lkml.org 
[lkml]   [2015]   [Jul]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2 2/3] dm: Export function dm_suspend_md()
On Sun, Jun 21 2015 at  7:20am -0400,
Pali Rohár <pali.rohar@gmail.com> 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@gmail.com>
> ---
> 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.


\
 
 \ /
  Last update: 2015-07-17 16:21    [W:0.131 / U:0.336 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site