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3fb1fcdea1
By design the zfs utility is supposed to handle mounting and unmounting a zfs filesystem. We could allow zfs to do this directly. There are system calls available to mount/umount a filesystem. And there are library calls available to manipulate /etc/mtab. But there are a couple very good reasons not to take this appraoch... for now. Instead of directly calling the system and library calls to (u)mount the filesystem we fork and exec a (u)mount process. The principle reason for this is to delegate the responsibility for locking and updating /etc/mtab to (u)mount(8). This ensures maximum portability and ensures the right locking scheme for your version of (u)mount will be used. If we didn't do this we would have to resort to an autoconf test to determine what locking mechanism is used. The downside to using mount(8) instead of mount(2) is that we lose the exact errno which was returned by the kernel. The return code from mount(8) provides some insight in to what went wrong but it not quite as good. For the moment this is translated as a best guess in to a errno for the higher layers of zfs. In the long term a shared library called libmount is under development which provides a common API to address the locking and errno issues. Once the standard mount utility has been updated to use this library we can then leverage it. Until then this is the only safe solution. http://www.kernel.org/pub/linux/utils/util-linux/libmount-docs/index.html
87 lines
2.3 KiB
C
87 lines
2.3 KiB
C
/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License, Version 1.0 only
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* (the "License"). You may not use this file except in compliance
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* with the License.
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*
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or http://www.opensolaris.org/os/licensing.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*/
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/* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T*/
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/* All Rights Reserved */
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/*
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* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
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* Use is subject to license terms.
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*/
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/* Copyright 2006 Ricardo Correia */
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#ifndef _SYS_MNTTAB_H
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#define _SYS_MNTTAB_H
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#include <stdio.h>
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#include <mntent.h>
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#include <sys/types.h>
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#ifdef MNTTAB
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#undef MNTTAB
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#endif /* MNTTAB */
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#define MNTTAB "/etc/mtab"
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#define MNT_LINE_MAX 1024
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#define MNT_TOOLONG 1 /* entry exceeds MNT_LINE_MAX */
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#define MNT_TOOMANY 2 /* too many fields in line */
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#define MNT_TOOFEW 3 /* too few fields in line */
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struct mnttab {
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char *mnt_special;
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char *mnt_mountp;
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char *mnt_fstype;
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char *mnt_mntopts;
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};
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/*
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* NOTE: fields in extmnttab should match struct mnttab till new fields
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* are encountered, this allows hasmntopt to work properly when its arg is
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* a pointer to an extmnttab struct cast to a mnttab struct pointer.
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*/
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struct extmnttab {
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char *mnt_special;
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char *mnt_mountp;
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char *mnt_fstype;
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char *mnt_mntopts;
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uint_t mnt_major;
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uint_t mnt_minor;
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};
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extern int getmntany(FILE *fp, struct mnttab *mp, struct mnttab *mpref);
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extern int _sol_getmntent(FILE *fp, struct mnttab *mp);
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extern int getextmntent(FILE *fp, struct extmnttab *mp, int len);
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static inline char *_sol_hasmntopt(struct mnttab *mnt, char *opt)
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{
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struct mntent mnt_new;
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mnt_new.mnt_opts = mnt->mnt_mntopts;
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return hasmntopt(&mnt_new, opt);
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}
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#define hasmntopt _sol_hasmntopt
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#define getmntent _sol_getmntent
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#endif
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