The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/fs/tmpfs/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 *, struct vnode **);
   75 static int      tmpfs_statfs(struct mount *, struct statfs *);
   76 
   77 /* --------------------------------------------------------------------- */
   78 
   79 static const char *tmpfs_opts[] = {
   80         "from", "size", "maxfilesize", "inodes", "uid", "gid", "mode", "export",
   81         NULL
   82 };
   83 
   84 static const char *tmpfs_updateopts[] = {
   85         "from", "export", NULL
   86 };
   87 
   88 /* --------------------------------------------------------------------- */
   89 
   90 static int
   91 tmpfs_node_ctor(void *mem, int size, void *arg, int flags)
   92 {
   93         struct tmpfs_node *node = (struct tmpfs_node *)mem;
   94 
   95         node->tn_gen++;
   96         node->tn_size = 0;
   97         node->tn_status = 0;
   98         node->tn_flags = 0;
   99         node->tn_links = 0;
  100         node->tn_vnode = NULL;
  101         node->tn_vpstate = 0;
  102 
  103         return (0);
  104 }
  105 
  106 static void
  107 tmpfs_node_dtor(void *mem, int size, void *arg)
  108 {
  109         struct tmpfs_node *node = (struct tmpfs_node *)mem;
  110         node->tn_type = VNON;
  111 }
  112 
  113 static int
  114 tmpfs_node_init(void *mem, int size, int flags)
  115 {
  116         struct tmpfs_node *node = (struct tmpfs_node *)mem;
  117         node->tn_id = 0;
  118 
  119         mtx_init(&node->tn_interlock, "tmpfs node interlock", NULL, MTX_DEF);
  120         node->tn_gen = arc4random();
  121 
  122         return (0);
  123 }
  124 
  125 static void
  126 tmpfs_node_fini(void *mem, int size)
  127 {
  128         struct tmpfs_node *node = (struct tmpfs_node *)mem;
  129 
  130         mtx_destroy(&node->tn_interlock);
  131 }
  132 
  133 static int
  134 tmpfs_mount(struct mount *mp)
  135 {
  136         struct tmpfs_mount *tmp;
  137         struct tmpfs_node *root;
  138         size_t pages;
  139         uint32_t nodes;
  140         int error;
  141         /* Size counters. */
  142         u_int nodes_max;
  143         u_quad_t size_max, maxfilesize;
  144 
  145         /* Root node attributes. */
  146         uid_t root_uid;
  147         gid_t root_gid;
  148         mode_t root_mode;
  149 
  150         struct vattr va;
  151 
  152         if (vfs_filteropt(mp->mnt_optnew, tmpfs_opts))
  153                 return (EINVAL);
  154 
  155         if (mp->mnt_flag & MNT_UPDATE) {
  156                 /* Only support update mounts for certain options. */
  157                 if (vfs_filteropt(mp->mnt_optnew, tmpfs_updateopts) != 0)
  158                         return (EOPNOTSUPP);
  159                 if (vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0) !=
  160                     ((struct tmpfs_mount *)mp->mnt_data)->tm_ronly)
  161                         return (EOPNOTSUPP);
  162                 return (0);
  163         }
  164 
  165         vn_lock(mp->mnt_vnodecovered, LK_SHARED | LK_RETRY);
  166         error = VOP_GETATTR(mp->mnt_vnodecovered, &va, mp->mnt_cred);
  167         VOP_UNLOCK(mp->mnt_vnodecovered, 0);
  168         if (error)
  169                 return (error);
  170 
  171         if (mp->mnt_cred->cr_ruid != 0 ||
  172             vfs_scanopt(mp->mnt_optnew, "gid", "%d", &root_gid) != 1)
  173                 root_gid = va.va_gid;
  174         if (mp->mnt_cred->cr_ruid != 0 ||
  175             vfs_scanopt(mp->mnt_optnew, "uid", "%d", &root_uid) != 1)
  176                 root_uid = va.va_uid;
  177         if (mp->mnt_cred->cr_ruid != 0 ||
  178             vfs_scanopt(mp->mnt_optnew, "mode", "%ho", &root_mode) != 1)
  179                 root_mode = va.va_mode;
  180         if (vfs_scanopt(mp->mnt_optnew, "inodes", "%u", &nodes_max) != 1)
  181                 nodes_max = 0;
  182         if (vfs_scanopt(mp->mnt_optnew, "size", "%qu", &size_max) != 1)
  183                 size_max = 0;
  184         if (vfs_scanopt(mp->mnt_optnew, "maxfilesize", "%qu",
  185             &maxfilesize) != 1)
  186                 maxfilesize = 0;
  187 
  188         /* Do not allow mounts if we do not have enough memory to preserve
  189          * the minimum reserved pages. */
  190         if (tmpfs_mem_info() < TMPFS_PAGES_RESERVED)
