linux-ext4 - Re: [PATCH] ext4: Ensure zeroout blocks have no dirty metadata

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Message-ID: <4B213391.4050603@redhat.com>
Date:	Thu, 10 Dec 2009 11:44:49 -0600
From:	Eric Sandeen <sandeen@...hat.com>
To:	Curt Wohlgemuth <curtw@...gle.com>
CC:	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] ext4: Ensure zeroout blocks have no dirty metadata

Curt Wohlgemuth wrote:
> This fixes a bug in which new blocks returned from an extent created with
> ext4_ext_zeroout() can have dirty metadata still associated with them.

Do you have a testcase or at least end result details for this corruption?

> 	Signed-off-by: Curt Wohlgemuth <curtw@...gle.com>
> ---
> 
> This is for the problem I reported on 23 Nov ("Bug in extent zeroout: blocks
> not marked as new").  I'm not seeing the corruption with this fix that I was
> seeing without it.
> 
> diff -uprN orig/fs/ext4/extents.c new/fs/ext4/extents.c
> --- orig/fs/ext4/extents.c	2009-12-09 15:09:25.000000000 -0800
> +++ new/fs/ext4/extents.c	2009-12-09 15:09:37.000000000 -0800
> @@ -2474,9 +2474,21 @@ static int ext4_ext_zeroout(struct inode
>  		submit_bio(WRITE, bio);
>  		wait_for_completion(&event);
> 
> -		if (test_bit(BIO_UPTODATE, &bio->bi_flags))
> +		/* On success, we need to insure all metadata associated

nitpick, "ensure" I think, although I guess they're mostly synonymous
today so do with that what you will :)

-Eric

> +		 * with each of these blocks is unmapped. */
> +		if (test_bit(BIO_UPTODATE, &bio->bi_flags)) {
> +			sector_t block = ee_pblock;
> +
>  			ret = 0;
> -		else {
> +			done = 0;
> +			while (done < len) {
> +				unmap_underlying_metadata(inode->i_sb->s_bdev,
> +							  block);
> +
> +				done++;
> +				block++;
> +			}
> +		} else {
>  			ret = -EIO;
>  			break;
>  		}
> --
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