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From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
To: akpm@linux-foundation.org
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
	Jeff Layton <jlayton@kernel.org>
Subject: [PATCH v10 11/33] mm: Handle per-folio private data
Date: Tue, 11 May 2021 22:47:13 +0100	[thread overview]
Message-ID: <20210511214735.1836149-12-willy@infradead.org> (raw)
In-Reply-To: <20210511214735.1836149-1-willy@infradead.org>

Add folio_get_private() which mirrors page_private() -- ie folio private
data is the same as page private data.  The only difference is that these
return a void * instead of an unsigned long, which matches the majority
of users.

Turn attach_page_private() into folio_attach_private() and reimplement
attach_page_private() as a wrapper.  No filesystem which uses page private
data currently supports compound pages, so we're free to define the rules.
attach_page_private() may only be called on a head page; if you want
to add private data to a tail page, you can call set_page_private()
directly (and shouldn't increment the page refcount!  That should be
done when adding private data to the head page / folio).

This saves 597 bytes of text with the distro-derived config that I'm
testing due to removing the calls to compound_head() in get_page()
& put_page().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
---
 include/linux/mm_types.h | 11 +++++++++
 include/linux/pagemap.h  | 48 ++++++++++++++++++++++++----------------
 2 files changed, 40 insertions(+), 19 deletions(-)

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 3118ba8b5a4e..943854268986 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -302,6 +302,12 @@ static inline atomic_t *compound_pincount_ptr(struct page *page)
 #define PAGE_FRAG_CACHE_MAX_SIZE	__ALIGN_MASK(32768, ~PAGE_MASK)
 #define PAGE_FRAG_CACHE_MAX_ORDER	get_order(PAGE_FRAG_CACHE_MAX_SIZE)
 
+/*
+ * page_private can be used on tail pages.  However, PagePrivate is only
+ * checked by the VM on the head page.  So page_private on the tail pages
+ * should be used for data that's ancillary to the head page (eg attaching
+ * buffer heads to tail pages after attaching buffer heads to the head page)
+ */
 #define page_private(page)		((page)->private)
 
 static inline void set_page_private(struct page *page, unsigned long private)
@@ -309,6 +315,11 @@ static inline void set_page_private(struct page *page, unsigned long private)
 	page->private = private;
 }
 
+static inline void *folio_get_private(struct folio *folio)
+{
+	return folio->private;
+}
+
 struct page_frag_cache {
 	void * va;
 #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 4900e64c880d..bc5fa3d7204e 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -184,42 +184,52 @@ static inline bool page_cache_get_speculative(struct page *page)
 }
 
 /**
- * attach_page_private - Attach private data to a page.
- * @page: Page to attach data to.
- * @data: Data to attach to page.
+ * folio_attach_private - Attach private data to a folio.
+ * @folio: Folio to attach data to.
+ * @data: Data to attach to folio.
  *
- * Attaching private data to a page increments the page's reference count.
- * The data must be detached before the page will be freed.
+ * Attaching private data to a folio increments the page's reference count.
+ * The data must be detached before the folio will be freed.
  */
-static inline void attach_page_private(struct page *page, void *data)
+static inline void folio_attach_private(struct folio *folio, void *data)
 {
-	get_page(page);
-	set_page_private(page, (unsigned long)data);
-	SetPagePrivate(page);
+	folio_get(folio);
+	folio->private = data;
+	folio_set_private_flag(folio);
 }
 
 /**
- * detach_page_private - Detach private data from a page.
- * @page: Page to detach data from.
+ * folio_detach_private - Detach private data from a folio.
+ * @folio: Folio to detach data from.
  *
- * Removes the data that was previously attached to the page and decrements
+ * Removes the data that was previously attached to the folio and decrements
  * the refcount on the page.
  *
- * Return: Data that was attached to the page.
+ * Return: Data that was attached to the folio.
  */
-static inline void *detach_page_private(struct page *page)
+static inline void *folio_detach_private(struct folio *folio)
 {
-	void *data = (void *)page_private(page);
+	void *data = folio_get_private(folio);
 
