diff mbox series

[v7,8/8] mm: Renumber FOLL_GET and FOLL_PIN down

Message ID 20230120175556.3556978-9-dhowells@redhat.com (mailing list archive)
State New
Headers show
Series None | expand

Commit Message

David Howells Jan. 20, 2023, 5:55 p.m. UTC 
Renumber FOLL_GET and FOLL_PIN down to bit 0 and 1 respectively so that
they are coincidentally the same as BIO_PAGE_REFFED and BIO_PAGE_PINNED and
also so that they can be stored in the bottom two bits of a page pointer
(something I'm looking at for zerocopy socket fragments).

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: Christoph Hellwig <hch@lst.de>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
---
 include/linux/mm.h | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

Comments

Matthew Wilcox Jan. 20, 2023, 6:59 p.m. UTC | #1 
On Fri, Jan 20, 2023 at 05:55:56PM +0000, David Howells wrote:
> Renumber FOLL_GET and FOLL_PIN down to bit 0 and 1 respectively so that
> they are coincidentally the same as BIO_PAGE_REFFED and BIO_PAGE_PINNED and
> also so that they can be stored in the bottom two bits of a page pointer
> (something I'm looking at for zerocopy socket fragments).
> 
> Signed-off-by: David Howells <dhowells@redhat.com>

Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Although I was hoping you'd renumber some of the others since we
currently have gaps at 0x200, 0x400, 0x1000, and 0x4000 as well
as the 0x40 you're using here.
David Howells Jan. 20, 2023, 7:18 p.m. UTC | #2 
Matthew Wilcox <willy@infradead.org> wrote:

> Although I was hoping you'd renumber some of the others since we
> currently have gaps at 0x200, 0x400, 0x1000, and 0x4000 as well
> as the 0x40 you're using here.

Since the other patches don't require this one, I can renumber them all and
send it directly to Andrew.

David
diff mbox series

Patch

diff --git a/include/linux/mm.h b/include/linux/mm.h
index f1cf8f4eb946..33c9eacd9548 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3074,12 +3074,13 @@  static inline vm_fault_t vmf_error(int err)
 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
 			 unsigned int foll_flags);
 
-#define FOLL_WRITE	0x01	/* check pte is writable */
-#define FOLL_TOUCH	0x02	/* mark page accessed */
-#define FOLL_GET	0x04	/* do get_page on page */
-#define FOLL_DUMP	0x08	/* give error on hole if it would be zero */
-#define FOLL_FORCE	0x10	/* get_user_pages read/write w/o permission */
-#define FOLL_NOWAIT	0x20	/* if a disk transfer is needed, start the IO
+#define FOLL_GET	0x01	/* do get_page on page (equivalent to BIO_FOLL_GET) */
+#define FOLL_PIN	0x02	/* pages must be released via unpin_user_page */
+#define FOLL_WRITE	0x04	/* check pte is writable */
+#define FOLL_TOUCH	0x08	/* mark page accessed */
+#define FOLL_DUMP	0x10	/* give error on hole if it would be zero */
+#define FOLL_FORCE	0x20	/* get_user_pages read/write w/o permission */
+#define FOLL_NOWAIT	0x40	/* if a disk transfer is needed, start the IO
 				 * and return without waiting upon it */
 #define FOLL_NOFAULT	0x80	/* do not fault in pages */
 #define FOLL_HWPOISON	0x100	/* check page is hwpoisoned */
@@ -3088,7 +3089,6 @@  struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
 #define FOLL_ANON	0x8000	/* don't do file mappings */
 #define FOLL_LONGTERM	0x10000	/* mapping lifetime is indefinite: see below */
 #define FOLL_SPLIT_PMD	0x20000	/* split huge pmd before returning */
-#define FOLL_PIN	0x40000	/* pages must be released via unpin_user_page */
 #define FOLL_FAST_ONLY	0x80000	/* gup_fast: prevent fall-back to slow gup */
 #define FOLL_PCI_P2PDMA	0x100000 /* allow returning PCI P2PDMA pages */
 #define FOLL_INTERRUPTIBLE  0x200000 /* allow interrupts from generic signals */