freebsd-dev/sys/fs/msdosfs/fat.h
Conrad Meyer aaa3852435 buf: Add B_INVALONERR flag to discard data
Setting the B_INVALONERR flag before a synchronous write causes the buf
cache to forcibly invalidate contents if the write fails (BIO_ERROR).

This is intended to be used to allow layers above the buffer cache to make
more informed decisions about when discarding dirty buffers without
successful write is acceptable.

As a proof of concept, use in msdosfs to handle failures to mark the on-disk
'dirty' bit during rw mount or ro->rw update.

Extending this to other filesystems is left as future work.

PR:		210316
Reviewed by:	kib (with objections)
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D21539
2019-09-11 21:24:14 +00:00

116 lines
4.8 KiB
C

/* $FreeBSD$ */
/* $NetBSD: fat.h,v 1.12 1997/11/17 15:36:36 ws Exp $ */
/*-
* SPDX-License-Identifier: BSD-4-Clause
*
* Copyright (C) 1994, 1997 Wolfgang Solfrank.
* Copyright (C) 1994, 1997 TooLs GmbH.
* All rights reserved.
* Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by TooLs GmbH.
* 4. The name of TooLs GmbH may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``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 TOOLS GMBH 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.
*/
/*-
* Written by Paul Popelka (paulp@uts.amdahl.com)
*
* You can do anything you want with this software, just don't say you wrote
* it, and don't remove this notice.
*
* This software is provided "as is".
*
* The author supplies this software to be publicly redistributed on the
* understanding that the author is not responsible for the correct
* functioning of this software in any circumstances and is not liable for
* any damages caused by this software.
*
* October 1992
*/
#ifndef _FS_MSDOSFS_FAT_H_
#define _FS_MSDOSFS_FAT_H_
/*
* Some useful cluster numbers.
*/
#define MSDOSFSROOT 0 /* cluster 0 means the root dir */
#define CLUST_FREE 0 /* cluster 0 also means a free cluster */
#define MSDOSFSFREE CLUST_FREE
#define CLUST_FIRST 2 /* first legal cluster number */
#define CLUST_RSRVD 0xfffffff6 /* reserved cluster range */
#define CLUST_BAD 0xfffffff7 /* a cluster with a defect */
#define CLUST_EOFS 0xfffffff8 /* start of eof cluster range */
#define CLUST_EOFE 0xffffffff /* end of eof cluster range */
#define FAT12_MASK 0x00000fff /* mask for 12 bit cluster numbers */
#define FAT16_MASK 0x0000ffff /* mask for 16 bit cluster numbers */
#define FAT32_MASK 0x0fffffff /* mask for FAT32 cluster numbers */
/*
* MSDOSFS:
* Return true if filesystem uses 12 bit FATs. Microsoft Programmer's
* Reference says if the maximum cluster number in a filesystem is greater
* than 4084 ((CLUST_RSRVD - CLUST_FIRST) & FAT12_MASK) then we've got a
* 16 bit FAT filesystem. While mounting, the result of this test is stored
* in pm_fatentrysize.
*/
#define FAT12(pmp) (pmp->pm_fatmask == FAT12_MASK)
#define FAT16(pmp) (pmp->pm_fatmask == FAT16_MASK)
#define FAT32(pmp) (pmp->pm_fatmask == FAT32_MASK)
#define MSDOSFSEOF(pmp, cn) ((((cn) | ~(pmp)->pm_fatmask) & CLUST_EOFS) == CLUST_EOFS)
#if defined (_KERNEL) || defined(MAKEFS)
/*
* These are the values for the function argument to the function
* fatentry().
*/
#define FAT_GET 0x0001 /* get a FAT entry */
#define FAT_SET 0x0002 /* set a FAT entry */
#define FAT_GET_AND_SET (FAT_GET | FAT_SET)
/*
* Flags to extendfile:
*/
#define DE_CLEAR 1 /* Zero out the blocks allocated */
int pcbmap(struct denode *dep, u_long findcn, daddr_t *bnp, u_long *cnp, int* sp);
int clusterfree(struct msdosfsmount *pmp, u_long cn, u_long *oldcnp);
int clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith, u_long *retcluster, u_long *got);
int fatentry(int function, struct msdosfsmount *pmp, u_long cluster, u_long *oldcontents, u_long newcontents);
int freeclusterchain(struct msdosfsmount *pmp, u_long startchain);
int extendfile(struct denode *dep, u_long count, struct buf **bpp, u_long *ncp, int flags);
void fc_purge(struct denode *dep, u_int frcn);
int markvoldirty_upgrade(struct msdosfsmount *pmp, bool dirty, bool rw_upgrade);
static inline int
markvoldirty(struct msdosfsmount *pmp, bool dirty)
{
return (markvoldirty_upgrade(pmp, dirty, false));
}
#endif /* _KERNEL || MAKEFS */
#endif /* !_FS_MSDOSFS_FAT_H_ */