[PATCH 13/17][cr][v4]: Add jiffies_begin field to ckpt_ctx

[Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>]

'jiffies_begin' is needed to compute relative time-offsets after restart.
We cannot use ->ktime_begin for these computations since, as pointed out
by John Stultz, converting jiffies to CLOCK_MONOTONIC can result in
incorrect values.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
---
 include/linux/checkpoint_types.h |    1 +
 kernel/checkpoint/sys.c          |    1 +
 2 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/include/linux/checkpoint_types.h b/include/linux/checkpoint_types.h
index 3ffe9bd..aba9380 100644
--- a/include/linux/checkpoint_types.h
+++ b/include/linux/checkpoint_types.h
@@ -33,6 +33,7 @@ struct ckpt_ctx {
 	int crid;		/* unique checkpoint id */
 
 	ktime_t ktime_begin;	/* checkpoint start time */
+	unsigned long jiffies_begin;
 
 	int root_init;				/* [container] root init ? */
 	pid_t root_pid;				/* [container] root pid */
diff --git a/kernel/checkpoint/sys.c b/kernel/checkpoint/sys.c
index b761ec0..0beeee5 100644
--- a/kernel/checkpoint/sys.c
+++ b/kernel/checkpoint/sys.c
@@ -278,6 +278,7 @@ static struct ckpt_ctx *ckpt_ctx_alloc(int fd, unsigned long uflags,
 	ctx->uflags = uflags;
 	ctx->kflags = kflags;
 	ctx->ktime_begin = ktime_get();
+	ctx->jiffies_begin = jiffies;
 	ctx->coord_pidns = get_pid_ns(current->nsproxy->pid_ns);
 
 	atomic_set(&ctx->refcount, 0);
-- 
1.6.0.4