-	if (!PagePrivate(page))
+	if (!folio_private(folio))
 		return NULL;
-	ClearPagePrivate(page);
-	set_page_private(page, 0);
-	put_page(page);
+	folio_clear_private_flag(folio);
+	folio->private = NULL;
+	folio_put(folio);
 
 	return data;
 }
 
+static inline void attach_page_private(struct page *page, void *data)
+{
+	folio_attach_private(page_folio(page), data);
+}
+
+static inline void *detach_page_private(struct page *page)
+{
+	return folio_detach_private(page_folio(page));
+}
+
 #ifdef CONFIG_NUMA
 extern struct page *__page_cache_alloc(gfp_t gfp);
 #else
-- 
2.30.2


  parent reply	other threads:[~2021-05-11 21:55 UTC|newest]

Thread overview: 96+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-11 21:47 [PATCH v10 00/33] Memory folios Matthew Wilcox (Oracle)
2021-05-11 21:47 ` [PATCH v10 01/33] mm: Introduce struct folio Matthew Wilcox (Oracle)
2021-05-14 10:34   ` Vlastimil Babka
2021-05-14 10:40   ` Vlastimil Babka
2021-05-14 11:47     ` Matthew Wilcox
2021-05-15 10:55   ` William Kucharski
2021-05-15 20:14     ` Matthew Wilcox
2021-05-16 19:26       ` William Kucharski
2021-05-27  8:09   ` Christoph Hellwig
2021-05-11 21:47 ` [PATCH v10 02/33] mm: Add folio_pgdat and folio_zone Matthew Wilcox (Oracle)
2021-05-14 10:35   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 03/33] mm/vmstat: Add functions to account folio statistics Matthew Wilcox (Oracle)
2021-05-14 10:36   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 04/33] mm/debug: Add VM_BUG_ON_FOLIO and VM_WARN_ON_ONCE_FOLIO Matthew Wilcox (Oracle)
2021-05-14 10:44   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 05/33] mm: Add folio reference count functions Matthew Wilcox (Oracle)
2021-05-14 11:04   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 06/33] mm: Add folio_put Matthew Wilcox (Oracle)
2021-05-14 11:52   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 07/33] mm: Add folio_get Matthew Wilcox (Oracle)
2021-05-14 11:56   ` Vlastimil Babka
2021-05-14 14:24     ` Matthew Wilcox
2021-05-14 15:39       ` Vlastimil Babka
2021-05-27  8:10       ` Christoph Hellwig
2021-05-27 22:53         ` Andrew Morton
2021-05-11 21:47 ` [PATCH v10 08/33] mm: Add folio_try_get_rcu Matthew Wilcox (Oracle)
2021-05-14 12:11   ` Vlastimil Babka
2021-05-27  8:16   ` Christoph Hellwig
2021-06-05  4:26     ` Matthew Wilcox
2021-06-06 14:13       ` Christoph Hellwig
2021-05-11 21:47 ` [PATCH v10 09/33] mm: Add folio flag manipulation functions Matthew Wilcox (Oracle)
2021-05-14 15:29   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 10/33] mm: Add folio_young and folio_idle Matthew Wilcox (Oracle)
2021-05-14 15:33   ` Vlastimil Babka
2021-05-27  8:17   ` Christoph Hellwig
2021-05-11 21:47 ` Matthew Wilcox (Oracle) [this message]
2021-05-14 15:41   ` [PATCH v10 11/33] mm: Handle per-folio private data Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 12/33] mm/filemap: Add folio_index, folio_file_page and folio_contains Matthew Wilcox (Oracle)
2021-05-14 15:55   ` Vlastimil Babka
2021-05-15 15:51     ` Matthew Wilcox
2021-05-11 21:47 ` [PATCH v10 13/33] mm/filemap: Add folio_next_index Matthew Wilcox (Oracle)
2021-05-14 17:07   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 14/33] mm/filemap: Add folio_offset and folio_file_offset Matthew Wilcox (Oracle)
