freebsd-skq/sys/vm/vnode_pager.h
Konstantin Belousov 84110e7e0b Account the writeable shared mappings backed by file in the vnode
v_writecount.  Keep the amount of the virtual address space used by
the mappings in the new vm_object un_pager.vnp.writemappings
counter. The vnode v_writecount is incremented when writemappings gets
non-zero value, and decremented when writemappings is returned to
zero.

Writeable shared vnode-backed mappings are accounted for in vm_mmap(),
and vm_map_insert() is instructed to set MAP_ENTRY_VN_WRITECNT flag on
the created map entry.  During deferred map entry deallocation,
vm_map_process_deferred() checks for MAP_ENTRY_VN_WRITECOUNT and
decrements writemappings for the vm object.

Now, the writeable mount cannot be demoted to read-only while
writeable shared mappings of the vnodes from the mount point
exist. Also, execve(2) fails for such files with ETXTBUSY, as it
should be.

Noted by:	tegge
Reviewed by:	tegge (long time ago, early version), alc
Tested by:	pho
MFC after:	3 weeks
2012-02-23 21:07:16 +00:00

57 lines
2.4 KiB
C

/*-
* Copyright (c) 1990 University of Utah.
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
* Science Department.
*
* 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.
* 4. Neither the name of the University 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 REGENTS 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 REGENTS 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.
*
* @(#)vnode_pager.h 8.1 (Berkeley) 6/11/93
* $FreeBSD$
*/
#ifndef _VNODE_PAGER_
#define _VNODE_PAGER_ 1
#ifdef _KERNEL
int vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m,
int count, int reqpage);
int vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *m,
int count, boolean_t sync,
int *rtvals);
void vnode_pager_release_writecount(vm_object_t object, vm_offset_t start,
vm_offset_t end);
void vnode_pager_undirty_pages(vm_page_t *ma, int *rtvals, int written);
void vnode_pager_update_writecount(vm_object_t object, vm_offset_t start,
vm_offset_t end);
#endif /* _KERNEL */
#endif /* _VNODE_PAGER_ */