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 struct vfsmount {
  49         struct list_head mnt_hash;
  50         struct vfsmount *mnt_parent;    /* fs we are mounted on */
  51         struct dentry *mnt_mountpoint;  /* dentry of mountpoint */
  52         struct dentry *mnt_root;        /* root of the mounted tree */
  53         struct super_block *mnt_sb;     /* pointer to superblock */
  54         struct list_head mnt_mounts;    /* list of children, anchored here */
  55         struct list_head mnt_child;     /* and going through their mnt_child */
  56         int mnt_flags;
  57         /* 4 bytes hole on 64bits arches */
  58         const char *mnt_devname;        /* Name of device e.g. /dev/dsk/hda1 */
  59         struct list_head mnt_list;
  60         struct list_head mnt_expire;    /* link in fs-specific expiry list */
  61         struct list_head mnt_share;     /* circular list of shared mounts */
  62         struct list_head mnt_slave_list;/* list of slave mounts */
  63         struct list_head mnt_slave;     /* slave list entry */
  64         struct vfsmount *mnt_master;    /* slave is on master->mnt_slave_list */
  65         struct mnt_namespace *mnt_ns;   /* containing namespace */
  66         int mnt_id;                     /* mount identifier */
  67         int mnt_group_id;               /* peer group identifier */
  68         /*
  69          * We put mnt_count & mnt_expiry_mark at the end of struct vfsmount
  70          * to let these frequently modified fields in a separate cache line
  71          * (so that reads of mnt_flags wont ping-pong on SMP machines)
  72          */
  73         atomic_t mnt_count;
  74         int mnt_expiry_mark;            /* true if marked for expiry */
  75         int mnt_pinned;
  76         int mnt_ghosts;
  77 #ifdef CONFIG_SMP
  78         int *mnt_writers;
  79 #else
  80         int mnt_writers;
  81 #endif
  82 };
  83
  84 static inline int *get_mnt_writers_ptr(struct vfsmount *mnt)
  85 {
  86 #ifdef CONFIG_SMP
  87         return mnt->mnt_writers;
  88 #else
  89         return &mnt->mnt_writers;
  90 #endif
  91 }
  92
  93 static inline struct vfsmount *mntget(struct vfsmount *mnt)
  94 {
  95         if (mnt)
  96                 atomic_inc(&mnt->mnt_count);
  97         return mnt;
  98 }
  99
 100 struct file; /* forward dec */
 101
 102 extern int mnt_want_write(struct vfsmount *mnt);
 103 extern int mnt_want_write_file(struct file *file);
 104 extern int mnt_clone_write(struct vfsmount *mnt);
 105 extern void mnt_drop_write(struct vfsmount *mnt);
 106 extern void mntput_no_expire(struct vfsmount *mnt);
 107 extern void mnt_pin(struct vfsmount *mnt);
 108 extern void mnt_unpin(struct vfsmount *mnt);
 109 extern int __mnt_is_readonly(struct vfsmount *mnt);
 110
 111 static inline void mntput(struct vfsmount *mnt)
 112 {
 113         if (mnt) {
 114                 mnt->mnt_expiry_mark = 0;
 115                 mntput_no_expire(mnt);
 116         }
 117 }
 118
 119 extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
 120                                       const char *name, void *data);
 121
 122 struct file_system_type;
 123 extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
 124                                       int flags, const char *name,
 125                                       void *data);
 126
 127 struct nameidata;
 128
 129 struct path;
 130 extern int do_add_mount(struct vfsmount *newmnt, struct path *path,
 131                         int mnt_flags, struct list_head *fslist);
 132
 133 extern void mark_mounts_for_expiry(struct list_head *mounts);
 134
 135 extern dev_t name_to_dev_t(char *name);
 136
 137 #endif /* _LINUX_MOUNT_H */