/* $NetBSD: null_vfsops.c,v 1.101 2023/02/06 10:32:58 hannken Exp $ */ /* * Copyright (c) 1999 National Aeronautics & Space Administration * All rights reserved. * * This software was written by William Studenmund of the * Numerical Aerospace Simulation Facility, NASA Ames Research Center. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the National Aeronautics & Space Administration * nor the names of its contributors may be used to endorse or promote * products derived from this software without specific prior written * permission. * * THIS SOFTWARE IS PROVIDED BY THE NATIONAL AERONAUTICS & SPACE ADMINISTRATION * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE ADMINISTRATION OR CONTRIB- * UTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * Copyright (c) 1992, 1993, 1995 * The Regents of the University of California. All rights reserved. * * This code is derived from software donated to Berkeley by * Jan-Simon Pendry. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * from: Id: lofs_vfsops.c,v 1.9 1992/05/30 10:26:24 jsp Exp * from: @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92 * @(#)null_vfsops.c 8.7 (Berkeley) 5/14/95 */ /* * Null file-system: VFS operations. * * See null_vnops.c for a description. */ #include <sys/cdefs.h> __KERNEL_RCSID(0, "$NetBSD: null_vfsops.c,v 1.101 2023/02/06 10:32:58 hannken Exp $"); #include <sys/param.h> #include <sys/systm.h> #include <sys/sysctl.h> #include <sys/vnode.h> #include <sys/mount.h> #include <sys/namei.h> #include <sys/module.h> #include <miscfs/nullfs/null.h> #include <miscfs/genfs/layer_extern.h> MODULE(MODULE_CLASS_VFS, null, "layerfs"); VFS_PROTOS(nullfs); int nullfs_mount(struct mount *mp, const char *path, void *data, size_t *data_len) { struct vnode *lowerrootvp, *vp; struct null_args *args = data; struct null_mount *nmp; struct layer_mount *lmp; struct pathbuf *pb; struct nameidata nd; int error; if (args == NULL) return EINVAL; if (*data_len < sizeof(*args)) return EINVAL; if (mp->mnt_flag & MNT_GETARGS) { lmp = MOUNTTOLAYERMOUNT(mp); if (lmp == NULL) return EIO; args->la.target = NULL; *data_len = sizeof(*args); return 0; } /* Update is not supported. */ if (mp->mnt_flag & MNT_UPDATE) return EOPNOTSUPP; /* Find the lower vnode and lock it. */ error = pathbuf_copyin(args->la.target, &pb); if (error) { return error; } NDINIT(&nd, LOOKUP, FOLLOW|LOCKLEAF, pb); if ((error = namei(&nd)) != 0) { pathbuf_destroy(pb); return error; } lowerrootvp = nd.ni_vp; pathbuf_destroy(pb); /* Create the mount point. */ nmp = kmem_zalloc(sizeof(struct null_mount), KM_SLEEP); mp->mnt_data = nmp; mp->mnt_iflag |= lowerrootvp->v_mount->mnt_iflag & IMNT_MPSAFE; mp->mnt_iflag |= lowerrootvp->v_mount->mnt_iflag & IMNT_SHRLOOKUP; /* * Make sure that the mount point is sufficiently initialized * that the node create call will work. */ vfs_getnewfsid(mp); error = vfs_set_lowermount(mp, lowerrootvp->v_mount); if (error) { vput(lowerrootvp); kmem_free(nmp, sizeof(struct null_mount)); return error; } nmp->nullm_size = sizeof(struct null_node); nmp->nullm_tag = VT_NULL; nmp->nullm_bypass = layer_bypass; nmp->nullm_vnodeop_p = null_vnodeop_p; /* Setup a null node for root vnode. */ VOP_UNLOCK(lowerrootvp); error = layer_node_create(mp, lowerrootvp, &vp); if (error) { vrele(lowerrootvp); kmem_free(nmp, sizeof(struct null_mount)); return error; } /* * Keep a held reference to the root vnode. It will be released on * umount. Note: nullfs is MP-safe. */ vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); vp->v_vflag |= VV_ROOT; nmp->nullm_rootvp = vp; VOP_UNLOCK(vp); error = set_statvfs_info(path, UIO_USERSPACE, args->la.target, UIO_USERSPACE, mp->mnt_op->vfs_name, mp, curlwp); if (error) return error; if (mp->mnt_lower->mnt_flag & MNT_LOCAL) mp->mnt_flag |= MNT_LOCAL; return 0; } int nullfs_unmount(struct mount *mp, int mntflags) { struct null_mount *nmp = MOUNTTONULLMOUNT(mp); struct vnode *null_rootvp = nmp->nullm_rootvp; int error, flags = 0; if (mntflags & MNT_FORCE) flags |= FORCECLOSE; if (vrefcnt(null_rootvp) > 1 && (mntflags & MNT_FORCE) == 0) return EBUSY; if ((error = vflush(mp, null_rootvp, flags)) != 0) return error; /* Eliminate all activity and release the vnode. */ vgone(null_rootvp); /* Finally, destroy the mount point structures. */ kmem_free(mp->mnt_data, sizeof(struct null_mount)); mp->mnt_data = NULL; return 0; } extern const struct vnodeopv_desc null_vnodeop_opv_desc; const struct vnodeopv_desc * const nullfs_vnodeopv_descs[] = { &null_vnodeop_opv_desc, NULL, }; struct vfsops nullfs_vfsops = { .vfs_name = MOUNT_NULL, .vfs_min_mount_data = sizeof (struct null_args), .vfs_mount = nullfs_mount, .vfs_start = layerfs_start, .vfs_unmount = nullfs_unmount, .vfs_root = layerfs_root, .vfs_quotactl = layerfs_quotactl, .vfs_statvfs = layerfs_statvfs, .vfs_sync = layerfs_sync, .vfs_loadvnode = layerfs_loadvnode, .vfs_vget = layerfs_vget, .vfs_fhtovp = layerfs_fhtovp, .vfs_vptofh = layerfs_vptofh, .vfs_init = layerfs_init, .vfs_done = layerfs_done, .vfs_snapshot = layerfs_snapshot, .vfs_extattrctl = vfs_stdextattrctl, .vfs_suspendctl = layerfs_suspendctl, .vfs_renamelock_enter = layerfs_renamelock_enter, .vfs_renamelock_exit = layerfs_renamelock_exit, .vfs_fsync = (void *)eopnotsupp, .vfs_opv_descs = nullfs_vnodeopv_descs }; SYSCTL_SETUP(nullfs_sysctl_setup, "nullfs sysctl") { sysctl_createv(clog, 0, NULL, NULL, CTLFLAG_PERMANENT, CTLTYPE_NODE, "null", SYSCTL_DESCR("Loopback file system"), NULL, 0, NULL, 0, CTL_VFS, 9, CTL_EOL); /* * XXX the "9" above could be dynamic, thereby eliminating * one more instance of the "number to vfs" mapping problem, * but "9" is the order as taken from sys/mount.h */ } static int null_modcmd(modcmd_t cmd, void *arg) { int error; switch (cmd) { case MODULE_CMD_INIT: error = vfs_attach(&nullfs_vfsops); if (error != 0) break; break; case MODULE_CMD_FINI: error = vfs_detach(&nullfs_vfsops); if (error != 0) break; break; default: error = ENOTTY; break; } return error; }
