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.
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