1 /* $NetBSD: tmpfs_vfsops.c,v 1.10 2005/12/11 12:24:29 christos Exp $ */
4 * SPDX-License-Identifier: BSD-2-Clause-NetBSD
6 * Copyright (c) 2005 The NetBSD Foundation, Inc.
9 * This code is derived from software contributed to The NetBSD Foundation
10 * by Julio M. Merino Vidal, developed as part of Google's Summer of Code
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
22 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
23 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
24 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
25 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
26 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
27 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
28 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
29 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
30 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
31 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
32 * POSSIBILITY OF SUCH DAMAGE.
36 * Efficient memory file system.
38 * tmpfs is a file system that uses FreeBSD's virtual memory
39 * sub-system to store file data and metadata in an efficient way.
40 * This means that it does not follow the structure of an on-disk file
41 * system because it simply does not need to. Instead, it uses
42 * memory-specific data structures and algorithms to automatically
43 * allocate and release resources.
45 #include <sys/cdefs.h>
46 __FBSDID("$FreeBSD$");
48 #include <sys/param.h>
49 #include <sys/dirent.h>
50 #include <sys/limits.h>
52 #include <sys/mount.h>
53 #include <sys/mutex.h>
56 #include <sys/kernel.h>
57 #include <sys/rwlock.h>
59 #include <sys/systm.h>
60 #include <sys/sysctl.h>
61 #include <sys/vnode.h>
64 #include <vm/vm_object.h>
65 #include <vm/vm_param.h>
67 #include <fs/tmpfs/tmpfs.h>
70 * Default permission for root node
72 #define TMPFS_DEFAULT_ROOT_MODE (S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH)
74 MALLOC_DEFINE(M_TMPFSMNT, "tmpfs mount", "tmpfs mount structures");
75 MALLOC_DEFINE(M_TMPFSNAME, "tmpfs name", "tmpfs file names");
77 static int tmpfs_mount(struct mount *);
78 static int tmpfs_unmount(struct mount *, int);
79 static int tmpfs_root(struct mount *, int flags, struct vnode **);
80 static int tmpfs_fhtovp(struct mount *, struct fid *, int,
82 static int tmpfs_statfs(struct mount *, struct statfs *);
83 static void tmpfs_susp_clean(struct mount *);
85 static const char *tmpfs_opts[] = {
86 "from", "size", "maxfilesize", "inodes", "uid", "gid", "mode", "export",
90 static const char *tmpfs_updateopts[] = {
91 "from", "export", NULL
95 tmpfs_node_ctor(void *mem, int size, void *arg, int flags)
97 struct tmpfs_node *node = (struct tmpfs_node *)mem;
104 node->tn_vnode = NULL;
105 node->tn_vpstate = 0;
111 tmpfs_node_dtor(void *mem, int size, void *arg)
113 struct tmpfs_node *node = (struct tmpfs_node *)mem;
114 node->tn_type = VNON;
118 tmpfs_node_init(void *mem, int size, int flags)
120 struct tmpfs_node *node = (struct tmpfs_node *)mem;
123 mtx_init(&node->tn_interlock, "tmpfs node interlock", NULL, MTX_DEF);
124 node->tn_gen = arc4random();
130 tmpfs_node_fini(void *mem, int size)
132 struct tmpfs_node *node = (struct tmpfs_node *)mem;
134 mtx_destroy(&node->tn_interlock);
138 tmpfs_mount(struct mount *mp)
140 const size_t nodes_per_page = howmany(PAGE_SIZE,
141 sizeof(struct tmpfs_dirent) + sizeof(struct tmpfs_node));
142 struct tmpfs_mount *tmp;
143 struct tmpfs_node *root;
144 struct thread *td = curthread;
149 off_t nodes_max, size_max, maxfilesize;
151 /* Root node attributes. */
158 if (!prison_allow(td->td_ucred, PR_ALLOW_MOUNT_TMPFS))
161 if (vfs_filteropt(mp->mnt_optnew, tmpfs_opts))
164 if (mp->mnt_flag & MNT_UPDATE) {
