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
  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
  38 struct 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
  74 static inline struct vfsmount *mntget(struct vfsmount *mnt)
  75 {
  76         if (mnt)
  77                 atomic_inc(&mnt->mnt_count);
  78         return mnt;
  79 }
  80
  81 extern int mnt_want_write(struct vfsmount *mnt);
  82 extern void mnt_drop_write(struct vfsmount *mnt);
  83 extern void mntput_no_expire(struct vfsmount *mnt);
  84 extern void mnt_pin(struct vfsmount *mnt);
  85 extern void mnt_unpin(struct vfsmount *mnt);
  86 extern int __mnt_is_readonly(struct vfsmount *mnt);
  87
  88 static inline void mntput(struct vfsmount *mnt)
  89 {
  90         if (mnt) {
  91                 mnt->mnt_expiry_mark = 0;
  92                 mntput_no_expire(mnt);
  93         }
  94 }
  95
  96 extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
  97                                       const char *name, void *data);
  98
  99 struct file_system_type;
 100 extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
 101                                       int flags, const char *name,
 102                                       void *data);
 103
 104 struct nameidata;
 105
 106 struct path;
 107 extern int do_add_mount(struct vfsmount *newmnt, struct path *path,
 108                         int mnt_flags, struct list_head *fslist);
 109
 110 extern void mark_mounts_for_expiry(struct list_head *mounts);
 111
 112 extern spinlock_t vfsmount_lock;
 113 extern dev_t name_to_dev_t(char *name);
 114
 115 #endif /* _LINUX_MOUNT_H */