On Friday 17 July 2015 10:04:39 Mike Snitzer wrote:
> On Sun, Jun 21 2015 at 7:20am -0400,
> Pali Rohár <pali.rohar@xxxxxxxxx> wrote:
>
> > This patch exports function dm_suspend_md() which suspend mapped device so other
> > kernel drivers can use it and could suspend mapped device when needed.
> >
> > Signed-off-by: Pali Rohár <pali.rohar@xxxxxxxxx>
> > ---
> > drivers/md/dm.c | 6 ++++++
> > drivers/md/dm.h | 5 +++++
> > 2 files changed, 11 insertions(+)
> >
> > diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> > index 2caf492..03298ff 100644
> > --- a/drivers/md/dm.c
> > +++ b/drivers/md/dm.c
> > @@ -3343,6 +3343,12 @@ out:
> > return r;
> > }
> >
> > +int dm_suspend_md(struct mapped_device *md)
> > +{
> > + return dm_suspend(md, DM_SUSPEND_LOCKFS_FLAG);
> > +}
> > +EXPORT_SYMBOL_GPL(dm_suspend_md);
> > +
> > /*
> > * Internal suspend/resume works like userspace-driven suspend. It waits
> > * until all bios finish and prevents issuing new bios to the target drivers.
>
> To do this properly you should be introducing a variant of
> dm_internal_suspend. We currently have two variants:
> dm_internal_suspend_fast
> dm_internal_suspend_noflush
>
> The reason to use a dm_internal_suspend variant is this suspend was
> _not_ initiated by an upper level ioctl (from userspace). It was
> done internally from within the target.
>
> You're explicitly using DM_SUSPEND_LOCKFS_FLAG above.. meaning you're
> interested in flushing all pending IO (in the FS layered on dm-crupt, if
> one exists).
>
> But see the comment in __dm_internal_suspend() about TASK_UNINTERRUPTIBLE.
> If you're OK with the dm-crypt initiated suspend being
> TASK_UNINTERRUPTIBLE then you could just introduce:
>
> void dm_internal_suspend_uninterruptible_flush(struct mapped_device *md)
> {
> mutex_lock(&md->suspend_lock);
> __dm_internal_suspend(md, DM_SUSPEND_LOCKFS_FLAG);
> mutex_unlock(&md->suspend_lock);
> }
> EXPORT_SYMBOL_GPL(dm_internal_suspend_uninterruptible_flush);
>
> Otherwise, there is much more extensive DM core changes needed to
> __dm_internal_suspend() and .presuspend to properly support
> TASK_INTERRUPTIBLE.
Hi! I will look at dm_internal_suspend. Anyway use case for suspend is
from dm-crypt to do both operations: suspend + key wipe. It means that
without entering key again from userspace, resume is not possible. So my
question is: It is possible to do internal suspend and then using resume
from userspace via ioctl?
--
Pali Rohár
pali.rohar@xxxxxxxxx
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