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Date: Wed, 16 Dec 2020 18:23:23 +0000
From: "Matthew Wilcox (Oracle)" <willy@...radead.org>
To: linux-fsdevel@...r.kernel.org, linux-mm@...ck.org
Cc: "Matthew Wilcox (Oracle)" <willy@...radead.org>,
linux-kernel@...r.kernel.org
Subject: [PATCH 13/25] mm: Add filemap_get_folio and find_get_folio
Turn pagecache_get_page() into a wrapper around filemap_get_folio().
Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
---
include/linux/pagemap.h | 21 +++++-
mm/filemap.c | 141 +++++++++++++++++++++-------------------
2 files changed, 94 insertions(+), 68 deletions(-)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 317f17e98412..2c2974970467 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -317,8 +317,10 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping,
#define FGP_HEAD 0x00000080
#define FGP_ENTRY 0x00000100
-struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
- int fgp_flags, gfp_t cache_gfp_mask);
+struct folio *filemap_get_folio(struct address_space *mapping, pgoff_t index,
+ int fgp_flags, gfp_t gfp);
+struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
+ int fgp_flags, gfp_t gfp);
/**
* find_get_page - find and get a page reference
@@ -336,6 +338,12 @@ static inline struct page *find_get_page(struct address_space *mapping,
return pagecache_get_page(mapping, offset, 0, 0);
}
+static inline struct folio *find_get_folio(struct address_space *mapping,
+ pgoff_t index)
+{
+ return filemap_get_folio(mapping, index, 0, 0);
+}
+
static inline struct page *find_get_page_flags(struct address_space *mapping,
pgoff_t offset, int fgp_flags)
{
@@ -451,6 +459,15 @@ static inline struct page *folio_page(struct folio *folio, pgoff_t index)
return &folio->page + index;
}
+/* Does this folio contain this index? */
+static inline bool folio_contains(struct folio *folio, pgoff_t index)
+{
+ /* HugeTLBfs indexes the page cache in units of hpage_size */
+ if (PageHuge(&folio->page))
+ return folio->page.index == index;
+ return index - folio_index(folio) < folio_nr_pages(folio);
+}
+
/*
* Given the page we found in the page cache, return the page corresponding
* to this index in the file
diff --git a/mm/filemap.c b/mm/filemap.c
index b9f25a2d8312..7ed9e3dcefc8 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1717,94 +1717,58 @@ static struct folio *mapping_get_entry(struct address_space *mapping,
return folio;
}
-/**
- * pagecache_get_page - Find and get a reference to a page.
- * @mapping: The address_space to search.
- * @index: The page index.
- * @fgp_flags: %FGP flags modify how the page is returned.
- * @gfp_mask: Memory allocation flags to use if %FGP_CREAT is specified.
- *
- * Looks up the page cache entry at @mapping & @index.
- *
- * @fgp_flags can be zero or more of these flags:
- *
- * * %FGP_ACCESSED - The page will be marked accessed.
- * * %FGP_LOCK - The page is returned locked.
- * * %FGP_HEAD - If the page is present and a THP, return the head page
- * rather than the exact page specified by the index.
- * * %FGP_ENTRY - If there is a shadow / swap / DAX entry, return it
- * instead of allocating a new page to replace it.
- * * %FGP_CREAT - If no page is present then a new page is allocated using
- * @gfp_mask and added to the page cache and the VM's LRU list.
- * The page is returned locked and with an increased refcount.
- * * %FGP_FOR_MMAP - The caller wants to do its own locking dance if the
- * page is already in cache. If the page was allocated, unlock it before
- * returning so the caller can do the same dance.
- * * %FGP_WRITE - The page will be written
- * * %FGP_NOFS - __GFP_FS will get cleared in gfp mask
- * * %FGP_NOWAIT - Don't get blocked by page lock
- *
- * If %FGP_LOCK or %FGP_CREAT are specified then the function may sleep even
- * if the %GFP flags specified for %FGP_CREAT are atomic.
- *
- * If there is a page cache page, it is returned with an increased refcount.
- *
- * Return: The found page or %NULL otherwise.
