2 * Copyright (c) 1997, Duke University
6 * Andrew Gallatin <gallatin@cs.duke.edu>
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. The name of Duke University may not be used to endorse or promote
17 * products derived from this software without specific prior written
20 * THIS SOFTWARE IS PROVIDED BY DUKE UNIVERSITY ``AS IS'' AND ANY
21 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL DUKE UNIVERSITY BE LIABLE
24 * 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 PROFITSOR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
28 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
29 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
30 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 * This is a set of routines for enabling and disabling copy on write
35 * protection for data written into sockets.
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/kernel.h>
46 #include <sys/mutex.h>
48 #include <sys/sf_buf.h>
49 #include <sys/socketvar.h>
53 #include <vm/vm_param.h>
55 #include <vm/vm_map.h>
56 #include <vm/vm_page.h>
57 #include <vm/vm_object.h>
60 struct netsend_cow_stats {
68 static struct netsend_cow_stats socow_stats;
70 static void socow_iodone(void *addr, void *args);
73 socow_iodone(void *addr, void *args)
81 /* remove COW mapping */
82 vm_page_lock_queues();
84 vm_page_unwire(pp, 0);
86 * Check for the object going away on us. This can
87 * happen since we don't hold a reference to it.
88 * If so, we're responsible for freeing the page.
90 if (pp->wire_count == 0 && pp->object == NULL)
92 vm_page_unlock_queues();
97 socow_setup(struct mbuf *m0, struct uio *uio)
103 struct vmspace *vmspace;
105 vm_offset_t offset, uva;
108 vmspace = curproc->p_vmspace;
109 map = &vmspace->vm_map;
110 uva = (vm_offset_t) uio->uio_iov->iov_base;
111 offset = uva & PAGE_MASK;
116 * verify page is mapped & not already wired for i/o
118 socow_stats.attempted++;
119 pa=pmap_extract(map->pmap, uva);
121 socow_stats.fail_not_mapped++;
125 pp = PHYS_TO_VM_PAGE(pa);
130 vm_page_lock_queues();
131 vm_page_cowsetup(pp);
134 * wire the page for I/O
137 vm_page_unlock_queues();
142 sf = sf_buf_alloc(pp, SFB_CATCH);
144 vm_page_lock_queues();
145 vm_page_cowclear(pp);
146 vm_page_unwire(pp, 0);
148 * Check for the object going away on us. This can
149 * happen since we don't hold a reference to it.
150 * If so, we're responsible for freeing the page.
152 if (pp->wire_count == 0 && pp->object == NULL)
154 vm_page_unlock_queues();
155 socow_stats.fail_sf_buf++;
162 MEXTADD(m0, sf_buf_kva(sf), PAGE_SIZE, socow_iodone, sf, M_RDONLY,
164 m0->m_len = PAGE_SIZE - offset;
165 m0->m_data = (caddr_t)sf_buf_kva(sf) + offset;
166 socow_stats.success++;
169 iov->iov_base = (char *)iov->iov_base + m0->m_len;
170 iov->iov_len -= m0->m_len;
171 uio->uio_resid -= m0->m_len;
172 uio->uio_offset += m0->m_len;
173 if (iov->iov_len == 0) {