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36 * @(#)null_vfsops.c 8.2 (Berkeley) 1/21/94
38 * @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92
39 * $FreeBSD: src/sys/miscfs/nullfs/null_vfsops.c,v 1.35.2.3 2001/07/26 20:37:11 iedowse Exp $
40 * $DragonFly: src/sys/vfs/nullfs/null_vfsops.c,v 1.31 2008/09/17 21:44:25 dillon Exp $
45 * (See null_vnops.c for a description of what this does.)
48 #include <sys/param.h>
49 #include <sys/systm.h>
50 #include <sys/kernel.h>
52 #include <sys/malloc.h>
53 #include <sys/vnode.h>
54 #include <sys/mount.h>
55 #include <sys/nlookup.h>
56 #include <sys/mountctl.h>
59 extern struct vop_ops null_vnode_vops;
61 static MALLOC_DEFINE(M_NULLFSMNT, "NULLFS mount", "NULLFS mount structure");
63 static int nullfs_root(struct mount *mp, struct vnode **vpp);
64 static int nullfs_statfs(struct mount *mp, struct statfs *sbp,
71 nullfs_mount(struct mount *mp, char *path, caddr_t data, struct ucred *cred)
74 struct null_args args;
76 struct null_mount *xmp;
78 struct nlookupdata nd;
81 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp);
86 error = copyin(data, (caddr_t)&args, sizeof(struct null_args));
91 * XXX: Should we process mount export info ?
92 * If not, returning zero here is enough as the actual ro/rw update is
93 * being done in sys_mount().
95 if (mp->mnt_flag & MNT_UPDATE) {
96 xmp = MOUNTTONULLMOUNT(mp);
97 error = vfs_export(mp, &xmp->export, &args.export);
105 error = nlookup_init(&nd, args.target, UIO_USERSPACE, NLC_FOLLOW);
108 error = nlookup(&nd);
111 error = cache_vget(&nd.nl_nch, nd.nl_cred, LK_EXCLUSIVE, &rootvp);
115 xmp = (struct null_mount *) kmalloc(sizeof(struct null_mount),
116 M_NULLFSMNT, M_WAITOK | M_ZERO);
119 * Save reference to underlying FS
121 * As lite stacking enters the scene, the old way of doing this
122 * -- via the vnode -- is not good enough anymore. Use the
123 * underlying filesystem's namecache handle as our mount point
124 * root, adjusting the mount to point to us.
126 * NCF_ISMOUNTPT is normally set on the mount point, but we also
127 * want to set it on the base directory being mounted to prevent
128 * that directory from being destroyed out from under the nullfs
131 * The forwarding mount pointer (xmp->nullm_vfs) must be set to
132 * the actual target filesystem. If the target filesystem was
133 * resolved via a nullfs mount nd.nl_nch.mount will be pointing
134 * to the nullfs mount structure instead of the target filesystem,
135 * which would otherwise cause the mount VOPS and VFSOPS to recurse
136 * endlessly. If we are mounting via a nullfs mount we inherit
137 * its read-only state, if set.
139 xmp->nullm_vfs = nd.nl_nch.mount;
140 if (xmp->nullm_vfs != rootvp->v_mount) {
141 if (xmp->nullm_vfs->mnt_flag & MNT_RDONLY)
142 mp->mnt_flag |= MNT_RDONLY;
143 if (xmp->nullm_vfs->mnt_flag & MNT_NOEXEC)
144 mp->mnt_flag |= MNT_NOEXEC;
145 xmp->nullm_vfs = rootvp->v_mount;
149 * ncmountpt is the parent glue. When mounting a nullfs via a nullfs
150 * we retain the parent nullfs to create a unique chain tuple.
152 mp->mnt_ncmountpt = nd.nl_nch;
153 cache_changemount(&mp->mnt_ncmountpt, mp);
154 mp->mnt_ncmountpt.ncp->nc_flag |= NCF_ISMOUNTPT;
155 cache_unlock(&mp->mnt_ncmountpt);
156 cache_zero(&nd.nl_nch);
159 vfs_add_vnodeops(mp, &null_vnode_vops, &mp->mnt_vn_norm_ops);
161 vn_unlock(rootvp); /* leave reference intact */
164 * Keep a held reference to the root vnode.
165 * It is vrele'd in nullfs_unmount.
167 xmp->nullm_rootvp = rootvp;
169 * XXX What's the proper safety condition for querying
170 * the underlying mount? Is this flag tuning necessary
173 if (xmp->nullm_vfs->mnt_flag & MNT_LOCAL)
174 mp->mnt_flag |= MNT_LOCAL;
175 mp->mnt_data = (qaddr_t) xmp;
178 * Try to create a unique but non-random fsid for the nullfs to
179 * allow it to be exported via NFS.
