoff_t max,
xa_mark_t mark)
{
- struct page *page;
+ struct folio *folio;

retry:
if (mark == XA_PRESENT)
- page = xas_find(xas, max);
+ folio = xas_find(xas, max);
else
- page = xas_find_marked(xas, max, mark);
+ folio = xas_find_marked(xas, max, mark);

- if (xas_retry(xas, page))
+ if (xas_retry(xas, folio))
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 (!folio || xa_is_value(folio))
+ return folio;

- if (!page_cache_get_speculative(page))
+ if (!folio_try_get_rcu(folio))
goto reset;

- /* Has the page moved or been split? */
- if (unlikely(page != xas_reload(xas))) {
- put_page(page);
+ if (unlikely(folio != xas_reload(xas))) {
+ folio_put(folio);
goto reset;
}

- return page;
+ return folio;
reset:
xas_reset(xas);
goto retry;
@@ -1978,7 +1977,7 @@ unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
unsigned nr_entries = PAGEVEC_SIZE;

rcu_read_lock();
- while ((page = find_get_entry(&xas, end, XA_PRESENT))) {
+ while ((page = &find_get_entry(&xas, end, XA_PRESENT)->page)) {
/*
* Terminate early on finding a THP, to allow the caller to
* handle it all at once; but continue if this is hugetlbfs.
@@ -2025,38 +2024,38 @@ unsigned find_lock_entries(struct address_space *mapping, pgoff_t start,
pgoff_t end, struct pagevec *pvec, pgoff_t *indices)
{
XA_STATE(xas, &mapping->i_pages, start);
- struct page *page;
+ struct folio *folio;

rcu_read_lock();
- while ((page = find_get_entry(&xas, end, XA_PRESENT))) {
- if (!xa_is_value(page)) {
- if (page->index < start)
+ while ((folio = find_get_entry(&xas, end, XA_PRESENT))) {
+ if (!xa_is_value(folio)) {
+ if (folio->index < start)
goto put;
- VM_BUG_ON_PAGE(page->index != xas.xa_index, page);
- if (page->index + thp_nr_pages(page) - 1 > end)
+ VM_BUG_ON_FOLIO(folio->index != xas.xa_index,
+ folio);
+ if (folio->index + folio_nr_pages(folio) - 1 > end)
goto put;
- if (!trylock_page(page))
+ if (!folio_trylock(folio))
goto put;
- if (page->mapping != mapping || PageWriteback(page))
+ if (folio->mapping != mapping ||
+ folio_test_writeback(folio))
goto unlock;
- VM_BUG_ON_PAGE(!thp_contains(page, xas.xa_index),
- page);
+ VM_BUG_ON_FOLIO(!folio_contains(folio, xas.xa_index),
+ folio);
}
indices[pvec->nr] = xas.xa_index;
- if (!pagevec_add(pvec, page))
+ if (!pagevec_add(pvec, &folio->page))
break;
goto next;
unlock:
- unlock_page(page);
+ folio_unlock(folio);
put:
- put_page(page);
+ folio_put(folio);
next:
- if (!xa_is_value(page) && PageTransHuge(page)) {
- unsigned int nr_pages = thp_nr_pages(page);
-
- /* Final THP may cross MAX_LFS_FILESIZE on 32-bit */
- xas_set(&xas, page->index + nr_pages);
- if (xas.xa_index < nr_pages)
+ if (!xa_is_value(folio) && folio_multi(folio)) {
+ xas_set(&xas, folio->index + folio_nr_pages(folio));
+ /* Did we wrap on 32-bit? */
+ if (!xas.xa_index)
break;
}
}
@@ -2091,19 +2090,19 @@ unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
struct page **pages)
{
XA_STATE(xas, &mapping->i_pages, *start);
- struct page *page;
+ struct folio *folio;
unsigned ret = 0;

if (unlikely(!nr_pages))
return 0;

rcu_read_lock();
- while ((page = find_get_entry(&xas, end, XA_PRESENT))) {
+ while ((folio = find_get_entry(&xas, end, XA_PRESENT))) {
/* Skip over shadow, swap and DAX entries */
- if (xa_is_value(page))
+ if (xa_is_value(folio))
continue;

- pages[ret] = find_subpage(page, xas.xa_index);
+ pages[ret] = folio_file_page(folio, xas.xa_index);
if (++ret == nr_pages) {
*start = xas.xa_index + 1;
goto out;
@@ -2200,25 +2199,25 @@ unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
struct page **pages)
{
XA_STATE(xas, &mapping->i_pages, *index);
- struct page *page;
+ struct folio *folio;
unsigned ret = 0;

if (unlikely(!nr_pages))
return 0;

rcu_read_lock();
- while ((page = find_get_entry(&xas, end, tag))) {
+ while ((folio = 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
* a page we saw tagged. Skip over it.
*/
- if (xa_is_value(page))
+ if (xa_is_value(folio))
continue;

