Commit a19672f6 authored by David Howells's avatar David Howells
Browse files

folio: Add a function to change the private data attached to a folio 



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: default avatarDavid Howells <dhowells@redhat.com>
Reviewed-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Tested-by: default avatarJeff Layton <jlayton@kernel.org>
Tested-by: default avatarDominique Martinet <asmadeus@codewreck.org>
Tested-by: default avatar <kafs-testing@auristor.com>
Link: https://lore.kernel.org/r/162981149911.1901565.17776700811659843340.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/163005743485.2472992.5100702469503007023.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163584180781.4023316.5037526301198034310.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/163649324326.309189.17817587229450840783.stgit@warthog.procyon.org.uk/ # v4
Link: https://lore.kernel.org/r/163657848531.834781.14269656212269187893.stgit@warthog.procyon.org.uk/ # v5
parent f89ce84b

include/linux/pagemap.h

+19 −0
Original line number Diff line number Diff line
@@ -279,6 +279,25 @@ 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.