From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Wed, 13 Sep 2017 12:32:34 +0200
Subject: [PATCH] fs/dcache: bring back explicit INIT_HLIST_BL_HEAD init
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/wagi/linux-stable-rt.git
Git-commit: c47fdc6b16dbf3fb58d70fe20e90e30d739ff36a
Patch-mainline: Queued in subsystem maintainer repository
References: SLE Realtime Extension

Commit 3d375d78593c ("mm: update callers to use HASH_ZERO flag") removed
INIT_HLIST_BL_HEAD and uses the ZERO flag instead for the init. However
on RT we have also a spinlock which needs an init call so we can't use
that.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
---
 fs/dcache.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -3139,6 +3139,8 @@ static int __init set_dhash_entries(char
 
 static void __init dcache_init_early(void)
 {
+	unsigned int loop;
+
 	/* If hashes are distributed across NUMA nodes, defer
 	 * hash allocation until vmalloc space is available.
 	 */
@@ -3155,11 +3157,16 @@ static void __init dcache_init_early(voi
 					NULL,
 					0,
 					0);
+
+	for (loop = 0; loop < (1U << d_hash_shift); loop++)
+		INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
+
 	d_hash_shift = 32 - d_hash_shift;
 }
 
 static void __init dcache_init(void)
 {
+	unsigned int loop;
 	/*
 	 * A constructor could be added for stable state like the lists,
 	 * but it is probably not worth it because of the cache nature
@@ -3183,6 +3190,10 @@ static void __init dcache_init(void)
 					NULL,
 					0,
 					0);
+
+	for (loop = 0; loop < (1U << d_hash_shift); loop++)
+		INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
+
 	d_hash_shift = 32 - d_hash_shift;
 }