From: Mike Galbraith <efault@gmx.de>
Date: Wed, 14 Sep 2016 17:57:03 +0200
Subject: fs/dcache: initialize dentry_hashtable
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
Git-commit: 95f12397b61a084952bd13f16dc6fc3b354cab32
Patch-mainline: Queued in subsystem maintainer repository
References: SLE Realtime Extension

3d375d78 ("mm: update callers to use HASH_ZERO flag") removed dentry_hashtable
hlist_bl_head initialization.  RT needs hlist_bl_head.lock (raw_spinlock_t) to
be properly initialized, so put it back.

Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
---
 fs/dcache.c |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -3611,6 +3611,15 @@ static void __init dcache_init_early(voi
 					&d_hash_mask,
 					0,
 					0);
+
+#ifdef CONFIG_PREEMPT_RT_BASE
+	/* RT: hlist_bl_head.lock must be initialized regardless of HASH_ZERO */
+	{
+		unsigned int loop;
+		for (loop = 0; loop < (1U << d_hash_shift); loop++)
+			INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
+	}
+#endif
 }
 
 static void __init dcache_init(void)
@@ -3637,6 +3646,15 @@ static void __init dcache_init(void)
 					&d_hash_mask,
 					0,
 					0);
+
+#ifdef CONFIG_PREEMPT_RT_BASE
+	/* RT: hlist_bl_head.lock must be initialized regardless of HASH_ZERO */
+	{
+		unsigned int loop;
+		for (loop = 0; loop < (1U << d_hash_shift); loop++)
+			INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
+	}
+#endif
 }
 
 /* SLAB cache for __getname() consumers */