On Tue, 2007-08-28 at 20:11 +0100, Christoph Hellwig wrote:
> Sorry for not replying to the previsious revisions, but I've been out
> for on vacation.
>
> I can't say I like this version. Now we've got callouts at two rather close
> levels which is not very nice from the interface POV.
Agreed.
> Maybe preference is for the first scheme where we simply move interpreation
> of the ATTR_KILL_SUID/ATTR_KILL_SGID into the setattr routine and provide
> a nice helper for the normal filesystem to use.
>
> If people are really concerned about adding two lines of code to the
> handfull of setattr operation there's a variant of this scheme that can
> avoid it:
>
> - notify_change is modified to not clear the ATTR_KILL_SUID/ATTR_KILL_SGID
> but update ia_mode and the ia_valid flag to include ATTR_MODE.
> - disk filesystems stay unchanged and never look at
> ATTR_KILL_SUID/ATTR_KILL_SGID, but nfs can check for it and ignore
> the ATTR_MODE flags and ia_valid in this case and do the right thing
> on the server side.
Hmm... There has to be an implicit promise here that nobody else will
ever try to set ATTR_KILL_SUID/ATTR_KILL_SGID and ATTR_MODE at the same
time. Currently, that assumption is not there:
> if (ia_valid & ATTR_KILL_SGID) {
> attr->ia_valid &= ~ ATTR_KILL_SGID;
> if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
> if (!(ia_valid & ATTR_MODE)) {
> ia_valid = attr->ia_valid |= ATTR_MODE;
> attr->ia_mode = inode->i_mode;
> }
> attr->ia_mode &= ~S_ISGID;
> }
> }
Should we perhaps just convert the above 'if (!(ia_valid & ATTR_MODE))'
into a 'BUG_ON(ia_valid & ATTR_MODE)'?
Trond
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