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

     /*      $NetBSD: tmpfs_vfsops.c,v 1.10 2005/12/11 12:24:29 christos Exp $       */
     
     /*-
      * Copyright (c) 2005 The NetBSD Foundation, Inc.
      * All rights reserved.
      *
      * This code is derived from software contributed to The NetBSD Foundation
      * by Julio M. Merino Vidal, developed as part of Google's Summer of Code
      * 2005 program.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     * POSSIBILITY OF SUCH DAMAGE.
     */
    
    /*
     * Efficient memory file system.
     *
     * tmpfs is a file system that uses NetBSD's virtual memory sub-system
     * (the well-known UVM) to store file data and metadata in an efficient
     * way.  This means that it does not follow the structure of an on-disk
     * file system because it simply does not need to.  Instead, it uses
     * memory-specific data structures and algorithms to automatically
     * allocate and release resources.
     */
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/10.0/sys/fs/tmpfs/tmpfs_vfsops.c 254741 2013-08-23 22:52:20Z delphij $");
    
    #include <sys/param.h>
    #include <sys/limits.h>
    #include <sys/lock.h>
    #include <sys/mutex.h>
    #include <sys/proc.h>
    #include <sys/jail.h>
    #include <sys/kernel.h>
    #include <sys/stat.h>
    #include <sys/systm.h>
    #include <sys/sysctl.h>
    
    #include <vm/vm.h>
    #include <vm/vm_object.h>
    #include <vm/vm_param.h>
    
    #include <fs/tmpfs/tmpfs.h>
    
    /*
     * Default permission for root node
     */
    #define TMPFS_DEFAULT_ROOT_MODE (S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH)
    
    MALLOC_DEFINE(M_TMPFSMNT, "tmpfs mount", "tmpfs mount structures");
    MALLOC_DEFINE(M_TMPFSNAME, "tmpfs name", "tmpfs file names");
    
    /* --------------------------------------------------------------------- */
    
    static int      tmpfs_mount(struct mount *);
    static int      tmpfs_unmount(struct mount *, int);
    static int      tmpfs_root(struct mount *, int flags, struct vnode **);
    static int      tmpfs_fhtovp(struct mount *, struct fid *, int,
                        struct vnode **);
    static int      tmpfs_statfs(struct mount *, struct statfs *);
    
    /* --------------------------------------------------------------------- */
    
    static const char *tmpfs_opts[] = {
            "from", "size", "maxfilesize", "inodes", "uid", "gid", "mode", "export",
            "union", NULL
    };
    
    static const char *tmpfs_updateopts[] = {
            "from", "export", NULL
    };
    
    /* --------------------------------------------------------------------- */
    
    static int
    tmpfs_node_ctor(void *mem, int size, void *arg, int flags)
    {
            struct tmpfs_node *node = (struct tmpfs_node *)mem;
    
            node->tn_gen++;
            node->tn_size = 0;
           node->tn_status = 0;
           node->tn_flags = 0;
           node->tn_links = 0;
           node->tn_vnode = NULL;
           node->tn_vpstate = 0;
   
           return (0);
   }
   
   static void
   tmpfs_node_dtor(void *mem, int size, void *arg)
   {
           struct tmpfs_node *node = (struct tmpfs_node *)mem;
           node->tn_type = VNON;
   }
   
   static int
   tmpfs_node_init(void *mem, int size, int flags)
   {
           struct tmpfs_node *node = (struct tmpfs_node *)mem;
           node->tn_id = 0;
   
           mtx_init(&node->tn_interlock, "tmpfs node interlock", NULL, MTX_DEF);
           node->tn_gen = arc4random();
   
           return (0);
   }
   
   static void
   tmpfs_node_fini(void *mem, int size)
   {
           struct tmpfs_node *node = (struct tmpfs_node *)mem;
   
           mtx_destroy(&node->tn_interlock);
   }
   
   static int
   tmpfs_mount(struct mount *mp)
   {
           const size_t nodes_per_page = howmany(PAGE_SIZE,
               sizeof(struct tmpfs_dirent) + sizeof(struct tmpfs_node));
           struct tmpfs_mount *tmp;
           struct tmpfs_node *root;
           struct thread *td = curthread;
           int error;
           /* Size counters. */
           u_quad_t pages;
           off_t nodes_max, size_max, maxfilesize;
   
           /* Root node attributes. */
           uid_t root_uid;
           gid_t root_gid;
           mode_t root_mode;
   
           struct vattr va;
   
           if (!prison_allow(td->td_ucred, PR_ALLOW_MOUNT_TMPFS))
                   return (EPERM);
   
           if (vfs_filteropt(mp->mnt_optnew, tmpfs_opts))
                   return (EINVAL);
   
           if (mp->mnt_flag & MNT_UPDATE) {
                   /* Only support update mounts for certain options. */
                   if (vfs_filteropt(mp->mnt_optnew, tmpfs_updateopts) != 0)
                           return (EOPNOTSUPP);
                   if (vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0) !=
                       ((struct tmpfs_mount *)mp->mnt_data)->tm_ronly)
                           return (EOPNOTSUPP);
                   return (0);
           }
   
