LXR linux/include/linux/mount.h

   1/*
   2 *
   3 * Definitions for mount interface. This describes the in the kernel build 
   4 * linkedlist with mounted filesystems.
   5 *
   6 * Author:  Marco van Wieringen <mvw@planets.elm.net>
   7 *
   8 */
   9#ifndef _LINUX_MOUNT_H
  10#define _LINUX_MOUNT_H
  11
  12#include <linux/types.h>
  13#include <linux/list.h>
  14#include <linux/nodemask.h>
  15#include <linux/spinlock.h>
  16#include <asm/atomic.h>
  17
  18struct super_block;
  19struct vfsmount;
  20struct dentry;
  21struct mnt_namespace;
  22
  23#define MNT_NOSUID      0x01
  24#define MNT_NODEV       0x02
  25#define MNT_NOEXEC      0x04
  26#define MNT_NOATIME     0x08
  27#define MNT_NODIRATIME  0x10
  28#define MNT_RELATIME    0x20
  29#define MNT_READONLY    0x40    /* does the user want this to be r/o? */
  30#define MNT_STRICTATIME 0x80
  31
  32#define MNT_SHRINKABLE  0x100
  33#define MNT_WRITE_HOLD  0x200
  34
  35#define MNT_SHARED      0x1000  /* if the vfsmount is a shared mount */
  36#define MNT_UNBINDABLE  0x2000  /* if the vfsmount is a unbindable mount */
  37/*
  38 * MNT_SHARED_MASK is the set of flags that should be cleared when a
  39 * mount becomes shared.  Currently, this is only the flag that says a
  40 * mount cannot be bind mounted, since this is how we create a mount
  41 * that shares events with another mount.  If you add a new MNT_*
  42 * flag, consider how it interacts with shared mounts.
  43 */
  44#define MNT_SHARED_MASK (MNT_UNBINDABLE)
  45#define MNT_PROPAGATION_MASK    (MNT_SHARED | MNT_UNBINDABLE)
  46
  47
  48#define MNT_INTERNAL    0x4000
  49
  50struct vfsmount {
  51        struct list_head mnt_hash;
  52        struct vfsmount *mnt_parent;    /* fs we are mounted on */
  53        struct dentry *mnt_mountpoint;  /* dentry of mountpoint */
  54        struct dentry *mnt_root;        /* root of the mounted tree */
  55        struct super_block *mnt_sb;     /* pointer to superblock */
  56        struct list_head mnt_mounts;    /* list of children, anchored here */
  57        struct list_head mnt_child;     /* and going through their mnt_child */
  58        int mnt_flags;
  59        /* 4 bytes hole on 64bits arches */
  60        const char *mnt_devname;        /* Name of device e.g. /dev/dsk/hda1 */
  61        struct list_head mnt_list;
  62        struct list_head mnt_expire;    /* link in fs-specific expiry list */
  63        struct list_head mnt_share;     /* circular list of shared mounts */
  64        struct list_head mnt_slave_list;/* list of slave mounts */
  65        struct list_head mnt_slave;     /* slave list entry */
  66        struct vfsmount *mnt_master;    /* slave is on master->mnt_slave_list */
  67        struct mnt_namespace *mnt_ns;   /* containing namespace */
  68        int mnt_id;                     /* mount identifier */
  69        int mnt_group_id;               /* peer group identifier */
  70        /*
  71         * We put mnt_count & mnt_expiry_mark at the end of struct vfsmount
  72         * to let these frequently modified fields in a separate cache line
  73         * (so that reads of mnt_flags wont ping-pong on SMP machines)
  74         */
  75        atomic_t mnt_count;
  76        int mnt_expiry_mark;            /* true if marked for expiry */
  77        int mnt_pinned;
  78        int mnt_ghosts;
  79#ifdef CONFIG_SMP
  80        int __percpu *mnt_writers;
  81#else
  82        int mnt_writers;
  83#endif
  84};
  85
  86static inline int *get_mnt_writers_ptr(struct vfsmount *mnt)
  87{
  88#ifdef CONFIG_SMP
  89        return mnt->mnt_writers;
  90#else
  91        return &mnt->mnt_writers;
  92#endif
  93}
  94
  95static inline struct vfsmount *mntget(struct vfsmount *mnt)
  96{
  97        if (mnt)
  98                atomic_inc(&mnt->mnt_count);
  99        return mnt;
 100}
 101
 102struct file; /* forward dec */
 103
 104extern int mnt_want_write(struct vfsmount *mnt);
 105extern int mnt_want_write_file(struct file *file);
 106extern int mnt_clone_write(struct vfsmount *mnt);
 107extern void mnt_drop_write(struct vfsmount *mnt);
 108extern void mntput_no_expire(struct vfsmount *mnt);
 109extern void mnt_pin(struct vfsmount *mnt);
 110extern void mnt_unpin(struct vfsmount *mnt);
 111extern int __mnt_is_readonly(struct vfsmount *mnt);
 112
 113static inline void mntput(struct vfsmount *mnt)
 114{
 115        if (mnt) {
 116                mnt->mnt_expiry_mark = 0;
 117                mntput_no_expire(mnt);
 118        }
 119}
 120
 121extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
 122                                      const char *name, void *data);
 123
 124struct file_system_type;
 125extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
 126                                      int flags, const char *name,
 127                                      void *data);
 128
 129struct nameidata;
 130
 131struct path;
 132extern int do_add_mount(struct vfsmount *newmnt, struct path *path,
 133                        int mnt_flags, struct list_head *fslist);
 134
 135extern void mark_mounts_for_expiry(struct list_head *mounts);
 136
 137extern dev_t name_to_dev_t(char *name);
 138
 139#endif /* _LINUX_MOUNT_H */
 140