From: Sage Weil <sage@newdream.net>
To: Li Dongyang <jerry87905@gmail.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: cp --reflink with Btrfs
Date: Wed, 16 Dec 2009 09:55:43 -0800 (PST) [thread overview]
Message-ID: <Pine.LNX.4.64.0912160943280.2801@cobra.newdream.net> (raw)
In-Reply-To: <4b287dd5.5744f10a.3536.2011@mx.google.com>
On Wed, 16 Dec 2009, Li Dongyang wrote:
> Have a look at line 998, ioctl.c, inside btrfs_ioctl_clone(),
> the src->i_size(the size of the testfile created by touch) is just 0, and this
> will cause btrfs_ioctl_clone just return -EINVAL.
> I'm not sure if it makes sense to clone a file which actually doesn't have any
> data extents.
Probably not, but it seems more consistent to return success instead than
-EINVAL. Requiring the caller to check and special case empty files isn't
very friendly...
sage
---
Subject: [PATCH] Btrfs: return success when cloning 0 byte range at eof
We currently return -EINVAL when cloning a zero byte range at EOF (most
commonly when cloning a 0 byte file). Return success instead, even though
this is a no-op.
Signed-off-by: Sage Weil <sage@newdream.net>
---
fs/btrfs/ioctl.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index cdbb054..1a964a4 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -994,8 +994,11 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
}
/* determine range to clone */
+ ret = 0;
+ if (off == src->i_size && len == 0)
+ goto out_unlock;
ret = -EINVAL;
- if (off >= src->i_size || off + len > src->i_size)
+ if (off > src->i_size || off + len > src->i_size)
goto out_unlock;
if (len == 0)
olen = len = src->i_size - off;
--
1.6.5
next prev parent reply other threads:[~2009-12-16 17:55 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-13 0:29 cp --reflink with Btrfs Jason White
2009-12-14 16:23 ` Josef Bacik
2009-12-15 23:37 ` Jason White
2009-12-16 6:27 ` Li Dongyang
2009-12-16 17:55 ` Sage Weil [this message]
2010-01-27 10:53 Andreas Barth
2010-01-28 21:09 ` Chris Mason
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