2c9178edde
superblock has a check-hash error, an error message noting the superblock check-hash failure is printed and the mount fails. The administrator then runs fsck to repair the filesystem and when successful, the filesystem can once again be mounted. This approach fails if the filesystem in question is a root filesystem from which you are trying to boot. Here, the loader fails when trying to access the filesystem to get the kernel to boot. So it is necessary to allow the loader to ignore the superblock check-hash error and make a best effort to read the kernel. The filesystem may be suffiently corrupted that the read attempt fails, but there is no harm in trying since the loader makes no attempt to write to the filesystem. Once the kernel is loaded and starts to run, it attempts to mount its root filesystem. Once again, failure means that it breaks to its prompt to ask where to get its root filesystem. Unless you have an alternate root filesystem, you are stuck. Since the root filesystem is initially mounted read-only, it is safe to make an attempt to mount the root filesystem with the failed superblock check-hash. Thus, when asked to mount a root filesystem with a failed superblock check-hash, the kernel prints a warning message that the root filesystem superblock check-hash needs repair, but notes that it is ignoring the error and proceeding. It does mark the filesystem as needing an fsck which prevents it from being enabled for writing until fsck has been run on it. The net effect is that the reboot fails to single user, but at least at that point the administrator has the tools at hand to fix the problem. Reported by: Rick Macklem (rmacklem@) Discussed with: Warner Losh (imp@) Sponsored by: Netflix
65 lines
2.1 KiB
C
65 lines
2.1 KiB
C
/*-
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* Copyright (c) 2002, 2003 Gordon Tetlow
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* Copyright (c) 2006 Pawel Jakub Dawidek <pjd@FreeBSD.org>
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* Copyright (c) 2014 The FreeBSD Foundation
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* All rights reserved.
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*
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* This software was developed by Edward Tomasz Napierala under sponsorship
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* from the FreeBSD Foundation.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/types.h>
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#include <ufs/ufs/dinode.h>
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#include <ufs/ffs/fs.h>
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#include <errno.h>
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#include <libufs.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "fstyp.h"
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int
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fstyp_ufs(FILE *fp, char *label, size_t labelsize)
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{
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struct fs *fs;
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switch (sbget(fileno(fp), &fs, STDSB)) {
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case 0:
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strlcpy(label, fs->fs_volname, labelsize);
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return (0);
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case ENOENT:
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/* Cannot find file system superblock */
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return (1);
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default:
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/* Unable to read file system superblock */
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return (1);
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}
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}
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