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Diffstat (limited to 'sys/fs/unionfs/union_vfsops.c')
-rw-r--r-- | sys/fs/unionfs/union_vfsops.c | 509 |
1 files changed, 509 insertions, 0 deletions
diff --git a/sys/fs/unionfs/union_vfsops.c b/sys/fs/unionfs/union_vfsops.c new file mode 100644 index 0000000..8b58e55 --- /dev/null +++ b/sys/fs/unionfs/union_vfsops.c @@ -0,0 +1,509 @@ +/* + * 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 + * $FreeBSD$ + */ + +/* + * Union Layer + */ + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/kernel.h> +#include <sys/proc.h> +#include <sys/vnode.h> +#include <sys/mount.h> +#include <sys/namei.h> +#include <sys/malloc.h> +#include <sys/filedesc.h> +#include <miscfs/union/union.h> +#include <vm/vm_zone.h> + +static MALLOC_DEFINE(M_UNIONFSMNT, "UNION mount", "UNION mount structure"); + +extern int union_init __P((struct vfsconf *)); +static int union_mount __P((struct mount *mp, char *path, caddr_t data, + struct nameidata *ndp, struct proc *p)); +static int union_root __P((struct mount *mp, struct vnode **vpp)); +static int union_statfs __P((struct mount *mp, struct statfs *sbp, + struct proc *p)); +static int union_unmount __P((struct mount *mp, int mntflags, + struct proc *p)); + +/* + * Mount union filesystem + */ +static int +union_mount(mp, path, data, ndp, p) + struct mount *mp; + char *path; + caddr_t data; + struct nameidata *ndp; + struct proc *p; +{ + int error = 0; + struct union_args args; + struct vnode *lowerrootvp = NULLVP; + struct vnode *upperrootvp = NULLVP; + struct union_mount *um = 0; + struct ucred *cred = 0; + char *cp = 0; + int len; + u_int size; + + UDEBUG(("union_mount(mp = %p)\n", (void *)mp)); + + /* + * 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_op == union_vnodeop_p) + VOP_UNLOCK(lowerrootvp, 0, p); +#endif + + /* + * Obtain upper vnode by calling namei() on the path. The + * upperrootvp will be turned referenced but not locked. + */ + NDINIT(ndp, LOOKUP, FOLLOW|WANTPARENT, + UIO_USERSPACE, args.target, p); + + error = namei(ndp); + +#if 0 + if (lowerrootvp->v_op == union_vnodeop_p) + vn_lock(lowerrootvp, LK_EXCLUSIVE | LK_RETRY, p); +#endif + if (error) + goto bad; + + NDFREE(ndp, NDF_ONLY_PNBUF); + upperrootvp = ndp->ni_vp; + vrele(ndp->ni_dvp); + ndp->ni_dvp = NULL; + + 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, LOOKUP); + if (error) + goto bad; + } + + um->um_cred = p->p_ucred; + crhold(um->um_cred); + um->um_cmode = UN_DIRMODE &~ p->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); + + (void) copyinstr(path, mp->mnt_stat.f_mntonname, MNAMELEN - 1, &size); + bzero(mp->mnt_stat.f_mntonname + size, MNAMELEN - size); + + switch (um->um_op) { + case UNMNT_ABOVE: + cp = "<above>:"; + break; + case UNMNT_BELOW: + cp = "<below>:"; + 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); + + (void)union_statfs(mp, &mp->mnt_stat, p); + + UDEBUG(("union_mount: from %s, on %s\n", + mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname)); + 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(mp, mntflags, p) + struct mount *mp; + int mntflags; + struct proc *p; +{ + struct union_mount *um = MOUNTTOUNIONMOUNT(mp); + struct vnode *um_rootvp; + int error; + int freeing; + int flags = 0; + + UDEBUG(("union_unmount(mp = %p)\n", (void *)mp)); + + if (mntflags & MNT_FORCE) + flags |= FORCECLOSE; + + if ((error = union_root(mp, &um_rootvp)) != 0) + return (error); + + /* + * 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; vflush(mp, um_rootvp, flags) != 0;) { + struct vnode *vp; + int n; + + /* count #vnodes held on mount list */ + for (n = 0, vp = mp->mnt_vnodelist.lh_first; + vp != NULLVP; + vp = vp->v_mntvnodes.le_next) + n++; + + /* if this is unchanged then stop */ + if (n == freeing) + break; + + /* otherwise try once more time */ + freeing = n; + } + + /* At this point the root vnode should have a single reference */ + if (um_rootvp->v_usecount > 1) { + vput(um_rootvp); + return (EBUSY); + } + +#ifdef DEBUG + vprint("union root", um_rootvp); +#endif + /* + * Discard references to upper and lower target vnodes. + */ + if (um->um_lowervp) + vrele(um->um_lowervp); + vrele(um->um_uppervp); + crfree(um->um_cred); + /* + * Release reference on underlying root vnode + */ + vput(um_rootvp); + /* + * And blow it away for future re-use + */ + vgone(um_rootvp); + /* + * Finally, throw away the union_mount structure + */ + free(mp->mnt_data, M_UNIONFSMNT); /* XXX */ + mp->mnt_data = 0; + return (0); +} + +static int +union_root(mp, vpp) + 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(mp, sbp, p) + struct mount *mp; + struct statfs *sbp; + struct proc *p; +{ + 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, p); + 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, p); + 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_mntonname, sbp->f_mntonname, MNAMELEN); + 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); |