freebsd-nq/sys/vm/vnode_pager.h
Konstantin Belousov 555b7bb4c8 Mark pages after EOF as clean after pageout.
Suppose that a file on NFS has partially filled last page, and this
page is dirty.  NFS VOP_PAGEOUT() method only marks the the page clean
up to the block of the last written byte, leaving other blocks dirty.
Also any page which erronously exists in the vnode vm_object past EOF
is also left marked as dirty.

With the introduction of the buf-cache coherent pager, each pass of
syncer over the object with such page results in creation of B_DELWRI
buffer due to VOP_WRITE() call.  This buffer is noted on next syncer
pass, which results e.g. a visible manifestation of shutdown never
finishing vnode sync.  Note that before buf-cache coherency commit, a
dirty page might left never synced to server if a partial writes
occur.

Fix this by clearing dirty bits after EOF.  Only blocks of the partial
page which are completely after EOF are marked clean, to avoid
possible user data loss.

Reported by:	mav
Reviewed by:	alc, markj
Tested by:	mav, pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D11697
2017-07-26 20:07:05 +00:00

60 lines
2.6 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.
* 3. 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 *rbehind, int *rahead, vop_getpages_iodone_t iodone,
void *arg);
int vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *m,
int count, int flags, int *rtvals);
int vnode_pager_local_getpages(struct vop_getpages_args *ap);
int vnode_pager_local_getpages_async(struct vop_getpages_async_args *ap);
int vnode_pager_putpages_ioflags(int pager_flags);
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,
off_t eof, int lpos);
void vnode_pager_update_writecount(vm_object_t object, vm_offset_t start,
vm_offset_t end);
#endif /* _KERNEL */
#endif /* _VNODE_PAGER_ */