fs: fs_struct use seqlock
Use a seqlock in the fs_struct to enable us to take an atomic copy of the
complete cwd and root paths. Use this in the RCU lookup path to avoid a
thread-shared spinlock in RCU lookup operations.
Multi-threaded apps may now perform path lookups with scalability matching
multi-process apps. Operations such as stat(2) become very scalable for
multi-threaded workload.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
diff --git a/include/linux/fs_struct.h b/include/linux/fs_struct.h
index a42b5bf..003dc0f 100644
--- a/include/linux/fs_struct.h
+++ b/include/linux/fs_struct.h
@@ -2,10 +2,13 @@
#define _LINUX_FS_STRUCT_H
#include <linux/path.h>
+#include <linux/spinlock.h>
+#include <linux/seqlock.h>
struct fs_struct {
int users;
spinlock_t lock;
+ seqcount_t seq;
int umask;
int in_exec;
struct path root, pwd;