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_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
  50 struct 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
  86 static 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
  95 static inline struct vfsmount *mntget(struct vfsmount *mnt)
  96 {
  97         if (mnt)
  98                 atomic_inc(&mnt->mnt_count);
  99         return mnt;
 100 }
 101
 102 struct file; /* forward dec */
 103
 104 extern int mnt_want_write(struct vfsmount *mnt);
 105 extern int mnt_want_write_file(struct file *file);
 106 extern int mnt_clone_write(struct vfsmount *mnt);
 107 extern void mnt_drop_write(struct vfsmount *mnt);
 108 extern void mntput_no_expire(struct vfsmount *mnt);
 109 extern void mnt_pin(struct vfsmount *mnt);
 110 extern void mnt_unpin(struct vfsmount *mnt);
 111 extern int __mnt_is_readonly(struct vfsmount *mnt);
 112
 113 static inline void mntput(struct vfsmount *mnt)
 114 {
 115         if (mnt) {
 116                 mnt->mnt_expiry_mark = 0;
 117                 mntput_no_expire(mnt);
 118         }
 119 }
 120
 121 extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
 122                                       const char *name, void *data);
 123
 124 struct file_system_type;
 125 extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
 126                                       int flags, const char *name,
 127                                       void *data);
 128
 129 struct nameidata;
 130
 131 struct path;
 132 extern int do_add_mount(struct vfsmount *newmnt, struct path *path,
 133                         int mnt_flags, struct list_head *fslist);
 134
 135 extern void mark_mounts_for_expiry(struct list_head *mounts);
 136
 137 extern dev_t name_to_dev_t(char *name);
 138
 139 #endif /* _LINUX_MOUNT_H */