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
  31#define MNT_SHRINKABLE  0x100
  32#define MNT_IMBALANCED_WRITE_COUNT      0x200 /* just for debugging */
  33
  34#define MNT_SHARED      0x1000  /* if the vfsmount is a shared mount */
  35#define MNT_UNBINDABLE  0x2000  /* if the vfsmount is a unbindable mount */
  36#define MNT_PNODE_MASK  0x3000  /* propagation flag mask */
  37
  38struct vfsmount {
  39        struct list_head mnt_hash;
  40        struct vfsmount *mnt_parent;    /* fs we are mounted on */
  41        struct dentry *mnt_mountpoint;  /* dentry of mountpoint */
  42        struct dentry *mnt_root;        /* root of the mounted tree */
  43        struct super_block *mnt_sb;     /* pointer to superblock */
  44        struct list_head mnt_mounts;    /* list of children, anchored here */
  45        struct list_head mnt_child;     /* and going through their mnt_child */
  46        int mnt_flags;
  47        /* 4 bytes hole on 64bits arches */
  48        const char *mnt_devname;        /* Name of device e.g. /dev/dsk/hda1 */
  49        struct list_head mnt_list;
  50        struct list_head mnt_expire;    /* link in fs-specific expiry list */
  51        struct list_head mnt_share;     /* circular list of shared mounts */
  52        struct list_head mnt_slave_list;/* list of slave mounts */
  53        struct list_head mnt_slave;     /* slave list entry */
  54        struct vfsmount *mnt_master;    /* slave is on master->mnt_slave_list */
  55        struct mnt_namespace *mnt_ns;   /* containing namespace */
  56        int mnt_id;                     /* mount identifier */
  57        int mnt_group_id;               /* peer group identifier */
  58        /*
  59         * We put mnt_count & mnt_expiry_mark at the end of struct vfsmount
  60         * to let these frequently modified fields in a separate cache line
  61         * (so that reads of mnt_flags wont ping-pong on SMP machines)
  62         */
  63        atomic_t mnt_count;
  64        int mnt_expiry_mark;            /* true if marked for expiry */
  65        int mnt_pinned;
  66        int mnt_ghosts;
  67        /*
  68         * This value is not stable unless all of the mnt_writers[] spinlocks
  69         * are held, and all mnt_writer[]s on this mount have 0 as their ->count
  70         */
  71        atomic_t __mnt_writers;
  72};
  73
  74static inline struct vfsmount *mntget(struct vfsmount *mnt)
  75{
  76        if (mnt)
  77                atomic_inc(&mnt->mnt_count);
  78        return mnt;
  79}
  80
  81extern int mnt_want_write(struct vfsmount *mnt);
  82extern void mnt_drop_write(struct vfsmount *mnt);
  83extern void mntput_no_expire(struct vfsmount *mnt);
  84extern void mnt_pin(struct vfsmount *mnt);
  85extern void mnt_unpin(struct vfsmount *mnt);
  86extern int __mnt_is_readonly(struct vfsmount *mnt);
  87
  88static inline void mntput(struct vfsmount *mnt)
  89{
  90        if (mnt) {
  91                mnt->mnt_expiry_mark = 0;
  92                mntput_no_expire(mnt);
  93        }
  94}
  95
  96extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
  97                                      const char *name, void *data);
  98
  99struct file_system_type;
 100extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
 101                                      int flags, const char *name,
 102                                      void *data);
 103
 104struct nameidata;
 105
 106struct path;
 107extern int do_add_mount(struct vfsmount *newmnt, struct path *path,
 108                        int mnt_flags, struct list_head *fslist);
 109
 110extern void mark_mounts_for_expiry(struct list_head *mounts);
 111
 112extern spinlock_t vfsmount_lock;
 113extern dev_t name_to_dev_t(char *name);
 114
 115#endif /* _LINUX_MOUNT_H */
 116