1 /* $NetBSD: tmpfs_vfsops.c,v 1.78 2022/11/10 10:54:14 hannken Exp $ */
2
3 /*
4 * Copyright (c) 2005, 2006, 2007 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Julio M. Merino Vidal, developed as part of Google's Summer of Code
9 * 2005 program.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 /*
34 * Efficient memory file system.
35 *
36 * tmpfs is a file system that uses NetBSD's virtual memory sub-system
37 * (the well-known UVM) to store file data and metadata in an efficient
38 * way. This means that it does not follow the structure of an on-disk
39 * file system because it simply does not need to. Instead, it uses
40 * memory-specific data structures and algorithms to automatically
41 * allocate and release resources.
42 */
43
44 #include <sys/cdefs.h>
45 __KERNEL_RCSID(0, "$NetBSD: tmpfs_vfsops.c,v 1.78 2022/11/10 10:54:14 hannken Exp $");
46
47 #include <sys/param.h>
48 #include <sys/atomic.h>
49 #include <sys/types.h>
50 #include <sys/kmem.h>
51 #include <sys/mount.h>
52 #include <sys/stat.h>
53 #include <sys/systm.h>
54 #include <sys/vnode.h>
55 #include <sys/kauth.h>
56 #include <sys/module.h>
57
58 #include <miscfs/genfs/genfs.h>
59 #include <fs/tmpfs/tmpfs.h>
60 #include <fs/tmpfs/tmpfs_args.h>
61
62 MODULE(MODULE_CLASS_VFS, tmpfs, NULL);
63
64 struct pool tmpfs_dirent_pool;
65 struct pool tmpfs_node_pool;
66
67 void
tmpfs_init(void)68 tmpfs_init(void)
69 {
70
71 pool_init(&tmpfs_dirent_pool, sizeof(tmpfs_dirent_t), 0, 0, 0,
72 "tmpfs_dirent", &pool_allocator_nointr, IPL_NONE);
73 pool_init(&tmpfs_node_pool, sizeof(tmpfs_node_t), 0, 0, 0,
74 "tmpfs_node", &pool_allocator_nointr, IPL_NONE);
75 }
76
77 void
tmpfs_done(void)78 tmpfs_done(void)
79 {
80
81 pool_destroy(&tmpfs_dirent_pool);
82 pool_destroy(&tmpfs_node_pool);
83 }
84
85 int
tmpfs_mount(struct mount * mp,const char * path,void * data,size_t * data_len)86 tmpfs_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
87 {
88 struct tmpfs_args *args = data;
89 tmpfs_mount_t *tmp;
90 tmpfs_node_t *root;
91 struct vattr va;
92 struct vnode *vp;
93 uint64_t memlimit;
94 ino_t nodes;
95 int error, flags;
96 bool set_memlimit;
97 bool set_nodes;
98
99 if (args == NULL)
100 return EINVAL;
101
102 /* Validate the version. */
103 if (*data_len < sizeof(*args) ||
104 args->ta_version != TMPFS_ARGS_VERSION)
105 return EINVAL;
106
107 /* Handle retrieval of mount point arguments. */
108 if (mp->mnt_flag & MNT_GETARGS) {
109 if (mp->mnt_data == NULL)
110 return EIO;
111 tmp = VFS_TO_TMPFS(mp);
112
113 args->ta_version = TMPFS_ARGS_VERSION;
114 args->ta_nodes_max = tmp->tm_nodes_max;
115 args->ta_size_max = tmp->tm_mem_limit;
116
117 root = tmp->tm_root;
118 args->ta_root_uid = root->tn_uid;
119 args->ta_root_gid = root->tn_gid;
120 args->ta_root_mode = root->tn_mode;
121
122 *data_len = sizeof(*args);
123 return 0;
124 }
125
126
127 /* Prohibit mounts if there is not enough memory. */
128 if (tmpfs_mem_info(true) < uvmexp.freetarg)
129 return EINVAL;
130
131 /* Check for invalid uid and gid arguments */
132 if (args->ta_root_uid == VNOVAL || args->ta_root_gid == VNOVAL)
133 return EINVAL;
134
135 /* Get the memory usage limit for this file-system. */
136 if (args->ta_size_max < PAGE_SIZE) {
137 memlimit = UINT64_MAX;
138 set_memlimit = false;
139 } else {