- */
-struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
- int fgp_flags, gfp_t gfp_mask)
+struct folio *filemap_get_folio(struct address_space *mapping, pgoff_t index,
+ int fgp_flags, gfp_t gfp)
{
- struct page *page;
+ struct folio *folio;
repeat:
- page = &mapping_get_entry(mapping, index)->page;
- if (xa_is_value(page)) {
+ folio = mapping_get_entry(mapping, index);
+ if (xa_is_value(folio)) {
if (fgp_flags & FGP_ENTRY)
- return page;
- page = NULL;
+ return folio;
+ folio = NULL;
}
- if (!page)
+ if (!folio)
goto no_page;
if (fgp_flags & FGP_LOCK) {
if (fgp_flags & FGP_NOWAIT) {
- if (!trylock_page(page)) {
- put_page(page);
+ if (!trylock_folio(folio)) {
+ put_folio(folio);
return NULL;
}
} else {
- lock_page(page);
+ lock_folio(folio);
}
/* Has the page been truncated? */
- if (unlikely(page->mapping != mapping)) {
- unlock_page(page);
- put_page(page);
+ if (unlikely(folio->page.mapping != mapping)) {
+ unlock_folio(folio);
+ put_folio(folio);
goto repeat;
}
- VM_BUG_ON_PAGE(!thp_contains(page, index), page);
+ VM_BUG_ON_PAGE(!folio_contains(folio, index), &folio->page);
}
if (fgp_flags & FGP_ACCESSED)
- mark_page_accessed(page);
+ mark_folio_accessed(folio);
else if (fgp_flags & FGP_WRITE) {
/* Clear idle flag for buffer write */
- if (page_is_idle(page))
- clear_page_idle(page);
+ if (page_is_idle(&folio->page))
+ clear_page_idle(&folio->page);
}
- if (!(fgp_flags & FGP_HEAD))
- page = find_subpage(page, index);
no_page:
- if (!page && (fgp_flags & FGP_CREAT)) {
+ if (!folio && (fgp_flags & FGP_CREAT)) {
int err;
if ((fgp_flags & FGP_WRITE) && mapping_can_writeback(mapping))
- gfp_mask |= __GFP_WRITE;
+ gfp |= __GFP_WRITE;
if (fgp_flags & FGP_NOFS)
- gfp_mask &= ~__GFP_FS;
+ gfp &= ~__GFP_FS;
- page = &__page_cache_alloc(gfp_mask, 0)->page;
- if (!page)
+ folio = __page_cache_alloc(gfp, 0);
+ if (!folio)
return NULL;
if (WARN_ON_ONCE(!(fgp_flags & (FGP_LOCK | FGP_FOR_MMAP))))
@@ -1812,12 +1776,12 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
/* Init accessed so avoid atomic mark_page_accessed later */
if (fgp_flags & FGP_ACCESSED)
- __SetPageReferenced(page);
+ __SetFolioReferenced(folio);
- err = add_to_page_cache_lru(page, mapping, index, gfp_mask);
+ err = add_to_page_cache_lru(&folio->page, mapping, index, gfp);
if (unlikely(err)) {
- put_page(page);
- page = NULL;
+ put_folio(folio);
+ folio = NULL;
if (err == -EEXIST)
goto repeat;
}
@@ -1826,11 +1790,56 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
* add_to_page_cache_lru locks the page, and for mmap we expect
* an unlocked page.
*/
- if (page && (fgp_flags & FGP_FOR_MMAP))
- unlock_page(page);
+ if (folio && (fgp_flags & FGP_FOR_MMAP))
+ unlock_folio(folio);
}
- return page;
+ return folio;
+}
+EXPORT_SYMBOL(filemap_get_folio);
+
+/**
+ * pagecache_get_page - Find and get a reference to a page.
+ * @mapping: The address_space to search.
+ * @index: The page index.
+ * @fgp_flags: %FGP flags modify how the page is returned.
+ * @gfp: Memory allocation flags to use if %FGP_CREAT is specified.
+ *
+ * Looks up the page cache entry at @mapping & @index.
+ *
+ * @fgp_flags can be zero or more of these flags:
+ *
+ * * %FGP_ACCESSED - The page will be marked accessed.
+ * * %FGP_LOCK - The page is returned locked.
+ * * %FGP_HEAD - If the page is present and a THP, return the head page
+ * rather than the exact page specified by the index.
+ * * %FGP_ENTRY - If there is a shadow / swap / DAX entry, return it
+ * instead of allocating a new page to replace it.
+ * * %FGP_CREAT - If no page is present then a new page is allocated using
+ * @gfp_mask and added to the page cache and the VM's LRU list.
+ * The page is returned locked and with an increased refcount.
+ * * %FGP_FOR_MMAP - The caller wants to do its own locking dance if the
+ * page is already in cache. If the page was allocated, unlock it before
+ * returning so the caller can do the same dance.
+ * * %FGP_WRITE - The page will be written
+ * * %FGP_NOFS - __GFP_FS will get cleared in gfp mask
+ * * %FGP_NOWAIT - Don't get blocked by page lock
+ *
+ * If %FGP_LOCK or %FGP_CREAT are specified then the function may sleep even
+ * if the %GFP flags specified for %FGP_CREAT are atomic.
+ *
+ * If there is a page cache page, it is returned with an increased refcount.
+ *
+ * Return: The found page or %NULL otherwise.
+ */
+struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
+ int fgp_flags, gfp_t gfp)
+{
+ struct folio *folio = filemap_get_folio(mapping, index, fgp_flags, gfp);
+
+ if ((fgp_flags & FGP_HEAD) || !folio || xa_is_value(folio))
+ return &folio->page;
+ return folio_page(folio, index);
}
EXPORT_SYMBOL(pagecache_get_page);
--
2.29.2
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