tmpfs_vfsops.c

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    1 /*      $NetBSD: tmpfs_vfsops.c,v 1.10 2005/12/11 12:24:29 christos Exp $       */
    2 
    3 /*-
    4  * Copyright (c) 2005 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 #include <sys/cdefs.h>
   44 __FBSDID("$FreeBSD$");
   45 
   46 #include <sys/param.h>
   47 #include <sys/limits.h>
   48 #include <sys/lock.h>
   49 #include <sys/mutex.h>
   50 #include <sys/kernel.h>
   51 #include <sys/stat.h>
   52 #include <sys/systm.h>
   53 #include <sys/sysctl.h>
   54 
   55 #include <vm/vm.h>
   56 #include <vm/vm_object.h>
   57 #include <vm/vm_param.h>
   58 
   59 #include <fs/tmpfs/tmpfs.h>
   60 
   61 /*
   62  * Default permission for root node
   63  */
   64 #define TMPFS_DEFAULT_ROOT_MODE (S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH)
   65 
   66 MALLOC_DEFINE(M_TMPFSMNT, "tmpfs mount", "tmpfs mount structures");
   67 MALLOC_DEFINE(M_TMPFSNAME, "tmpfs name", "tmpfs file names");
   68 
   69 /* --------------------------------------------------------------------- */
   70 
   71 static int      tmpfs_mount(struct mount *);
   72 static int      tmpfs_unmount(struct mount *, int);
   73 static int      tmpfs_root(struct mount *, int flags, struct vnode **);
   74 static int      tmpfs_fhtovp(struct mount *, struct fid *, int,
   75                     struct vnode **);
   76 static int      tmpfs_statfs(struct mount *, struct statfs *);
   77 
   78 /* --------------------------------------------------------------------- */
   79 
   80 static const char *tmpfs_opts[] = {
   81         "from", "size", "maxfilesize", "inodes", "uid", "gid", "mode", "export",
   82         NULL
   83 };
   84 
   85 static const char *tmpfs_updateopts[] = {
   86         "from", "export", NULL
   87 };
   88 
   89 /* --------------------------------------------------------------------- */
   90 
   91 static int
   92 tmpfs_getopt_size(struct vfsoptlist *opts, const char *name, off_t *value)
   93 {
   94         char *opt_value, *vtp;
   95         quad_t iv;
   96         int error, opt_len;
   97 
   98         error = vfs_getopt(opts, name, (void **)&opt_value, &opt_len);
   99         if (error != 0)
  100                 return (error);
  101         if (opt_len == 0 || opt_value == NULL)
  102                 return (EINVAL);
  103         if (opt_value[0] == '\0' || opt_value[opt_len - 1] != '\0')
  104                 return (EINVAL);
  105         iv = strtoq(opt_value, &vtp, 0);
  106         if (vtp == opt_value || (vtp[0] != '\0' && vtp[1] != '\0'))
  107                 return (EINVAL);
  108         if (iv < 0)
  109                 return (EINVAL);
  110         switch (vtp[0]) {
  111         case 't':
  112         case 'T':
  113                 iv *= 1024;
  114         case 'g':
  115         case 'G':
  116                 iv *= 1024;
  117         case 'm':
  118         case 'M':
  119                 iv *= 1024;
  120         case 'k':
  121         case 'K':
  122                 iv *= 1024;
  123         case '\0':
  124                 break;
  125         default:
  126                 return (EINVAL);
  127         }
  128         *value = iv;
  129 
  130         return (0);
  131 }
  132 
  133 
  134 static int
  135 tmpfs_node_ctor(void *mem, int size, void *arg, int flags)
  136 {
  137         struct tmpfs_node *node = (struct tmpfs_node *)mem;
  138 
  139         node->tn_gen++;
  140         node->tn_size = 0;
  141         node->tn_status = 0;
  142         node->tn_flags = 0;
  143         node->tn_links = 0;
  144         node->tn_vnode = NULL;
  145         node->tn_vpstate = 0;
  146 
  147         return (0);
  148 }
  149 
  150 static void
  151 tmpfs_node_dtor(void *mem, int size, void *arg)
  152 {
  153         struct tmpfs_node *node = (struct tmpfs_node *)mem;
  154         node->tn_type = VNON;
  155 }
  156 
  157 static int
  158 tmpfs_node_init(void *mem, int size, int flags)
  159 {
  160         struct tmpfs_node *node = (struct tmpfs_node *)mem;
  161         node->tn_id = 0;
  162 
