2 * Copyright (c) 1994, 1995 The Regents of the University of California.
3 * Copyright (c) 1994, 1995 Jan-Simon Pendry.
6 * This code is derived from software donated to Berkeley by
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37 * @(#)union_vfsops.c 8.20 (Berkeley) 5/20/95
38 * $FreeBSD: src/sys/miscfs/union/union_vfsops.c,v 1.39.2.2 2001/10/25 19:18:53 dillon Exp $
39 * $DragonFly: src/sys/vfs/union/union_vfsops.c,v 1.29 2006/12/23 00:41:30 swildner Exp $
46 #include <sys/param.h>
47 #include <sys/systm.h>
48 #include <sys/kernel.h>
50 #include <sys/vnode.h>
51 #include <sys/mount.h>
52 #include <sys/nlookup.h>
53 #include <sys/namei.h>
54 #include <sys/malloc.h>
55 #include <sys/filedesc.h>
57 #include <vm/vm_zone.h>
59 extern struct vop_ops union_vnode_vops;
61 static MALLOC_DEFINE(M_UNIONFSMNT, "UNION mount", "UNION mount structure");
63 extern int union_init (struct vfsconf *);
64 static int union_mount (struct mount *mp, char *path, caddr_t data,
66 static int union_root (struct mount *mp, struct vnode **vpp);
67 static int union_statfs (struct mount *mp, struct statfs *sbp,
69 static int union_unmount (struct mount *mp, int mntflags);
72 * Mount union filesystem
75 union_mount(struct mount *mp, char *path, caddr_t data, struct ucred *cred)
78 struct union_args args;
79 struct vnode *lowerrootvp = NULLVP;
80 struct vnode *upperrootvp = NULLVP;
81 struct union_mount *um = 0;
82 struct ucred *cred = 0;
83 struct nlookupdata nd;
88 UDEBUG(("union_mount(mp = %p)\n", (void *)mp));
91 * Disable clustered write, otherwise system becomes unstable.
93 mp->mnt_flag |= MNT_NOCLUSTERW;
98 if (mp->mnt_flag & MNT_UPDATE) {
101 * 1. a way to convert between rdonly and rdwr mounts.
102 * 2. support for nfs exports.
111 error = copyin(data, (caddr_t)&args, sizeof(struct union_args));
116 * Obtain lower vnode.
119 lowerrootvp = mp->mnt_vnodecovered;
124 * Unlock lower node to avoid deadlock.
126 if (lowerrootvp->v_tag == VT_UNION)
127 vn_unlock(lowerrootvp);
131 * Obtain upper vnode by calling nlookup() on the path. The
132 * upperrootvp will be turned referenced but not locked.
134 error = nlookup_init(&nd, args.target, UIO_USERSPACE, NLC_FOLLOW);
136 error = nlookup(&nd);
138 error = cache_vref(&nd.nl_nch, nd.nl_cred, &upperrootvp);
143 UDEBUG(("mount_root UPPERVP %p locked = %d\n", upperrootvp,
144 vn_islocked(upperrootvp)));
147 * Check multi union mount to avoid `lock myself again' panic.
148 * Also require that it be a directory.
150 if (upperrootvp == VTOUNION(lowerrootvp)->un_uppervp) {
152 kprintf("union_mount: multi union mount?\n");
158 if (upperrootvp->v_type != VDIR) {
164 * Allocate our union_mount structure and populate the fields.
165 * The vnode references are stored in the union_mount as held,
166 * unlocked references. Depending on the _BELOW flag, the
167 * filesystems are viewed in a different order. In effect this
168 * is the same as providing a mount-under option to the mount
172 um = (struct union_mount *) malloc(sizeof(struct union_mount),
173 M_UNIONFSMNT, M_WAITOK);
175 bzero(um, sizeof(struct union_mount));
177 um->um_op = args.mntflags & UNMNT_OPMASK;
181 um->um_lowervp = lowerrootvp;
182 um->um_uppervp = upperrootvp;
188 um->um_lowervp = upperrootvp;
189 um->um_uppervp = lowerrootvp;
197 um->um_uppervp = upperrootvp;
198 um->um_lowervp = lowerrootvp;
208 * Unless the mount is readonly, ensure that the top layer
209 * supports whiteout operations
211 if ((mp->mnt_flag & MNT_RDONLY) == 0) {
212 error = VOP_WHITEOUT(um->um_uppervp, NULL, NAMEI_LOOKUP);
218 * File creds and modes for shadowed files are based on the user
219 * that did the mount.
221 um->um_cred = crhold(cred);
222 um->um_cmode = UN_DIRMODE;
224 um->um_cmode &= ~curproc->p_fd->fd_cmask;
227 * Depending on what you think the MNT_LOCAL flag might mean,
228 * you may want the && to be || on the conditional below.
229 * At the moment it has been defined that the filesystem is
230 * only local if it is all local, ie the MNT_LOCAL flag implies
231 * that the entire namespace is local. If you think the MNT_LOCAL
232 * flag implies that some of the files might be stored locally
233 * then you will want to change the conditional.
235 if (um->um_op == UNMNT_ABOVE) {
236 if (((um->um_lowervp == NULLVP) ||
237 (um->um_lowervp->v_mount->mnt_flag & MNT_LOCAL)) &&
238 (um->um_uppervp->v_mount->mnt_flag & MNT_LOCAL))
239 mp->mnt_flag |= MNT_LOCAL;
243 * Copy in the upper layer's RDONLY flag. This is for the benefit
244 * of lookup() which explicitly checks the flag, rather than asking
245 * the filesystem for its own opinion. This means, that an update
246 * mount of the underlying filesystem to go from rdonly to rdwr
247 * will leave the unioned view as read-only.
