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!
diff --git a/include/linux/blockgroup_lock.h b/include/linux/blockgroup_lock.h
new file mode 100644
index 0000000..0137ee5
--- /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