sys/miscfs/overlay/overlay_vfsops.c

   1 /*      $NetBSD: overlay_vfsops.c,v 1.53 2008/06/28 01:34:06 rumble Exp $       */
   2
   3 /*
   4  * Copyright (c) 1999, 2000 National Aeronautics & Space Administration
   5  * All rights reserved.
   6  *
   7  * This software was written by William Studenmund of the
   8  * Numerical Aerospace Simulation Facility, NASA Ames Research Center.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the National Aeronautics & Space Administration
  19  *    nor the names of its contributors may be used to endorse or promote
  20  *    products derived from this software without specific prior written
  21  *    permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE NATIONAL AERONAUTICS & SPACE ADMINISTRATION
  24  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  25  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  26  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE ADMINISTRATION OR CONTRIB-
  27  * UTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
  28  * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  29  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  30  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  31  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  32  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  33  * POSSIBILITY OF SUCH DAMAGE.
  34  */
  35 /*
  36  * Copyright (c) 1992, 1993, 1995
  37  *      The Regents of the University of California.  All rights reserved.
  38  *
  39  * This code is derived from software donated to Berkeley by
  40  * Jan-Simon Pendry.
  41  *
  42  * Redistribution and use in source and binary forms, with or without
  43  * modification, are permitted provided that the following conditions
  44  * are met:
  45  * 1. Redistributions of source code must retain the above copyright
  46  *    notice, this list of conditions and the following disclaimer.
  47  * 2. Redistributions in binary form must reproduce the above copyright
  48  *    notice, this list of conditions and the following disclaimer in the
  49  *    documentation and/or other materials provided with the distribution.
  50  * 3. Neither the name of the University nor the names of its contributors
  51  *    may be used to endorse or promote products derived from this software
  52  *    without specific prior written permission.
  53  *
  54  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  55  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  56  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  57  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  58  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  59  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  60  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  61  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  62  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  63  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  64  * SUCH DAMAGE.
  65  *
  66  *      from: Id: lofs_vfsops.c,v 1.9 1992/05/30 10:26:24 jsp Exp
  67  *      from: @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92
  68  *      @(#)null_vfsops.c       8.7 (Berkeley) 5/14/95
  69  */
  70
  71 /*
  72  * Overlay Layer
  73  * (See overlay_vnops.c for a description of what this does.)
  74  */
  75
  76 #include <sys/cdefs.h>
  77 __KERNEL_RCSID(0, "$NetBSD: overlay_vfsops.c,v 1.53 2008/06/28 01:34:06 rumble Exp $");
  78
  79 #include <sys/param.h>
  80 #include <sys/systm.h>
  81 #include <sys/sysctl.h>
  82 #include <sys/time.h>
  83 #include <sys/proc.h>
  84 #include <sys/vnode.h>
  85 #include <sys/mount.h>
  86 #include <sys/namei.h>
  87 #include <sys/malloc.h>
  88 #include <sys/module.h>
  89 #include <miscfs/overlay/overlay.h>
  90 #include <miscfs/genfs/layer_extern.h>
  91
  92 MODULE(MODULE_CLASS_VFS, overlay, "layerfs");
  93
  94 VFS_PROTOS(ov);
  95
  96 static struct sysctllog *overlay_sysctl_log;
  97
  98 #define NOVERLAYNODECACHE       16
  99
 100 /*
 101  * Mount overlay layer
 102  */
 103 int
 104 ov_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
 105 {
 106         struct lwp *l = curlwp;
 107         int error = 0;
 108         struct overlay_args *args = data;
 109         struct vnode *lowerrootvp, *vp;
 110         struct overlay_mount *nmp;
 111         struct layer_mount *lmp;
 112
 113 #ifdef OVERLAYFS_DIAGNOSTIC
 114         printf("ov_mount(mp = %p)\n", mp);
 115 #endif
 116
 117         if (*data_len < sizeof *args)
 118                 return EINVAL;
 119
 120         if (mp->mnt_flag & MNT_GETARGS) {
 121                 lmp = MOUNTTOLAYERMOUNT(mp);
 122                 if (lmp == NULL)
 123                         return EIO;
 124                 args->la.target = NULL;
 125                 *data_len = sizeof *args;
 126                 return 0;
 127         }
 128
 129         /*
 130          * Update is not supported
 131          */
 132         if (mp->mnt_flag & MNT_UPDATE)
 133                 return EOPNOTSUPP;
 134
 135         /*
 136          * Find lower node
 137          */
 138         lowerrootvp = mp->mnt_vnodecovered;
 139         if ((error = vget(lowerrootvp, LK_EXCLUSIVE | LK_RETRY)))
 140                 return (error);
 141
 142         /*
 143          * First cut at fixing up upper mount point
 144          */
 145         nmp = (struct overlay_mount *) malloc(sizeof(struct overlay_mount),
 146                                 M_UFSMNT, M_WAITOK);    /* XXX */
 147         memset(nmp, 0, sizeof(struct overlay_mount));
 148
 149         mp->mnt_data = nmp;
 150         nmp->ovm_vfs = lowerrootvp->v_mount;
 151         if (nmp->ovm_vfs->mnt_flag & MNT_LOCAL)
 152                 mp->mnt_flag |= MNT_LOCAL;
 153
 154         /*
 155          * Make sure that the mount point is sufficiently initialized
 156          * that the node create call will work.