181 bzero(&fh, sizeof(fh));
182 fh.fh_fsid = rootvp->v_mount->mnt_stat.f_fsid;
183 if (VFS_VPTOFH(rootvp, &fh.fh_fid) == 0) {
184 fh.fh_fsid.val[1] ^= crc32(&fh.fh_fid, sizeof(fh.fh_fid));
185 vfs_setfsid(mp, &fh.fh_fsid);
190 (void) copyinstr(args.target, mp->mnt_stat.f_mntfromname, MNAMELEN - 1,
192 bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size);
193 (void)nullfs_statfs(mp, &mp->mnt_stat, cred);
194 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n",
195 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntfromname);
198 * Set NCALIASED so unmount won't complain about namecache refs
201 * All NULLFS operations are MPSAFE, though it will be short-lived
202 * if the underlying filesystem is not.
204 mp->mnt_kern_flag |= MNTK_NCALIASED | MNTK_ALL_MPSAFE;
213 * Free reference to null layer
216 nullfs_unmount(struct mount *mp, int mntflags)
218 struct null_mount *xmp;
221 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp);
223 if (mntflags & MNT_FORCE)
227 * Finally, throw away the null_mount structure
229 xmp = (void *)mp->mnt_data;
231 if (xmp->nullm_rootvp) {
232 vrele(xmp->nullm_rootvp);
233 xmp->nullm_rootvp = NULL;
235 kfree(xmp, M_NULLFSMNT);
240 nullfs_root(struct mount *mp, struct vnode **vpp)
245 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p)\n", (void *)mp,
246 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp);
249 * Return locked reference to root.
251 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp;
252 error = vget(vp, LK_EXCLUSIVE | LK_RETRY);
259 nullfs_quotactl(struct mount *mp, int cmd, uid_t uid, caddr_t arg,
262 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, cred);
266 nullfs_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred)
271 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p)\n", (void *)mp,
272 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp);
274 bzero(&mstat, sizeof(mstat));
276 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, cred);
280 /* now copy across the "interesting" information and fake the rest */
281 sbp->f_type = mstat.f_type;
282 sbp->f_flags = mstat.f_flags;
283 sbp->f_bsize = mstat.f_bsize;
284 sbp->f_iosize = mstat.f_iosize;
285 sbp->f_blocks = mstat.f_blocks;
286 sbp->f_bfree = mstat.f_bfree;
287 sbp->f_bavail = mstat.f_bavail;
288 sbp->f_files = mstat.f_files;
289 sbp->f_ffree = mstat.f_ffree;
290 if (sbp != &mp->mnt_stat) {
291 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid));
292 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
298 * Implement NFS export tracking
301 nullfs_checkexp(struct mount *mp, struct sockaddr *nam, int *extflagsp,
302 struct ucred **credanonp)
304 struct null_mount *xmp = (void *)mp->mnt_data;
308 np = vfs_export_lookup(mp, &xmp->export, nam);
310 *extflagsp = np->netc_exflags;
311 *credanonp = &np->netc_anon;
318 return VFS_CHECKEXP(MOUNTTONULLMOUNT(mp)->nullm_vfs, nam,
319 extflagsp, credanonp);
324 nullfs_export(struct mount *mp, int op, const struct export_args *export)
326 struct null_mount *xmp = (void *)mp->mnt_data;
330 case MOUNTCTL_SET_EXPORT:
331 error = vfs_export(mp, &xmp->export, export);
341 * Pass through file handle conversion functions.
344 nullfs_vptofh(struct vnode *vp, struct fid *fhp)
346 return VFS_VPTOFH(vp, fhp);
350 * Pass through file handle conversion functions.
352 * NOTE: currently only HAMMER uses rootvp. HAMMER uses rootvp only
353 * to enforce PFS isolation.
356 nullfs_fhtovp(struct mount *mp, struct vnode *rootvp,
357 struct fid *fhp, struct vnode **vpp)
359 struct null_mount *xmp = MOUNTTONULLMOUNT(mp);
361 return VFS_FHTOVP(xmp->nullm_vfs, xmp->nullm_rootvp, fhp, vpp);
365 nullfs_extattrctl(struct mount *mp, int cmd, struct vnode *vp,
366 int attrnamespace, const char *attrname, struct ucred *cred)
368 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd,
369 vp, attrnamespace, attrname, cred);
373 static struct vfsops null_vfsops = {
374 .vfs_mount = nullfs_mount,
375 .vfs_unmount = nullfs_unmount,
376 .vfs_root = nullfs_root,
377 .vfs_quotactl = nullfs_quotactl,
378 .vfs_statfs = nullfs_statfs,
379 .vfs_sync = vfs_stdsync,
380 .vfs_extattrctl = nullfs_extattrctl,
381 .vfs_fhtovp = nullfs_fhtovp,
382 .vfs_vptofh = nullfs_vptofh,
383 .vfs_checkexp = nullfs_checkexp
386 VFS_SET(null_vfsops, null, VFCF_LOOPBACK);