140 memlimit = args->ta_size_max;
141 set_memlimit = true;
142 }
143 KASSERT(memlimit > 0);
144
145 if (args->ta_nodes_max <= 3) {
146 nodes = 3 + (memlimit / 1024);
147 set_nodes = false;
148 } else {
149 nodes = args->ta_nodes_max;
150 set_nodes = true;
151 }
152 nodes = MIN(nodes, INT_MAX);
153 KASSERT(nodes >= 3);
154
155 if (mp->mnt_flag & MNT_UPDATE) {
156 tmp = VFS_TO_TMPFS(mp);
157 if (set_nodes && nodes < tmp->tm_nodes_cnt)
158 return EBUSY;
159 if ((mp->mnt_iflag & IMNT_WANTRDONLY)) {
160 /* Changing from read/write to read-only. */
161 flags = WRITECLOSE;
162 if ((mp->mnt_flag & MNT_FORCE))
163 flags |= FORCECLOSE;
164 error = vflush(mp, NULL, flags);
165 if (error)
166 return error;
167 }
168 if (set_memlimit) {
169 if ((error = tmpfs_mntmem_set(tmp, memlimit)) != 0)
170 return error;
171 }
172 if (set_nodes)
173 tmp->tm_nodes_max = nodes;
174 root = tmp->tm_root;
175 root->tn_uid = args->ta_root_uid;
176 root->tn_gid = args->ta_root_gid;
177 root->tn_mode = args->ta_root_mode;
178 return 0;
179 }
180
181 mp->mnt_flag |= MNT_LOCAL;
182 mp->mnt_stat.f_namemax = TMPFS_MAXNAMLEN;
183 mp->mnt_fs_bshift = PAGE_SHIFT;
184 mp->mnt_dev_bshift = DEV_BSHIFT;
185 mp->mnt_iflag |= IMNT_MPSAFE | IMNT_CAN_RWTORO | IMNT_SHRLOOKUP |
186 IMNT_NCLOOKUP;
187 vfs_getnewfsid(mp);
188
189 /* Allocate the tmpfs mount structure and fill it. */
190 tmp = kmem_zalloc(sizeof(tmpfs_mount_t), KM_SLEEP);
191 tmp->tm_nodes_max = nodes;
192 tmp->tm_nodes_cnt = 0;
193 LIST_INIT(&tmp->tm_nodes);
194
195 mutex_init(&tmp->tm_lock, MUTEX_DEFAULT, IPL_NONE);
196 tmpfs_mntmem_init(tmp, memlimit);
197 mp->mnt_data = tmp;
198
199 error = set_statvfs_info(path, UIO_USERSPACE, "tmpfs", UIO_SYSSPACE,
200 mp->mnt_op->vfs_name, mp, curlwp);
201 if (error)
202 goto errout;
203
204 /* Allocate the root node. */
205 vattr_null(&va);
206 va.va_type = VDIR;
207 va.va_mode = args->ta_root_mode & ALLPERMS;
208 va.va_uid = args->ta_root_uid;
209 va.va_gid = args->ta_root_gid;
210 error = vcache_new(mp, NULL, &va, NOCRED, NULL, &vp);
211 if (error)
212 goto errout;
213 KASSERT(vp != NULL);
214 root = VP_TO_TMPFS_NODE(vp);
215 KASSERT(root != NULL);
216
217 /*
218 * Parent of the root inode is itself. Also, root inode has no
219 * directory entry (i.e. is never attached), thus hold an extra
220 * reference (link) for it.
221 */
222 root->tn_links++;
223 root->tn_spec.tn_dir.tn_parent = root;
224 tmp->tm_root = root;
225 vrele(vp);
226
227 return 0;
228
229 errout:
230 mp->mnt_data = NULL;
231 tmpfs_mntmem_destroy(tmp);
232 mutex_destroy(&tmp->tm_lock);
233 kmem_free(tmp, sizeof(*tmp));
234
235 return error;
236 }
237
238 int
tmpfs_start(struct mount * mp,int flags)239 tmpfs_start(struct mount *mp, int flags)
240 {
241
242 return 0;
243 }
244
245 int
tmpfs_unmount(struct mount * mp,int mntflags)246 tmpfs_unmount(struct mount *mp, int mntflags)
247 {
248 tmpfs_mount_t *tmp = VFS_TO_TMPFS(mp);
249 tmpfs_node_t *node, *cnode;
250 int error, flags = 0;
251
252 /* Handle forced unmounts. */
253 if (mntflags & MNT_FORCE)
254 flags |= FORCECLOSE;
255
256 /* Finalize all pending I/O. */
257 error = vflush(mp, NULL, flags);
258 if (error != 0)
259 return error;
260
261 /*
262 * First round, detach and destroy all directory entries.
263 * Also, clear the pointers to the vnodes - they are gone.