165 /* Only support update mounts for certain options. */
166 if (vfs_filteropt(mp->mnt_optnew, tmpfs_updateopts) != 0)
168 if (vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0) !=
169 ((struct tmpfs_mount *)mp->mnt_data)->tm_ronly)
174 vn_lock(mp->mnt_vnodecovered, LK_SHARED | LK_RETRY);
175 error = VOP_GETATTR(mp->mnt_vnodecovered, &va, mp->mnt_cred);
176 VOP_UNLOCK(mp->mnt_vnodecovered, 0);
180 if (mp->mnt_cred->cr_ruid != 0 ||
181 vfs_scanopt(mp->mnt_optnew, "gid", "%d", &root_gid) != 1)
182 root_gid = va.va_gid;
183 if (mp->mnt_cred->cr_ruid != 0 ||
184 vfs_scanopt(mp->mnt_optnew, "uid", "%d", &root_uid) != 1)
185 root_uid = va.va_uid;
186 if (mp->mnt_cred->cr_ruid != 0 ||
187 vfs_scanopt(mp->mnt_optnew, "mode", "%ho", &root_mode) != 1)
188 root_mode = va.va_mode;
189 if (vfs_getopt_size(mp->mnt_optnew, "inodes", &nodes_max) != 0)
191 if (vfs_getopt_size(mp->mnt_optnew, "size", &size_max) != 0)
193 if (vfs_getopt_size(mp->mnt_optnew, "maxfilesize", &maxfilesize) != 0)
195 nonc = vfs_getopt(mp->mnt_optnew, "nonc", NULL, NULL) == 0;
197 /* Do not allow mounts if we do not have enough memory to preserve
198 * the minimum reserved pages. */
199 if (tmpfs_mem_avail() < TMPFS_PAGES_MINRESERVED)
202 /* Get the maximum number of memory pages this file system is
203 * allowed to use, based on the maximum size the user passed in
204 * the mount structure. A value of zero is treated as if the
205 * maximum available space was requested. */
206 if (size_max == 0 || size_max > OFF_MAX - PAGE_SIZE ||
207 (SIZE_MAX < OFF_MAX && size_max / PAGE_SIZE >= SIZE_MAX))
210 size_max = roundup(size_max, PAGE_SIZE);
211 pages = howmany(size_max, PAGE_SIZE);
215 if (nodes_max <= 3) {
216 if (pages < INT_MAX / nodes_per_page)
217 nodes_max = pages * nodes_per_page;
221 if (nodes_max > INT_MAX)
223 MPASS(nodes_max >= 3);
225 /* Allocate the tmpfs mount structure and fill it. */
226 tmp = (struct tmpfs_mount *)malloc(sizeof(struct tmpfs_mount),
227 M_TMPFSMNT, M_WAITOK | M_ZERO);
229 mtx_init(&tmp->tm_allnode_lock, "tmpfs allnode lock", NULL, MTX_DEF);
230 tmp->tm_nodes_max = nodes_max;
231 tmp->tm_nodes_inuse = 0;
232 tmp->tm_refcount = 1;
233 tmp->tm_maxfilesize = maxfilesize > 0 ? maxfilesize : OFF_MAX;
234 LIST_INIT(&tmp->tm_nodes_used);
236 tmp->tm_pages_max = pages;
237 tmp->tm_pages_used = 0;
238 tmp->tm_ino_unr = new_unrhdr(2, INT_MAX, &tmp->tm_allnode_lock);
239 tmp->tm_dirent_pool = uma_zcreate("TMPFS dirent",
240 sizeof(struct tmpfs_dirent), NULL, NULL, NULL, NULL,
242 tmp->tm_node_pool = uma_zcreate("TMPFS node",
243 sizeof(struct tmpfs_node), tmpfs_node_ctor, tmpfs_node_dtor,
244 tmpfs_node_init, tmpfs_node_fini, UMA_ALIGN_PTR, 0);
245 tmp->tm_ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
248 /* Allocate the root node. */
249 error = tmpfs_alloc_node(mp, tmp, VDIR, root_uid, root_gid,
250 root_mode & ALLPERMS, NULL, NULL, VNOVAL, &root);
252 if (error != 0 || root == NULL) {
253 uma_zdestroy(tmp->tm_node_pool);
254 uma_zdestroy(tmp->tm_dirent_pool);
255 delete_unrhdr(tmp->tm_ino_unr);
256 free(tmp, M_TMPFSMNT);
259 KASSERT(root->tn_id == 2,
260 ("tmpfs root with invalid ino: %ju", (uintmax_t)root->tn_id));
264 mp->mnt_flag |= MNT_LOCAL;
265 mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED;
269 mp->mnt_stat.f_namemax = MAXNAMLEN;
271 vfs_mountedfrom(mp, "tmpfs");
278 tmpfs_unmount(struct mount *mp, int mntflags)
280 struct tmpfs_mount *tmp;
281 struct tmpfs_node *node;
284 flags = (mntflags & MNT_FORCE) != 0 ? FORCECLOSE : 0;
285 tmp = VFS_TO_TMPFS(mp);
288 error = vfs_write_suspend_umnt(mp);
292 * At this point, nodes cannot be destroyed by any other
293 * thread because write suspension is started.
