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32 * @(#)null_vfsops.c 8.2 (Berkeley) 1/21/94
34 * @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92
35 * $FreeBSD: src/sys/miscfs/nullfs/null_vfsops.c,v 1.35.2.3 2001/07/26 20:37:11 iedowse Exp $
36 * $DragonFly: src/sys/vfs/nullfs/null_vfsops.c,v 1.31 2008/09/17 21:44:25 dillon Exp $
41 * (See null_vnops.c for a description of what this does.)
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/kernel.h>
48 #include <sys/malloc.h>
49 #include <sys/vnode.h>
50 #include <sys/mount.h>
51 #include <sys/namecache.h>
52 #include <sys/nlookup.h>
53 #include <sys/mountctl.h>
56 extern struct vop_ops null_vnode_vops;
58 static MALLOC_DEFINE(M_NULLFSMNT, "NULLFS mount", "NULLFS mount structure");
60 static int nullfs_root(struct mount *mp, struct vnode **vpp);
61 static int nullfs_statfs(struct mount *mp, struct statfs *sbp,
68 nullfs_mount(struct mount *mp, char *path, caddr_t data, struct ucred *cred)
71 struct null_args args;
73 struct null_mount *xmp;
75 struct nlookupdata nd;
78 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp);
83 error = copyin(data, (caddr_t)&args, sizeof(struct null_args));
88 * XXX: Should we process mount export info ?
89 * If not, returning zero here is enough as the actual ro/rw update is
90 * being done in sys_mount().
92 if (mp->mnt_flag & MNT_UPDATE) {
93 xmp = MOUNTTONULLMOUNT(mp);
94 error = vfs_export(mp, &xmp->export, &args.export);
102 error = nlookup_init(&nd, args.target, UIO_USERSPACE, NLC_FOLLOW);
105 error = nlookup(&nd);
108 error = cache_vget(&nd.nl_nch, nd.nl_cred, LK_EXCLUSIVE, &rootvp);
112 xmp = (struct null_mount *) kmalloc(sizeof(struct null_mount),
113 M_NULLFSMNT, M_WAITOK | M_ZERO);
116 * Save reference to underlying FS
118 * As lite stacking enters the scene, the old way of doing this
119 * -- via the vnode -- is not good enough anymore. Use the
120 * underlying filesystem's namecache handle as our mount point
121 * root, adjusting the mount to point to us.
123 * NCF_ISMOUNTPT is normally set on the mount point, but we also
124 * want to set it on the base directory being mounted to prevent
125 * that directory from being destroyed out from under the nullfs
128 * The forwarding mount pointer (xmp->nullm_vfs) must be set to
129 * the actual target filesystem. If the target filesystem was
130 * resolved via a nullfs mount nd.nl_nch.mount will be pointing
131 * to the nullfs mount structure instead of the target filesystem,
132 * which would otherwise cause the mount VOPS and VFSOPS to recurse
133 * endlessly. If we are mounting via a nullfs mount we inherit
134 * its read-only state, if set.
136 xmp->nullm_vfs = nd.nl_nch.mount;
137 if (xmp->nullm_vfs != rootvp->v_mount) {
138 if (xmp->nullm_vfs->mnt_flag & MNT_RDONLY)
139 mp->mnt_flag |= MNT_RDONLY;
140 if (xmp->nullm_vfs->mnt_flag & MNT_NOEXEC)
141 mp->mnt_flag |= MNT_NOEXEC;
142 xmp->nullm_vfs = rootvp->v_mount;
146 * ncmountpt is the parent glue. When mounting a nullfs via a nullfs
147 * we retain the parent nullfs to create a unique chain tuple.
149 mp->mnt_ncmountpt = nd.nl_nch;
150 cache_changemount(&mp->mnt_ncmountpt, mp);
151 mp->mnt_ncmountpt.ncp->nc_flag |= NCF_ISMOUNTPT;
152 cache_unlock(&mp->mnt_ncmountpt);
153 cache_zero(&nd.nl_nch);
156 vfs_add_vnodeops(mp, &null_vnode_vops, &mp->mnt_vn_norm_ops);
158 vn_unlock(rootvp); /* leave reference intact */
161 * Keep a held reference to the root vnode.
162 * It is vrele'd in nullfs_unmount.
164 xmp->nullm_rootvp = rootvp;
166 * XXX What's the proper safety condition for querying
167 * the underlying mount? Is this flag tuning necessary
170 if (xmp->nullm_vfs->mnt_flag & MNT_LOCAL)
171 mp->mnt_flag |= MNT_LOCAL;
172 mp->mnt_data = (qaddr_t) xmp;
175 * Try to create a unique but non-random fsid for the nullfs to
176 * allow it to be exported via NFS.
178 bzero(&fh, sizeof(fh));
179 fh.fh_fsid = rootvp->v_mount->mnt_stat.f_fsid;
180 if (VFS_VPTOFH(rootvp, &fh.fh_fid) == 0) {
181 fh.fh_fsid.val[1] ^= crc32(&fh.fh_fid, sizeof(fh.fh_fid));
182 vfs_setfsid(mp, &fh.fh_fsid);
187 (void) copyinstr(args.target, mp->mnt_stat.f_mntfromname, MNAMELEN - 1,
189 bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size);
190 (void)nullfs_statfs(mp, &mp->mnt_stat, cred);
191 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n",
192 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntfromname);
194 bzero(mp->mnt_stat.f_mntonname, MNAMELEN);
196 (void) copyinstr(path, mp->mnt_stat.f_mntonname, MNAMELEN - 1,
201 * Set NCALIASED so unmount won't complain about namecache refs
204 * All NULLFS operations are MPSAFE, though it will be short-lived
205 * if the underlying filesystem is not.
