Re: [PATCH] 9p: add write-cache support to loose cache mode (take 3)

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On 2/16/07, Andrew Morton <[email protected]> wrote:
On Fri, 16 Feb 2007 09:37:01 -0600 Eric Van Hensbergen <[email protected]> wrote:

> +static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc)
> +{
> +     char *buffer = NULL;
> +     struct address_space *mapping = page->mapping;
> +     int retval = -EIO;
> +     loff_t offset = 0;
> +     pgoff_t end_index;
> +     int count = PAGE_CACHE_SIZE;
> +     struct file *filp = v9fs_find_file(page);
> +     struct inode *inode = mapping->host;
> +
> +     dprintk(DEBUG_VFS, "page: %p\n", page);
> +
> +     if ((!inode) || (!filp))
> +             goto UnlockPage;
> +
> +     end_index = inode->i_size >> PAGE_CACHE_SHIFT;
> +
> +     /* complicated case at end of file */
> +     if (page->index >= end_index) {
> +             /* things got complicated... */
> +             count = inode->i_size & (PAGE_CACHE_SIZE - 1);
> +             if (page->index >= end_index + 1 || !count)
> +                     return 0;       /* truncated - don't care */
> +     }
> +
> +     buffer = kmap(page);
> +     offset = ((loff_t) page->index << PAGE_CACHE_SHIFT);
> +     page_cache_get(page);
> +     retval = v9fs_write(filp, NULL, buffer, count, &offset);
> +
>       kunmap(page);
> +
> +      UnlockPage:
>       unlock_page(page);
> +     page_cache_release(page);
> +
>       return retval;
>  }

The page_cache_get/release here aren't needed: lock_page suffices.

Are you sure the page refcounting is right if the `goto UnlockPage'
happens?

Can that goto actually happen??


It shouldn't, if it does we are probably in big trouble anyways.  I'll
pull it out.  Thanks.

                 -eric
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