locks: add a dedicated spinlock to protect i_flctx lists

We can now add a dedicated spinlock without expanding struct inode.
Change to using that to protect the various i_flctx lists.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Acked-by: Christoph Hellwig <hch@lst.de>
diff --git a/fs/lockd/svcsubs.c b/fs/lockd/svcsubs.c
index 5300bb5..665ef5a 100644
--- a/fs/lockd/svcsubs.c
+++ b/fs/lockd/svcsubs.c
@@ -171,7 +171,7 @@
 		return 0;
 again:
 	file->f_locks = 0;
-	spin_lock(&inode->i_lock);
+	spin_lock(&flctx->flc_lock);
 	list_for_each_entry(fl, &flctx->flc_posix, fl_list) {
 		if (fl->fl_lmops != &nlmsvc_lock_operations)
 			continue;
@@ -183,7 +183,7 @@
 		if (match(lockhost, host)) {
 			struct file_lock lock = *fl;
 
-			spin_unlock(&inode->i_lock);
+			spin_unlock(&flctx->flc_lock);
 			lock.fl_type  = F_UNLCK;
 			lock.fl_start = 0;
 			lock.fl_end   = OFFSET_MAX;
@@ -195,7 +195,7 @@
 			goto again;
 		}
 	}
-	spin_unlock(&inode->i_lock);
+	spin_unlock(&flctx->flc_lock);
 
 	return 0;
 }
@@ -232,14 +232,14 @@
 		return 1;
 
 	if (flctx && !list_empty_careful(&flctx->flc_posix)) {
-		spin_lock(&inode->i_lock);
+		spin_lock(&flctx->flc_lock);
 		list_for_each_entry(fl, &flctx->flc_posix, fl_list) {
 			if (fl->fl_lmops == &nlmsvc_lock_operations) {
-				spin_unlock(&inode->i_lock);
+				spin_unlock(&flctx->flc_lock);
 				return 1;
 			}
 		}
-		spin_unlock(&inode->i_lock);
+		spin_unlock(&flctx->flc_lock);
 	}
 	file->f_locks = 0;
 	return 0;