linux-stable/include/linux/fs_struct.h
Nick Piggin c28cc36469 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>
2011-01-07 17:50:27 +11:00

54 lines
1.2 KiB
C

#ifndef _LINUX_FS_STRUCT_H
#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;
};
extern struct kmem_cache *fs_cachep;
extern void exit_fs(struct task_struct *);
extern void set_fs_root(struct fs_struct *, struct path *);
extern void set_fs_pwd(struct fs_struct *, struct path *);
extern struct fs_struct *copy_fs_struct(struct fs_struct *);
extern void free_fs_struct(struct fs_struct *);
extern void daemonize_fs_struct(void);
extern int unshare_fs_struct(void);
static inline void get_fs_root(struct fs_struct *fs, struct path *root)
{
spin_lock(&fs->lock);
*root = fs->root;
path_get(root);
spin_unlock(&fs->lock);
}
static inline void get_fs_pwd(struct fs_struct *fs, struct path *pwd)
{
spin_lock(&fs->lock);
*pwd = fs->pwd;
path_get(pwd);
spin_unlock(&fs->lock);
}
static inline void get_fs_root_and_pwd(struct fs_struct *fs, struct path *root,
struct path *pwd)
{
spin_lock(&fs->lock);
*root = fs->root;
path_get(root);
*pwd = fs->pwd;
path_get(pwd);
spin_unlock(&fs->lock);
}
#endif /* _LINUX_FS_STRUCT_H */