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.
46 #include "opt_tmpfs.h"
48 #include <sys/cdefs.h>
49 __FBSDID("$FreeBSD$");
51 #include <sys/param.h>
52 #include <sys/systm.h>
53 #include <sys/dirent.h>
54 #include <sys/limits.h>
56 #include <sys/mount.h>
57 #include <sys/mutex.h>
60 #include <sys/kernel.h>
61 #include <sys/rwlock.h>
64 #include <sys/sysctl.h>
65 #include <sys/vnode.h>
68 #include <vm/vm_param.h>
70 #include <vm/vm_extern.h>
71 #include <vm/vm_map.h>
72 #include <vm/vm_object.h>
73 #include <vm/vm_param.h>
75 #include <fs/tmpfs/tmpfs.h>
78 * Default permission for root node
80 #define TMPFS_DEFAULT_ROOT_MODE (S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH)
82 MALLOC_DEFINE(M_TMPFSMNT, "tmpfs mount", "tmpfs mount structures");
83 MALLOC_DEFINE(M_TMPFSNAME, "tmpfs name", "tmpfs file names");
85 static int tmpfs_mount(struct mount *);
86 static int tmpfs_unmount(struct mount *, int);
87 static int tmpfs_root(struct mount *, int flags, struct vnode **);
88 static int tmpfs_fhtovp(struct mount *, struct fid *, int,
90 static int tmpfs_statfs(struct mount *, struct statfs *);
91 static void tmpfs_susp_clean(struct mount *);
93 static const char *tmpfs_opts[] = {
94 "from", "size", "maxfilesize", "inodes", "uid", "gid", "mode", "export",
98 static const char *tmpfs_updateopts[] = {
99 "from", "export", "size", NULL
103 tmpfs_node_ctor(void *mem, int size, void *arg, int flags)
105 struct tmpfs_node *node = (struct tmpfs_node *)mem;
112 node->tn_vnode = NULL;
113 node->tn_vpstate = 0;
119 tmpfs_node_dtor(void *mem, int size, void *arg)
121 struct tmpfs_node *node = (struct tmpfs_node *)mem;
122 node->tn_type = VNON;
126 tmpfs_node_init(void *mem, int size, int flags)
128 struct tmpfs_node *node = (struct tmpfs_node *)mem;
131 mtx_init(&node->tn_interlock, "tmpfs node interlock", NULL, MTX_DEF);
132 node->tn_gen = arc4random();
138 tmpfs_node_fini(void *mem, int size)
140 struct tmpfs_node *node = (struct tmpfs_node *)mem;
142 mtx_destroy(&node->tn_interlock);
146 * Handle updates of time from writes to mmaped regions. Use
147 * MNT_VNODE_FOREACH_ALL instead of MNT_VNODE_FOREACH_ACTIVE, since
148 * unmap of the tmpfs-backed vnode does not call vinactive(), due to
149 * vm object type is OBJT_SWAP.
150 * If lazy, only handle delayed update of mtime due to the writes to
154 tmpfs_update_mtime(struct mount *mp, bool lazy)
156 struct vnode *vp, *mvp;
157 struct vm_object *obj;
159 MNT_VNODE_FOREACH_ALL(vp, mp, mvp) {
160 if (vp->v_type != VREG) {
165 KASSERT((obj->flags & (OBJ_TMPFS_NODE | OBJ_TMPFS)) ==
166 (OBJ_TMPFS_NODE | OBJ_TMPFS), ("non-tmpfs obj"));
169 * In lazy case, do unlocked read, avoid taking vnode
170 * lock if not needed. Lost update will be handled on
172 * For non-lazy case, we must flush all pending
173 * metadata changes now.
175 if (!lazy || (obj->flags & OBJ_TMPFS_DIRTY) != 0) {
176 if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK,
179 tmpfs_check_mtime(vp);
190 struct tmpfs_check_rw_maps_arg {
195 tmpfs_check_rw_maps_cb(struct mount *mp __unused, vm_map_t map __unused,
196 vm_map_entry_t entry __unused, void *arg)
198 struct tmpfs_check_rw_maps_arg *a;
206 * Revoke write permissions from all mappings of regular files
207 * belonging to the specified tmpfs mount.
