freebsd-nq/sys/vm/vm_object.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

247 lines
8.6 KiB
C

/*-
* 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 Mach Operating System project at Carnegie-Mellon University.
*
* 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.
*
* from: @(#)vm_object.h 8.3 (Berkeley) 1/12/94
*
*
* Copyright (c) 1987, 1990 Carnegie-Mellon University.
* All rights reserved.
*
* Authors: Avadis Tevanian, Jr., Michael Wayne Young
*
* Permission to use, copy, modify and distribute this software and
* its documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*
* $FreeBSD$
*/
/*
* Virtual memory object module definitions.
*/
#ifndef _VM_OBJECT_
#define _VM_OBJECT_
#include <sys/queue.h>
#include <sys/_lock.h>
#include <sys/_mutex.h>
/*
* Types defined:
*
* vm_object_t Virtual memory object.
*
* List of locks
* (c) const until freed
*
*/
struct vm_object {
struct mtx mtx;
TAILQ_ENTRY(vm_object) object_list; /* list of all objects */
LIST_HEAD(, vm_object) shadow_head; /* objects that this is a shadow for */
LIST_ENTRY(vm_object) shadow_list; /* chain of shadow objects */
TAILQ_HEAD(, vm_page) memq; /* list of resident pages */
vm_page_t root; /* root of the resident page splay tree */
vm_pindex_t size; /* Object size */
int generation; /* generation ID */
int ref_count; /* How many refs?? */
int shadow_count; /* how many objects that this is a shadow for */
vm_memattr_t memattr; /* default memory attribute for pages */
objtype_t type; /* type of pager */
u_short flags; /* see below */
u_short pg_color; /* (c) color of first page in obj */
u_int paging_in_progress; /* Paging (in or out) so don't collapse or destroy */
int resident_page_count; /* number of resident pages */
struct vm_object *backing_object; /* object that I'm a shadow of */
vm_ooffset_t backing_object_offset;/* Offset in backing object */
TAILQ_ENTRY(vm_object) pager_object_list; /* list of all objects of this pager type */
LIST_HEAD(, vm_reserv) rvq; /* list of reservations */
vm_page_t cache; /* root of the cache page splay tree */
void *handle;
union {
/*
* VNode pager
*
* vnp_size - current size of file
*/
struct {
off_t vnp_size;
vm_ooffset_t writemappings;
} vnp;
/*
* Device pager
*
* devp_pglist - list of allocated pages
*/
struct {
TAILQ_HEAD(, vm_page) devp_pglist;
struct cdev_pager_ops *ops;
} devp;
/*
* SG pager
*
* sgp_pglist - list of allocated pages
*/
struct {
TAILQ_HEAD(, vm_page) sgp_pglist;
} sgp;
/*
* Swap pager
*
* swp_bcount - number of swap 'swblock' metablocks, each
* contains up to 16 swapblk assignments.
* see vm/swap_pager.h
*/
struct {
int swp_bcount;
} swp;
} un_pager;
struct ucred *cred;
vm_ooffset_t charge;
};
/*
* Flags
*/
#define OBJ_ACTIVE 0x0004 /* active objects */
#define OBJ_DEAD 0x0008 /* dead objects (during rundown) */
#define OBJ_NOSPLIT 0x0010 /* dont split this object */
#define OBJ_PIPWNT 0x0040 /* paging in progress wanted */
#define OBJ_MIGHTBEDIRTY 0x0100 /* object might be dirty, only for vnode */
#define OBJ_COLORED 0x1000 /* pg_color is defined */
#define OBJ_ONEMAPPING 0x2000 /* One USE (a single, non-forked) mapping flag */
#define OBJ_DISCONNECTWNT 0x4000 /* disconnect from vnode wanted */
#define IDX_TO_OFF(idx) (((vm_ooffset_t)(idx)) << PAGE_SHIFT)
#define OFF_TO_IDX(off) ((vm_pindex_t)(((vm_ooffset_t)(off)) >> PAGE_SHIFT))
#ifdef _KERNEL
#define OBJPC_SYNC 0x1 /* sync I/O */
#define OBJPC_INVAL 0x2 /* invalidate */
#define OBJPC_NOSYNC 0x4 /* skip if PG_NOSYNC */
/*
* The following options are supported by vm_object_page_remove().
