From: Clark Williams <williams@redhat.com>
Date: Tue, 3 Jul 2018 13:34:30 -0500
Subject: [PATCH] fscache: initialize cookie hash table raw spinlocks
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/wagi/linux-stable-rt.git
Git-commit: 9e3b3d3434a3c7bd3243e8c2d49a5fc8ecf675a0
Patch-mainline: Queued in subsystem maintainer repository
References: SLE Realtime Extension

The fscache cookie mechanism uses a hash table of hlist_bl_head structures. The
PREEMPT_RT patcheset adds a raw spinlock to this structure and so on PREEMPT_RT
the structures get used uninitialized, causing warnings about bad magic numbers
when spinlock debugging is turned on.

Use the init function for fscache cookies.

Signed-off-by: Clark Williams <williams@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
---
 fs/fscache/cookie.c     |    8 ++++++++
 fs/fscache/main.c       |    1 +
 include/linux/fscache.h |    1 +
 3 files changed, 10 insertions(+)

--- a/fs/fscache/cookie.c
+++ b/fs/fscache/cookie.c
@@ -958,3 +958,11 @@ int __fscache_check_consistency(struct f
 	return -ESTALE;
 }
 EXPORT_SYMBOL(__fscache_check_consistency);
+
+void __init fscache_cookie_init(void)
+{
+	int i;
+
+	for (i = 0; i < (1 << fscache_cookie_hash_shift) - 1; i++)
+		INIT_HLIST_BL_HEAD(&fscache_cookie_hash[i]);
+}
--- a/fs/fscache/main.c
+++ b/fs/fscache/main.c
@@ -145,6 +145,7 @@ static int __init fscache_init(void)
 		ret = -ENOMEM;
 		goto error_cookie_jar;
 	}
+	fscache_cookie_init();
 
 	fscache_root = kobject_create_and_add("fscache", kernel_kobj);
 	if (!fscache_root)
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -226,6 +226,7 @@ extern void __fscache_readpages_cancel(s
 extern void __fscache_disable_cookie(struct fscache_cookie *, const void *, bool);
 extern void __fscache_enable_cookie(struct fscache_cookie *, const void *, loff_t,
 				    bool (*)(void *), void *);
+extern void fscache_cookie_init(void);
 
 /**
  * fscache_register_netfs - Register a filesystem as desiring caching services