Re: [PATCH] Btrfs: update inode flags when renaming

[Liu Bo <bo.li.liu@oracle.com>]

On Mon, Feb 25, 2013 at 12:23:03PM +0800, Miao Xie wrote:
> On 	mon, 25 Feb 2013 11:50:01 +0800, Liu Bo wrote:
> > On Fri, Feb 22, 2013 at 11:04:40PM +0100, David Sterba wrote:
> >> On Fri, Feb 22, 2013 at 05:34:47PM +0800, Miao Xie wrote:
> >>> On 	fri, 22 Feb 2013 16:40:35 +0800, Liu Bo wrote:
> >>>> On Fri, Feb 22, 2013 at 03:32:50AM -0500, Marios Titas wrote:
> >>>>> Sorry, but the bug persists even with the above patch.
> >>>>>
> >>>>> touch test
> >>>>> chattr +C test
> >>>>> lsattr test
> >>>>> mv test test2
> >>>>> lsattr test2
> >>>>>
> >>>>> In the above scenario test2 will not have the C flag.
> >>>>
> >>>> What do you expect?  IMO it's right that test2 does not have the C flag.
> >>>
> >>> No, it's not right.
> >>> For the users, they expect the C flag is not lost because they just do
> >>> a rename operation. but fixup_inode_flags() re-sets the flags by the
> >>> parent directory's flag.
> >>>
> >>> I think we should inherit the flags from the parent just when we create
> >>> a new file/directory, in the other cases, just give a option to the users.
> >>> How do you think about?
> >>
> >> I agree with that. The COW status of a file should not be changed at all
> >> when renamed. The typical users are database files and vm images, losing
> >> the NOCOW flag just from moving here and back is quite unexpected.
> >>
> >> david
> > 
> > Yeah, I agree to remove this bad 'change in rename', will send a patch to
> > address it.
> 
> I think we can add a mount option, if the option is set, when we move a file 
> to a new directory, or create a new file, we will inherit the flags of the parent.
> If not set, we inherit the flags only when create a new file.
> How do you think about it?
> 

I'm ok with the option, but...
from some reports on the list, end users are more likely to control, use chattr
files by themselves, inheriting flags via moving a file to a new directory is
indeed not very welcomed.

So for practical use, I assume that it's fairly enough to inherit flags only on
creation?

thanks,
liubo