4cda7f7ece
- Suspend filesystem for unmount. This prevents new tmpfs nodes from instantiating, and also ensures that only unmount thread can destroy nodes. - Do not start tmpfs node deletion until all vnodes are reclaimed, which guarantees that no thread can access tmpfs data. For this, call vflush() in the loop, until the mnt_nvnodelistsize is non-zero. Note that after mnt_nvnodelistsize becomes 0, insmntque() blocks insertion of a vnode germ into the mount list of vnodes. - Fail node allocation when the filesystem is being unmounted. This is race-free due to the vflush() call in loop. This is mostly cosmetic, avoiding some more work which might be done until suspension in unmount is started. Note that there is currently no way to prevent new vnode instantiation from readers during the unmount. Due to this, forced unmount might live-lock if vflush() loop cannot get to the zero vnode count due to races with readers. The unmount would proceed after the load is lifted. Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 2 weeks
442 lines
11 KiB
C
442 lines
11 KiB
C
/* $NetBSD: tmpfs_vfsops.c,v 1.10 2005/12/11 12:24:29 christos Exp $ */
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/*-
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* Copyright (c) 2005 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Julio M. Merino Vidal, developed as part of Google's Summer of Code
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* 2005 program.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Efficient memory file system.
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*
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* tmpfs is a file system that uses NetBSD's virtual memory sub-system
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* (the well-known UVM) to store file data and metadata in an efficient
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* way. This means that it does not follow the structure of an on-disk
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* file system because it simply does not need to. Instead, it uses
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* memory-specific data structures and algorithms to automatically
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* allocate and release resources.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/limits.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/jail.h>
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#include <sys/kernel.h>
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#include <sys/stat.h>
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#include <sys/systm.h>
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#include <sys/sysctl.h>
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#include <vm/vm.h>
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#include <vm/vm_object.h>
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#include <vm/vm_param.h>
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#include <fs/tmpfs/tmpfs.h>
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/*
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* Default permission for root node
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*/
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#define TMPFS_DEFAULT_ROOT_MODE (S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH)
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MALLOC_DEFINE(M_TMPFSMNT, "tmpfs mount", "tmpfs mount structures");
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MALLOC_DEFINE(M_TMPFSNAME, "tmpfs name", "tmpfs file names");
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static int tmpfs_mount(struct mount *);
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static int tmpfs_unmount(struct mount *, int);
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static int tmpfs_root(struct mount *, int flags, struct vnode **);
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static int tmpfs_fhtovp(struct mount *, struct fid *, int,
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struct vnode **);
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static int tmpfs_statfs(struct mount *, struct statfs *);
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static const char *tmpfs_opts[] = {
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"from", "size", "maxfilesize", "inodes", "uid", "gid", "mode", "export",
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"union", NULL
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};
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static const char *tmpfs_updateopts[] = {
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"from", "export", NULL
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};
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static int
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tmpfs_node_ctor(void *mem, int size, void *arg, int flags)
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{
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struct tmpfs_node *node = (struct tmpfs_node *)mem;
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node->tn_gen++;
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node->tn_size = 0;
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node->tn_status = 0;
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node->tn_flags = 0;
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node->tn_links = 0;
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node->tn_vnode = NULL;
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node->tn_vpstate = 0;
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return (0);
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}
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static void
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tmpfs_node_dtor(void *mem, int size, void *arg)
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{
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struct tmpfs_node *node = (struct tmpfs_node *)mem;
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node->tn_type = VNON;
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}
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static int
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tmpfs_node_init(void *mem, int size, int flags)
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{
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struct tmpfs_node *node = (struct tmpfs_node *)mem;
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node->tn_id = 0;
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mtx_init(&node->tn_interlock, "tmpfs node interlock", NULL, MTX_DEF);
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node->tn_gen = arc4random();
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return (0);
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}
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static void
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tmpfs_node_fini(void *mem, int size)
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{
