On Wed, 2013-07-10 at 18:26 +0200, Jan Kara wrote:
> On Wed 10-07-13 10:55:38, Ben Myers wrote:
> > Hey Chandra,
<snip>
> > > diff --git a/fs/quota/quota.c b/fs/quota/quota.c
> > > index c7314f1..ae6526e 100644
> > > --- a/fs/quota/quota.c
> > > +++ b/fs/quota/quota.c
> > > @@ -207,12 +207,57 @@ static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
> > > static int quota_getxstate(struct super_block *sb, void __user *addr)
> > > {
> > > struct fs_quota_stat fqs;
> > > - int ret;
> > > + struct fs_quota_stat_v1 fqs_v1;
> > > + int ret, size;
> > > + void *fqsp;
> > >
> > > if (!sb->s_qcop->get_xstate)
> > > return -ENOSYS;
> > > +
> > > + memset(&fqs, 0, sizeof(struct fs_quota_stat));
> > > + if (copy_from_user(&fqs, addr, 1)) /* just get the version */
> > > + return -EFAULT;
> > > +
> > > + switch (fqs.qs_version) {
> > > + case FS_QSTAT_VERSION_2:
> > > + size = FS_QSTAT_V2_SIZE;
> > > + break;
> > > + default:
> > > + fqs.qs_version = FS_QSTAT_VERSION;
> > > + /* fallthrough */
> > > + case FS_QSTAT_VERSION:
> > > + size = FS_QSTAT_V1_SIZE;
> > > + break;
> > > + }
> Guys, you cannot really do this. If anyone is using getxstate() with
> uninitialized buffer (which is fine so far), you cannot suddently start to
> rely on the contents of qs_version field. That's ABI (and even API)
> breakage.
Agree, it is a API breakage.
Will fix it by adding a new quotactl value as you suggest.
Does
#define Q_XGETQSTAT2 XQM_CMD(8)
sound good ?
>
> Unless I'm missing something, the only clean way is to use new quotactl
> value for the interface with version field used for input as well.
>
> Honza
>
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