 157          */
 158         vfs_getnewfsid(mp);
 159
 160         nmp->ovm_size = sizeof (struct overlay_node);
 161         nmp->ovm_tag = VT_OVERLAY;
 162         nmp->ovm_bypass = layer_bypass;
 163         nmp->ovm_alloc = layer_node_alloc;      /* the default alloc is fine */
 164         nmp->ovm_vnodeop_p = overlay_vnodeop_p;
 165         mutex_init(&nmp->ovm_hashlock, MUTEX_DEFAULT, IPL_NONE);
 166         nmp->ovm_node_hashtbl = hashinit(NOVERLAYNODECACHE, HASH_LIST, true,
 167              &nmp->ovm_node_hash);
 168
 169         /*
 170          * Fix up overlay node for root vnode
 171          */
 172         error = layer_node_create(mp, lowerrootvp, &vp);
 173         /*
 174          * Make sure the fixup worked
 175          */
 176         if (error) {
 177                 vput(lowerrootvp);
 178                 hashdone(nmp->ovm_node_hashtbl, HASH_LIST, nmp->ovm_node_hash);
 179                 free(nmp, M_UFSMNT);    /* XXX */
 180                 return (error);
 181         }
 182         /*
 183          * Unlock the node
 184          */
 185         VOP_UNLOCK(vp, 0);
 186
 187         /*
 188          * Keep a held reference to the root vnode.
 189          * It is vrele'd in ov_unmount.
 190          */
 191         vp->v_vflag |= VV_ROOT;
 192         nmp->ovm_rootvp = vp;
 193
 194         error = set_statvfs_info(path, UIO_USERSPACE, args->la.target,
 195             UIO_USERSPACE, mp->mnt_op->vfs_name, mp, l);
 196 #ifdef OVERLAYFS_DIAGNOSTIC
 197         printf("ov_mount: lower %s, alias at %s\n",
 198             mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
 199 #endif
 200         return error;
 201 }
 202
 203 /*
 204  * Free reference to overlay layer
 205  */
 206 int
 207 ov_unmount(struct mount *mp, int mntflags)
 208 {
 209         struct vnode *overlay_rootvp = MOUNTTOOVERLAYMOUNT(mp)->ovm_rootvp;
 210         struct overlay_mount *omp;
 211         int error;
 212         int flags = 0;
 213
 214 #ifdef OVERLAYFS_DIAGNOSTIC
 215         printf("ov_unmount(mp = %p)\n", mp);
 216 #endif
 217
 218         if (mntflags & MNT_FORCE)
 219                 flags |= FORCECLOSE;
 220
 221         if (overlay_rootvp->v_usecount > 1 && (mntflags & MNT_FORCE) == 0)
 222                 return (EBUSY);
 223         if ((error = vflush(mp, overlay_rootvp, flags)) != 0)
 224                 return (error);
 225
 226 #ifdef OVERLAYFS_DIAGNOSTIC
 227         vprint("alias root of lower", overlay_rootvp);
 228 #endif
 229         /*
 230          * Blow it away for future re-use
 231          */
 232         vgone(overlay_rootvp);
 233         /*
 234          * Finally, throw away the overlay_mount structure
 235          */
 236         omp = mp->mnt_data;
 237         mutex_destroy(&omp->ovm_hashlock);
 238         hashdone(omp->ovm_node_hashtbl, HASH_LIST, omp->ovm_node_hash);
 239         free(omp, M_UFSMNT);    /* XXX */
 240         mp->mnt_data = NULL;
 241         return 0;
 242 }
 243
 244 extern const struct vnodeopv_desc overlay_vnodeop_opv_desc;
 245
 246 const struct vnodeopv_desc * const ov_vnodeopv_descs[] = {
 247         &overlay_vnodeop_opv_desc,
 248         NULL,
 249 };
 250
 251 struct vfsops overlay_vfsops = {
 252         MOUNT_OVERLAY,
 253         sizeof (struct overlay_args),
 254         ov_mount,
 255         layerfs_start,
 256         ov_unmount,
 257         layerfs_root,
 258         layerfs_quotactl,
 259         layerfs_statvfs,
 260         layerfs_sync,
 261         layerfs_vget,
 262         layerfs_fhtovp,
 263         layerfs_vptofh,
 264         layerfs_init,
 265         NULL,
 266         layerfs_done,
 267         NULL,                           /* vfs_mountroot */
 268         layerfs_snapshot,
 269         vfs_stdextattrctl,
 270         (void *)eopnotsupp,             /* vfs_suspendctl */
 271         layerfs_renamelock_enter,
 272         layerfs_renamelock_exit,
 273         (void *)eopnotsupp,
 274         ov_vnodeopv_descs,
 275         0,
 276         { NULL, NULL },
 277 };
 278
 279 static int
 280 overlay_modcmd(modcmd_t cmd, void *arg)
 281 {
 282         int error;
 283
 284         switch (cmd) {
 285         case MODULE_CMD_INIT:
 286                 error = vfs_attach(&overlay_vfsops);
 287                 if (error != 0)
 288                         break;
 289                 sysctl_createv(&overlay_sysctl_log, 0, NULL, NULL,
 290                                CTLFLAG_PERMANENT, CTLTYPE_NODE, "vfs", NULL,
 291                                NULL, 0, NULL, 0,
 292                                CTL_VFS, CTL_EOL);
 293                 sysctl_createv(&overlay_sysctl_log, 0, NULL, NULL,
 294                                CTLFLAG_PERMANENT, CTLTYPE_NODE, "overlay",
 295                                SYSCTL_DESCR("Overlay file system"),
 296                                NULL, 0, NULL, 0,
 297                                CTL_VFS, CTL_CREATE, CTL_EOL);
 298                 break;
 299         case MODULE_CMD_FINI:
 300                 error = vfs_detach(&overlay_vfsops);
 301                 if (error != 0)
 302                         break;
 303                 sysctl_teardown(&overlay_sysctl_log);
 304                 break;
 305         default:
 306                 error = ENOTTY;
 307                 break;
 308         }
 309
 310         return (error);
 311 }