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