/* * Copyright (c) 1994, 1995 The Regents of the University of California. * Copyright (c) 1994, 1995 Jan-Simon Pendry. * 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. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. 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. * * @(#)union_vfsops.c 8.20 (Berkeley) 5/20/95 * $FreeBSD: src/sys/miscfs/union/union_vfsops.c,v 1.39.2.2 2001/10/25 19:18:53 dillon Exp $ * $DragonFly: src/sys/vfs/union/union_vfsops.c,v 1.19 2005/02/02 21:34:19 joerg Exp $ */ /* * Union Layer */ #include #include #include #include #include #include #include #include #include #include #include "union.h" #include extern struct vnodeopv_entry_desc union_vnodeop_entries[]; static MALLOC_DEFINE(M_UNIONFSMNT, "UNION mount", "UNION mount structure"); extern int union_init (struct vfsconf *); static int union_mount (struct mount *mp, char *path, caddr_t data, struct thread *td); static int union_root (struct mount *mp, struct vnode **vpp); static int union_statfs (struct mount *mp, struct statfs *sbp, struct thread *td); static int union_unmount (struct mount *mp, int mntflags, struct thread *td); /* * Mount union filesystem */ static int union_mount(struct mount *mp, char *path, caddr_t data, struct thread *td) { int error = 0; struct union_args args; struct vnode *lowerrootvp = NULLVP; struct vnode *upperrootvp = NULLVP; struct union_mount *um = 0; struct ucred *cred = 0; struct nlookupdata nd; char *cp = 0; int len; u_int size; UDEBUG(("union_mount(mp = %p)\n", (void *)mp)); KKASSERT(td->td_proc); /* * Disable clustered write, otherwise system becomes unstable. */ mp->mnt_flag |= MNT_NOCLUSTERW; /* * Update is a no-op */ if (mp->mnt_flag & MNT_UPDATE) { /* * Need to provide. * 1. a way to convert between rdonly and rdwr mounts. * 2. support for nfs exports. */ error = EOPNOTSUPP; goto bad; } /* * Get argument */ error = copyin(data, (caddr_t)&args, sizeof(struct union_args)); if (error) goto bad; /* * Obtain lower vnode. Vnode is stored in mp->mnt_vnodecovered. * We need to reference it but not lock it. */ lowerrootvp = mp->mnt_vnodecovered; vref(lowerrootvp); #if 0 /* * Unlock lower node to avoid deadlock. */ if (lowerrootvp->v_tag == VT_UNION) VOP_UNLOCK(lowerrootvp, 0, td); #endif /* * Obtain upper vnode by calling nlookup() on the path. The * upperrootvp will be turned referenced but not locked. */ error = nlookup_init(&nd, args.target, UIO_USERSPACE, NLC_FOLLOW); if (error == 0) error = nlookup(&nd); if (error == 0) error = cache_vref(nd.nl_ncp, nd.nl_cred, &upperrootvp); nlookup_done(&nd); if (error) goto bad; UDEBUG(("mount_root UPPERVP %p locked = %d\n", upperrootvp, VOP_ISLOCKED(upperrootvp, NULL))); /* * Check multi union mount to avoid `lock myself again' panic. * Also require that it be a directory. */ if (upperrootvp == VTOUNION(lowerrootvp)->un_uppervp) { #ifdef DIAGNOSTIC printf("union_mount: multi union mount?