Re: [PATCH 10/10] mm/migrate.c: call detach_page_private to cleanup code

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 5/19/20 7:12 AM, Andrew Morton wrote:
On Sun, 17 May 2020 23:47:18 +0200 Guoqing Jiang <guoqing.jiang@xxxxxxxxxxxxxxx> wrote:

We can cleanup code a little by call detach_page_private here.

...

--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -804,10 +804,7 @@ static int __buffer_migrate_page(struct address_space *mapping,
  	if (rc != MIGRATEPAGE_SUCCESS)
  		goto unlock_buffers;
- ClearPagePrivate(page);
-	set_page_private(newpage, page_private(page));
-	set_page_private(page, 0);
-	put_page(page);
+	set_page_private(newpage, detach_page_private(page));
  	get_page(newpage);
bh = head;
mm/migrate.c: In function '__buffer_migrate_page':
./include/linux/mm_types.h:243:52: warning: assignment makes integer from pointer without a cast [-Wint-conversion]
  #define set_page_private(page, v) ((page)->private = (v))
                                                     ^
mm/migrate.c:800:2: note: in expansion of macro 'set_page_private'
   set_page_private(newpage, detach_page_private(page));
   ^~~~~~~~~~~~~~~~

The fact that set_page_private(detach_page_private()) generates a type
mismatch warning seems deeply wrong, surely.

Please let's get the types sorted out - either unsigned long or void *,
not half-one and half-the other.  Whatever needs the least typecasting
at callsites, I suggest.

Sorry about that, I should notice the warning before. I will double check if other
places need the typecast or not, then send a new version.

And can we please implement set_page_private() and page_private() with
inlined C code?  There is no need for these to be macros.

Just did a quick change.

-#define page_private(page)             ((page)->private)
-#define set_page_private(page, v)      ((page)->private = (v))
+static inline unsigned long page_private(struct page *page)
+{
+       return page->private;
+}
+
+static inline void set_page_private(struct page *page, unsigned long priv_data)
+{
+       page->private = priv_data;
+}

Then I get error like.

fs/erofs/zdata.h: In function ‘z_erofs_onlinepage_index’:
fs/erofs/zdata.h:126:8: error: lvalue required as unary ‘&’ operand
  u.v = &page_private(page);
        ^

I guess it is better to keep page_private as macro, please correct me in case I
missed something.

Thanks,
Guoqing




[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [Samba]     [Device Mapper]     [CEPH Development]

  Powered by Linux