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struct tmpfs_node *node = (struct tmpfs_node *)mem;
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mtx_destroy(&node->tn_interlock);
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}
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static int
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tmpfs_mount(struct mount *mp)
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{
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const size_t nodes_per_page = howmany(PAGE_SIZE,
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sizeof(struct tmpfs_dirent) + sizeof(struct tmpfs_node));
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struct tmpfs_mount *tmp;
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struct tmpfs_node *root;
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struct thread *td = curthread;
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int error;
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/* Size counters. */
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u_quad_t pages;
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off_t nodes_max, size_max, maxfilesize;
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/* Root node attributes. */
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uid_t root_uid;
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gid_t root_gid;
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mode_t root_mode;
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struct vattr va;
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if (!prison_allow(td->td_ucred, PR_ALLOW_MOUNT_TMPFS))
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return (EPERM);
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if (vfs_filteropt(mp->mnt_optnew, tmpfs_opts))
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return (EINVAL);
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if (mp->mnt_flag & MNT_UPDATE) {
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/* Only support update mounts for certain options. */
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if (vfs_filteropt(mp->mnt_optnew, tmpfs_updateopts) != 0)
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return (EOPNOTSUPP);
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if (vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0) !=
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((struct tmpfs_mount *)mp->mnt_data)->tm_ronly)
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return (EOPNOTSUPP);
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return (0);
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}
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vn_lock(mp->mnt_vnodecovered, LK_SHARED | LK_RETRY);
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error = VOP_GETATTR(mp->mnt_vnodecovered, &va, mp->mnt_cred);
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VOP_UNLOCK(mp->mnt_vnodecovered, 0);
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if (error)
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return (error);
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if (mp->mnt_cred->cr_ruid != 0 ||
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vfs_scanopt(mp->mnt_optnew, "gid", "%d", &root_gid) != 1)
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root_gid = va.va_gid;
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if (mp->mnt_cred->cr_ruid != 0 ||
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vfs_scanopt(mp->mnt_optnew, "uid", "%d", &root_uid) != 1)
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root_uid = va.va_uid;
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if (mp->mnt_cred->cr_ruid != 0 ||
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vfs_scanopt(mp->mnt_optnew, "mode", "%ho", &root_mode) != 1)
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root_mode = va.va_mode;
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if (vfs_getopt_size(mp->mnt_optnew, "inodes", &nodes_max) != 0)
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nodes_max = 0;
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if (vfs_getopt_size(mp->mnt_optnew, "size", &size_max) != 0)
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size_max = 0;
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if (vfs_getopt_size(mp->mnt_optnew, "maxfilesize", &maxfilesize) != 0)
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maxfilesize = 0;
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/* Do not allow mounts if we do not have enough memory to preserve
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* the minimum reserved pages. */
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if (tmpfs_mem_avail() < TMPFS_PAGES_MINRESERVED)
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return ENOSPC;
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/* Get the maximum number of memory pages this file system is
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* allowed to use, based on the maximum size the user passed in
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* the mount structure. A value of zero is treated as if the
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* maximum available space was requested. */
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if (size_max == 0 || size_max > OFF_MAX - PAGE_SIZE ||
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(SIZE_MAX < OFF_MAX && size_max / PAGE_SIZE >= SIZE_MAX))
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pages = SIZE_MAX;
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else {
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size_max = roundup(size_max, PAGE_SIZE);
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pages = howmany(size_max, PAGE_SIZE);
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}
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MPASS(pages > 0);
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if (nodes_max <= 3) {
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if (pages < INT_MAX / nodes_per_page)
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nodes_max = pages * nodes_per_page;
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else
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nodes_max = INT_MAX;
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}
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if (nodes_max > INT_MAX)
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nodes_max = INT_MAX;
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MPASS(nodes_max >= 3);
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/* Allocate the tmpfs mount structure and fill it. */
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tmp = (struct tmpfs_mount *)malloc(sizeof(struct tmpfs_mount),
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M_TMPFSMNT, M_WAITOK | M_ZERO);
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mtx_init(&tmp->allnode_lock, "tmpfs allnode lock", NULL, MTX_DEF);
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tmp->tm_nodes_max = nodes_max;
