From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@ppc970.osdl.org>
Date: Sat, 16 Apr 2005 15:20:36 -0700
Subject: Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
---
 include/linux/blockgroup_lock.h | 60 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 include/linux/blockgroup_lock.h

(limited to 'include/linux/blockgroup_lock.h')

diff --git a/include/linux/blockgroup_lock.h b/include/linux/blockgroup_lock.h
new file mode 100644
index 000000000000..0137ee5dd43c
--- /dev/null
+++ b/include/linux/blockgroup_lock.h
@@ -0,0 +1,60 @@
+#ifndef _LINUX_BLOCKGROUP_LOCK_H
+#define _LINUX_BLOCKGROUP_LOCK_H
+/*
+ * Per-blockgroup locking for ext2 and ext3.
+ *
+ * Simple hashed spinlocking.
+ */
+
+#include <linux/config.h>
+#include <linux/spinlock.h>
+#include <linux/cache.h>
+
+#ifdef CONFIG_SMP
+
+/*
+ * We want a power-of-two.  Is there a better way than this?
+ */
+
+#if NR_CPUS >= 32
+#define NR_BG_LOCKS	128
+#elif NR_CPUS >= 16
+#define NR_BG_LOCKS	64
+#elif NR_CPUS >= 8
+#define NR_BG_LOCKS	32
+#elif NR_CPUS >= 4
+#define NR_BG_LOCKS	16
+#elif NR_CPUS >= 2
+#define NR_BG_LOCKS	8
+#else
+#define NR_BG_LOCKS	4
+#endif
+
+#else	/* CONFIG_SMP */
+#define NR_BG_LOCKS	1
+#endif	/* CONFIG_SMP */
+
+struct bgl_lock {
+	spinlock_t lock;
+} ____cacheline_aligned_in_smp;
+
+struct blockgroup_lock {
+	struct bgl_lock locks[NR_BG_LOCKS];
+};
+
+static inline void bgl_lock_init(struct blockgroup_lock *bgl)
+{
+	int i;
+
+	for (i = 0; i < NR_BG_LOCKS; i++)
+		spin_lock_init(&bgl->locks[i].lock);
+}
+
+/*
+ * The accessor is a macro so we can embed a blockgroup_lock into different
+ * superblock types
+ */
+#define sb_bgl_lock(sb, block_group) \
+	(&(sb)->s_blockgroup_lock.locks[(block_group) & (NR_BG_LOCKS-1)].lock)
+
+#endif
-- 
cgit