[Ocfs2-devel] [PATCH] ocfs2: lock the page in __ocfs2_page_mkwrite()
Joel Becker
Joel.Becker at oracle.com
Wed Nov 17 15:21:49 PST 2010
On Fri, Nov 05, 2010 at 12:53:16PM +0800, Wengang Wang wrote:
Here's review based on the assumption we need this change.
> @@ -1097,6 +1097,7 @@ static int ocfs2_grab_pages_for_write(struct address_space *mapping,
> unsigned long start, target_index, end_index, index;
> struct inode *inode = mapping->host;
> loff_t last_byte;
> + int lockpg= !PageLocked(mmap_page);
This change is not necessary. If mmap_page exists, it came from
__ocfs2_page_mkwrite(), where you've locked it, so you know it is
locked.
>
> target_index = user_pos >> PAGE_CACHE_SHIFT;
>
> @@ -1133,11 +1134,15 @@ static int ocfs2_grab_pages_for_write(struct address_space *mapping,
> * ocfs2_pagemkwrite() is a little different
> * and wants us to directly use the page
> * passed in.
> + * in ocfs2_page_mkwirte() path, the page is already
> + * locked, don't lock it again.
> */
> - lock_page(mmap_page);
> + if (lockpg)
> + lock_page(mmap_page);
This block is only accessed when mmap_page is not NULL. Thus
the page must exist and must be locked (as stated above). You should
just BUG_ON(!PageLocked(mmap_page)) here.
Joel
--
"I think it would be a good idea."
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Joel Becker
Senior Development Manager
Oracle
E-mail: joel.becker at oracle.com
Phone: (650) 506-8127
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