linux-kernel - Re: [patch 68/85] fs: symlink write

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Date:	Thu, 15 Jan 2009 14:31:17 -0800
From:	Greg KH <greg@...ah.com>
To:	Nick Piggin <npiggin@...e.de>
Cc:	linux-kernel@...r.kernel.org, stable@...nel.org,
	Justin Forbes <jmforbes@...uxtx.org>,
	Zwane Mwaikambo <zwane@....linux.org.uk>,
	Theodore Ts'o <tytso@....edu>,
	Randy Dunlap <rdunlap@...otime.net>,
	Dave Jones <davej@...hat.com>,
	Chuck Wolber <chuckw@...ntumlinux.com>,
	Chris Wedgwood <reviews@...cw.f00f.org>,
	Michael Krufky <mkrufky@...uxtv.org>,
	Chuck Ebbert <cebbert@...hat.com>,
	Domenico Andreoli <cavokz@...il.com>, Willy Tarreau <w@....eu>,
	Rodrigo Rubira Branco <rbranco@...checkpoint.com>,
	Jake Edge <jake@....net>, Eugene Teo <eteo@...hat.com>,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Nick Piggin <npiggin@...e.de>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Subject: Re: [patch 68/85] fs: symlink write_begin allocation context fix

On Thu, Jan 15, 2009 at 02:01:36PM -0800, Greg KH wrote:
> 2.6.27-stable review patch.  If anyone has any objections, please let us know.

Hm, I think I got the backport of this patch wrong in two place:

> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -2033,7 +2033,7 @@ int pagecache_write_begin(struct file *f
>  		struct inode *inode = mapping->host;
>  		struct page *page;
>  again:
> -		page = __grab_cache_page(mapping, index);
> +		page = grab_cache_page_write_begin(mapping, index, flags);

I think this shouldn't be "flags", but 0, right?

>  		*pagep = page;
>  		if (!page)
>  			return -ENOMEM;
> @@ -2197,19 +2197,24 @@ EXPORT_SYMBOL(generic_file_direct_write)
>   * Find or create a page at the given pagecache position. Return the locked
>   * page. This function is specifically for buffered writes.
>   */
> -struct page *__grab_cache_page(struct address_space *mapping, pgoff_t index)
> +struct page *grab_cache_page_write_begin(struct address_space *mapping,
> +					pgoff_t index, unsigned flags)
>  {
>  	int status;
>  	struct page *page;
> +	gfp_t gfp_notmask = 0;
> +	if (flags & AOP_FLAG_NOFS)
> +		gfp_notmask = __GFP_FS;
>  repeat:
>  	page = find_lock_page(mapping, index);
>  	if (likely(page))
>  		return page;
>  
> -	page = page_cache_alloc(mapping);
> +	page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~gfp_notmask);
>  	if (!page)
>  		return NULL;
> -	status = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL);
> +	status = add_to_page_cache_lru(page, mapping, index,
> +						GFP_KERNEL & ~gfp_notmask);
>  	if (unlikely(status)) {
>  		page_cache_release(page);
>  		if (status == -EEXIST)
> @@ -2218,7 +2223,7 @@ repeat:
>  	}
>  	return page;
>  }
> -EXPORT_SYMBOL(__grab_cache_page);
> +EXPORT_SYMBOL(grab_cache_page_write_begin);
>  
>  static ssize_t generic_perform_write_2copy(struct file *file,
>  				struct iov_iter *i, loff_t pos)
> @@ -2263,7 +2268,7 @@ static ssize_t generic_perform_write_2co
>  			break;
>  		}
>  
> -		page = __grab_cache_page(mapping, index);
> +		page = grab_cache_page_write_begin(mapping, index, GFP_KERNEL);

And this one?  Is GFP_KERNEL ok, or 0?

Nick, your thoughts?

greg "i'm no mm hacker" k-h
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