47cbff34fa
When an NFS mount is hung against an unresponsive NFS server, the "umount -f" option can be used to dismount the mount. Unfortunately, "umount -f" gets hung as well if a "umount" without "-f" has already been done. Usually, this is because of a vnode lock being held by the "umount" for the mounted-on vnode. This patch adds kernel code so that a new "-N" option can be added to "umount", allowing it to avoid getting hung for this case. It adds two flags. One indicates that a forced dismount is about to happen and the other is used, along with setting mnt_data == NULL, to handshake with the nfs_unmount() VFS call. It includes a slight change to the interface used between the client and common NFS modules, so I bumped __FreeBSD_version to ensure both modules are rebuilt. Tested by: pho Reviewed by: kib MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D11735
158 lines
5.0 KiB
C
158 lines
5.0 KiB
C
/*-
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* Copyright (c) 1989, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Rick Macklem at The University of Guelph.
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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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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_nfs.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/sysproto.h>
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#include <sys/kernel.h>
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#include <sys/sysctl.h>
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#include <sys/priv.h>
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#include <sys/proc.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/module.h>
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#include <sys/sysent.h>
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#include <sys/syscall.h>
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#include <sys/sysproto.h>
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#include <security/audit/audit.h>
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#include <nfs/nfssvc.h>
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static int nfssvc_offset = SYS_nfssvc;
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static struct sysent nfssvc_prev_sysent;
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MAKE_SYSENT(nfssvc);
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/*
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* This tiny module simply handles the nfssvc() system call. The other
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* nfs modules that use the system call register themselves by setting
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* the nfsd_call_xxx function pointers non-NULL.
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*/
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int (*nfsd_call_nfsserver)(struct thread *, struct nfssvc_args *) = NULL;
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int (*nfsd_call_nfscommon)(struct thread *, struct nfssvc_args *) = NULL;
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int (*nfsd_call_nfscl)(struct thread *, struct nfssvc_args *) = NULL;
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int (*nfsd_call_nfsd)(struct thread *, struct nfssvc_args *) = NULL;
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/*
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* Nfs server pseudo system call for the nfsd's
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*/
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int
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sys_nfssvc(struct thread *td, struct nfssvc_args *uap)
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{
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int error;
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KASSERT(!mtx_owned(&Giant), ("nfssvc(): called with Giant"));
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AUDIT_ARG_CMD(uap->flag);
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/* Allow anyone to get the stats. */
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if ((uap->flag & ~NFSSVC_GETSTATS) != 0) {
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error = priv_check(td, PRIV_NFS_DAEMON);
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if (error != 0)
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return (error);
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}
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error = EINVAL;
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if ((uap->flag & (NFSSVC_ADDSOCK | NFSSVC_OLDNFSD | NFSSVC_NFSD)) &&
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nfsd_call_nfsserver != NULL)
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error = (*nfsd_call_nfsserver)(td, uap);
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else if ((uap->flag & (NFSSVC_CBADDSOCK | NFSSVC_NFSCBD |
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NFSSVC_DUMPMNTOPTS | NFSSVC_FORCEDISM)) && nfsd_call_nfscl != NULL)
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error = (*nfsd_call_nfscl)(td, uap);
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else if ((uap->flag & (NFSSVC_IDNAME | NFSSVC_GETSTATS |
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NFSSVC_GSSDADDPORT | NFSSVC_GSSDADDFIRST | NFSSVC_GSSDDELETEALL |
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NFSSVC_NFSUSERDPORT | NFSSVC_NFSUSERDDELPORT)) &&
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nfsd_call_nfscommon != NULL)
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error = (*nfsd_call_nfscommon)(td, uap);
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else if ((uap->flag & (NFSSVC_NFSDNFSD | NFSSVC_NFSDADDSOCK |
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NFSSVC_PUBLICFH | NFSSVC_V4ROOTEXPORT | NFSSVC_NOPUBLICFH |
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NFSSVC_STABLERESTART | NFSSVC_ADMINREVOKE |
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NFSSVC_DUMPCLIENTS | NFSSVC_DUMPLOCKS | NFSSVC_BACKUPSTABLE |
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NFSSVC_SUSPENDNFSD | NFSSVC_RESUMENFSD)) &&
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nfsd_call_nfsd != NULL)
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error = (*nfsd_call_nfsd)(td, uap);
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if (error == EINTR || error == ERESTART)
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error = 0;
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return (error);
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}
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/*
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* Called once to initialize data structures...
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*/
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static int
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nfssvc_modevent(module_t mod, int type, void *data)
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{
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static int registered;
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int error = 0;
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switch (type) {
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case MOD_LOAD:
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error = syscall_register(&nfssvc_offset, &nfssvc_sysent,
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&nfssvc_prev_sysent, SY_THR_STATIC_KLD);
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if (error)
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break;
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registered = 1;
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break;
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case MOD_UNLOAD:
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if (nfsd_call_nfsserver != NULL || nfsd_call_nfscommon != NULL
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|| nfsd_call_nfscl != NULL || nfsd_call_nfsd != NULL) {
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error = EBUSY;
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break;
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}
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if (registered)
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syscall_deregister(&nfssvc_offset, &nfssvc_prev_sysent);
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registered = 0;
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break;
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default:
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error = EOPNOTSUPP;
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break;
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}
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return error;
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}
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static moduledata_t nfssvc_mod = {
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"nfssvc",
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nfssvc_modevent,
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NULL,
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};
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DECLARE_MODULE(nfssvc, nfssvc_mod, SI_SUB_VFS, SI_ORDER_ANY);
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/* So that loader and kldload(2) can find us, wherever we are.. */
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MODULE_VERSION(nfssvc, 1);
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