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From: David Howells <dhowells@redhat.com>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: dhowells@redhat.com, Jeff Layton <jlayton@kernel.org>,
	Ilya Dryomov <idryomov@gmail.com>,
	linux-fsdevel@vger.kernel.org, linux-cachefs@redhat.com,
	linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org,
	linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org,
	v9fs-developer@lists.sourceforge.net, devel@lists.orangefs.org,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2 3/6] folio: Add a function to change the private data attached to a folio
Date: Fri, 27 Aug 2021 10:43:54 +0100	[thread overview]
Message-ID: <163005743485.2472992.5100702469503007023.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <163005740700.2472992.12365214290752300378.stgit@warthog.procyon.org.uk>

Add a function, folio_change_private(), that will change the private data
attached to a folio, without the need to twiddle the private bit or the
refcount.  It assumes that folio_add_private() has already been called on
the page.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/162981149911.1901565.17776700811659843340.stgit@warthog.procyon.org.uk/
---

 include/linux/pagemap.h |   19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index f55d8d9001a9..c8d336e62177 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -229,6 +229,25 @@ static inline void folio_attach_private(struct folio *folio, void *data)
 	folio_set_private(folio);
 }
 
+/**
+ * folio_change_private - Change private data on a folio.
+ * @folio: Folio to change the data on.
+ * @data: Data to set on the folio.
+ *
+ * Change the private data attached to a folio and return the old
+ * data.  The page must previously have had data attached and the data
+ * must be detached before the folio will be freed.
+ *
+ * Return: Data that was previously attached to the folio.
+ */
+static inline void *folio_change_private(struct folio *folio, void *data)
+{
+	void *old = folio_get_private(folio);
+
+	folio->private = data;
+	return old;
+}
+
 /**
  * folio_detach_private - Detach private data from a folio.
  * @folio: Folio to detach data from.



  parent reply	other threads:[~2021-08-27  9:46 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-27  9:43 [PATCH v2 0/6] netfs, afs, ceph: Support folios, at least partially David Howells
2021-08-27  9:43 ` [PATCH v2 1/6] afs: Fix afs_launder_page() to set correct start file position David Howells
2021-08-27  9:43 ` [PATCH v2 2/6] afs: Sort out symlink reading David Howells
2021-08-27  9:43 ` David Howells [this message]
2021-08-27  9:44 ` [PATCH v2 4/6] folio: Add a function to get the host inode for a folio David Howells
2021-08-27  9:44 ` [PATCH v2 5/6] netfs, afs, ceph: Use folios David Howells
2021-09-08 19:06   ` Jeff Layton
2021-08-27  9:44 ` [PATCH v2 6/6] afs: Use folios in directory handling David Howells

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