- pages[ret] = page;
+ pages[ret] = &folio->page;
if (++ret == nr_pages) {
- *index = page->index + thp_nr_pages(page);
+ *index = folio->index + folio_nr_pages(folio);
goto out;
}
}
@@ -2697,44 +2696,44 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
}
EXPORT_SYMBOL(generic_file_read_iter);

-static inline loff_t page_seek_hole_data(struct xa_state *xas,
- struct address_space *mapping, struct page *page,
+static inline loff_t folio_seek_hole_data(struct xa_state *xas,
+ struct address_space *mapping, struct folio *folio,
loff_t start, loff_t end, bool seek_data)
{
const struct address_space_operations *ops = mapping->a_ops;
size_t offset, bsz = i_blocksize(mapping->host);

- if (xa_is_value(page) || PageUptodate(page))
+ if (xa_is_value(folio) || folio_test_uptodate(folio))
return seek_data ? start : end;
if (!ops->is_partially_uptodate)
return seek_data ? end : start;

xas_pause(xas);
rcu_read_unlock();
- lock_page(page);
- if (unlikely(page->mapping != mapping))
+ folio_lock(folio);
+ if (unlikely(folio->mapping != mapping))
goto unlock;

- offset = offset_in_thp(page, start) & ~(bsz - 1);
+ offset = offset_in_folio(folio, start) & ~(bsz - 1);

do {
- if (ops->is_partially_uptodate(page, offset, bsz) == seek_data)
+ if (ops->is_partially_uptodate(&folio->page, offset, bsz) ==
+ seek_data)
break;
start = (start + bsz) & ~(bsz - 1);
offset += bsz;
- } while (offset < thp_size(page));
+ } while (offset < folio_size(folio));
unlock:
- unlock_page(page);
+ folio_unlock(folio);
rcu_read_lock();
return start;
}

-static inline
-unsigned int seek_page_size(struct xa_state *xas, struct page *page)
+static inline size_t seek_folio_size(struct xa_state *xas, struct folio *folio)
{
- if (xa_is_value(page))
+ if (xa_is_value(folio))
return PAGE_SIZE << xa_get_order(xas->xa, xas->xa_index);
- return thp_size(page);
+ return folio_size(folio);
}

/**
@@ -2761,15 +2760,15 @@ loff_t mapping_seek_hole_data(struct address_space *mapping, loff_t start,
XA_STATE(xas, &mapping->i_pages, start >> PAGE_SHIFT);
pgoff_t max = (end - 1) >> PAGE_SHIFT;
bool seek_data = (whence == SEEK_DATA);
- struct page *page;
+ struct folio *folio;

if (end <= start)
return -ENXIO;

rcu_read_lock();
- while ((page = find_get_entry(&xas, max, XA_PRESENT))) {
- loff_t pos = (u64)xas.xa_index << PAGE_SHIFT;
- unsigned int seek_size;
+ while ((folio = find_get_entry(&xas, max, XA_PRESENT))) {
+ loff_t pos = xas.xa_index * PAGE_SIZE;
+ size_t seek_size;

if (start < pos) {
if (!seek_data)
@@ -2777,9 +2776,9 @@ loff_t mapping_seek_hole_data(struct address_space *mapping, loff_t start,
start = pos;
}

- seek_size = seek_page_size(&xas, page);
- pos = round_up(pos + 1, seek_size);
- start = page_seek_hole_data(&xas, mapping, page, start, pos,
+ seek_size = seek_folio_size(&xas, folio);
+ pos = round_up((u64)pos + 1, seek_size);
+ start = folio_seek_hole_data(&xas, mapping, folio, start, pos,
seek_data);
if (start < pos)
goto unlock;
@@ -2787,15 +2786,15 @@ loff_t mapping_seek_hole_data(struct address_space *mapping, loff_t start,
break;
if (seek_size > PAGE_SIZE)
xas_set(&xas, pos >> PAGE_SHIFT);
- if (!xa_is_value(page))
- put_page(page);
+ if (!xa_is_value(folio))
+ folio_put(folio);
}
if (seek_data)
start = -ENXIO;
unlock:
rcu_read_unlock();
- if (page && !xa_is_value(page))
- put_page(page);
+ if (folio && !xa_is_value(folio))
+ folio_put(folio);
if (start > end)
return end;
return start;
--
2.30.2