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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 1.29 2006/10/27 04:56:34 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>
58 extern struct vop_ops null_vnode_vops;
60 static MALLOC_DEFINE(M_NULLFSMNT, "NULLFS mount", "NULLFS mount structure");
62 static int nullfs_root(struct mount *mp, struct vnode **vpp);
63 static int nullfs_statfs(struct mount *mp, struct statfs *sbp,
70 nullfs_mount(struct mount *mp, char *path, caddr_t data, struct ucred *cred)
73 struct null_args args;
75 struct null_mount *xmp;
77 struct nlookupdata nd;
79 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp);
84 if (mp->mnt_flag & MNT_UPDATE) {
91 error = copyin(data, (caddr_t)&args, sizeof(struct null_args));
99 error = nlookup_init(&nd, args.target, UIO_USERSPACE, NLC_FOLLOW);
102 error = nlookup(&nd);
105 error = cache_vget(&nd.nl_nch, nd.nl_cred, LK_EXCLUSIVE, &rootvp);
109 xmp = (struct null_mount *) kmalloc(sizeof(struct null_mount),
110 M_NULLFSMNT, M_WAITOK); /* XXX */
113 * Save reference to underlying FS
115 * As lite stacking enters the scene, the old way of doing this
116 * -- via the vnode -- is not good enough anymore. Use the
117 * underlying filesystem's namecache handle as our mount point
118 * root, adjusting the mount to point to us.
120 * NCF_ISMOUNTPT is normally set on the mount point, but we also
121 * want to set it on the base directory being mounted to prevent
122 * that directory from being destroyed out from under the nullfs
125 xmp->nullm_vfs = nd.nl_nch.mount;
126 mp->mnt_ncmountpt = nd.nl_nch;
127 cache_changemount(&mp->mnt_ncmountpt, mp);
128 mp->mnt_ncmountpt.ncp->nc_flag |= NCF_ISMOUNTPT;
129 cache_unlock(&mp->mnt_ncmountpt);
130 cache_zero(&nd.nl_nch);
133 vfs_add_vnodeops(mp, &null_vnode_vops, &mp->mnt_vn_norm_ops);
135 vn_unlock(rootvp); /* leave reference intact */
138 * Keep a held reference to the root vnode.
139 * It is vrele'd in nullfs_unmount.
141 xmp->nullm_rootvp = rootvp;
143 * XXX What's the proper safety condition for querying
144 * the underlying mount? Is this flag tuning necessary
147 if (xmp->nullm_vfs->mnt_flag & MNT_LOCAL)
148 mp->mnt_flag |= MNT_LOCAL;
149 mp->mnt_data = (qaddr_t) xmp;
152 (void) copyinstr(args.target, mp->mnt_stat.f_mntfromname, MNAMELEN - 1,
154 bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size);
155 (void)nullfs_statfs(mp, &mp->mnt_stat, cred);
156 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n",
157 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntfromname);
160 * So unmount won't complain about namecache refs still existing
162 mp->mnt_kern_flag |= MNTK_NCALIASED;
171 * Free reference to null layer
174 nullfs_unmount(struct mount *mp, int mntflags)
176 struct null_mount *xmp;
179 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp);
181 if (mntflags & MNT_FORCE)
185 * Finally, throw away the null_mount structure
187 xmp = (void *)mp->mnt_data;
189 if (xmp->nullm_rootvp) {
190 vrele(xmp->nullm_rootvp);
191 xmp->nullm_rootvp = NULL;
193 kfree(xmp, M_NULLFSMNT);
198 nullfs_root(struct mount *mp, struct vnode **vpp)
203 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p)\n", (void *)mp,
204 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp);
207 * Return locked reference to root.
209 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp;
210 error = vget(vp, LK_EXCLUSIVE | LK_RETRY);
217 nullfs_quotactl(struct mount *mp, int cmd, uid_t uid, caddr_t arg,
220 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, cred);
224 nullfs_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred)
229 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p)\n", (void *)mp,
230 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp);
232 bzero(&mstat, sizeof(mstat));
234 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, cred);
238 /* now copy across the "interesting" information and fake the rest */
239 sbp->f_type = mstat.f_type;
240 sbp->f_flags = mstat.f_flags;
241 sbp->f_bsize = mstat.f_bsize;
242 sbp->f_iosize = mstat.f_iosize;
243 sbp->f_blocks = mstat.f_blocks;
244 sbp->f_bfree = mstat.f_bfree;
245 sbp->f_bavail = mstat.f_bavail;
246 sbp->f_files = mstat.f_files;
247 sbp->f_ffree = mstat.f_ffree;
248 if (sbp != &mp->mnt_stat) {
249 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid));
250 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
256 nullfs_checkexp(struct mount *mp, struct sockaddr *nam, int *extflagsp,
257 struct ucred **credanonp)
260 return VFS_CHECKEXP(MOUNTTONULLMOUNT(mp)->nullm_vfs, nam,
261 extflagsp, credanonp);
265 nullfs_extattrctl(struct mount *mp, int cmd, const char *attrname, caddr_t arg,
268 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, attrname,
273 static struct vfsops null_vfsops = {
274 .vfs_mount = nullfs_mount,
275 .vfs_unmount = nullfs_unmount,
276 .vfs_root = nullfs_root,
277 .vfs_quotactl = nullfs_quotactl,
278 .vfs_statfs = nullfs_statfs,
279 .vfs_sync = vfs_stdsync,
280 .vfs_checkexp = nullfs_checkexp,
281 .vfs_extattrctl = nullfs_extattrctl
284 VFS_SET(null_vfsops, null, VFCF_LOOPBACK);