From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Yan, Zheng " <yanzheng@21cn.com>
Subject: Re: [PATCH 12/12] Btrfs: Fix file clone when source offset is not 0
Date: Thu, 2 Feb 2012 12:25:27 +0800
Message-ID: <CAAM7YA=fCFfv-qObkpovQ6D7_6BdT1xU1c-0sVJNWjmPYHQBiw@mail.gmail.com>
References: <4D412FE6.7050101@cn.fujitsu.com>
	<4D4130D4.2000001@cn.fujitsu.com>
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Cc: Chris Mason <chris.mason@oracle.com>,
	"linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>
To: Li Zefan <lizf@cn.fujitsu.com>
Return-path: <linux-btrfs-owner@vger.kernel.org>
In-Reply-To: <4D4130D4.2000001@cn.fujitsu.com>
List-ID: <linux-btrfs.vger.kernel.org>

On Thu, Jan 27, 2011 at 4:46 PM, Li Zefan <lizf@cn.fujitsu.com> wrote:
> Suppose:
> - the source extent is: [0, 100]
> - the src offset is 10
> - the clone length is 90
> - the dest offset is 0
>
> This statement:
>
> =A0 =A0 =A0 =A0new_key.offset =3D key.offset + destoff - off
>
> will produce such an extent for the dest file:
>
> =A0 =A0 =A0 =A0[ino, BTRFS_EXTENT_DATA_KEY, -10]
>
> , which is obviously wrong.
>
> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
> ---
> =A0fs/btrfs/ioctl.c | =A0 =A05 ++++-
> =A01 files changed, 4 insertions(+), 1 deletions(-)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index f87552a..1b61dab 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -1788,7 +1788,10 @@ static noinline long btrfs_ioctl_clone(struct =
file *file, unsigned long srcfd,
>
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0memcpy(&new_key, &key,=
 sizeof(new_key));
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0new_key.objectid =3D i=
node->i_ino;
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 new_key.offset =3D key.=
offset + destoff - off;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (off <=3D key.offset=
)
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 new_key=
=2Eoffset =3D key.offset + destoff - off;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 else
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 new_key=
=2Eoffset =3D destoff;
>
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0trans =3D btrfs_start_=
transaction(root, 1);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0if (IS_ERR(trans)) {

This is a disk format change, will cause Oops when deleting or
truncating the file.
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