src/lxc/bdev.h

   1 /*
   2  * lxc: linux Container library
   3  *
   4  * (C) Copyright IBM Corp. 2007, 2008
   5  *
   6  * Authors:
   7  * Daniel Lezcano <daniel.lezcano at free.fr>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #ifndef __LXC_BDEV_H
  25 #define __LXC_BDEV_H
  26 /* blockdev operations for:
  27  * aufs, dir, raw, btrfs, overlayfs, aufs, lvm, loop, zfs
  28  * someday: qemu-nbd, qcow2, qed
  29  */
  30
  31 #include "config.h"
  32 #include <stdint.h>
  33 #include <lxc/lxccontainer.h>
  34
  35 struct bdev;
  36
  37 /*
  38  * specifications for how to create a new backing store
  39  */
  40 struct bdev_specs {
  41         char *fstype;
  42         uint64_t fssize;  // fs size in bytes
  43         struct {
  44                 char *zfsroot;
  45         } zfs;
  46         struct {
  47                 char *vg;
  48                 char *lv;
  49                 char *thinpool; // lvm thin pool to use, if any
  50         } lvm;
  51 };
  52
  53 struct bdev_ops {
  54         /* detect whether path is of this bdev type */
  55         int (*detect)(const char *path);
  56         // mount requires src and dest to be set.
  57         int (*mount)(struct bdev *bdev);
  58         int (*umount)(struct bdev *bdev);
  59         int (*destroy)(struct bdev *bdev);
  60         int (*create)(struct bdev *bdev, const char *dest, const char *n,
  61                         struct bdev_specs *specs);
  62         /* given original mount, rename the paths for cloned container */
  63         int (*clone_paths)(struct bdev *orig, struct bdev *new, const char *oldname,
  64                         const char *cname, const char *oldpath, const char *lxcpath,
  65                         int snap, uint64_t newsize);
  66         bool can_snapshot;
  67 };
  68
  69 /*
  70  * When lxc-start (conf.c) is mounting a rootfs, then src will be the
  71  * 'lxc.rootfs' value, dest will be mount dir (i.e. $libdir/lxc)  When clone
  72  * or create is doing so, then dest will be $lxcpath/$lxcname/rootfs, since
  73  * we may need to rsync from one to the other.
  74  * data is so far unused.
  75  */
  76 struct bdev {
  77         const struct bdev_ops *ops;
  78         const char *type;
  79         char *src;
  80         char *dest;
  81         char *mntopts;
  82         // turn the following into a union if need be
  83         // lofd is the open fd for the mounted loopback file
  84         int lofd;
  85 };
  86
  87 char *overlay_getlower(char *p);
  88
  89 bool bdev_is_dir(const char *path);
  90
  91 /*
  92  * Instantiate a bdev object.  The src is used to determine which blockdev
  93  * type this should be.  The dst and data are optional, and will be used
  94  * in case of mount/umount.
  95  *
  96  * Optionally, src can be 'dir:/var/lib/lxc/c1' or 'lvm:/dev/lxc/c1'.  For
  97  * other backing stores, this will allow additional options.  In particular,
  98  * "overlayfs:/var/lib/lxc/canonical/rootfs:/var/lib/lxc/c1/delta" will mean
  99  * use /var/lib/lxc/canonical/rootfs as lower dir, and /var/lib/lxc/c1/delta
 100  * as the upper, writeable layer.
 101  */
 102 struct bdev *bdev_init(const char *src, const char *dst, const char *data);
 103
 104 struct bdev *bdev_copy(struct lxc_container *c0, const char *cname,
 105                         const char *lxcpath, const char *bdevtype,
 106                         int flags, const char *bdevdata, uint64_t newsize,
 107                         int *needs_rdep);
 108 struct bdev *bdev_create(const char *dest, const char *type,
 109                         const char *cname, struct bdev_specs *specs);
 110 void bdev_put(struct bdev *bdev);
 111
 112 /* define constants if the kernel/glibc headers don't define them */
 113 #ifndef MS_DIRSYNC
 114 #define MS_DIRSYNC  128
 115 #endif
 116
 117 #ifndef MS_REC
 118 #define MS_REC 16384
 119 #endif
 120
 121 #ifndef MNT_DETACH
 122 #define MNT_DETACH 2
 123 #endif
 124
 125 #ifndef MS_SLAVE
 126 #define MS_SLAVE (1<<19)
 127 #endif
 128
 129 #ifndef MS_RELATIME
 130 #define MS_RELATIME (1 << 21)
 131 #endif
 132
 133 #ifndef MS_STRICTATIME
 134 #define MS_STRICTATIME (1 << 24)
 135 #endif
 136
 137 #endif