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tmp->tm_nodes_inuse = 0;
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tmp->tm_maxfilesize = maxfilesize > 0 ? maxfilesize : OFF_MAX;
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LIST_INIT(&tmp->tm_nodes_used);
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tmp->tm_pages_max = pages;
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tmp->tm_pages_used = 0;
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tmp->tm_ino_unr = new_unrhdr(2, INT_MAX, &tmp->allnode_lock);
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tmp->tm_dirent_pool = uma_zcreate("TMPFS dirent",
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sizeof(struct tmpfs_dirent),
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NULL, NULL, NULL, NULL,
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UMA_ALIGN_PTR, 0);
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tmp->tm_node_pool = uma_zcreate("TMPFS node",
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sizeof(struct tmpfs_node),
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tmpfs_node_ctor, tmpfs_node_dtor,
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tmpfs_node_init, tmpfs_node_fini,
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UMA_ALIGN_PTR, 0);
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tmp->tm_ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
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/* Allocate the root node. */
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error = tmpfs_alloc_node(mp, tmp, VDIR, root_uid,
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root_gid, root_mode & ALLPERMS, NULL, NULL,
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VNOVAL, &root);
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if (error != 0 || root == NULL) {
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uma_zdestroy(tmp->tm_node_pool);
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uma_zdestroy(tmp->tm_dirent_pool);
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delete_unrhdr(tmp->tm_ino_unr);
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free(tmp, M_TMPFSMNT);
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return error;
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}
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KASSERT(root->tn_id == 2,
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("tmpfs root with invalid ino: %ju", (uintmax_t)root->tn_id));
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tmp->tm_root = root;
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MNT_ILOCK(mp);
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mp->mnt_flag |= MNT_LOCAL;
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MNT_IUNLOCK(mp);
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mp->mnt_data = tmp;
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mp->mnt_stat.f_namemax = MAXNAMLEN;
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vfs_getnewfsid(mp);
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vfs_mountedfrom(mp, "tmpfs");
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return 0;
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}
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/* ARGSUSED2 */
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static int
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tmpfs_unmount(struct mount *mp, int mntflags)
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{
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struct tmpfs_mount *tmp;
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struct tmpfs_node *node;
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int error, flags;
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flags = (mntflags & MNT_FORCE) != 0 ? FORCECLOSE : 0;
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tmp = VFS_TO_TMPFS(mp);
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/* Stop writers */
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error = vfs_write_suspend_umnt(mp);
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if (error != 0)
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return (error);
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/*
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* At this point, nodes cannot be destroyed by any other
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* thread because write suspension is started.
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*/
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for (;;) {
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error = vflush(mp, 0, flags, curthread);
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if (error != 0) {
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vfs_write_resume(mp, VR_START_WRITE);
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return (error);
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}
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MNT_ILOCK(mp);
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if (mp->mnt_nvnodelistsize == 0) {
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MNT_IUNLOCK(mp);
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break;
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}
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MNT_IUNLOCK(mp);
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if ((mntflags & MNT_FORCE) == 0) {
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vfs_write_resume(mp, VR_START_WRITE);
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return (EBUSY);
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}
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}
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TMPFS_LOCK(tmp);
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while ((node = LIST_FIRST(&tmp->tm_nodes_used)) != NULL) {
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TMPFS_UNLOCK(tmp);
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if (node->tn_type == VDIR)
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tmpfs_dir_destroy(tmp, node);
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tmpfs_free_node(tmp, node);
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TMPFS_LOCK(tmp);
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}
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TMPFS_UNLOCK(tmp);
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uma_zdestroy(tmp->tm_dirent_pool);
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uma_zdestroy(tmp->tm_node_pool);
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delete_unrhdr(tmp->tm_ino_unr);
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mtx_destroy(&tmp->allnode_lock);
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MPASS(tmp->tm_pages_used == 0);
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MPASS(tmp->tm_nodes_inuse == 0);
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/* Throw away the tmpfs_mount structure. */
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free(mp->mnt_data, M_TMPFSMNT);