  163         mtx_init(&node->tn_interlock, "tmpfs node interlock", NULL, MTX_DEF);
  164         node->tn_gen = arc4random();
  165 
  166         return (0);
  167 }
  168 
  169 static void
  170 tmpfs_node_fini(void *mem, int size)
  171 {
  172         struct tmpfs_node *node = (struct tmpfs_node *)mem;
  173 
  174         mtx_destroy(&node->tn_interlock);
  175 }
  176 
  177 static int
  178 tmpfs_mount(struct mount *mp)
  179 {
  180         const size_t nodes_per_page = howmany(PAGE_SIZE,
  181             sizeof(struct tmpfs_dirent) + sizeof(struct tmpfs_node));
  182         struct tmpfs_mount *tmp;
  183         struct tmpfs_node *root;
  184         int error;
  185         /* Size counters. */
  186         u_quad_t pages;
  187         off_t nodes_max, size_max, maxfilesize;
  188 
  189         /* Root node attributes. */
  190         uid_t root_uid;
  191         gid_t root_gid;
  192         mode_t root_mode;
  193 
  194         struct vattr va;
  195 
  196         if (vfs_filteropt(mp->mnt_optnew, tmpfs_opts))
  197                 return (EINVAL);
  198 
  199         if (mp->mnt_flag & MNT_UPDATE) {
  200                 /* Only support update mounts for certain options. */
  201                 if (vfs_filteropt(mp->mnt_optnew, tmpfs_updateopts) != 0)
  202                         return (EOPNOTSUPP);
  203                 if (vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0) !=
  204                     ((struct tmpfs_mount *)mp->mnt_data)->tm_ronly)
  205                         return (EOPNOTSUPP);
  206                 return (0);
  207         }
  208 
  209         vn_lock(mp->mnt_vnodecovered, LK_SHARED | LK_RETRY);
  210         error = VOP_GETATTR(mp->mnt_vnodecovered, &va, mp->mnt_cred);
  211         VOP_UNLOCK(mp->mnt_vnodecovered, 0);
  212         if (error)
  213                 return (error);
  214 
  215         if (mp->mnt_cred->cr_ruid != 0 ||
  216             vfs_scanopt(mp->mnt_optnew, "gid", "%d", &root_gid) != 1)
  217                 root_gid = va.va_gid;
  218         if (mp->mnt_cred->cr_ruid != 0 ||
  219             vfs_scanopt(mp->mnt_optnew, "uid", "%d", &root_uid) != 1)
  220                 root_uid = va.va_uid;
  221         if (mp->mnt_cred->cr_ruid != 0 ||
  222             vfs_scanopt(mp->mnt_optnew, "mode", "%ho", &root_mode) != 1)
  223                 root_mode = va.va_mode;
  224         if (tmpfs_getopt_size(mp->mnt_optnew, "inodes", &nodes_max) != 0)
  225                 nodes_max = 0;
  226         if (tmpfs_getopt_size(mp->mnt_optnew, "size", &size_max) != 0)
  227                 size_max = 0;
  228         if (tmpfs_getopt_size(mp->mnt_optnew, "maxfilesize", &maxfilesize) != 0)
  229                 maxfilesize = 0;
  230 
  231         /* Do not allow mounts if we do not have enough memory to preserve
  232          * the minimum reserved pages. */
  233         if (tmpfs_mem_avail() < TMPFS_PAGES_MINRESERVED)
  234                 return ENOSPC;
  235 
  236         /* Get the maximum number of memory pages this file system is
  237          * allowed to use, based on the maximum size the user passed in
  238          * the mount structure.  A value of zero is treated as if the
  239          * maximum available space was requested. */
  240         if (size_max == 0 || size_max > OFF_MAX - PAGE_SIZE ||
  241             (SIZE_MAX < OFF_MAX && size_max / PAGE_SIZE >= SIZE_MAX))
  242                 pages = SIZE_MAX;
  243         else {
  244                 size_max = roundup(size_max, PAGE_SIZE);
  245                 pages = howmany(size_max, PAGE_SIZE);
  246         }
  247         MPASS(pages > 0);
  248 
  249         if (nodes_max <= 3) {
  250                 if (pages < INT_MAX / nodes_per_page)
  251                         nodes_max = pages * nodes_per_page;
  252                 else
  253                         nodes_max = INT_MAX;
  254         }
  255         if (nodes_max > INT_MAX)
  256                 nodes_max = INT_MAX;
  257         MPASS(nodes_max >= 3);
  258 
  259         /* Allocate the tmpfs mount structure and fill it. */