249 mp->mnt_flag |= (um->um_uppervp->v_mount->mnt_flag & MNT_RDONLY);
251 mp->mnt_data = (qaddr_t) um;
266 bcopy(cp, mp->mnt_stat.f_mntfromname, len);
268 cp = mp->mnt_stat.f_mntfromname + len;
269 len = MNAMELEN - len;
271 (void) copyinstr(args.target, cp, len - 1, &size);
272 bzero(cp + size, len - size);
274 vfs_add_vnodeops(mp, &union_vnode_vops, &mp->mnt_vn_norm_ops);
276 (void)union_statfs(mp, &mp->mnt_stat, cred);
283 vrele(um->um_uppervp);
285 vrele(um->um_lowervp);
286 /* XXX other fields */
287 kfree(um, M_UNIONFSMNT);
299 * Free reference to union layer
302 union_unmount(struct mount *mp, int mntflags)
304 struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
309 UDEBUG(("union_unmount(mp = %p)\n", (void *)mp));
311 if (mntflags & MNT_FORCE)
315 * Keep flushing vnodes from the mount list.
316 * This is needed because of the un_pvp held
317 * reference to the parent vnode.
318 * If more vnodes have been freed on a given pass,
319 * the try again. The loop will iterate at most
320 * (d) times, where (d) is the maximum tree depth
323 for (freeing = 0; (error = vflush(mp, 0, flags)) != 0;) {
324 int n = mp->mnt_nvnodelistsize;
326 /* if this is unchanged then stop */
330 /* otherwise try once more time */
334 /* If the most recent vflush failed, the filesystem is still busy. */
339 * Discard references to upper and lower target vnodes.
342 vrele(um->um_lowervp);
343 vrele(um->um_uppervp);
346 * Finally, throw away the union_mount structure
348 kfree(mp->mnt_data, M_UNIONFSMNT); /* XXX */
354 union_root(struct mount *mp, struct vnode **vpp)
356 struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
360 * Supply an unlocked reference to um_uppervp and to um_lowervp. It
361 * is possible for um_uppervp to be locked without the associated
362 * root union_node being locked. We let union_allocvp() deal with
365 UDEBUG(("union_root UPPERVP %p locked = %d\n", um->um_uppervp,
366 vn_islocked(um->um_uppervp)));
368 vref(um->um_uppervp);
370 vref(um->um_lowervp);
372 error = union_allocvp(vpp, mp, NULLVP, NULLVP, NULL,
373 um->um_uppervp, um->um_lowervp, 1);
374 UDEBUG(("error %d\n", error));
375 UDEBUG(("union_root2 UPPERVP %p locked = %d\n", um->um_uppervp,
376 vn_islocked(um->um_uppervp)));
382 union_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred)
385 struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
389 UDEBUG(("union_statfs(mp = %p, lvp = %p, uvp = %p)\n",
390 (void *)mp, (void *)um->um_lowervp, (void *)um->um_uppervp));
392 bzero(&mstat, sizeof(mstat));
394 if (um->um_lowervp) {
395 error = VFS_STATFS(um->um_lowervp->v_mount, &mstat, cred);
400 /* now copy across the "interesting" information and fake the rest */
402 sbp->f_type = mstat.f_type;
403 sbp->f_flags = mstat.f_flags;
404 sbp->f_bsize = mstat.f_bsize;
405 sbp->f_iosize = mstat.f_iosize;
407 lbsize = mstat.f_bsize;
408 sbp->f_blocks = mstat.f_blocks;
409 sbp->f_bfree = mstat.f_bfree;
410 sbp->f_bavail = mstat.f_bavail;
411 sbp->f_files = mstat.f_files;
412 sbp->f_ffree = mstat.f_ffree;
414 error = VFS_STATFS(um->um_uppervp->v_mount, &mstat, cred);
418 sbp->f_flags = mstat.f_flags;
419 sbp->f_bsize = mstat.f_bsize;
420 sbp->f_iosize = mstat.f_iosize;
423 * if the lower and upper blocksizes differ, then frig the
424 * block counts so that the sizes reported by df make some
425 * kind of sense. none of this makes sense though.
428 if (mstat.f_bsize != lbsize)
429 sbp->f_blocks = ((off_t) sbp->f_blocks * lbsize) / mstat.f_bsize;
432 * The "total" fields count total resources in all layers,
433 * the "free" fields count only those resources which are
434 * free in the upper layer (since only the upper layer
437 sbp->f_blocks += mstat.f_blocks;
438 sbp->f_bfree = mstat.f_bfree;
439 sbp->f_bavail = mstat.f_bavail;
440 sbp->f_files += mstat.f_files;
441 sbp->f_ffree = mstat.f_ffree;
443 if (sbp != &mp->mnt_stat) {
444 sbp->f_type = mp->mnt_vfc->vfc_typenum;
445 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid));
446 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
451 static struct vfsops union_vfsops = {
452 .vfs_mount = union_mount,
453 .vfs_unmount = union_unmount,
454 .vfs_root = union_root,
455 .vfs_statfs = union_statfs,
456 .vfs_sync = vfs_stdsync,
457 .vfs_init = union_init
460 VFS_SET(union_vfsops, union, VFCF_LOOPBACK);