264 */
265 LIST_FOREACH(node, &tmp->tm_nodes, tn_entries) {
266 tmpfs_dirent_t *de;
267
268 node->tn_vnode = NULL;
269 if (node->tn_type != VDIR) {
270 continue;
271 }
272 while ((de = TAILQ_FIRST(&node->tn_spec.tn_dir.tn_dir)) != NULL) {
273 cnode = de->td_node;
274 if (cnode && cnode != TMPFS_NODE_WHITEOUT) {
275 cnode->tn_vnode = NULL;
276 }
277 tmpfs_dir_detach(node, de);
278 tmpfs_free_dirent(tmp, de);
279 }
280 /* Extra virtual entry (itself for the root). */
281 node->tn_links--;
282 }
283
284 /* Release the reference on root (diagnostic). */
285 node = tmp->tm_root;
286 node->tn_links--;
287
288 /* Second round, destroy all inodes. */
289 while ((node = LIST_FIRST(&tmp->tm_nodes)) != NULL) {
290 tmpfs_free_node(tmp, node);
291 }
292
293 /* Throw away the tmpfs_mount structure. */
294 tmpfs_mntmem_destroy(tmp);
295 mutex_destroy(&tmp->tm_lock);
296 kmem_free(tmp, sizeof(*tmp));
297 mp->mnt_data = NULL;
298
299 return 0;
300 }
301
302 int
tmpfs_root(struct mount * mp,int lktype,vnode_t ** vpp)303 tmpfs_root(struct mount *mp, int lktype, vnode_t **vpp)
304 {
305 tmpfs_node_t *node = VFS_TO_TMPFS(mp)->tm_root;
306 int error;
307
308 error = vcache_get(mp, &node, sizeof(node), vpp);
309 if (error)
310 return error;
311 error = vn_lock(*vpp, lktype);
312 if (error) {
313 vrele(*vpp);
314 *vpp = NULL;
315 return error;
316 }
317
318 return 0;
319 }
320
321 int
tmpfs_vget(struct mount * mp,ino_t ino,int lktype,vnode_t ** vpp)322 tmpfs_vget(struct mount *mp, ino_t ino, int lktype, vnode_t **vpp)
323 {
324
325 return EOPNOTSUPP;
326 }
327
328 int
tmpfs_fhtovp(struct mount * mp,struct fid * fhp,int lktype,vnode_t ** vpp)329 tmpfs_fhtovp(struct mount *mp, struct fid *fhp, int lktype, vnode_t **vpp)
330 {
331 tmpfs_mount_t *tmp = VFS_TO_TMPFS(mp);
332 tmpfs_node_t *node;
333 tmpfs_fid_t tfh;
334 int error;
335
336 if (fhp->fid_len != sizeof(tmpfs_fid_t)) {
337 return EINVAL;
338 }
339 memcpy(&tfh, fhp, sizeof(tmpfs_fid_t));
340
341 mutex_enter(&tmp->tm_lock);
342 /* XXX big oof .. use a better data structure */
343 LIST_FOREACH(node, &tmp->tm_nodes, tn_entries) {
344 if (node->tn_id == tfh.tf_id) {
345 /* Prevent this node from disappearing. */
346 atomic_inc_32(&node->tn_holdcount);
347 break;
348 }
349 }
350 mutex_exit(&tmp->tm_lock);
351 if (node == NULL)
352 return ESTALE;
353
354 error = vcache_get(mp, &node, sizeof(node), vpp);
355 /* If this node has been reclaimed free it now. */
356 if (atomic_dec_32_nv(&node->tn_holdcount) == TMPFS_NODE_RECLAIMED) {
357 KASSERT(error != 0);
358 tmpfs_free_node(tmp, node);
359 }
360 if (error)
361 return (error == ENOENT ? ESTALE : error);
362 error = vn_lock(*vpp, lktype);
363 if (error) {
364 vrele(*vpp);
365 *vpp = NULL;
366 return error;
367 }
368 if (TMPFS_NODE_GEN(node) != tfh.tf_gen) {
369 vput(*vpp);
370 *vpp = NULL;
371 return ESTALE;
372 }
373
374 return 0;
375 }
376
377 int
tmpfs_vptofh(vnode_t * vp,struct fid * fhp,size_t * fh_size)378 tmpfs_vptofh(vnode_t *vp, struct fid *fhp, size_t *fh_size)
379 {
380 tmpfs_fid_t tfh;
381 tmpfs_node_t *node;
382
383 if (*fh_size < sizeof(tmpfs_fid_t)) {
