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Re: [PATCH 2/2] ext4: Fix mmap data corruption when blocksize < pagesize

To: linux-fsdevel@xxxxxxxxxxxxxxx
Subject: Re: [PATCH 2/2] ext4: Fix mmap data corruption when blocksize < pagesize
From: Jan Kara <jack@xxxxxxx>
Date: Wed, 24 Sep 2014 10:45:19 +0200
Cc: linux-mm@xxxxxxxxx, Dave Chinner <david@xxxxxxxxxxxxx>, linux-ext4@xxxxxxxxxxxxxxx, Ted Tso <tytso@xxxxxxx>, Jan Kara <jack@xxxxxxx>, xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1411484603-17756-3-git-send-email-jack@xxxxxxx>
References: <1411484603-17756-1-git-send-email-jack@xxxxxxx> <1411484603-17756-3-git-send-email-jack@xxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Tue 23-09-14 17:03:23, Jan Kara wrote:
> Use block_create_hole() when hole is being created in a file so that
> ->page_mkwrite() will get called for the partial tail page if it is
> mmaped (see the first patch in the series for details).
  Just out of curiosity I did a change similar to this one for ext4 to XFS
and indeed it fixed generic/030 test failures for XFS with blocksize 1k.

                                                                Honza

PS: I forgot to CC xfs list in the original posting. You can find the VFS
    patch e.g. at http://www.spinics.net/lists/linux-mm/msg78976.html

> Signed-off-by: Jan Kara <jack@xxxxxxx>
> ---
>  fs/ext4/inode.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 3aa26e9117c4..fdcb007c2c9e 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4536,8 +4536,12 @@ int ext4_setattr(struct dentry *dentry, struct iattr 
> *attr)
>                               ext4_orphan_del(NULL, inode);
>                               goto err_out;
>                       }
> -             } else
> +             } else {
> +                     loff_t old_size = inode->i_size;
> +
>                       i_size_write(inode, attr->ia_size);
> +                     block_create_hole(inode, old_size, inode->i_size);
> +             }
>  
>               /*
>                * Blocks are going to be removed from the inode. Wait
> -- 
> 1.8.1.4
> 
-- 
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR

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