[RFC PATCH 12/12] PM / hibernate: update the resume offset on SNAPSHOT_SET_SWAP_AREA

[Anchal Agarwal <anchalag@amazon.com>]

From: Aleksei Besogonov <cyberax@amazon.com>

The SNAPSHOT_SET_SWAP_AREA is supposed to be used to set the hibernation
offset on a running kernel to enable hibernating to a swap file.
However, it doesn't actually update the swsusp_resume_block variable. As
a result, the hibernation fails at the last step (after all the data is
written out) in the validation of the swap signature in
mark_swapfiles().

Before this patch, the command line processing was the only place where
swsusp_resume_block was set.

Signed-off-by: Aleksei Besogonov <cyberax@amazon.com>
Signed-off-by: Munehisa Kamata <kamatam@amazon.com>
Signed-off-by: Anchal Agarwal <anchalag@amazon.com>
Reviewed-by: Munehisa Kamata <kamatam@amazon.com>
Reviewed-by: Eduardo Valentin <eduval@amazon.com>
---
 kernel/power/user.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/power/user.c b/kernel/power/user.c
index abd2255..b522a42 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -379,8 +379,12 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 			if (swdev) {
 				offset = swap_area.offset;
 				data->swap = swap_type_of(swdev, offset, NULL);
-				if (data->swap < 0)
+				if (data->swap < 0) {
 					error = -ENODEV;
+				} else {
+					swsusp_resume_device = swdev;
+					swsusp_resume_block = offset;
+				}
 			} else {
 				data->swap = -1;
 				error = -EINVAL;
-- 
2.7.4