root/include/linux/mount.h

INCLUDED FROM

DEFINITIONS

1. mntget
2. mntput

/*
 *
 * Definitions for mount interface. This describes the in the kernel build 
 * linkedlist with mounted filesystems.
 *
 * Author:  Marco van Wieringen <mvw@planets.elm.net>
 *
 * Version: $Id: mount.h,v 2.0 1996/11/17 16:48:14 mvw Exp mvw $
 *
 */
#ifndef _LINUX_MOUNT_H
#define _LINUX_MOUNT_H

#include <linux/types.h>
#include <linux/list.h>
#include <linux/nodemask.h>
#include <linux/spinlock.h>
#include <asm/atomic.h>

struct super_block;
struct vfsmount;
struct dentry;
struct mnt_namespace;

#define MNT_NOSUID      0x01
#define MNT_NODEV       0x02
#define MNT_NOEXEC      0x04
#define MNT_NOATIME     0x08
#define MNT_NODIRATIME  0x10
#define MNT_RELATIME    0x20
#define MNT_READONLY    0x40    /* does the user want this to be r/o? */

#define MNT_SHRINKABLE  0x100
#define MNT_IMBALANCED_WRITE_COUNT      0x200 /* just for debugging */

#define MNT_SHARED      0x1000  /* if the vfsmount is a shared mount */
#define MNT_UNBINDABLE  0x2000  /* if the vfsmount is a unbindable mount */
#define MNT_PNODE_MASK  0x3000  /* propagation flag mask */

struct vfsmount {
        struct list_head mnt_hash;
        struct vfsmount *mnt_parent;    /* fs we are mounted on */
        struct dentry *mnt_mountpoint;  /* dentry of mountpoint */
        struct dentry *mnt_root;        /* root of the mounted tree */
        struct super_block *mnt_sb;     /* pointer to superblock */
        struct list_head mnt_mounts;    /* list of children, anchored here */
        struct list_head mnt_child;     /* and going through their mnt_child */
        int mnt_flags;
        /* 4 bytes hole on 64bits arches */
        const char *mnt_devname;        /* Name of device e.g. /dev/dsk/hda1 */
        struct list_head mnt_list;
        struct list_head mnt_expire;    /* link in fs-specific expiry list */
        struct list_head mnt_share;     /* circular list of shared mounts */
        struct list_head mnt_slave_list;/* list of slave mounts */
        struct list_head mnt_slave;     /* slave list entry */
        struct vfsmount *mnt_master;    /* slave is on master->mnt_slave_list */
        struct mnt_namespace *mnt_ns;   /* containing namespace */
        int mnt_id;                     /* mount identifier */
        int mnt_group_id;               /* peer group identifier */
        /*
         * We put mnt_count & mnt_expiry_mark at the end of struct vfsmount
         * to let these frequently modified fields in a separate cache line
         * (so that reads of mnt_flags wont ping-pong on SMP machines)
         */
        atomic_t mnt_count;
        int mnt_expiry_mark;            /* true if marked for expiry */
        int mnt_pinned;
        int mnt_ghosts;
        /*
         * This value is not stable unless all of the mnt_writers[] spinlocks
         * are held, and all mnt_writer[]s on this mount have 0 as their ->count
         */
        atomic_t __mnt_writers;
};

static inline struct vfsmount *mntget(struct vfsmount *mnt)
{
        if (mnt)
                atomic_inc(&mnt->mnt_count);
        return mnt;
}

extern int mnt_want_write(struct vfsmount *mnt);
extern void mnt_drop_write(struct vfsmount *mnt);
extern void mntput_no_expire(struct vfsmount *mnt);
extern void mnt_pin(struct vfsmount *mnt);
extern void mnt_unpin(struct vfsmount *mnt);
extern int __mnt_is_readonly(struct vfsmount *mnt);

static inline void mntput(struct vfsmount *mnt)
{
        if (mnt) {
                mnt->mnt_expiry_mark = 0;
                mntput_no_expire(mnt);
        }
}

extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
                                      const char *name, void *data);

struct file_system_type;
extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
                                      int flags, const char *name,
                                      void *data);

struct nameidata;

struct path;
extern int do_add_mount(struct vfsmount *newmnt, struct path *path,
                        int mnt_flags, struct list_head *fslist);

extern void mark_mounts_for_expiry(struct list_head *mounts);

extern spinlock_t vfsmount_lock;
extern dev_t name_to_dev_t(char *name);

#endif /* _LINUX_MOUNT_H */