210 tmpfs_revoke_rw_maps_cb(struct mount *mp __unused, vm_map_t map,
211 vm_map_entry_t entry, void *arg __unused)
215 * XXXKIB: might be invalidate the mapping
216 * instead ? The process is not going to be
219 entry->max_protection &= ~VM_PROT_WRITE;
220 if ((entry->protection & VM_PROT_WRITE) != 0) {
221 entry->protection &= ~VM_PROT_WRITE;
222 pmap_protect(map->pmap, entry->start, entry->end,
229 tmpfs_all_rw_maps(struct mount *mp, bool (*cb)(struct mount *mp, vm_map_t,
230 vm_map_entry_t, void *), void *cb_arg)
235 vm_map_entry_t entry;
242 sx_slock(&allproc_lock);
245 FOREACH_PROC_IN_SYSTEM(p) {
247 if (p->p_state != PRS_NORMAL || (p->p_flag & (P_INEXEC |
248 P_SYSTEM | P_WEXIT)) != 0) {
252 vm = vmspace_acquire_ref(p);
259 sx_sunlock(&allproc_lock);
264 vm_map_wait_busy(map);
265 for (entry = map->header.next; entry != &map->header;
266 entry = entry->next) {
267 if ((entry->eflags & (MAP_ENTRY_GUARD |
268 MAP_ENTRY_IS_SUB_MAP | MAP_ENTRY_COW)) != 0 ||
269 (entry->max_protection & VM_PROT_WRITE) == 0)
271 object = entry->object.vm_object;
272 if (object == NULL || object->type != OBJT_SWAP ||
273 (object->flags & OBJ_TMPFS_NODE) == 0)
276 * No need to dig into shadow chain, mapping
277 * of the object not at top is readonly.
280 VM_OBJECT_RLOCK(object);
281 if (object->type == OBJT_DEAD) {
282 VM_OBJECT_RUNLOCK(object);
285 MPASS(object->ref_count > 1);
286 if ((object->flags & (OBJ_TMPFS_NODE | OBJ_TMPFS)) !=
287 (OBJ_TMPFS_NODE | OBJ_TMPFS)) {
288 VM_OBJECT_RUNLOCK(object);
291 vp = object->un_pager.swp.swp_tmpfs;
292 if (vp->v_mount != mp) {
293 VM_OBJECT_RUNLOCK(object);
297 terminate = cb(mp, map, entry, cb_arg);
298 VM_OBJECT_RUNLOCK(object);
305 sx_slock(&allproc_lock);
310 if (!terminate && gen != allproc_gen)
312 sx_sunlock(&allproc_lock);
316 tmpfs_check_rw_maps(struct mount *mp)
318 struct tmpfs_check_rw_maps_arg ca;
321 tmpfs_all_rw_maps(mp, tmpfs_check_rw_maps_cb, &ca);
326 tmpfs_rw_to_ro(struct mount *mp)
331 forced = (mp->mnt_flag & MNT_FORCE) != 0;
332 flags = WRITECLOSE | (forced ? FORCECLOSE : 0);
334 if ((error = vn_start_write(NULL, &mp, V_WAIT)) != 0)
336 error = vfs_write_suspend_umnt(mp);
339 if (!forced && tmpfs_check_rw_maps(mp)) {
343 VFS_TO_TMPFS(mp)->tm_ronly = 1;
345 mp->mnt_flag |= MNT_RDONLY;
348 tmpfs_all_rw_maps(mp, tmpfs_revoke_rw_maps_cb, NULL);
349 tmpfs_update_mtime(mp, false);
350 error = vflush(mp, 0, flags, curthread);
352 VFS_TO_TMPFS(mp)->tm_ronly = 0;
354 mp->mnt_flag &= ~MNT_RDONLY;
358 if (!tmpfs_check_rw_maps(mp))
362 vfs_write_resume(mp, 0);
367 tmpfs_mount(struct mount *mp)
369 const size_t nodes_per_page = howmany(PAGE_SIZE,
370 sizeof(struct tmpfs_dirent) + sizeof(struct tmpfs_node));
371 struct tmpfs_mount *tmp;
372 struct tmpfs_node *root;
377 off_t nodes_max, size_max, maxfilesize;
379 /* Root node attributes. */
386 if (vfs_filteropt(mp->mnt_optnew, tmpfs_opts))
389 if (mp->mnt_flag & MNT_UPDATE) {
390 /* Only support update mounts for certain options. */
391 if (vfs_filteropt(mp->mnt_optnew, tmpfs_updateopts) != 0)
393 if (vfs_getopt_size(mp->mnt_optnew, "size", &size_max) == 0) {
395 * On-the-fly resizing is not supported (yet). We still
396 * need to have "size" listed as "supported", otherwise
397 * trying to update fs that is listed in fstab with size
398 * parameter, say trying to change rw to ro or vice
399 * versa, would cause vfs_filteropt() to bail.