384 *fh_size = sizeof(tmpfs_fid_t);
385 return E2BIG;
386 }
387 *fh_size = sizeof(tmpfs_fid_t);
388 node = VP_TO_TMPFS_NODE(vp);
389
390 memset(&tfh, 0, sizeof(tfh));
391 tfh.tf_len = sizeof(tmpfs_fid_t);
392 tfh.tf_gen = TMPFS_NODE_GEN(node);
393 tfh.tf_id = node->tn_id;
394 memcpy(fhp, &tfh, sizeof(tfh));
395
396 return 0;
397 }
398
399 int
tmpfs_statvfs(struct mount * mp,struct statvfs * sbp)400 tmpfs_statvfs(struct mount *mp, struct statvfs *sbp)
401 {
402 tmpfs_mount_t *tmp;
403 fsfilcnt_t freenodes;
404 size_t avail;
405
406 tmp = VFS_TO_TMPFS(mp);
407
408 sbp->f_iosize = sbp->f_frsize = sbp->f_bsize = PAGE_SIZE;
409
410 mutex_enter(&tmp->tm_acc_lock);
411 avail = tmpfs_pages_avail(tmp);
412 sbp->f_blocks = (tmpfs_bytes_max(tmp) >> PAGE_SHIFT);
413 sbp->f_bavail = sbp->f_bfree = avail;
414 sbp->f_bresvd = 0;
415
416 freenodes = MIN(tmp->tm_nodes_max - tmp->tm_nodes_cnt,
417 avail * PAGE_SIZE / sizeof(tmpfs_node_t));
418
419 sbp->f_files = tmp->tm_nodes_cnt + freenodes;
420 sbp->f_favail = sbp->f_ffree = freenodes;
421 sbp->f_fresvd = 0;
422 mutex_exit(&tmp->tm_acc_lock);
423
424 copy_statvfs_info(sbp, mp);
425
426 return 0;
427 }
428
429 int
tmpfs_sync(struct mount * mp,int waitfor,kauth_cred_t uc)430 tmpfs_sync(struct mount *mp, int waitfor, kauth_cred_t uc)
431 {
432
433 return 0;
434 }
435
436 int
tmpfs_snapshot(struct mount * mp,vnode_t * vp,struct timespec * ctime)437 tmpfs_snapshot(struct mount *mp, vnode_t *vp, struct timespec *ctime)
438 {
439
440 return EOPNOTSUPP;
441 }
442
443 /*
444 * tmpfs vfs operations.
445 */
446
447 extern const struct vnodeopv_desc tmpfs_fifoop_opv_desc;
448 extern const struct vnodeopv_desc tmpfs_specop_opv_desc;
449 extern const struct vnodeopv_desc tmpfs_vnodeop_opv_desc;
450
451 const struct vnodeopv_desc * const tmpfs_vnodeopv_descs[] = {
452 &tmpfs_fifoop_opv_desc,
453 &tmpfs_specop_opv_desc,
454 &tmpfs_vnodeop_opv_desc,
455 NULL,
456 };
457
458 struct vfsops tmpfs_vfsops = {
459 .vfs_name = MOUNT_TMPFS,
460 .vfs_min_mount_data = sizeof (struct tmpfs_args),
461 .vfs_mount = tmpfs_mount,
462 .vfs_start = tmpfs_start,
463 .vfs_unmount = tmpfs_unmount,
464 .vfs_root = tmpfs_root,
465 .vfs_quotactl = (void *)eopnotsupp,
466 .vfs_statvfs = tmpfs_statvfs,
467 .vfs_sync = tmpfs_sync,
468 .vfs_vget = tmpfs_vget,
469 .vfs_loadvnode = tmpfs_loadvnode,
470 .vfs_newvnode = tmpfs_newvnode,
471 .vfs_fhtovp = tmpfs_fhtovp,
472 .vfs_vptofh = tmpfs_vptofh,
473 .vfs_init = tmpfs_init,
474 .vfs_done = tmpfs_done,
475 .vfs_snapshot = tmpfs_snapshot,
476 .vfs_extattrctl = vfs_stdextattrctl,
477 .vfs_suspendctl = genfs_suspendctl,
478 .vfs_renamelock_enter = genfs_renamelock_enter,
479 .vfs_renamelock_exit = genfs_renamelock_exit,
480 .vfs_fsync = (void *)eopnotsupp,
481 .vfs_opv_descs = tmpfs_vnodeopv_descs
482 };
483
484 static int
tmpfs_modcmd(modcmd_t cmd,void * arg)485 tmpfs_modcmd(modcmd_t cmd, void *arg)
486 {
487
488 switch (cmd) {
489 case MODULE_CMD_INIT:
490 return vfs_attach(&tmpfs_vfsops);
491 case MODULE_CMD_FINI:
492 return vfs_detach(&tmpfs_vfsops);
493 default:
494 return ENOTTY;
495 }
496 }
497