Initial Spring 2016 commit.
This commit is contained in:
Geoffrey Challen
177
kern/vfs/vnode.c
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177
kern/vfs/vnode.c
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/*
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* Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
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* The President and Fellows of Harvard College.
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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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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* Basic vnode support functions.
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*/
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#include <types.h>
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#include <kern/errno.h>
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#include <lib.h>
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#include <synch.h>
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#include <vfs.h>
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#include <vnode.h>
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/*
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* Initialize an abstract vnode.
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*/
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int
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vnode_init(struct vnode *vn, const struct vnode_ops *ops,
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struct fs *fs, void *fsdata)
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{
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KASSERT(vn != NULL);
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KASSERT(ops != NULL);
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vn->vn_ops = ops;
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vn->vn_refcount = 1;
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spinlock_init(&vn->vn_countlock);
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vn->vn_fs = fs;
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vn->vn_data = fsdata;
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return 0;
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}
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/*
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* Destroy an abstract vnode.
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*/
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void
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vnode_cleanup(struct vnode *vn)
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{
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KASSERT(vn->vn_refcount == 1);
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spinlock_cleanup(&vn->vn_countlock);
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vn->vn_ops = NULL;
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vn->vn_refcount = 0;
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vn->vn_fs = NULL;
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vn->vn_data = NULL;
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}
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/*
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* Increment refcount.
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* Called by VOP_INCREF.
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*/
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void
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vnode_incref(struct vnode *vn)
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{
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KASSERT(vn != NULL);
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spinlock_acquire(&vn->vn_countlock);
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vn->vn_refcount++;
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spinlock_release(&vn->vn_countlock);
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}
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/*
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* Decrement refcount.
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* Called by VOP_DECREF.
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* Calls VOP_RECLAIM if the refcount hits zero.
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*/
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void
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vnode_decref(struct vnode *vn)
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{
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bool destroy;
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int result;
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KASSERT(vn != NULL);
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spinlock_acquire(&vn->vn_countlock);
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KASSERT(vn->vn_refcount > 0);
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if (vn->vn_refcount > 1) {
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vn->vn_refcount--;
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destroy = false;
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}
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else {
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/* Don't decrement; pass the reference to VOP_RECLAIM. */
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destroy = true;
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}
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spinlock_release(&vn->vn_countlock);
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if (destroy) {
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result = VOP_RECLAIM(vn);
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if (result != 0 && result != EBUSY) {
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// XXX: lame.
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kprintf("vfs: Warning: VOP_RECLAIM: %s\n",
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strerror(result));
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}
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}
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}
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/*
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* Check for various things being valid.
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* Called before all VOP_* calls.
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*/
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void
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vnode_check(struct vnode *v, const char *opstr)
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{
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vfs_biglock_acquire();
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if (v == NULL) {
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panic("vnode_check: vop_%s: null vnode\n", opstr);
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}
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if (v == (void *)0xdeadbeef) {
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panic("vnode_check: vop_%s: deadbeef vnode\n", opstr);
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}
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if (v->vn_ops == NULL) {
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panic("vnode_check: vop_%s: null ops pointer\n", opstr);
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}
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if (v->vn_ops == (void *)0xdeadbeef) {
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panic("vnode_check: vop_%s: deadbeef ops pointer\n", opstr);
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}
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if (v->vn_ops->vop_magic != VOP_MAGIC) {
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panic("vnode_check: vop_%s: ops with bad magic number %lx\n",
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opstr, v->vn_ops->vop_magic);
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}
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// Device vnodes have null fs pointers.
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//if (v->vn_fs == NULL) {
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// panic("vnode_check: vop_%s: null fs pointer\n", opstr);
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//}
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if (v->vn_fs == (void *)0xdeadbeef) {
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panic("vnode_check: vop_%s: deadbeef fs pointer\n", opstr);
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}
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spinlock_acquire(&v->vn_countlock);
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if (v->vn_refcount < 0) {
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panic("vnode_check: vop_%s: negative refcount %d\n", opstr,
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v->vn_refcount);
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}
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else if (v->vn_refcount == 0) {
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panic("vnode_check: vop_%s: zero refcount\n", opstr);
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}
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else if (v->vn_refcount > 0x100000) {
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kprintf("vnode_check: vop_%s: warning: large refcount %d\n",
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opstr, v->vn_refcount);
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}
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spinlock_release(&v->vn_countlock);
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vfs_biglock_release();
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}
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