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  * Version: $Id: mount.h,v 2.0 1996/11/17 16:48:14 mvw Exp mvw $
   9  *
  10  */
  11 #ifndef _LINUX_MOUNT_H
  12 #define _LINUX_MOUNT_H
  13 #ifdef __KERNEL__
  14
  15 #include <linux/types.h>
  16 #include <linux/list.h>
  17 #include <linux/nodemask.h>
  18 #include <linux/spinlock.h>
  19 #include <asm/atomic.h>
  20
  21 struct super_block;
  22 struct vfsmount;
  23 struct dentry;
  24 struct mnt_namespace;
  25
  26 #define MNT_NOSUID      0x01
  27 #define MNT_NODEV       0x02
  28 #define MNT_NOEXEC      0x04
  29 #define MNT_NOATIME     0x08
  30 #define MNT_NODIRATIME  0x10
  31 #define MNT_RELATIME    0x20
  32 #define MNT_READONLY    0x40    /* does the user want this to be r/o? */
  33
  34 #define MNT_SHRINKABLE  0x100
  35 #define MNT_IMBALANCED_WRITE_COUNT      0x200 /* just for debugging */
  36
  37 #define MNT_SHARED      0x1000  /* if the vfsmount is a shared mount */
  38 #define MNT_UNBINDABLE  0x2000  /* if the vfsmount is a unbindable mount */
  39 #define MNT_PNODE_MASK  0x3000  /* propagation flag mask */
  40
  41 struct vfsmount {
  42         struct list_head mnt_hash;
  43         struct vfsmount *mnt_parent;    /* fs we are mounted on */
  44         struct dentry *mnt_mountpoint;  /* dentry of mountpoint */
  45         struct dentry *mnt_root;        /* root of the mounted tree */
  46         struct super_block *mnt_sb;     /* pointer to superblock */
  47         struct list_head mnt_mounts;    /* list of children, anchored here */
  48         struct list_head mnt_child;     /* and going through their mnt_child */
  49         int mnt_flags;
  50         /* 4 bytes hole on 64bits arches */
  51         char *mnt_devname;              /* Name of device e.g. /dev/dsk/hda1 */
  52         struct list_head mnt_list;
  53         struct list_head mnt_expire;    /* link in fs-specific expiry list */
  54         struct list_head mnt_share;     /* circular list of shared mounts */
  55         struct list_head mnt_slave_list;/* list of slave mounts */
  56         struct list_head mnt_slave;     /* slave list entry */
  57         struct vfsmount *mnt_master;    /* slave is on master->mnt_slave_list */
  58         struct mnt_namespace *mnt_ns;   /* containing namespace */
  59         int mnt_id;                     /* mount identifier */
  60         int mnt_group_id;               /* peer group identifier */
  61         /*
  62          * We put mnt_count & mnt_expiry_mark at the end of struct vfsmount
  63          * to let these frequently modified fields in a separate cache line
  64          * (so that reads of mnt_flags wont ping-pong on SMP machines)
  65          */
  66         atomic_t mnt_count;
  67         int mnt_expiry_mark;            /* true if marked for expiry */
  68         int mnt_pinned;
  69         int mnt_ghosts;
  70         /*
  71          * This value is not stable unless all of the mnt_writers[] spinlocks
  72          * are held, and all mnt_writer[]s on this mount have 0 as their ->count
  73          */
  74         atomic_t __mnt_writers;
  75 };
  76
  77 static inline struct vfsmount *mntget(struct vfsmount *mnt)
  78 {
  79         if (mnt)
  80                 atomic_inc(&mnt->mnt_count);
  81         return mnt;
  82 }
  83
  84 extern int mnt_want_write(struct vfsmount *mnt);
  85 extern void mnt_drop_write(struct vfsmount *mnt);
  86 extern void mntput_no_expire(struct vfsmount *mnt);
  87 extern void mnt_pin(struct vfsmount *mnt);
  88 extern void mnt_unpin(struct vfsmount *mnt);
  89 extern int __mnt_is_readonly(struct vfsmount *mnt);
  90
  91 static inline void mntput(struct vfsmount *mnt)
  92 {
  93         if (mnt) {
  94                 mnt->mnt_expiry_mark = 0;
  95                 mntput_no_expire(mnt);
  96         }
  97 }
  98
  99 extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
 100                                       const char *name, void *data);
 101
 102 struct file_system_type;
 103 extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
 104                                       int flags, const char *name,
 105                                       void *data);
 106
 107 struct nameidata;
 108
 109 extern int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd,
 110                         int mnt_flags, struct list_head *fslist);
 111
 112 extern void mark_mounts_for_expiry(struct list_head *mounts);
 113
 114 extern spinlock_t vfsmount_lock;
 115 extern dev_t name_to_dev_t(char *name);
 116
 117 #endif
 118 #endif /* _LINUX_MOUNT_H */