401 if (size_max != VFS_TO_TMPFS(mp)->tm_size_max)
404 if (vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0) &&
405 !(VFS_TO_TMPFS(mp)->tm_ronly)) {
407 return (tmpfs_rw_to_ro(mp));
408 } else if (!vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0) &&
409 VFS_TO_TMPFS(mp)->tm_ronly) {
411 VFS_TO_TMPFS(mp)->tm_ronly = 0;
413 mp->mnt_flag &= ~MNT_RDONLY;
419 vn_lock(mp->mnt_vnodecovered, LK_SHARED | LK_RETRY);
420 error = VOP_GETATTR(mp->mnt_vnodecovered, &va, mp->mnt_cred);
421 VOP_UNLOCK(mp->mnt_vnodecovered, 0);
425 if (mp->mnt_cred->cr_ruid != 0 ||
426 vfs_scanopt(mp->mnt_optnew, "gid", "%d", &root_gid) != 1)
427 root_gid = va.va_gid;
428 if (mp->mnt_cred->cr_ruid != 0 ||
429 vfs_scanopt(mp->mnt_optnew, "uid", "%d", &root_uid) != 1)
430 root_uid = va.va_uid;
431 if (mp->mnt_cred->cr_ruid != 0 ||
432 vfs_scanopt(mp->mnt_optnew, "mode", "%ho", &root_mode) != 1)
433 root_mode = va.va_mode;
434 if (vfs_getopt_size(mp->mnt_optnew, "inodes", &nodes_max) != 0)
436 if (vfs_getopt_size(mp->mnt_optnew, "size", &size_max) != 0)
438 if (vfs_getopt_size(mp->mnt_optnew, "maxfilesize", &maxfilesize) != 0)
440 nonc = vfs_getopt(mp->mnt_optnew, "nonc", NULL, NULL) == 0;
442 /* Do not allow mounts if we do not have enough memory to preserve
443 * the minimum reserved pages. */
444 if (tmpfs_mem_avail() < TMPFS_PAGES_MINRESERVED)
447 /* Get the maximum number of memory pages this file system is
448 * allowed to use, based on the maximum size the user passed in
449 * the mount structure. A value of zero is treated as if the
450 * maximum available space was requested. */
451 if (size_max == 0 || size_max > OFF_MAX - PAGE_SIZE ||
452 (SIZE_MAX < OFF_MAX && size_max / PAGE_SIZE >= SIZE_MAX))
455 size_max = roundup(size_max, PAGE_SIZE);
456 pages = howmany(size_max, PAGE_SIZE);
460 if (nodes_max <= 3) {
461 if (pages < INT_MAX / nodes_per_page)
462 nodes_max = pages * nodes_per_page;
466 if (nodes_max > INT_MAX)
468 MPASS(nodes_max >= 3);
470 /* Allocate the tmpfs mount structure and fill it. */
471 tmp = (struct tmpfs_mount *)malloc(sizeof(struct tmpfs_mount),
472 M_TMPFSMNT, M_WAITOK | M_ZERO);
474 mtx_init(&tmp->tm_allnode_lock, "tmpfs allnode lock", NULL, MTX_DEF);
475 tmp->tm_nodes_max = nodes_max;
476 tmp->tm_nodes_inuse = 0;
477 tmp->tm_refcount = 1;
478 tmp->tm_maxfilesize = maxfilesize > 0 ? maxfilesize : OFF_MAX;
479 LIST_INIT(&tmp->tm_nodes_used);
481 tmp->tm_size_max = size_max;
482 tmp->tm_pages_max = pages;
483 tmp->tm_pages_used = 0;
484 new_unrhdr64(&tmp->tm_ino_unr, 2);
485 tmp->tm_dirent_pool = uma_zcreate("TMPFS dirent",
486 sizeof(struct tmpfs_dirent), NULL, NULL, NULL, NULL,
488 tmp->tm_node_pool = uma_zcreate("TMPFS node",
489 sizeof(struct tmpfs_node), tmpfs_node_ctor, tmpfs_node_dtor,
490 tmpfs_node_init, tmpfs_node_fini, UMA_ALIGN_PTR, 0);
491 tmp->tm_ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
494 /* Allocate the root node. */
495 error = tmpfs_alloc_node(mp, tmp, VDIR, root_uid, root_gid,
496 root_mode & ALLPERMS, NULL, NULL, VNOVAL, &root);
498 if (error != 0 || root == NULL) {
499 uma_zdestroy(tmp->tm_node_pool);
500 uma_zdestroy(tmp->tm_dirent_pool);
501 free(tmp, M_TMPFSMNT);
504 KASSERT(root->tn_id == 2,
505 ("tmpfs root with invalid ino: %ju", (uintmax_t)root->tn_id));
509 mp->mnt_flag |= MNT_LOCAL;
510 mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED |
515 mp->mnt_stat.f_namemax = MAXNAMLEN;
517 vfs_mountedfrom(mp, "tmpfs");
524 tmpfs_unmount(struct mount *mp, int mntflags)
526 struct tmpfs_mount *tmp;
527 struct tmpfs_node *node;
530 flags = (mntflags & MNT_FORCE) != 0 ? FORCECLOSE : 0;
531 tmp = VFS_TO_TMPFS(mp);
534 error = vfs_write_suspend_umnt(mp);
538 * At this point, nodes cannot be destroyed by any other
539 * thread because write suspension is started.
