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, nbd (qcow2, raw, vdi, qed)
  28  */
  29
  30 #include "config.h"
  31 #include <stdint.h>
  32 #include <lxc/lxccontainer.h>
  33
  34 struct bdev;
  35
  36 struct bdev_ops {
  37         /* detect whether path is of this bdev type */
  38         int (*detect)(const char *path);
  39         // mount requires src and dest to be set.
  40         int (*mount)(struct bdev *bdev);
  41         int (*umount)(struct bdev *bdev);
  42         int (*destroy)(struct bdev *bdev);
  43         int (*create)(struct bdev *bdev, const char *dest, const char *n,
  44                         struct bdev_specs *specs);
  45         /* given original mount, rename the paths for cloned container */
  46         int (*clone_paths)(struct bdev *orig, struct bdev *new, const char *oldname,
  47                         const char *cname, const char *oldpath, const char *lxcpath,
  48                         int snap, uint64_t newsize, struct lxc_conf *conf);
  49         bool can_snapshot;
  50         bool can_backup;
  51 };
  52
  53 /*
  54  * When lxc-start (conf.c) is mounting a rootfs, then src will be the
  55  * 'lxc.rootfs' value, dest will be mount dir (i.e. $libdir/lxc)  When clone
  56  * or create is doing so, then dest will be $lxcpath/$lxcname/rootfs, since
  57  * we may need to rsync from one to the other.
  58  * data is so far unused.
  59  */
  60 struct bdev {
  61         const struct bdev_ops *ops;
  62         const char *type;
  63         char *src;
  64         char *dest;
  65         char *mntopts;
  66         // turn the following into a union if need be
  67         // lofd is the open fd for the mounted loopback file
  68         int lofd;
  69         // index for the connected nbd device
  70         int nbd_idx;
  71 };
  72
  73 char *overlay_getlower(char *p);
  74
  75 bool bdev_is_dir(struct lxc_conf *conf, const char *path);
  76 bool bdev_can_backup(struct lxc_conf *conf);
  77
  78 /*
  79  * Instantiate a bdev object.  The src is used to determine which blockdev
  80  * type this should be.  The dst and data are optional, and will be used
  81  * in case of mount/umount.
  82  *
  83  * Optionally, src can be 'dir:/var/lib/lxc/c1' or 'lvm:/dev/lxc/c1'.  For
  84  * other backing stores, this will allow additional options.  In particular,
  85  * "overlayfs:/var/lib/lxc/canonical/rootfs:/var/lib/lxc/c1/delta" will mean
  86  * use /var/lib/lxc/canonical/rootfs as lower dir, and /var/lib/lxc/c1/delta
  87  * as the upper, writeable layer.
  88  */
  89 struct bdev *bdev_init(struct lxc_conf *conf, const char *src, const char *dst,
  90                         const char *data);
  91
  92 struct bdev *bdev_copy(struct lxc_container *c0, const char *cname,
  93                         const char *lxcpath, const char *bdevtype,
  94                         int flags, const char *bdevdata, uint64_t newsize,
  95                         int *needs_rdep);
  96 struct bdev *bdev_create(const char *dest, const char *type,
  97                         const char *cname, struct bdev_specs *specs);
  98 void bdev_put(struct bdev *bdev);
  99
 100 /*
 101  * these are really for qemu-nbd support, as container shutdown
 102  * must explicitly request device detach.
 103  */
 104 bool attach_block_device(struct lxc_conf *conf);
 105 void detach_block_device(struct lxc_conf *conf);
 106
 107 bool rootfs_is_blockdev(struct lxc_conf *conf);
 108
 109 /* define constants if the kernel/glibc headers don't define them */
 110 #ifndef MS_DIRSYNC
 111 #define MS_DIRSYNC  128
 112 #endif
 113
 114 #ifndef MS_REC
 115 #define MS_REC 16384
 116 #endif
 117
 118 #ifndef MNT_DETACH
 119 #define MNT_DETACH 2
 120 #endif
 121
 122 #ifndef MS_SLAVE
 123 #define MS_SLAVE (1<<19)
 124 #endif
 125
 126 #ifndef MS_RELATIME
 127 #define MS_RELATIME (1 << 21)
 128 #endif
 129
 130 #ifndef MS_STRICTATIME
 131 #define MS_STRICTATIME (1 << 24)
 132 #endif
 133
 134 #endif