linux-kernel - Re: [PATCH 10/13] xfs: use get_unused_fd_flags(0) instead of get_unused

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Date:	Wed, 10 Jul 2013 12:00:57 +0200
From:	Yann Droneaud <ydroneaud@...eya.com>
To:	Ben Myers <bpm@....com>
Cc:	linux-kernel@...r.kernel.org, xfs@....sgi.com, ydroneaud@...eya.com
Subject: Re: [PATCH 10/13] xfs: use get_unused_fd_flags(0) instead of get_unused_fd()

Hi,

Le 09.07.2013 22:53, Ben Myers a écrit :
> On Mon, Jul 08, 2013 at 05:41:33PM -0500, Ben Myers wrote:
>> On Tue, Jul 02, 2013 at 06:39:34PM +0200, Yann Droneaud wrote:

>> > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
>> > index 5e99968..dc5b659 100644
>> > --- a/fs/xfs/xfs_ioctl.c
>> > +++ b/fs/xfs/xfs_ioctl.c
>> > @@ -248,7 +248,7 @@ xfs_open_by_handle(
>> >  		goto out_dput;
>> >  	}
>> >
>> > -	fd = get_unused_fd();
>> > +	fd = get_unused_fd_flags(0);
>> 
>> O_CLOEXEC should be fine in this case.
>> 
>> Reviewed-by: Ben Myers <bpm@....com>
> 
> Applied at git://oss.sgi.com/xfs/xfs.git.  Looks like I was wrong about
> O_CLOEXEC being ok here.  There may be applications which 
> open_by_handle then
> fork/exec and expect to still be able to use that file descriptor.
> 

OK, it's very important to not cause regression here.

For the record, xfs_open_by_handle() is not related to 
open_by_handle_at() syscall.

It's an ioctl (XFS_IOC_OPEN_BY_HANDLE) which is used by xfsprogs's 
libhandle
in functions open_by_fshandle() and open_by_handle().

http://sources.debian.net/src/xfsprogs/3.1.9/libhandle/handle.c?hl=284#L284
http://sources.debian.net/src/xfsprogs/3.1.9/libhandle/handle.c?hl=308#L308

According to codesearch.debian.org, libhandle's open_by_handle() is only 
used
by xfsdump

http://sources.debian.net/src/xfsdump/3.1.1/restore/tree.c?hl=2534#L2534

So there's no many *known* users of this features ... but it's more 
important
not to break *unknown* users of it.

BTW, thanks for the review and applying.

Regards.

-- 
Yann Droneaud
OPTEYA

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