1f15ccf88SChuck Silvers /*-
24d846d26SWarner Losh * SPDX-License-Identifier: BSD-2-Clause
3f15ccf88SChuck Silvers *
4f15ccf88SChuck Silvers * Copyright (c) 2020 Netflix, Inc.
5f15ccf88SChuck Silvers *
6f15ccf88SChuck Silvers * Redistribution and use in source and binary forms, with or without
7f15ccf88SChuck Silvers * modification, are permitted provided that the following conditions
8f15ccf88SChuck Silvers * are met:
9f15ccf88SChuck Silvers *
10f15ccf88SChuck Silvers * 1. Redistributions of source code must retain the above copyright
11f15ccf88SChuck Silvers * notice, this list of conditions and the following disclaimer.
12f15ccf88SChuck Silvers * 2. Redistributions in binary form must reproduce the above copyright
13f15ccf88SChuck Silvers * notice, this list of conditions and the following disclaimer in the
14f15ccf88SChuck Silvers * documentation and/or other materials provided with the distribution.
15f15ccf88SChuck Silvers *
16f15ccf88SChuck Silvers * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
17f15ccf88SChuck Silvers * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18f15ccf88SChuck Silvers * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19f15ccf88SChuck Silvers * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20f15ccf88SChuck Silvers * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21f15ccf88SChuck Silvers * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22f15ccf88SChuck Silvers * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
23f15ccf88SChuck Silvers * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
24f15ccf88SChuck Silvers * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
25f15ccf88SChuck Silvers * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26f15ccf88SChuck Silvers */
27f15ccf88SChuck Silvers
28f15ccf88SChuck Silvers #include <sys/param.h>
29f15ccf88SChuck Silvers #include <sys/conf.h>
30f15ccf88SChuck Silvers #include <sys/mount.h>
31f15ccf88SChuck Silvers #include <sys/vnode.h>
32f15ccf88SChuck Silvers
33f15ccf88SChuck Silvers /*
34f15ccf88SChuck Silvers * The "mntfs" VCHR vnodes implemented here provide a safe way for file systems
35f15ccf88SChuck Silvers * to access their disk devices. Using the normal devfs vnode has the problem
36f15ccf88SChuck Silvers * that if the device disappears, the devfs vnode is vgone'd as part of
37f15ccf88SChuck Silvers * removing it from the application-visible namespace, and some file systems
38f15ccf88SChuck Silvers * (notably FFS with softdep) get very unhappy if their dirty buffers are
39f15ccf88SChuck Silvers * invalidated out from under them. By using a separate, private vnode,
40f15ccf88SChuck Silvers * file systems are able to clean up their buffer state in a controlled fashion
41f15ccf88SChuck Silvers * when the underlying device disappears.
42f15ccf88SChuck Silvers */
43f15ccf88SChuck Silvers
44f15ccf88SChuck Silvers static int
mntfs_reclaim(struct vop_reclaim_args * ap)45f15ccf88SChuck Silvers mntfs_reclaim(struct vop_reclaim_args *ap)
46f15ccf88SChuck Silvers {
47f15ccf88SChuck Silvers struct vnode *vp = ap->a_vp;
48f15ccf88SChuck Silvers
49f15ccf88SChuck Silvers dev_rel(vp->v_rdev);
50f15ccf88SChuck Silvers return (0);
51f15ccf88SChuck Silvers }
52f15ccf88SChuck Silvers
53f15ccf88SChuck Silvers struct vop_vector mntfs_vnodeops = {
54f15ccf88SChuck Silvers .vop_default = &default_vnodeops,
55f15ccf88SChuck Silvers
56f15ccf88SChuck Silvers .vop_fsync = vop_stdfsync,
57f15ccf88SChuck Silvers .vop_strategy = VOP_PANIC,
58f15ccf88SChuck Silvers .vop_reclaim = mntfs_reclaim,
59f15ccf88SChuck Silvers };
60f15ccf88SChuck Silvers VFS_VOP_VECTOR_REGISTER(mntfs_vnodeops);
61f15ccf88SChuck Silvers
62f15ccf88SChuck Silvers /*
63f15ccf88SChuck Silvers * Allocate a private VCHR vnode for use by a mounted fs.
64f15ccf88SChuck Silvers * The underlying device will be the same as for the given vnode.
65f15ccf88SChuck Silvers * This mntfs vnode must be freed with mntfs_freevp() rather than just
66f15ccf88SChuck Silvers * releasing the reference.
67f15ccf88SChuck Silvers */
68f15ccf88SChuck Silvers struct vnode *
mntfs_allocvp(struct mount * mp,struct vnode * ovp)69f15ccf88SChuck Silvers mntfs_allocvp(struct mount *mp, struct vnode *ovp)
70f15ccf88SChuck Silvers {
71f15ccf88SChuck Silvers struct vnode *vp;
72f15ccf88SChuck Silvers struct cdev *dev;
73f15ccf88SChuck Silvers
74f15ccf88SChuck Silvers ASSERT_VOP_ELOCKED(ovp, __func__);
75f15ccf88SChuck Silvers
76f15ccf88SChuck Silvers dev = ovp->v_rdev;
77f15ccf88SChuck Silvers
78f15ccf88SChuck Silvers getnewvnode("mntfs", mp, &mntfs_vnodeops, &vp);
79f15ccf88SChuck Silvers vp->v_type = VCHR;
80f15ccf88SChuck Silvers vp->v_data = NULL;
81f15ccf88SChuck Silvers dev_ref(dev);
82f15ccf88SChuck Silvers vp->v_rdev = dev;
83f15ccf88SChuck Silvers
84ed1bb254SMateusz Guzik VOP_UNLOCK(ovp);
85ed1bb254SMateusz Guzik vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
86829f0bcbSMateusz Guzik vn_set_state(vp, VSTATE_CONSTRUCTED);
87f15ccf88SChuck Silvers return (vp);
88f15ccf88SChuck Silvers }
89f15ccf88SChuck Silvers
90f15ccf88SChuck Silvers void
mntfs_freevp(struct vnode * vp)91f15ccf88SChuck Silvers mntfs_freevp(struct vnode *vp)
92f15ccf88SChuck Silvers {
9325809a01SKonstantin Belousov ASSERT_VOP_ELOCKED(vp, "mntfs_freevp");
94f15ccf88SChuck Silvers vgone(vp);
9525809a01SKonstantin Belousov vput(vp);
96f15ccf88SChuck Silvers }
97