297 error = vflush(mp, 0, flags, curthread);
299 vfs_write_resume(mp, VR_START_WRITE);
303 if (mp->mnt_nvnodelistsize == 0) {
308 if ((mntflags & MNT_FORCE) == 0) {
309 vfs_write_resume(mp, VR_START_WRITE);
315 while ((node = LIST_FIRST(&tmp->tm_nodes_used)) != NULL) {
316 TMPFS_NODE_LOCK(node);
317 if (node->tn_type == VDIR)
318 tmpfs_dir_destroy(tmp, node);
319 if (tmpfs_free_node_locked(tmp, node, true))
322 TMPFS_NODE_UNLOCK(node);
327 vfs_write_resume(mp, VR_START_WRITE);
330 mp->mnt_flag &= ~MNT_LOCAL;
337 tmpfs_free_tmp(struct tmpfs_mount *tmp)
340 MPASS(tmp->tm_refcount > 0);
342 if (tmp->tm_refcount > 0) {
348 uma_zdestroy(tmp->tm_dirent_pool);
349 uma_zdestroy(tmp->tm_node_pool);
350 clear_unrhdr(tmp->tm_ino_unr);
351 delete_unrhdr(tmp->tm_ino_unr);
353 mtx_destroy(&tmp->tm_allnode_lock);
354 MPASS(tmp->tm_pages_used == 0);
355 MPASS(tmp->tm_nodes_inuse == 0);
357 free(tmp, M_TMPFSMNT);
361 tmpfs_root(struct mount *mp, int flags, struct vnode **vpp)
365 error = tmpfs_alloc_vp(mp, VFS_TO_TMPFS(mp)->tm_root, flags, vpp);
367 (*vpp)->v_vflag |= VV_ROOT;
372 tmpfs_fhtovp(struct mount *mp, struct fid *fhp, int flags,
375 struct tmpfs_fid *tfhp;
376 struct tmpfs_mount *tmp;
377 struct tmpfs_node *node;
380 tmp = VFS_TO_TMPFS(mp);
382 tfhp = (struct tmpfs_fid *)fhp;
383 if (tfhp->tf_len != sizeof(struct tmpfs_fid))
386 if (tfhp->tf_id >= tmp->tm_nodes_max)
390 LIST_FOREACH(node, &tmp->tm_nodes_used, tn_entries) {
391 if (node->tn_id == tfhp->tf_id &&
392 node->tn_gen == tfhp->tf_gen) {
393 tmpfs_ref_node(node);
400 error = tmpfs_alloc_vp(mp, node, LK_EXCLUSIVE, vpp);
401 tmpfs_free_node(tmp, node);
409 tmpfs_statfs(struct mount *mp, struct statfs *sbp)
411 struct tmpfs_mount *tmp;
414 tmp = VFS_TO_TMPFS(mp);
416 sbp->f_iosize = PAGE_SIZE;
417 sbp->f_bsize = PAGE_SIZE;
419 used = tmpfs_pages_used(tmp);
420 if (tmp->tm_pages_max != ULONG_MAX)
421 sbp->f_blocks = tmp->tm_pages_max;
423 sbp->f_blocks = used + tmpfs_mem_avail();
424 if (sbp->f_blocks <= used)
427 sbp->f_bavail = sbp->f_blocks - used;
428 sbp->f_bfree = sbp->f_bavail;
429 used = tmp->tm_nodes_inuse;
430 sbp->f_files = tmp->tm_nodes_max;
431 if (sbp->f_files <= used)
434 sbp->f_ffree = sbp->f_files - used;
435 /* sbp->f_owner = tmp->tn_uid; */
441 tmpfs_sync(struct mount *mp, int waitfor)
443 struct vnode *vp, *mvp;
444 struct vm_object *obj;
446 if (waitfor == MNT_SUSPEND) {
448 mp->mnt_kern_flag |= MNTK_SUSPEND2 | MNTK_SUSPENDED;
450 } else if (waitfor == MNT_LAZY) {
452 * Handle lazy updates of mtime from writes to mmaped
453 * regions. Use MNT_VNODE_FOREACH_ALL instead of
454 * MNT_VNODE_FOREACH_ACTIVE, since unmap of the
455 * tmpfs-backed vnode does not call vinactive(), due
456 * to vm object type is OBJT_SWAP.
458 MNT_VNODE_FOREACH_ALL(vp, mp, mvp) {
459 if (vp->v_type != VREG) {
464 KASSERT((obj->flags & (OBJ_TMPFS_NODE | OBJ_TMPFS)) ==
465 (OBJ_TMPFS_NODE | OBJ_TMPFS), ("non-tmpfs obj"));
468 * Unlocked read, avoid taking vnode lock if
469 * not needed. Lost update will be handled on
472 if ((obj->flags & OBJ_TMPFS_DIRTY) == 0) {
476 if (vget(vp, LK_EXCLUSIVE | LK_RETRY | LK_INTERLOCK,
479 tmpfs_check_mtime(vp);
487 * The presence of a susp_clean method tells the VFS to track writes.
490 tmpfs_susp_clean(struct mount *mp __unused)
495 * tmpfs vfs operations.
498 struct vfsops tmpfs_vfsops = {
499 .vfs_mount = tmpfs_mount,
500 .vfs_unmount = tmpfs_unmount,
501 .vfs_root = tmpfs_root,
502 .vfs_statfs = tmpfs_statfs,
503 .vfs_fhtovp = tmpfs_fhtovp,
504 .vfs_sync = tmpfs_sync,
505 .vfs_susp_clean = tmpfs_susp_clean,
507 VFS_SET(tmpfs_vfsops, tmpfs, VFCF_JAIL);