2021-05-14 17:08   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 15/33] mm/util: Add folio_mapping and folio_file_mapping Matthew Wilcox (Oracle)
2021-05-14 17:29   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 16/33] mm: Add folio_mapcount Matthew Wilcox (Oracle)
2021-05-14 17:39   ` Vlastimil Babka
2021-05-18 18:45   ` Matthew Wilcox
2021-05-11 21:47 ` [PATCH v10 17/33] mm/memcg: Add folio wrappers for various functions Matthew Wilcox (Oracle)
2021-05-18  9:57   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 18/33] mm/filemap: Add folio_unlock Matthew Wilcox (Oracle)
2021-05-18 10:06   ` Vlastimil Babka
2021-05-18 11:30     ` Matthew Wilcox
2021-05-11 21:47 ` [PATCH v10 19/33] mm/filemap: Add folio_lock Matthew Wilcox (Oracle)
2021-05-18 10:26   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 20/33] mm/filemap: Add folio_lock_killable Matthew Wilcox (Oracle)
2021-05-18 10:31   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 21/33] mm/filemap: Add __folio_lock_async Matthew Wilcox (Oracle)
2021-05-18 10:34   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 22/33] mm/filemap: Add __folio_lock_or_retry Matthew Wilcox (Oracle)
2021-05-18 10:38   ` Vlastimil Babka
2021-05-18 10:45     ` Vlastimil Babka
2021-05-18 13:35     ` Matthew Wilcox
2021-05-11 21:47 ` [PATCH v10 23/33] mm/filemap: Add folio_wait_locked Matthew Wilcox (Oracle)
2021-05-18 10:41   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 24/33] mm/swap: Add folio_rotate_reclaimable Matthew Wilcox (Oracle)
2021-05-18 10:48   ` Vlastimil Babka
2021-05-27  8:19   ` Christoph Hellwig
2021-05-11 21:47 ` [PATCH v10 25/33] mm/filemap: Add folio_end_writeback Matthew Wilcox (Oracle)
2021-05-18 11:08   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 26/33] mm/writeback: Add folio_wait_writeback Matthew Wilcox (Oracle)
2021-05-18 11:12   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 27/33] mm/writeback: Add folio_wait_stable Matthew Wilcox (Oracle)
2021-05-18 11:42   ` Vlastimil Babka
2021-05-18 13:55     ` Matthew Wilcox
2021-05-11 21:47 ` [PATCH v10 28/33] mm/filemap: Add folio_wait_bit Matthew Wilcox (Oracle)
2021-05-18 11:51   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 29/33] mm/filemap: Add folio_wake_bit Matthew Wilcox (Oracle)
2021-05-18 11:53   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 30/33] mm/filemap: Convert page wait queues to be folios Matthew Wilcox (Oracle)
2021-05-18 12:23   ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 31/33] mm/filemap: Add folio private_2 functions Matthew Wilcox (Oracle)
2021-05-18 12:26   ` Vlastimil Babka
2021-05-27  8:21   ` Christoph Hellwig
2021-05-11 21:47 ` [PATCH v10 32/33] fs/netfs: Add folio fscache functions Matthew Wilcox (Oracle)
2021-05-18 13:48   ` Vlastimil Babka
2021-05-27  8:23   ` Christoph Hellwig
2021-05-11 21:47 ` [PATCH v10 33/33] mm: Add folio_mapped Matthew Wilcox (Oracle)
2021-05-18 14:17   ` Vlastimil Babka
2021-05-27  8:31   ` Christoph Hellwig
2021-05-13 14:50 ` [PATCH v10 00/33] Memory folios Matthew Wilcox
2021-05-15 10:26 ` William Kucharski
2021-06-04  1:07 ` Matteo Croce
2021-06-04  2:13   ` Matthew Wilcox
2021-06-08 14:56     ` Matteo Croce

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