\n"); #endif error = EDEADLK; goto bad; } if (upperrootvp->v_type != VDIR) { error = EINVAL; goto bad; } /* * Allocate our union_mount structure and populate the fields. * The vnode references are stored in the union_mount as held, * unlocked references. Depending on the _BELOW flag, the * filesystems are viewed in a different order. In effect this * is the same as providing a mount-under option to the mount * syscall. */ um = (struct union_mount *) malloc(sizeof(struct union_mount), M_UNIONFSMNT, M_WAITOK); bzero(um, sizeof(struct union_mount)); um->um_op = args.mntflags & UNMNT_OPMASK; switch (um->um_op) { case UNMNT_ABOVE: um->um_lowervp = lowerrootvp; um->um_uppervp = upperrootvp; upperrootvp = NULL; lowerrootvp = NULL; break; case UNMNT_BELOW: um->um_lowervp = upperrootvp; um->um_uppervp = lowerrootvp; upperrootvp = NULL; lowerrootvp = NULL; break; case UNMNT_REPLACE: vrele(lowerrootvp); lowerrootvp = NULL; um->um_uppervp = upperrootvp; um->um_lowervp = lowerrootvp; upperrootvp = NULL; break; default: error = EINVAL; goto bad; } /* * Unless the mount is readonly, ensure that the top layer * supports whiteout operations */ if ((mp->mnt_flag & MNT_RDONLY) == 0) { error = VOP_WHITEOUT(um->um_uppervp, NULL, NAMEI_LOOKUP); if (error) goto bad; } um->um_cred = crhold(td->td_proc->p_ucred); um->um_cmode = UN_DIRMODE & ~td->td_proc->p_fd->fd_cmask; /* * Depending on what you think the MNT_LOCAL flag might mean, * you may want the && to be || on the conditional below. * At the moment it has been defined that the filesystem is * only local if it is all local, ie the MNT_LOCAL flag implies * that the entire namespace is local. If you think the MNT_LOCAL * flag implies that some of the files might be stored locally * then you will want to change the conditional. */ if (um->um_op == UNMNT_ABOVE) { if (((um->um_lowervp == NULLVP) || (um->um_lowervp->v_mount->mnt_flag & MNT_LOCAL)) && (um->um_uppervp->v_mount->mnt_flag & MNT_LOCAL)) mp->mnt_flag |= MNT_LOCAL; } /* * Copy in the upper layer's RDONLY flag. This is for the benefit * of lookup() which explicitly checks the flag, rather than asking * the filesystem for its own opinion. This means, that an update * mount of the underlying filesystem to go from rdonly to rdwr * will leave the unioned view as read-only. */ mp->mnt_flag |= (um->um_uppervp->v_mount->mnt_flag & MNT_RDONLY); mp->mnt_data = (qaddr_t) um; vfs_getnewfsid(mp); switch (um->um_op) { case UNMNT_ABOVE: cp = ":"; break; case UNMNT_BELOW: cp = ":"; break; case UNMNT_REPLACE: cp = ""; break; } len = strlen(cp); bcopy(cp, mp->mnt_stat.f_mntfromname, len); cp = mp->mnt_stat.f_mntfromname + len; len = MNAMELEN - len; (void) copyinstr(args.target, cp, len - 1, &size); bzero(cp + size, len - size); vfs_add_vnodeops(mp, &mp->mnt_vn_norm_ops, union_vnodeop_entries); (void)union_statfs(mp, &mp->mnt_stat, td); return (0); bad: if (um) { if (um->um_uppervp) vrele(um->um_uppervp); if (um->um_lowervp) vrele(um->um_lowervp); /* XXX other fields */ free(um, M_UNIONFSMNT); } if (cred) crfree(cred); if (upperrootvp) vrele(upperrootvp); if (lowerrootvp) vrele(lowerrootvp); return (error); } /* * Free reference to union layer */ static int union_unmount(struct mount *mp, int mntflags, struct thread *td) { struct union_mount *um = MOUNTTOUNIONMOUNT(mp); int error; int freeing; int flags = 0; UDEBUG(("union_unmount(mp = %p)\n", (void *)mp)); if (mntflags & MNT_FORCE) flags |= FORCECLOSE; /* * Keep flushing vnodes from the mount list. * This is needed because of the un_pvp held * reference to the parent vnode. * If more vnodes have been freed on a given pass, * the try again. The loop will iterate at most * (d) times, where (d) is the maximum tree depth * in the filesystem. */ for (freeing = 0; (error = vflush(mp, 0, flags)) != 0;) { int n = mp->mnt_nvnodelistsize; /* if this is unchanged