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/ceph/locks.c b/fs/ceph/locks.c
index 19beeed..0303da8 100644
--- a/fs/ceph/locks.c
+++ b/fs/ceph/locks.c
@@ -255,12 +255,12 @@
 
 	ctx = inode->i_flctx;
 	if (ctx) {
-		spin_lock(&inode->i_lock);
+		spin_lock(&ctx->flc_lock);
 		list_for_each_entry(lock, &ctx->flc_posix, fl_list)
 			++(*fcntl_count);
 		list_for_each_entry(lock, &ctx->flc_flock, fl_list)
 			++(*flock_count);
-		spin_unlock(&inode->i_lock);
+		spin_unlock(&ctx->flc_lock);
 	}
 	dout("counted %d flock locks and %d fcntl locks",
 	     *flock_count, *fcntl_count);
@@ -288,7 +288,7 @@
 	if (!ctx)
 		return 0;
 
-	spin_lock(&inode->i_lock);
+	spin_lock(&ctx->flc_lock);
 	list_for_each_entry(lock, &ctx->flc_flock, fl_list) {
 		++seen_fcntl;
 		if (seen_fcntl > num_fcntl_locks) {
@@ -312,7 +312,7 @@
 		++l;
 	}
 fail:
-	spin_unlock(&inode->i_lock);
+	spin_unlock(&ctx->flc_lock);
 	return err;
 }