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: releng/9.0/sys/fs/tmpfs/tmpfs_vfsops.c 222167 2011-05-22 01:07:54Z rmacklem $");
   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 /* --------------------------------------------------------------------- */
   86 
   87 static int
   88 tmpfs_node_ctor(void *mem, int size, void *arg, int flags)
   89 {
   90         struct tmpfs_node *node = (struct tmpfs_node *)mem;
   91 
   92         node->tn_gen++;
   93         node->tn_size = 0;
   94         node->tn_status = 0;
   95         node->tn_flags = 0;
   96         node->tn_links = 0;
   97         node->tn_vnode = NULL;
   98         node->tn_vpstate = 0;
   99 
  100         return (0);
  101 }
  102 
  103 static void
  104 tmpfs_node_dtor(void *mem, int size, void *arg)
  105 {
  106         struct tmpfs_node *node = (struct tmpfs_node *)mem;
  107         node->tn_type = VNON;
  108 }
  109 
  110 static int
  111 tmpfs_node_init(void *mem, int size, int flags)
  112 {
  113         struct tmpfs_node *node = (struct tmpfs_node *)mem;
  114         node->tn_id = 0;
  115 
  116         mtx_init(&node->tn_interlock, "tmpfs node interlock", NULL, MTX_DEF);
  117         node->tn_gen = arc4random();
  118 
  119         return (0);
  120 }
  121 
  122 static void
  123 tmpfs_node_fini(void *mem, int size)
  124 {
  125         struct tmpfs_node *node = (struct tmpfs_node *)mem;
  126 
  127         mtx_destroy(&node->tn_interlock);
  128 }
  129 
  130 static int
  131 tmpfs_mount(struct mount *mp)
  132 {
  133         struct tmpfs_mount *tmp;
  134         struct tmpfs_node *root;
  135         size_t pages;
  136         uint32_t nodes;
  137         int error;
  138         /* Size counters. */
  139         u_int nodes_max;
  140         u_quad_t size_max, maxfilesize;
  141 
  142         /* Root node attributes. */
  143         uid_t root_uid;
  144         gid_t root_gid;
  145         mode_t root_mode;
  146 
  147         struct vattr va;
  148 
  149         if (vfs_filteropt(mp->mnt_optnew, tmpfs_opts))
  150                 return (EINVAL);
  151 
  152         if (mp->mnt_flag & MNT_UPDATE) {
  153                 /* XXX: There is no support yet to update file system
  154                  * settings.  Should be added. */
  155 
  156                 return EOPNOTSUPP;
  157         }
  158 
  159         printf("WARNING: TMPFS is considered to be a highly experimental "
  160             "feature in FreeBSD.\n");
  161 
  162         vn_lock(mp->mnt_vnodecovered, LK_SHARED | LK_RETRY);
  163         error = VOP_GETATTR(mp->mnt_vnodecovered, &va, mp->mnt_cred);
  164         VOP_UNLOCK(mp->mnt_vnodecovered, 0);
  165         if (error)
  166                 return (error);
  167 
  168         if (mp->mnt_cred->cr_ruid != 0 ||
  169             vfs_scanopt(mp->mnt_optnew, "gid", "%d", &root_gid) != 1)
  170                 root_gid = va.va_gid;
  171         if (mp->mnt_cred->cr_ruid != 0 ||
  172             vfs_scanopt(mp->mnt_optnew, "uid", "%d", &root_uid) != 1)
  173                 root_uid = va.va_uid;
  174         if (mp->mnt_cred->cr_ruid != 0 ||
  175             vfs_scanopt(mp->mnt_optnew, "mode", "%ho", &root_mode) != 1)
  176                 root_mode = va.va_mode;
  177         if (vfs_scanopt(mp->mnt_optnew, "inodes", "%u", &nodes_max) != 1)
  178                 nodes_max = 0;
  179         if (vfs_scanopt(mp->mnt_optnew, "size", "%qu", &size_max) != 1)
  180                 size_max = 0;
  181         if (vfs_scanopt(mp->mnt_optnew, "maxfilesize", "%qu",
  182             &maxfilesize) != 1)
  183                 maxfilesize = 0;
  184 
  185         /* Do not allow mounts if we do not have enough memory to preserve
  186          * the minimum reserved pages. */
  187         if (tmpfs_mem_info() < TMPFS_PAGES_RESERVED)
  188                 return ENOSPC;
  189 
  190         /* Get the maximum number of memory pages this file system is
  191          * allowed to use, based on the maximum size the user passed in
  192          * the mount structure.  A value of zero is treated as if the
  193          * maximum available space was requested. */