then stop */ if (n == freeing) break; /* otherwise try once more time */ freeing = n; } /* If the most recent vflush failed, the filesystem is still busy. */ if (error) return (error); /* * Discard references to upper and lower target vnodes. */ if (um->um_lowervp) vrele(um->um_lowervp); vrele(um->um_uppervp); crfree(um->um_cred); /* * Finally, throw away the union_mount structure */ free(mp->mnt_data, M_UNIONFSMNT); /* XXX */ mp->mnt_data = 0; return (0); } static int union_root(struct mount *mp, struct vnode **vpp) { struct union_mount *um = MOUNTTOUNIONMOUNT(mp); int error; /* * Supply an unlocked reference to um_uppervp and to um_lowervp. It * is possible for um_uppervp to be locked without the associated * root union_node being locked. We let union_allocvp() deal with * it. */ UDEBUG(("union_root UPPERVP %p locked = %d\n", um->um_uppervp, VOP_ISLOCKED(um->um_uppervp, NULL))); vref(um->um_uppervp); if (um->um_lowervp) vref(um->um_lowervp); error = union_allocvp(vpp, mp, NULLVP, NULLVP, NULL, um->um_uppervp, um->um_lowervp, 1); UDEBUG(("error %d\n", error)); UDEBUG(("union_root2 UPPERVP %p locked = %d\n", um->um_uppervp, VOP_ISLOCKED(um->um_uppervp, NULL))); return (error); } static int union_statfs(struct mount *mp, struct statfs *sbp, struct thread *td) { int error; struct union_mount *um = MOUNTTOUNIONMOUNT(mp); struct statfs mstat; int lbsize; UDEBUG(("union_statfs(mp = %p, lvp = %p, uvp = %p)\n", (void *)mp, (void *)um->um_lowervp, (void *)um->um_uppervp)); bzero(&mstat, sizeof(mstat)); if (um->um_lowervp) { error = VFS_STATFS(um->um_lowervp->v_mount, &mstat, td); if (error) return (error); } /* now copy across the "interesting" information and fake the rest */ #if 0 sbp->f_type = mstat.f_type; sbp->f_flags = mstat.f_flags; sbp->f_bsize = mstat.f_bsize; sbp->f_iosize = mstat.f_iosize; #endif lbsize = mstat.f_bsize; sbp->f_blocks = mstat.f_blocks; sbp->f_bfree = mstat.f_bfree; sbp->f_bavail = mstat.f_bavail; sbp->f_files = mstat.f_files; sbp->f_ffree = mstat.f_ffree; error = VFS_STATFS(um->um_uppervp->v_mount, &mstat, td); if (error) return (error); sbp->f_flags = mstat.f_flags; sbp->f_bsize = mstat.f_bsize; sbp->f_iosize = mstat.f_iosize; /* * if the lower and upper blocksizes differ, then frig the * block counts so that the sizes reported by df make some * kind of sense. none of this makes sense though. */ if (mstat.f_bsize != lbsize) sbp->f_blocks = ((off_t) sbp->f_blocks * lbsize) / mstat.f_bsize; /* * The "total" fields count total resources in all layers, * the "free" fields count only those resources which are * free in the upper layer (since only the upper layer * is writeable). */ sbp->f_blocks += mstat.f_blocks; sbp->f_bfree = mstat.f_bfree; sbp->f_bavail = mstat.f_bavail; sbp->f_files += mstat.f_files; sbp->f_ffree = mstat.f_ffree; if (sbp != &mp->mnt_stat) { sbp->f_type = mp->mnt_vfc->vfc_typenum; bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid)); bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN); } return (0); } static struct vfsops union_vfsops = { union_mount, vfs_stdstart, /* underlying start already done */ union_unmount, union_root, vfs_stdquotactl, union_statfs, vfs_stdsync, /* XXX assumes no cached data on union level */ vfs_stdvget, vfs_stdfhtovp, vfs_stdcheckexp, vfs_stdvptofh, union_init, vfs_stduninit, vfs_stdextattrctl, }; VFS_SET(union_vfsops, union, VFCF_LOOPBACK);