543 error = vflush(mp, 0, flags, curthread);
545 vfs_write_resume(mp, VR_START_WRITE);
549 if (mp->mnt_nvnodelistsize == 0) {
554 if ((mntflags & MNT_FORCE) == 0) {
555 vfs_write_resume(mp, VR_START_WRITE);
561 while ((node = LIST_FIRST(&tmp->tm_nodes_used)) != NULL) {
562 TMPFS_NODE_LOCK(node);
563 if (node->tn_type == VDIR)
564 tmpfs_dir_destroy(tmp, node);
565 if (tmpfs_free_node_locked(tmp, node, true))
568 TMPFS_NODE_UNLOCK(node);
573 vfs_write_resume(mp, VR_START_WRITE);
576 mp->mnt_flag &= ~MNT_LOCAL;
583 tmpfs_free_tmp(struct tmpfs_mount *tmp)
586 MPASS(tmp->tm_refcount > 0);
588 if (tmp->tm_refcount > 0) {
594 uma_zdestroy(tmp->tm_dirent_pool);
595 uma_zdestroy(tmp->tm_node_pool);
597 mtx_destroy(&tmp->tm_allnode_lock);
598 MPASS(tmp->tm_pages_used == 0);
599 MPASS(tmp->tm_nodes_inuse == 0);
601 free(tmp, M_TMPFSMNT);
605 tmpfs_root(struct mount *mp, int flags, struct vnode **vpp)
609 error = tmpfs_alloc_vp(mp, VFS_TO_TMPFS(mp)->tm_root, flags, vpp);
611 (*vpp)->v_vflag |= VV_ROOT;
616 tmpfs_fhtovp(struct mount *mp, struct fid *fhp, int flags,
619 struct tmpfs_fid *tfhp;
620 struct tmpfs_mount *tmp;
621 struct tmpfs_node *node;
624 tmp = VFS_TO_TMPFS(mp);
626 tfhp = (struct tmpfs_fid *)fhp;
627 if (tfhp->tf_len != sizeof(struct tmpfs_fid))
630 if (tfhp->tf_id >= tmp->tm_nodes_max)
634 LIST_FOREACH(node, &tmp->tm_nodes_used, tn_entries) {
635 if (node->tn_id == tfhp->tf_id &&
636 node->tn_gen == tfhp->tf_gen) {
637 tmpfs_ref_node(node);
644 error = tmpfs_alloc_vp(mp, node, LK_EXCLUSIVE, vpp);
645 tmpfs_free_node(tmp, node);
653 tmpfs_statfs(struct mount *mp, struct statfs *sbp)
655 struct tmpfs_mount *tmp;
658 tmp = VFS_TO_TMPFS(mp);
660 sbp->f_iosize = PAGE_SIZE;
661 sbp->f_bsize = PAGE_SIZE;
663 used = tmpfs_pages_used(tmp);
664 if (tmp->tm_pages_max != ULONG_MAX)
665 sbp->f_blocks = tmp->tm_pages_max;
667 sbp->f_blocks = used + tmpfs_mem_avail();
668 if (sbp->f_blocks <= used)
671 sbp->f_bavail = sbp->f_blocks - used;
672 sbp->f_bfree = sbp->f_bavail;
673 used = tmp->tm_nodes_inuse;
674 sbp->f_files = tmp->tm_nodes_max;
675 if (sbp->f_files <= used)
678 sbp->f_ffree = sbp->f_files - used;
679 /* sbp->f_owner = tmp->tn_uid; */
685 tmpfs_sync(struct mount *mp, int waitfor)
688 if (waitfor == MNT_SUSPEND) {
690 mp->mnt_kern_flag |= MNTK_SUSPEND2 | MNTK_SUSPENDED;
692 } else if (waitfor == MNT_LAZY) {
693 tmpfs_update_mtime(mp, true);
699 * The presence of a susp_clean method tells the VFS to track writes.
702 tmpfs_susp_clean(struct mount *mp __unused)
707 * tmpfs vfs operations.
710 struct vfsops tmpfs_vfsops = {
711 .vfs_mount = tmpfs_mount,
712 .vfs_unmount = tmpfs_unmount,
713 .vfs_root = vfs_cache_root,
714 .vfs_cachedroot = tmpfs_root,
715 .vfs_statfs = tmpfs_statfs,
716 .vfs_fhtovp = tmpfs_fhtovp,
717 .vfs_sync = tmpfs_sync,
718 .vfs_susp_clean = tmpfs_susp_clean,
720 VFS_SET(tmpfs_vfsops, tmpfs, VFCF_JAIL);