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.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *        This product includes software developed by the NetBSD
     *        Foundation, Inc. and its contributors.
     * 4. Neither the name of The NetBSD Foundation nor the names of its
     *    contributors may be used to endorse or promote products derived
     *    from this software without specific prior written permission.
     *
     * 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("$FreeBSD$");
    
    #include <sys/param.h>
    #include <sys/limits.h>
    #include <sys/lock.h>
    #include <sys/mutex.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 *, struct thread *);
    static int      tmpfs_unmount(struct mount *, int, struct thread *);
    static int      tmpfs_root(struct mount *, int flags, struct vnode **,
                        struct thread *);
    static int      tmpfs_fhtovp(struct mount *, struct fid *, struct vnode **);
    static int      tmpfs_statfs(struct mount *, struct statfs *, struct thread *);
    
    /* --------------------------------------------------------------------- */
    
    static const char *tmpfs_opts[] = {
            "from", "size", "inodes", "uid", "gid", "mode", "export",
            NULL
    };
    
    /* --------------------------------------------------------------------- */
    
    #define SWI_MAXMIB      3
    
    static u_int
    get_swpgtotal(void)
    {
            struct xswdev xsd;
           char *sname = "vm.swap_info";
           int soid[SWI_MAXMIB], oid[2];
           u_int unswdev, total, dmmax, nswapdev;
           size_t mibi, len;
   
           total = 0;
   
           len = sizeof(dmmax);
           if (kernel_sysctlbyname(curthread, "vm.dmmax", &dmmax, &len,
                                   NULL, 0, NULL, 0) != 0)
                   return total;
   
           len = sizeof(nswapdev);
           if (kernel_sysctlbyname(curthread, "vm.nswapdev",
                                   &nswapdev, &len,
                                   NULL, 0, NULL, 0) != 0)
                   return total;
   
           mibi = (SWI_MAXMIB - 1) * sizeof(int);
           oid[0] = 0;
           oid[1] = 3;
   
           if (kernel_sysctl(curthread, oid, 2,
                           soid, &mibi, (void *)sname, strlen(sname),
                           NULL, 0) != 0)
                   return total;
   
           mibi = (SWI_MAXMIB - 1);
           for (unswdev = 0; unswdev < nswapdev; ++unswdev) {
                   soid[mibi] = unswdev;
                   len = sizeof(struct xswdev);
                   if (kernel_sysctl(curthread,
                                   soid, mibi + 1, &xsd, &len, NULL, 0,
                                   NULL, 0) != 0)
                           return total;
                   if (len == sizeof(struct xswdev))
                           total += (xsd.xsw_nblks - dmmax);
           }
   
           /* Not Reached */
           return total;
   }
   
   /* --------------------------------------------------------------------- */
   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_lockf = NULL;
           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, struct thread *td)
   {
           struct tmpfs_mount *tmp;
           struct tmpfs_node *root;
           size_t pages, mem_size;
           ino_t nodes;
           int error;
           /* Size counters. */
           ino_t   nodes_max;
           off_t   size_max;
   
           /* Root node attributes. */
           uid_t   root_uid;
           gid_t   root_gid;
           mode_t  root_mode;
   
           struct vattr    va;
   
           if (vfs_filteropt(mp->mnt_optnew, tmpfs_opts))
                   return (EINVAL);
   
           if (mp->mnt_flag & MNT_UPDATE) {
                   /* XXX: There is no support yet to update file system
                    * settings.  Should be added. */
   
                   return EOPNOTSUPP;
           }
   
           printf("WARNING: TMPFS is considered to be a highly experimental "
               "feature in FreeBSD.\n");
   
           vn_lock(mp->mnt_vnodecovered, LK_SHARED | LK_RETRY, td);
           error = VOP_GETATTR(mp->mnt_vnodecovered, &va, mp->mnt_cred, td);
           VOP_UNLOCK(mp->mnt_vnodecovered, 0, td);
           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_scanopt(mp->mnt_optnew, "inodes", "%d", &nodes_max) != 1)
                   nodes_max = 0;
           if (vfs_scanopt(mp->mnt_optnew, "size", "%qu", &size_max) != 1)
                   size_max = 0;
   
           /* Do not allow mounts if we do not have enough memory to preserve
            * the minimum reserved pages. */
           mem_size = cnt.v_free_count + cnt.v_inactive_count + get_swpgtotal();
           mem_size -= mem_size > cnt.v_wire_count ? cnt.v_wire_count : mem_size;
           if (mem_size < TMPFS_PAGES_RESERVED)
                   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 >= SIZE_MAX)
                   pages = SIZE_MAX;
           else
                   pages = howmany(size_max, PAGE_SIZE);
           MPASS(pages > 0);
   
           if (nodes_max <= 3)
                   nodes = 3 + pages * PAGE_SIZE / 1024;
           else
                   nodes = nodes_max;
           MPASS(nodes >= 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;
           tmp->tm_nodes_inuse = 0;
           tmp->tm_maxfilesize = (u_int64_t)(cnt.v_page_count + get_swpgtotal()) * PAGE_SIZE;
           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);
   
           /* Allocate the root node. */
           error = tmpfs_alloc_node(tmp, VDIR, root_uid,
               root_gid, root_mode & ALLPERMS, NULL, NULL,
               VNOVAL, td, &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: %d", root->tn_id));
           tmp->tm_root = root;
   
           MNT_ILOCK(mp);
           mp->mnt_flag |= MNT_LOCAL;
           mp->mnt_kern_flag |= MNTK_MPSAFE;
           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, struct thread *l)
   {
           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, l);
           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) {
                           struct tmpfs_dirent *de;
   
                           de = TAILQ_FIRST(&node->tn_dir.tn_dirhead);
                           while (de != NULL) {
                                   struct tmpfs_dirent *nde;
   
                                   nde = TAILQ_NEXT(de, td_entries);
                                   tmpfs_free_dirent(tmp, de, FALSE);
                                   de = nde;
                                   node->tn_size -= sizeof(struct tmpfs_dirent);
                           }
                   }
   
                   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, struct thread *td)
   {
           int error;
           error = tmpfs_alloc_vp(mp, VFS_TO_TMPFS(mp)->tm_root, flags, vpp, td);
   
           if (!error)
                   (*vpp)->v_vflag |= VV_ROOT;
   
           return error;
   }
   
   /* --------------------------------------------------------------------- */
   
   static int
   tmpfs_fhtovp(struct mount *mp, struct fid *fhp, 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, curthread));
   
           return (EINVAL);
   }
   
   /* --------------------------------------------------------------------- */
   
   /* ARGSUSED2 */
   static int
   tmpfs_statfs(struct mount *mp, struct statfs *sbp, struct thread *l)
   {
           fsfilcnt_t freenodes;
           struct tmpfs_mount *tmp;
   
           tmp = VFS_TO_TMPFS(mp);
   
           sbp->f_iosize = PAGE_SIZE;
           sbp->f_bsize = PAGE_SIZE;
   
           sbp->f_blocks = TMPFS_PAGES_MAX(tmp);
           sbp->f_bavail = sbp->f_bfree = TMPFS_PAGES_AVAIL(tmp);
   
           freenodes = MIN(tmp->tm_nodes_max - tmp->tm_nodes_inuse,
               TMPFS_PAGES_AVAIL(tmp) * PAGE_SIZE / sizeof(struct tmpfs_node));
   
           sbp->f_files = freenodes + tmp->tm_nodes_inuse;
           sbp->f_ffree = freenodes;
           /* 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, 0);

Cache object: a15757eab2622801c5096f62c71da358