*/
#define OBJPR_CLEANONLY 0x1 /* Don't remove dirty pages. */
#define OBJPR_NOTMAPPED 0x2 /* Don't unmap pages. */
TAILQ_HEAD(object_q, vm_object);
extern struct object_q vm_object_list; /* list of allocated objects */
extern struct mtx vm_object_list_mtx; /* lock for object list and count */
extern struct vm_object kernel_object_store;
extern struct vm_object kmem_object_store;
#define kernel_object (&kernel_object_store)
#define kmem_object (&kmem_object_store)
#define VM_OBJECT_LOCK(object) mtx_lock(&(object)->mtx)
#define VM_OBJECT_LOCK_ASSERT(object, type) \
mtx_assert(&(object)->mtx, (type))
#define VM_OBJECT_LOCK_INIT(object, type) \
mtx_init(&(object)->mtx, "vm object", \
(type), MTX_DEF | MTX_DUPOK)
#define VM_OBJECT_LOCKED(object) mtx_owned(&(object)->mtx)
#define VM_OBJECT_MTX(object) (&(object)->mtx)
#define VM_OBJECT_TRYLOCK(object) mtx_trylock(&(object)->mtx)
#define VM_OBJECT_UNLOCK(object) mtx_unlock(&(object)->mtx)
/*
* The object must be locked or thread private.
*/
static __inline void
vm_object_set_flag(vm_object_t object, u_short bits)
{
object->flags |= bits;
}
void vm_object_clear_flag(vm_object_t object, u_short bits);
void vm_object_pip_add(vm_object_t object, short i);
void vm_object_pip_subtract(vm_object_t object, short i);
void vm_object_pip_wakeup(vm_object_t object);
void vm_object_pip_wakeupn(vm_object_t object, short i);
void vm_object_pip_wait(vm_object_t object, char *waitid);
vm_object_t vm_object_allocate (objtype_t, vm_pindex_t);
void _vm_object_allocate (objtype_t, vm_pindex_t, vm_object_t);
boolean_t vm_object_coalesce(vm_object_t, vm_ooffset_t, vm_size_t, vm_size_t,
boolean_t);
void vm_object_collapse (vm_object_t);
void vm_object_deallocate (vm_object_t);
void vm_object_destroy (vm_object_t);
void vm_object_terminate (vm_object_t);
void vm_object_set_writeable_dirty (vm_object_t);
void vm_object_init (void);
void vm_object_page_cache(vm_object_t object, vm_pindex_t start,
vm_pindex_t end);
void vm_object_page_clean(vm_object_t object, vm_ooffset_t start,
vm_ooffset_t end, int flags);
void vm_object_page_remove(vm_object_t object, vm_pindex_t start,
vm_pindex_t end, int options);
boolean_t vm_object_populate(vm_object_t, vm_pindex_t, vm_pindex_t);
void vm_object_print(long addr, boolean_t have_addr, long count, char *modif);
void vm_object_reference (vm_object_t);
void vm_object_reference_locked(vm_object_t);
int vm_object_set_memattr(vm_object_t object, vm_memattr_t memattr);
void vm_object_shadow (vm_object_t *, vm_ooffset_t *, vm_size_t);
void vm_object_split(vm_map_entry_t);
void vm_object_sync(vm_object_t, vm_ooffset_t, vm_size_t, boolean_t,
boolean_t);
void vm_object_madvise (vm_object_t, vm_pindex_t, int, int);
#endif /* _KERNEL */
#endif /* _VM_OBJECT_ */