  191                 return ENOSPC;
  192 
  193         /* Get the maximum number of memory pages this file system is
  194          * allowed to use, based on the maximum size the user passed in
  195          * the mount structure.  A value of zero is treated as if the
  196          * maximum available space was requested. */
  197         if (size_max < PAGE_SIZE || size_max > SIZE_MAX - PAGE_SIZE)
  198                 pages = SIZE_MAX;
  199         else
  200                 pages = howmany(size_max, PAGE_SIZE);
  201         MPASS(pages > 0);
  202 
  203         if (nodes_max <= 3) {
  204                 if (pages > UINT32_MAX - 3)
  205                         nodes = UINT32_MAX;
  206                 else
  207                         nodes = pages + 3;
  208         } else
  209                 nodes = nodes_max;
  210         MPASS(nodes >= 3);
  211 
  212         /* Allocate the tmpfs mount structure and fill it. */
  213         tmp = (struct tmpfs_mount *)malloc(sizeof(struct tmpfs_mount),
  214             M_TMPFSMNT, M_WAITOK | M_ZERO);
  215 
  216         mtx_init(&tmp->allnode_lock, "tmpfs allnode lock", NULL, MTX_DEF);
  217         tmp->tm_nodes_max = nodes;
  218         tmp->tm_nodes_inuse = 0;
  219         tmp->tm_maxfilesize = maxfilesize > 0 ? maxfilesize : UINT64_MAX;
  220         LIST_INIT(&tmp->tm_nodes_used);
  221 
  222         tmp->tm_pages_max = pages;
  223         tmp->tm_pages_used = 0;
  224         tmp->tm_ino_unr = new_unrhdr(2, INT_MAX, &tmp->allnode_lock);
  225         tmp->tm_dirent_pool = uma_zcreate("TMPFS dirent",
  226             sizeof(struct tmpfs_dirent),
  227             NULL, NULL, NULL, NULL,
  228             UMA_ALIGN_PTR, 0);
  229         tmp->tm_node_pool = uma_zcreate("TMPFS node",
  230             sizeof(struct tmpfs_node),
  231             tmpfs_node_ctor, tmpfs_node_dtor,
  232             tmpfs_node_init, tmpfs_node_fini,
  233             UMA_ALIGN_PTR, 0);
  234         tmp->tm_ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
  235 
  236         /* Allocate the root node. */
  237         error = tmpfs_alloc_node(tmp, VDIR, root_uid,
  238             root_gid, root_mode & ALLPERMS, NULL, NULL,
  239             VNOVAL, &root);
  240 
  241         if (error != 0 || root == NULL) {
  242             uma_zdestroy(tmp->tm_node_pool);
  243             uma_zdestroy(tmp->tm_dirent_pool);
  244             delete_unrhdr(tmp->tm_ino_unr);
  245             free(tmp, M_TMPFSMNT);
  246             return error;
  247         }
  248         KASSERT(root->tn_id == 2, ("tmpfs root with invalid ino: %d", root->tn_id));
  249         tmp->tm_root = root;
  250 
  251         MNT_ILOCK(mp);
  252         mp->mnt_flag |= MNT_LOCAL;
  253         mp->mnt_kern_flag |= MNTK_MPSAFE;
  254         MNT_IUNLOCK(mp);
  255 
  256         mp->mnt_data = tmp;
  257         mp->mnt_stat.f_namemax = MAXNAMLEN;
  258         vfs_getnewfsid(mp);
  259         vfs_mountedfrom(mp, "tmpfs");
  260 
  261         return 0;
  262 }
  263 
  264 /* --------------------------------------------------------------------- */
  265 
  266 /* ARGSUSED2 */
  267 static int
  268 tmpfs_unmount(struct mount *mp, int mntflags)
  269 {
  270         int error;
  271         int flags = 0;
  272         struct tmpfs_mount *tmp;
  273         struct tmpfs_node *node;
  274 
  275         /* Handle forced unmounts. */
  276         if (mntflags & MNT_FORCE)
  277                 flags |= FORCECLOSE;
  278 
  279         /* Finalize all pending I/O. */
  280         error = vflush(mp, 0, flags, curthread);
  281         if (error != 0)
  282                 return error;
  283 
  284         tmp = VFS_TO_TMPFS(mp);
  285 
  286         /* Free all associated data.  The loop iterates over the linked list
  287          * we have containing all used nodes.  For each of them that is
  288          * a directory, we free all its directory entries.  Note that after
  289          * freeing a node, it will automatically go to the available list,
  290          * so we will later have to iterate over it to release its items. */
  291         node = LIST_FIRST(&tmp->tm_nodes_used);
  292         while (node != NULL) {
  293                 struct tmpfs_node *next;
  294 
  295                 if (node->tn_type == VDIR) {
  296                         struct tmpfs_dirent *de;
  297 