  260         tmp = (struct tmpfs_mount *)malloc(sizeof(struct tmpfs_mount),
  261             M_TMPFSMNT, M_WAITOK | M_ZERO);
  262 
  263         mtx_init(&tmp->allnode_lock, "tmpfs allnode lock", NULL, MTX_DEF);
  264         tmp->tm_nodes_max = nodes_max;
  265         tmp->tm_nodes_inuse = 0;
  266         tmp->tm_maxfilesize = maxfilesize > 0 ? maxfilesize : OFF_MAX;
  267         LIST_INIT(&tmp->tm_nodes_used);
  268 
  269         tmp->tm_pages_max = pages;
  270         tmp->tm_pages_used = 0;
  271         tmp->tm_ino_unr = new_unrhdr(2, INT_MAX, &tmp->allnode_lock);
  272         tmp->tm_dirent_pool = uma_zcreate("TMPFS dirent",
  273             sizeof(struct tmpfs_dirent),
  274             NULL, NULL, NULL, NULL,
  275             UMA_ALIGN_PTR, 0);
  276         tmp->tm_node_pool = uma_zcreate("TMPFS node",
  277             sizeof(struct tmpfs_node),
  278             tmpfs_node_ctor, tmpfs_node_dtor,
  279             tmpfs_node_init, tmpfs_node_fini,
  280             UMA_ALIGN_PTR, 0);
  281         tmp->tm_ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
  282 
  283         /* Allocate the root node. */
  284         error = tmpfs_alloc_node(tmp, VDIR, root_uid,
  285             root_gid, root_mode & ALLPERMS, NULL, NULL,
  286             VNOVAL, &root);
  287 
  288         if (error != 0 || root == NULL) {
  289             uma_zdestroy(tmp->tm_node_pool);
  290             uma_zdestroy(tmp->tm_dirent_pool);
  291             delete_unrhdr(tmp->tm_ino_unr);
  292             free(tmp, M_TMPFSMNT);
  293             return error;
  294         }
  295         KASSERT(root->tn_id == 2, ("tmpfs root with invalid ino: %d", root->tn_id));
  296         tmp->tm_root = root;
  297 
  298         MNT_ILOCK(mp);
  299         mp->mnt_flag |= MNT_LOCAL;
  300         mp->mnt_kern_flag |= MNTK_MPSAFE;
  301         MNT_IUNLOCK(mp);
  302 
  303         mp->mnt_data = tmp;
  304         mp->mnt_stat.f_namemax = MAXNAMLEN;
  305         vfs_getnewfsid(mp);
  306         vfs_mountedfrom(mp, "tmpfs");
  307 
  308         return 0;
  309 }
  310 
  311 /* --------------------------------------------------------------------- */
  312 
  313 /* ARGSUSED2 */
  314 static int
  315 tmpfs_unmount(struct mount *mp, int mntflags)
  316 {
  317         int error;
  318         int flags = 0;
  319         struct tmpfs_mount *tmp;
  320         struct tmpfs_node *node;
  321 
  322         /* Handle forced unmounts. */
  323         if (mntflags & MNT_FORCE)
  324                 flags |= FORCECLOSE;
  325 
  326         /* Finalize all pending I/O. */
  327         error = vflush(mp, 0, flags, curthread);
  328         if (error != 0)
  329                 return error;
  330 
  331         tmp = VFS_TO_TMPFS(mp);
  332 
  333         /* Free all associated data.  The loop iterates over the linked list
  334          * we have containing all used nodes.  For each of them that is
  335          * a directory, we free all its directory entries.  Note that after
  336          * freeing a node, it will automatically go to the available list,
  337          * so we will later have to iterate over it to release its items. */
  338         node = LIST_FIRST(&tmp->tm_nodes_used);
  339         while (node != NULL) {
  340                 struct tmpfs_node *next;
  341 
  342                 if (node->tn_type == VDIR) {
  343                         struct tmpfs_dirent *de;
  344 
  345                         de = TAILQ_FIRST(&node->tn_dir.tn_dirhead);
  346                         while (de != NULL) {
  347                                 struct tmpfs_dirent *nde;
  348 
  349                                 nde = TAILQ_NEXT(de, td_entries);
  350                                 tmpfs_free_dirent(tmp, de, FALSE);
  351                                 de = nde;
  352                                 node->tn_size -= sizeof(struct tmpfs_dirent);
  353                         }
  354                 }
  355 
  356                 next = LIST_NEXT(node, tn_entries);
  357                 tmpfs_free_node(tmp, node);
  358                 node = next;
  359         }