           vn_lock(mp->mnt_vnodecovered, LK_SHARED | LK_RETRY);
           error = VOP_GETATTR(mp->mnt_vnodecovered, &va, mp->mnt_cred);
           VOP_UNLOCK(mp->mnt_vnodecovered, 0);
           if (error)
                   return (error);
   
           if (mp->mnt_cred->cr_ruid != 0 ||
               vfs_scanopt(mp->mnt_optnew, "gid", "%d", &root_gid) != 1)
                   root_gid = va.va_gid;
           if (mp->mnt_cred->cr_ruid != 0 ||
               vfs_scanopt(mp->mnt_optnew, "uid", "%d", &root_uid) != 1)
                   root_uid = va.va_uid;
           if (mp->mnt_cred->cr_ruid != 0 ||
               vfs_scanopt(mp->mnt_optnew, "mode", "%ho", &root_mode) != 1)
                   root_mode = va.va_mode;
           if (vfs_getopt_size(mp->mnt_optnew, "inodes", &nodes_max) != 0)
                   nodes_max = 0;
           if (vfs_getopt_size(mp->mnt_optnew, "size", &size_max) != 0)
                   size_max = 0;
           if (vfs_getopt_size(mp->mnt_optnew, "maxfilesize", &maxfilesize) != 0)
                   maxfilesize = 0;
   
           /* Do not allow mounts if we do not have enough memory to preserve
            * the minimum reserved pages. */
           if (tmpfs_mem_avail() < TMPFS_PAGES_MINRESERVED)
                   return ENOSPC;
   
           /* Get the maximum number of memory pages this file system is
            * allowed to use, based on the maximum size the user passed in
            * the mount structure.  A value of zero is treated as if the
            * maximum available space was requested. */
           if (size_max < PAGE_SIZE || size_max > OFF_MAX - PAGE_SIZE ||
               (SIZE_MAX < OFF_MAX && size_max / PAGE_SIZE >= SIZE_MAX))
                   pages = SIZE_MAX;
           else
                   pages = howmany(size_max, PAGE_SIZE);
           MPASS(pages > 0);
   
           if (nodes_max <= 3) {
                   if (pages < INT_MAX / nodes_per_page)
                           nodes_max = pages * nodes_per_page;
                   else
                           nodes_max = INT_MAX;
           }
           if (nodes_max > INT_MAX)
                   nodes_max = INT_MAX;
           MPASS(nodes_max >= 3);
   
           /* Allocate the tmpfs mount structure and fill it. */
           tmp = (struct tmpfs_mount *)malloc(sizeof(struct tmpfs_mount),
               M_TMPFSMNT, M_WAITOK | M_ZERO);
   
           mtx_init(&tmp->allnode_lock, "tmpfs allnode lock", NULL, MTX_DEF);
           tmp->tm_nodes_max = nodes_max;
           tmp->tm_nodes_inuse = 0;
           tmp->tm_maxfilesize = maxfilesize > 0 ? maxfilesize : OFF_MAX;
           LIST_INIT(&tmp->tm_nodes_used);
   
           tmp->tm_pages_max = pages;
           tmp->tm_pages_used = 0;
           tmp->tm_ino_unr = new_unrhdr(2, INT_MAX, &tmp->allnode_lock);
           tmp->tm_dirent_pool = uma_zcreate("TMPFS dirent",
               sizeof(struct tmpfs_dirent),
               NULL, NULL, NULL, NULL,
               UMA_ALIGN_PTR, 0);
           tmp->tm_node_pool = uma_zcreate("TMPFS node",
               sizeof(struct tmpfs_node),
               tmpfs_node_ctor, tmpfs_node_dtor,
               tmpfs_node_init, tmpfs_node_fini,
               UMA_ALIGN_PTR, 0);
           tmp->tm_ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
   
           /* Allocate the root node. */
           error = tmpfs_alloc_node(tmp, VDIR, root_uid,
               root_gid, root_mode & ALLPERMS, NULL, NULL,
               VNOVAL, &root);
   
           if (error != 0 || root == NULL) {
               uma_zdestroy(tmp->tm_node_pool);
               uma_zdestroy(tmp->tm_dirent_pool);
               delete_unrhdr(tmp->tm_ino_unr);
               free(tmp, M_TMPFSMNT);
               return error;
           }
           KASSERT(root->tn_id == 2,
               ("tmpfs root with invalid ino: %ju", (uintmax_t)root->tn_id));
           tmp->tm_root = root;
   
           MNT_ILOCK(mp);
           mp->mnt_flag |= MNT_LOCAL;
           MNT_IUNLOCK(mp);
   
           mp->mnt_data = tmp;
           mp->mnt_stat.f_namemax = MAXNAMLEN;
           vfs_getnewfsid(mp);
           vfs_mountedfrom(mp, "tmpfs");
   
           return 0;
   }
   
   /* --------------------------------------------------------------------- */
   
   /* ARGSUSED2 */
   static int
   tmpfs_unmount(struct mount *mp, int mntflags)
   {
           int error;
           int flags = 0;
           struct tmpfs_mount *tmp;
           struct tmpfs_node *node;
   
