[PATCH 11/17][cr][v4]: Add ->fl_type_prev field.

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

In preparation for checkpoint/restart of file leases, add ->fl_type_prev
field to 'struct file_lock'. This field is needed to correctly restore
file leases in case of recursive checkpoint/restart of an in-progress
lease.

This ->fl_type_prev is only initialized in this patch. It will actually
be used when restoring file leases after a checkpoint.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
---
 fs/locks.c         |   10 ++++++++++
 include/linux/fs.h |    1 +
 2 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c
index 0bd5af7..9a00876 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -184,6 +184,7 @@ void locks_init_lock(struct file_lock *fl)
 	fl->fl_file = NULL;
 	fl->fl_flags = 0;
 	fl->fl_type = 0;
+	fl->fl_type_prev = 0;
 	fl->fl_start = fl->fl_end = 0;
 	fl->fl_break_time = 0UL;
 	fl->fl_ops = NULL;
@@ -227,6 +228,7 @@ void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl)
 	new->fl_file = NULL;
 	new->fl_flags = fl->fl_flags;
 	new->fl_type = fl->fl_type;
+	new->fl_type_prev = fl->fl_type_prev;
 	new->fl_start = fl->fl_start;
 	new->fl_end = fl->fl_end;
 	new->fl_break_time = 0UL;
@@ -293,6 +295,13 @@ static int assign_type(struct file_lock *fl, int type)
 	case F_WRLCK:
 	case F_UNLCK:
 		fl->fl_type = type;
+		/*
+		 * Clear ->fl_type_prev since this is a new lease type.
+		 * break_lease() will use this cleared state to know
+		 * if it must save the lease-type in case of checkpoint/
+		 * restart.
+		 */
+		fl->fl_type_prev = 0;
 		break;
 	default:
 		return -EINVAL;
@@ -1222,6 +1231,7 @@ int __break_lease(struct inode *inode, unsigned int mode)
 
 	for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) {
 		if (fl->fl_type != future) {
+			fl->fl_type_prev = fl->fl_type;
 			fl->fl_type = future;
 			fl->fl_break_time = break_time;
 			/* lease must have lmops break callback */
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 49d4eeb..299cc09 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1066,6 +1066,7 @@ struct file_lock {
 	fl_owner_t fl_owner;
 	unsigned char fl_flags;
 	unsigned char fl_type;
+	unsigned char fl_type_prev;
 	unsigned int fl_pid;
 	struct pid *fl_nspid;
 	wait_queue_head_t fl_wait;
-- 
1.6.0.4