  194         if (size_max < PAGE_SIZE || size_max > SIZE_MAX - PAGE_SIZE)
  195                 pages = SIZE_MAX;
  196         else
  197                 pages = howmany(size_max, PAGE_SIZE);
  198         MPASS(pages > 0);
  199 
  200         if (nodes_max <= 3) {
  201                 if (pages > UINT32_MAX - 3)
  202                         nodes = UINT32_MAX;
  203                 else
  204                         nodes = pages + 3;
  205         } else
  206                 nodes = nodes_max;
  207         MPASS(nodes >= 3);
  208 
  209         /* Allocate the tmpfs mount structure and fill it. */
  210         tmp = (struct tmpfs_mount *)malloc(sizeof(struct tmpfs_mount),
  211             M_TMPFSMNT, M_WAITOK | M_ZERO);
  212 
  213         mtx_init(&tmp->allnode_lock, "tmpfs allnode lock", NULL, MTX_DEF);
  214         tmp->tm_nodes_max = nodes;
  215         tmp->tm_nodes_inuse = 0;
  216         tmp->tm_maxfilesize = maxfilesize > 0 ? maxfilesize : UINT64_MAX;
  217         LIST_INIT(&tmp->tm_nodes_used);
  218 
  219         tmp->tm_pages_max = pages;
  220         tmp->tm_pages_used = 0;
  221         tmp->tm_ino_unr = new_unrhdr(2, INT_MAX, &tmp->allnode_lock);
  222         tmp->tm_dirent_pool = uma_zcreate("TMPFS dirent",
  223             sizeof(struct tmpfs_dirent),
  224             NULL, NULL, NULL, NULL,
  225             UMA_ALIGN_PTR, 0);
  226         tmp->tm_node_pool = uma_zcreate("TMPFS node",
  227             sizeof(struct tmpfs_node),
  228             tmpfs_node_ctor, tmpfs_node_dtor,
  229             tmpfs_node_init, tmpfs_node_fini,
  230             UMA_ALIGN_PTR, 0);
  231 
  232         /* Allocate the root node. */
  233         error = tmpfs_alloc_node(tmp, VDIR, root_uid,
  234             root_gid, root_mode & ALLPERMS, NULL, NULL,
  235             VNOVAL, &root);
  236 
  237         if (error != 0 || root == NULL) {
  238             uma_zdestroy(tmp->tm_node_pool);
  239             uma_zdestroy(tmp->tm_dirent_pool);
  240             delete_unrhdr(tmp->tm_ino_unr);
  241             free(tmp, M_TMPFSMNT);
  242             return error;
  243         }
  244         KASSERT(root->tn_id == 2, ("tmpfs root with invalid ino: %d", root->tn_id));
  245         tmp->tm_root = root;
  246 
  247         MNT_ILOCK(mp);
  248         mp->mnt_flag |= MNT_LOCAL;
  249         mp->mnt_kern_flag |= MNTK_MPSAFE;
  250         MNT_IUNLOCK(mp);
  251 
  252         mp->mnt_data = tmp;
  253         mp->mnt_stat.f_namemax = MAXNAMLEN;
  254         vfs_getnewfsid(mp);
  255         vfs_mountedfrom(mp, "tmpfs");
  256 
  257         return 0;
  258 }
  259 
  260 /* --------------------------------------------------------------------- */
  261 
  262 /* ARGSUSED2 */
  263 static int
  264 tmpfs_unmount(struct mount *mp, int mntflags)
  265 {
  266         int error;
  267         int flags = 0;
  268         struct tmpfs_mount *tmp;
  269         struct tmpfs_node *node;
  270 
  271         /* Handle forced unmounts. */
  272         if (mntflags & MNT_FORCE)
  273                 flags |= FORCECLOSE;
  274 
  275         /* Finalize all pending I/O. */
  276         error = vflush(mp, 0, flags, curthread);
  277         if (error != 0)
  278                 return error;
  279 
  280         tmp = VFS_TO_TMPFS(mp);
  281 
  282         /* Free all associated data.  The loop iterates over the linked list
  283          * we have containing all used nodes.  For each of them that is
  284          * a directory, we free all its directory entries.  Note that after
  285          * freeing a node, it will automatically go to the available list,
  286          * so we will later have to iterate over it to release its items. */
  287         node = LIST_FIRST(&tmp->tm_nodes_used);
  288         while (node != NULL) {
  289                 struct tmpfs_node *next;
  290 
  291                 if (node->tn_type == VDIR) {
  292                         struct tmpfs_dirent *de;
  293 
  294                         de = TAILQ_FIRST(&node->tn_dir.tn_dirhead);
  295                         while (de != NULL) {
  296                                 struct tmpfs_dirent *nde;
  297 