  298                         de = TAILQ_FIRST(&node->tn_dir.tn_dirhead);
  299                         while (de != NULL) {
  300                                 struct tmpfs_dirent *nde;
  301 
  302                                 nde = TAILQ_NEXT(de, td_entries);
  303                                 tmpfs_free_dirent(tmp, de, FALSE);
  304                                 de = nde;
  305                                 node->tn_size -= sizeof(struct tmpfs_dirent);
  306                         }
  307                 }
  308 
  309                 next = LIST_NEXT(node, tn_entries);
  310                 tmpfs_free_node(tmp, node);
  311                 node = next;
  312         }
  313 
  314         uma_zdestroy(tmp->tm_dirent_pool);
  315         uma_zdestroy(tmp->tm_node_pool);
  316         delete_unrhdr(tmp->tm_ino_unr);
  317 
  318         mtx_destroy(&tmp->allnode_lock);
  319         MPASS(tmp->tm_pages_used == 0);
  320         MPASS(tmp->tm_nodes_inuse == 0);
  321 
  322         /* Throw away the tmpfs_mount structure. */
  323         free(mp->mnt_data, M_TMPFSMNT);
  324         mp->mnt_data = NULL;
  325 
  326         MNT_ILOCK(mp);
  327         mp->mnt_flag &= ~MNT_LOCAL;
  328         MNT_IUNLOCK(mp);
  329         return 0;
  330 }
  331 
  332 /* --------------------------------------------------------------------- */
  333 
  334 static int
  335 tmpfs_root(struct mount *mp, int flags, struct vnode **vpp)
  336 {
  337         int error;
  338         error = tmpfs_alloc_vp(mp, VFS_TO_TMPFS(mp)->tm_root, flags, vpp);
  339 
  340         if (!error)
  341                 (*vpp)->v_vflag |= VV_ROOT;
  342 
  343         return error;
  344 }
  345 
  346 /* --------------------------------------------------------------------- */
  347 
  348 static int
  349 tmpfs_fhtovp(struct mount *mp, struct fid *fhp, struct vnode **vpp)
  350 {
  351         boolean_t found;
  352         struct tmpfs_fid *tfhp;
  353         struct tmpfs_mount *tmp;
  354         struct tmpfs_node *node;
  355 
  356         tmp = VFS_TO_TMPFS(mp);
  357 
  358         tfhp = (struct tmpfs_fid *)fhp;
  359         if (tfhp->tf_len != sizeof(struct tmpfs_fid))
  360                 return EINVAL;
  361 
  362         if (tfhp->tf_id >= tmp->tm_nodes_max)
  363                 return EINVAL;
  364 
  365         found = FALSE;
  366 
  367         TMPFS_LOCK(tmp);
  368         LIST_FOREACH(node, &tmp->tm_nodes_used, tn_entries) {
  369                 if (node->tn_id == tfhp->tf_id &&
  370                     node->tn_gen == tfhp->tf_gen) {
  371                         found = TRUE;
  372                         break;
  373                 }
  374         }
  375         TMPFS_UNLOCK(tmp);
  376 
  377         if (found)
  378                 return (tmpfs_alloc_vp(mp, node, LK_EXCLUSIVE, vpp));
  379 
  380         return (EINVAL);
  381 }
  382 
  383 /* --------------------------------------------------------------------- */
  384 
  385 /* ARGSUSED2 */
  386 static int
  387 tmpfs_statfs(struct mount *mp, struct statfs *sbp)
  388 {
  389         fsfilcnt_t freenodes;
  390         struct tmpfs_mount *tmp;
  391 
  392         tmp = VFS_TO_TMPFS(mp);
  393 
  394         sbp->f_iosize = PAGE_SIZE;
  395         sbp->f_bsize = PAGE_SIZE;
  396 
  397         sbp->f_blocks = TMPFS_PAGES_MAX(tmp);
  398         sbp->f_bavail = sbp->f_bfree = TMPFS_PAGES_AVAIL(tmp);
  399 
  400         freenodes = MIN(tmp->tm_nodes_max - tmp->tm_nodes_inuse,
  401             TMPFS_PAGES_AVAIL(tmp) * PAGE_SIZE / sizeof(struct tmpfs_node));
  402 
  403         sbp->f_files = freenodes + tmp->tm_nodes_inuse;
  404         sbp->f_ffree = freenodes;
  405         /* sbp->f_owner = tmp->tn_uid; */
  406 
  407         return 0;
  408 }
  409 
  410 /* --------------------------------------------------------------------- */
  411 
  412 /*
  413  * tmpfs vfs operations.
  414  */
  415 
  416 struct vfsops tmpfs_vfsops = {
  417         .vfs_mount =                    tmpfs_mount,
  418         .vfs_unmount =                  tmpfs_unmount,
  419         .vfs_root =                     tmpfs_root,
  420         .vfs_statfs =                   tmpfs_statfs,
  421         .vfs_fhtovp =                   tmpfs_fhtovp,
  422 };
  423 VFS_SET(tmpfs_vfsops, tmpfs, 0);

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