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mp->mnt_data = NULL;
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vfs_write_resume(mp, VR_START_WRITE);
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MNT_ILOCK(mp);
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mp->mnt_flag &= ~MNT_LOCAL;
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MNT_IUNLOCK(mp);
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return (0);
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}
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static int
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tmpfs_root(struct mount *mp, int flags, struct vnode **vpp)
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{
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int error;
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error = tmpfs_alloc_vp(mp, VFS_TO_TMPFS(mp)->tm_root, flags, vpp);
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if (!error)
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(*vpp)->v_vflag |= VV_ROOT;
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return error;
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}
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static int
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tmpfs_fhtovp(struct mount *mp, struct fid *fhp, int flags,
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struct vnode **vpp)
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{
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boolean_t found;
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struct tmpfs_fid *tfhp;
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struct tmpfs_mount *tmp;
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struct tmpfs_node *node;
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tmp = VFS_TO_TMPFS(mp);
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tfhp = (struct tmpfs_fid *)fhp;
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if (tfhp->tf_len != sizeof(struct tmpfs_fid))
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return EINVAL;
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if (tfhp->tf_id >= tmp->tm_nodes_max)
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return EINVAL;
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found = FALSE;
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TMPFS_LOCK(tmp);
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LIST_FOREACH(node, &tmp->tm_nodes_used, tn_entries) {
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if (node->tn_id == tfhp->tf_id &&
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node->tn_gen == tfhp->tf_gen) {
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found = TRUE;
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break;
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}
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}
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TMPFS_UNLOCK(tmp);
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if (found)
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return (tmpfs_alloc_vp(mp, node, LK_EXCLUSIVE, vpp));
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return (EINVAL);
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}
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/* ARGSUSED2 */
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static int
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tmpfs_statfs(struct mount *mp, struct statfs *sbp)
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{
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struct tmpfs_mount *tmp;
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size_t used;
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tmp = VFS_TO_TMPFS(mp);
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sbp->f_iosize = PAGE_SIZE;
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sbp->f_bsize = PAGE_SIZE;
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used = tmpfs_pages_used(tmp);
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if (tmp->tm_pages_max != SIZE_MAX)
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sbp->f_blocks = tmp->tm_pages_max;
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else
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sbp->f_blocks = used + tmpfs_mem_avail();
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if (sbp->f_blocks <= used)
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sbp->f_bavail = 0;
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else
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sbp->f_bavail = sbp->f_blocks - used;
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sbp->f_bfree = sbp->f_bavail;
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used = tmp->tm_nodes_inuse;
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sbp->f_files = tmp->tm_nodes_max;
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if (sbp->f_files <= used)
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sbp->f_ffree = 0;
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else
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sbp->f_ffree = sbp->f_files - used;
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/* sbp->f_owner = tmp->tn_uid; */
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return 0;
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}
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static int
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tmpfs_sync(struct mount *mp, int waitfor)
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{
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if (waitfor == MNT_SUSPEND) {
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MNT_ILOCK(mp);
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mp->mnt_kern_flag |= MNTK_SUSPEND2 | MNTK_SUSPENDED;
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MNT_IUNLOCK(mp);
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}
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return (0);
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}
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/*
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* tmpfs vfs operations.
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*/
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struct vfsops tmpfs_vfsops = {
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.vfs_mount = tmpfs_mount,
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.vfs_unmount = tmpfs_unmount,
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.vfs_root = tmpfs_root,
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.vfs_statfs = tmpfs_statfs,
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.vfs_fhtovp = tmpfs_fhtovp,
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.vfs_sync = tmpfs_sync,
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};
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VFS_SET(tmpfs_vfsops, tmpfs, VFCF_JAIL);
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