207 mp->mnt_kern_flag |= MNTK_NCALIASED | MNTK_ALL_MPSAFE;
210 * And we don't need a syncer thread
212 vn_syncer_thr_stop(mp);
221 * Free reference to null layer
224 nullfs_unmount(struct mount *mp, int mntflags)
226 struct null_mount *xmp;
228 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp);
231 * Throw away the null_mount structure
233 xmp = (void *)mp->mnt_data;
235 if (xmp->nullm_rootvp) {
236 vrele(xmp->nullm_rootvp);
237 xmp->nullm_rootvp = NULL;
239 kfree(xmp, M_NULLFSMNT);
244 nullfs_root(struct mount *mp, struct vnode **vpp)
249 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p)\n", (void *)mp,
250 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp);
253 * Return locked reference to root.
255 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp;
256 error = vget(vp, LK_EXCLUSIVE | LK_RETRY);
263 nullfs_quotactl(struct mount *mp, int cmd, uid_t uid, caddr_t arg,
266 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, cred);
270 nullfs_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred)
275 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p)\n", (void *)mp,
276 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp);
278 bzero(&mstat, sizeof(mstat));
280 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, cred);
284 /* now copy across the "interesting" information and fake the rest */
285 sbp->f_type = mstat.f_type;
286 sbp->f_flags = mstat.f_flags;
287 sbp->f_bsize = mstat.f_bsize;
288 sbp->f_iosize = mstat.f_iosize;
289 sbp->f_blocks = mstat.f_blocks;
290 sbp->f_bfree = mstat.f_bfree;
291 sbp->f_bavail = mstat.f_bavail;
292 sbp->f_files = mstat.f_files;
293 sbp->f_ffree = mstat.f_ffree;
294 if (sbp != &mp->mnt_stat) {
295 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid));
296 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
297 bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN);
303 * Implement NFS export tracking
306 nullfs_checkexp(struct mount *mp, struct sockaddr *nam, int *extflagsp,
307 struct ucred **credanonp)
309 struct null_mount *xmp = (void *)mp->mnt_data;
313 np = vfs_export_lookup(mp, &xmp->export, nam);
315 *extflagsp = np->netc_exflags;
316 *credanonp = &np->netc_anon;
323 return VFS_CHECKEXP(MOUNTTONULLMOUNT(mp)->nullm_vfs, nam,
324 extflagsp, credanonp);
329 nullfs_export(struct mount *mp, int op, const struct export_args *export)
331 struct null_mount *xmp = (void *)mp->mnt_data;
335 case MOUNTCTL_SET_EXPORT:
336 error = vfs_export(mp, &xmp->export, export);
346 * Pass through file handle conversion functions.
349 nullfs_vptofh(struct vnode *vp, struct fid *fhp)
351 return VFS_VPTOFH(vp, fhp);
355 * Pass through file handle conversion functions.
357 * NOTE: currently only HAMMER uses rootvp. HAMMER uses rootvp only
358 * to enforce PFS isolation.
361 nullfs_fhtovp(struct mount *mp, struct vnode *rootvp,
362 struct fid *fhp, struct vnode **vpp)
364 struct null_mount *xmp = MOUNTTONULLMOUNT(mp);
366 return VFS_FHTOVP(xmp->nullm_vfs, xmp->nullm_rootvp, fhp, vpp);
370 nullfs_extattrctl(struct mount *mp, int cmd, struct vnode *vp,
371 int attrnamespace, const char *attrname, struct ucred *cred)
373 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd,
374 vp, attrnamespace, attrname, cred);
378 nullfs_ncpgen_set(struct mount *mp, struct namecache *ncp)
380 struct null_mount *xmp = MOUNTTONULLMOUNT(mp);
382 VFS_NCPGEN_SET(xmp->nullm_vfs, ncp);
387 nullfs_ncpgen_test(struct mount *mp, struct namecache *ncp)
389 struct null_mount *xmp = MOUNTTONULLMOUNT(mp);
391 return VFS_NCPGEN_TEST(xmp->nullm_vfs, ncp);
395 static struct vfsops null_vfsops = {
396 .vfs_mount = nullfs_mount,
397 .vfs_unmount = nullfs_unmount,
398 .vfs_root = nullfs_root,
399 .vfs_quotactl = nullfs_quotactl,
400 .vfs_statfs = nullfs_statfs,
401 .vfs_sync = vfs_stdsync,
402 .vfs_extattrctl = nullfs_extattrctl,
403 .vfs_fhtovp = nullfs_fhtovp,
404 .vfs_vptofh = nullfs_vptofh,
405 .vfs_ncpgen_set = nullfs_ncpgen_set,
406 .vfs_ncpgen_test = nullfs_ncpgen_test,
407 .vfs_checkexp = nullfs_checkexp
410 VFS_SET(null_vfsops, null, VFCF_LOOPBACK);
411 MODULE_VERSION(null, 1);