  298                                 nde = TAILQ_NEXT(de, td_entries);
  299                                 tmpfs_free_dirent(tmp, de, FALSE);
  300                                 de = nde;
  301                                 node->tn_size -= sizeof(struct tmpfs_dirent);
  302                         }
  303                 }
  304 
  305                 next = LIST_NEXT(node, tn_entries);
  306                 tmpfs_free_node(tmp, node);
  307                 node = next;
  308         }
  309 
  310         uma_zdestroy(tmp->tm_dirent_pool);
  311         uma_zdestroy(tmp->tm_node_pool);
  312         delete_unrhdr(tmp->tm_ino_unr);
  313 
  314         mtx_destroy(&tmp->allnode_lock);
  315         MPASS(tmp->tm_pages_used == 0);
  316         MPASS(tmp->tm_nodes_inuse == 0);
  317 
  318         /* Throw away the tmpfs_mount structure. */
  319         free(mp->mnt_data, M_TMPFSMNT);
  320         mp->mnt_data = NULL;
  321 
  322         MNT_ILOCK(mp);
  323         mp->mnt_flag &= ~MNT_LOCAL;
  324         MNT_IUNLOCK(mp);
  325         return 0;
  326 }
  327 
  328 /* --------------------------------------------------------------------- */
  329 
  330 static int
  331 tmpfs_root(struct mount *mp, int flags, struct vnode **vpp)
  332 {
  333         int error;
  334         error = tmpfs_alloc_vp(mp, VFS_TO_TMPFS(mp)->tm_root, flags, vpp);
  335 
  336         if (!error)
  337                 (*vpp)->v_vflag |= VV_ROOT;
  338 
  339         return error;
  340 }
  341 
  342 /* --------------------------------------------------------------------- */
  343 
  344 static int
  345 tmpfs_fhtovp(struct mount *mp, struct fid *fhp, int flags,
  346     struct vnode **vpp)
  347 {
  348         boolean_t found;
  349         struct tmpfs_fid *tfhp;
  350         struct tmpfs_mount *tmp;
  351         struct tmpfs_node *node;
  352 
  353         tmp = VFS_TO_TMPFS(mp);
  354 
  355         tfhp = (struct tmpfs_fid *)fhp;
  356         if (tfhp->tf_len != sizeof(struct tmpfs_fid))
  357                 return EINVAL;
  358 
  359         if (tfhp->tf_id >= tmp->tm_nodes_max)
  360                 return EINVAL;
  361 
  362         found = FALSE;
  363 
  364         TMPFS_LOCK(tmp);
  365         LIST_FOREACH(node, &tmp->tm_nodes_used, tn_entries) {
  366                 if (node->tn_id == tfhp->tf_id &&
  367                     node->tn_gen == tfhp->tf_gen) {
  368                         found = TRUE;
  369                         break;
  370                 }
  371         }
  372         TMPFS_UNLOCK(tmp);
  373 
  374         if (found)
  375                 return (tmpfs_alloc_vp(mp, node, LK_EXCLUSIVE, vpp));
  376 
  377         return (EINVAL);
  378 }
  379 
  380 /* --------------------------------------------------------------------- */
  381 
  382 /* ARGSUSED2 */
  383 static int
  384 tmpfs_statfs(struct mount *mp, struct statfs *sbp)
  385 {
  386         fsfilcnt_t freenodes;
  387         struct tmpfs_mount *tmp;
  388 
  389         tmp = VFS_TO_TMPFS(mp);
  390 
  391         sbp->f_iosize = PAGE_SIZE;
  392         sbp->f_bsize = PAGE_SIZE;
  393 
  394         sbp->f_blocks = TMPFS_PAGES_MAX(tmp);
  395         sbp->f_bavail = sbp->f_bfree = TMPFS_PAGES_AVAIL(tmp);
  396 
  397         freenodes = MIN(tmp->tm_nodes_max - tmp->tm_nodes_inuse,
  398             TMPFS_PAGES_AVAIL(tmp) * PAGE_SIZE / sizeof(struct tmpfs_node));
  399 
  400         sbp->f_files = freenodes + tmp->tm_nodes_inuse;
  401         sbp->f_ffree = freenodes;
  402         /* sbp->f_owner = tmp->tn_uid; */
  403 
  404         return 0;
  405 }
  406 
  407 /* --------------------------------------------------------------------- */
  408 
  409 /*
  410  * tmpfs vfs operations.
  411  */
  412 
  413 struct vfsops tmpfs_vfsops = {
  414         .vfs_mount =                    tmpfs_mount,
  415         .vfs_unmount =                  tmpfs_unmount,
  416         .vfs_root =                     tmpfs_root,
  417         .vfs_statfs =                   tmpfs_statfs,
  418         .vfs_fhtovp =                   tmpfs_fhtovp,
  419 };
  420 VFS_SET(tmpfs_vfsops, tmpfs, 0);

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