Re: [RFC PATCH v2] dm ioctl: fix erroneous EINVAL when signaled

[Zdenek Kabelac]

Dne 23. 07. 24 v 14:51 Mikulas Patocka napsal(a):
> On Wed, 17 Jul 2024, Khazhismel Kumykov wrote:
>
> > do_resume when loading a new map first calls dm_suspend, which could
> > silently fail. When we proceeded to dm_swap_table, we would bail out
> > with EINVAL. Instead, attempt to restore new_map and return ERESTARTSYS
> > when signaled.
> >
> > Signed-off-by: Khazhismel Kumykov <khazhy@xxxxxxxxxx>
> > ---
> >   drivers/md/dm-ioctl.c | 23 +++++++++++++++++++++--
> >   1 file changed, 21 insertions(+), 2 deletions(-)
> >
> > v2: don't leak new_map if we can't assign it back to hc.
> >
> > diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
> > index c2c07bfa6471..0591455ad63c 100644
> > --- a/drivers/md/dm-ioctl.c
> > +++ b/drivers/md/dm-ioctl.c
> > @@ -1181,8 +1181,27 @@ static int do_resume(struct dm_ioctl *param)
> >   			suspend_flags &= ~DM_SUSPEND_LOCKFS_FLAG;
> >   		if (param->flags & DM_NOFLUSH_FLAG)
> >   			suspend_flags |= DM_SUSPEND_NOFLUSH_FLAG;
> > -		if (!dm_suspended_md(md))
> > -			dm_suspend(md, suspend_flags);
> > +		if (!dm_suspended_md(md)) {
> > +			r = dm_suspend(md, suspend_flags);
> > +			if (r == -EINTR)
> > +				r = -ERESTARTSYS;
>
> I'd like to ask why the "EINTR -> ERESTARTSYS" conversion is here and why
> it isn't in dm_suspend?
>
> What do libdevmapper+lvm maintainers think about it? Does lvm hadle EINTR
> by restarting the ioctl syscall? Should we return ERESTARTSYS when suspend
> is interrupted?

In general - with suspend failures - we are just stopping whole operation - 
and restoring previous state - so user can run operation again.

There is no special check for exact reason of ioctl failure.

Regards

Zdenek