linux-kernel - Re: [PATCH] jfs: clear PAGECACHE_TAG

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Message-Id: <E1J8RJw-0001ge-DP@localhost>
Date:	Sat, 29 Dec 2007 10:21:04 +0800
From:	Fengguang Wu <wfg@...l.ustc.edu.cn>
To:	Dave Kleikamp <shaggy@...ux.vnet.ibm.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	jfs-discussion@...ts.sourceforge.net,
	Nick Piggin <nickpiggin@...oo.com.au>
Subject: Re: [PATCH] jfs: clear PAGECACHE_TAG_DIRTY for no-write pages

On Fri, Dec 28, 2007 at 10:53:14AM -0600, Dave Kleikamp wrote:


> ---
> 
> diff -Nurp linux-2.6.24-rc6-git5/fs/jfs/jfs_metapage.c linux/fs/jfs/jfs_metapage.c
> --- linux-2.6.24-rc6-git5/fs/jfs/jfs_metapage.c	2007-12-28 10:28:33.000000000 -0600
> +++ linux/fs/jfs/jfs_metapage.c	2007-12-28 10:37:30.000000000 -0600
> @@ -360,6 +360,7 @@ static int metapage_writepage(struct pag
>  	struct metapage *mp;
>  	int redirty = 0;
>  	sector_t lblock;
> +	int nr_underway = 0;
>  	sector_t pblock;
>  	sector_t next_block = 0;
>  	sector_t page_start;
> @@ -371,6 +372,7 @@ static int metapage_writepage(struct pag
>  		     (PAGE_CACHE_SHIFT - inode->i_blkbits);
>  	BUG_ON(!PageLocked(page));
>  	BUG_ON(PageWriteback(page));

This line should be moved below:
> +	set_page_writeback(page);

>  
>  	for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
>  		mp = page_to_mp(page, offset);
> @@ -413,11 +415,10 @@ static int metapage_writepage(struct pag
>  			if (!bio->bi_size)
>  				goto dump_bio;
>  			submit_bio(WRITE, bio);
> +			nr_underway++;
>  			bio = NULL;
> -		} else {
> -			set_page_writeback(page);
> +		} else
>  			inc_io(page);
> -		}
>  		xlen = (PAGE_CACHE_SIZE - offset) >> inode->i_blkbits;
>  		pblock = metapage_get_blocks(inode, lblock, &xlen);
>  		if (!pblock) {
> @@ -449,12 +450,16 @@ static int metapage_writepage(struct pag
>  			goto dump_bio;
>  
>  		submit_bio(WRITE, bio);
> +		nr_underway++;
>  	}
>  	if (redirty)
>  		redirty_page_for_writepage(wbc, page);
+       else
+               set_page_writeback(page);
>  
>  	unlock_page(page);
>  
> +	if (nr_underway == 0)
  +     if (nr_underway == 0 && redirty == 0)

> +		end_page_writeback(page);
> +
>  	return 0;
>  add_failed:
>  	/* We should never reach here, since we're only adding one vec */

Otherwise looks pretty good.

Reviewed-by: Fengguang Wu <wfg@...l.ustc.edu.cn>

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