  360 
  361         uma_zdestroy(tmp->tm_dirent_pool);
  362         uma_zdestroy(tmp->tm_node_pool);
  363         delete_unrhdr(tmp->tm_ino_unr);
  364 
  365         mtx_destroy(&tmp->allnode_lock);
  366         MPASS(tmp->tm_pages_used == 0);
  367         MPASS(tmp->tm_nodes_inuse == 0);
  368 
  369         /* Throw away the tmpfs_mount structure. */
  370         free(mp->mnt_data, M_TMPFSMNT);
  371         mp->mnt_data = NULL;
  372 
  373         MNT_ILOCK(mp);
  374         mp->mnt_flag &= ~MNT_LOCAL;
  375         MNT_IUNLOCK(mp);
  376         return 0;
  377 }
  378 
  379 /* --------------------------------------------------------------------- */
  380 
  381 static int
  382 tmpfs_root(struct mount *mp, int flags, struct vnode **vpp)
  383 {
  384         int error;
  385         error = tmpfs_alloc_vp(mp, VFS_TO_TMPFS(mp)->tm_root, flags, vpp);
  386 
  387         if (!error)
  388                 (*vpp)->v_vflag |= VV_ROOT;
  389 
  390         return error;
  391 }
  392 
  393 /* --------------------------------------------------------------------- */
  394 
  395 static int
  396 tmpfs_fhtovp(struct mount *mp, struct fid *fhp, int flags,
  397     struct vnode **vpp)
  398 {
  399         boolean_t found;
  400         struct tmpfs_fid *tfhp;
  401         struct tmpfs_mount *tmp;
  402         struct tmpfs_node *node;
  403 
  404         tmp = VFS_TO_TMPFS(mp);
  405 
  406         tfhp = (struct tmpfs_fid *)fhp;
  407         if (tfhp->tf_len != sizeof(struct tmpfs_fid))
  408                 return EINVAL;
  409 
  410         if (tfhp->tf_id >= tmp->tm_nodes_max)
  411                 return EINVAL;
  412 
  413         found = FALSE;
  414 
  415         TMPFS_LOCK(tmp);
  416         LIST_FOREACH(node, &tmp->tm_nodes_used, tn_entries) {
  417                 if (node->tn_id == tfhp->tf_id &&
  418                     node->tn_gen == tfhp->tf_gen) {
  419                         found = TRUE;
  420                         break;
  421                 }
  422         }
  423         TMPFS_UNLOCK(tmp);
  424 
  425         if (found)
  426                 return (tmpfs_alloc_vp(mp, node, LK_EXCLUSIVE, vpp));
  427 
  428         return (EINVAL);
  429 }
  430 
  431 /* --------------------------------------------------------------------- */
  432 
  433 /* ARGSUSED2 */
  434 static int
  435 tmpfs_statfs(struct mount *mp, struct statfs *sbp)
  436 {
  437         struct tmpfs_mount *tmp;
  438         size_t used;
  439 
  440         tmp = VFS_TO_TMPFS(mp);
  441 
  442         sbp->f_iosize = PAGE_SIZE;
  443         sbp->f_bsize = PAGE_SIZE;
  444 
  445         used = tmpfs_pages_used(tmp);
  446         if (tmp->tm_pages_max != SIZE_MAX)
  447                  sbp->f_blocks = tmp->tm_pages_max;
  448         else
  449                  sbp->f_blocks = used + tmpfs_mem_avail();
  450         if (sbp->f_blocks <= used)
  451                 sbp->f_bavail = 0;
  452         else
  453                 sbp->f_bavail = sbp->f_blocks - used;
  454         sbp->f_bfree = sbp->f_bavail;
  455         used = tmp->tm_nodes_inuse;
  456         sbp->f_files = tmp->tm_nodes_max;
  457         if (sbp->f_files <= used)
  458                 sbp->f_ffree = 0;
  459         else
  460                 sbp->f_ffree = sbp->f_files - used;
  461         /* sbp->f_owner = tmp->tn_uid; */
  462 
  463         return 0;
  464 }
  465 
  466 /* --------------------------------------------------------------------- */
  467 
  468 /*
  469  * tmpfs vfs operations.
  470  */
  471 
  472 struct vfsops tmpfs_vfsops = {
  473         .vfs_mount =                    tmpfs_mount,
  474         .vfs_unmount =                  tmpfs_unmount,
  475         .vfs_root =                     tmpfs_root,
  476         .vfs_statfs =                   tmpfs_statfs,
  477         .vfs_fhtovp =                   tmpfs_fhtovp,
  478 };
  479 VFS_SET(tmpfs_vfsops, tmpfs, 0);
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FreeBSD/Linux Kernel Cross Reference sys/fs/tmpfs/tmpfs_vfsops.c

FreeBSD/Linux Kernel Cross Reference
sys/fs/tmpfs/tmpfs_vfsops.c