           /* Handle forced unmounts. */
           if (mntflags & MNT_FORCE)
                   flags |= FORCECLOSE;
   
           /* Finalize all pending I/O. */
           error = vflush(mp, 0, flags, curthread);
           if (error != 0)
                   return error;
   
           tmp = VFS_TO_TMPFS(mp);
   
           /* Free all associated data.  The loop iterates over the linked list
            * we have containing all used nodes.  For each of them that is
            * a directory, we free all its directory entries.  Note that after
            * freeing a node, it will automatically go to the available list,
            * so we will later have to iterate over it to release its items. */
           node = LIST_FIRST(&tmp->tm_nodes_used);
           while (node != NULL) {
                   struct tmpfs_node *next;
   
                   if (node->tn_type == VDIR)
                           tmpfs_dir_destroy(tmp, node);
   
                   next = LIST_NEXT(node, tn_entries);
                   tmpfs_free_node(tmp, node);
                   node = next;
           }
   
           uma_zdestroy(tmp->tm_dirent_pool);
           uma_zdestroy(tmp->tm_node_pool);
           delete_unrhdr(tmp->tm_ino_unr);
   
           mtx_destroy(&tmp->allnode_lock);
           MPASS(tmp->tm_pages_used == 0);
           MPASS(tmp->tm_nodes_inuse == 0);
   
           /* Throw away the tmpfs_mount structure. */
           free(mp->mnt_data, M_TMPFSMNT);
           mp->mnt_data = NULL;
   
           MNT_ILOCK(mp);
           mp->mnt_flag &= ~MNT_LOCAL;
           MNT_IUNLOCK(mp);
           return 0;
   }
   
   /* --------------------------------------------------------------------- */
   
   static int
   tmpfs_root(struct mount *mp, int flags, struct vnode **vpp)
   {
           int error;
           error = tmpfs_alloc_vp(mp, VFS_TO_TMPFS(mp)->tm_root, flags, vpp);
   
           if (!error)
                   (*vpp)->v_vflag |= VV_ROOT;
   
           return error;
   }
   
   /* --------------------------------------------------------------------- */
   
   static int
   tmpfs_fhtovp(struct mount *mp, struct fid *fhp, int flags,
       struct vnode **vpp)
   {
           boolean_t found;
           struct tmpfs_fid *tfhp;
           struct tmpfs_mount *tmp;
           struct tmpfs_node *node;
   
           tmp = VFS_TO_TMPFS(mp);
   
           tfhp = (struct tmpfs_fid *)fhp;
           if (tfhp->tf_len != sizeof(struct tmpfs_fid))
                   return EINVAL;
   
           if (tfhp->tf_id >= tmp->tm_nodes_max)
                   return EINVAL;
   
           found = FALSE;
   
           TMPFS_LOCK(tmp);
           LIST_FOREACH(node, &tmp->tm_nodes_used, tn_entries) {
                   if (node->tn_id == tfhp->tf_id &&
                       node->tn_gen == tfhp->tf_gen) {
                           found = TRUE;
                           break;
                   }
           }
           TMPFS_UNLOCK(tmp);
   
           if (found)
                   return (tmpfs_alloc_vp(mp, node, LK_EXCLUSIVE, vpp));
   
           return (EINVAL);
   }
   
   /* --------------------------------------------------------------------- */
   
   /* ARGSUSED2 */
   static int
   tmpfs_statfs(struct mount *mp, struct statfs *sbp)
   {
           struct tmpfs_mount *tmp;
           size_t used;
   
           tmp = VFS_TO_TMPFS(mp);
   
           sbp->f_iosize = PAGE_SIZE;
           sbp->f_bsize = PAGE_SIZE;
   
           used = tmpfs_pages_used(tmp);
           if (tmp->tm_pages_max != SIZE_MAX)
                    sbp->f_blocks = tmp->tm_pages_max;
           else
                    sbp->f_blocks = used + tmpfs_mem_avail();
           if (sbp->f_blocks <= used)
                   sbp->f_bavail = 0;
           else
                   sbp->f_bavail = sbp->f_blocks - used;
           sbp->f_bfree = sbp->f_bavail;
           used = tmp->tm_nodes_inuse;
           sbp->f_files = tmp->tm_nodes_max;
           if (sbp->f_files <= used)
                   sbp->f_ffree = 0;
           else
                   sbp->f_ffree = sbp->f_files - used;
           /* sbp->f_owner = tmp->tn_uid; */
   
           return 0;
   }
   
   /* --------------------------------------------------------------------- */
   
   /*
    * tmpfs vfs operations.
    */
   
   struct vfsops tmpfs_vfsops = {
           .vfs_mount =                    tmpfs_mount,
           .vfs_unmount =                  tmpfs_unmount,
           .vfs_root =                     tmpfs_root,
           .vfs_statfs =                   tmpfs_statfs,
           .vfs_fhtovp =                   tmpfs_fhtovp,
   };
   VFS_SET(tmpfs_vfsops, tmpfs, VFCF_JAIL);

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