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PR kern/39307 (mfs will sometimes panic at umount time) 

Change dounmount() so that it never drops the caller provided reference.
Garbage collecting 'struct mount' is up to the caller.
This commit is contained in:
ad 2008-09-25 14:17:29 +00:00
parent 968f739190
commit 43f2119341
2 changed files with 10 additions and 18 deletions
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16
sys/fs/puffs/puffs_msgif.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: puffs_msgif.c,v 1.71 2008/05/06 18:43:44 ad Exp $ */
/* $NetBSD: puffs_msgif.c,v 1.72 2008/09/25 14:17:29 ad Exp $ */
/*
* Copyright (c) 2005, 2006, 2007 Antti Kantee. All Rights Reserved.
@ -30,7 +30,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: puffs_msgif.c,v 1.71 2008/05/06 18:43:44 ad Exp $");
__KERNEL_RCSID(0, "$NetBSD: puffs_msgif.c,v 1.72 2008/09/25 14:17:29 ad Exp $");
#include <sys/param.h>
#include <sys/atomic.h>
@ -1018,19 +1018,13 @@ puffs_msgif_close(void *this)
}
/* Won't access pmp from here anymore */
atomic_inc_uint((unsigned int*)&mp->mnt_refcnt);
puffs_mp_release(pmp);
mutex_exit(&pmp->pmp_lock);
/*
* Detach from VFS. First do necessary XXX-dance (from
* sys_unmount() & other callers of dounmount()
*
* XXX2: take a reference to the mountpoint before starting to
* wait for syncer_mutex. Otherwise the mointpoint can be
* wiped out while we wait. XXX Should be done earlier
*/
atomic_inc_uint((unsigned int*)&mp->mnt_refcnt);
/* Detach from VFS. */
(void)dounmount(mp, MNT_FORCE, curlwp);
vfs_destroy(mp);
return 0;
}

12
sys/kern/vfs_syscalls.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: vfs_syscalls.c,v 1.373 2008/09/24 10:07:19 ad Exp $ */
/* $NetBSD: vfs_syscalls.c,v 1.374 2008/09/25 14:17:29 ad Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
@ -63,7 +63,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vfs_syscalls.c,v 1.373 2008/09/24 10:07:19 ad Exp $");
__KERNEL_RCSID(0, "$NetBSD: vfs_syscalls.c,v 1.374 2008/09/25 14:17:29 ad Exp $");
#include "opt_compat_netbsd.h"
#include "opt_compat_43.h"
@ -695,6 +695,7 @@ sys_unmount(struct lwp *l, const struct sys_unmount_args *uap, register_t *retva
vrele(vp);
error = dounmount(mp, SCARG(uap, flags), l);
vfs_destroy(mp);
return error;
}
@ -702,8 +703,7 @@ sys_unmount(struct lwp *l, const struct sys_unmount_args *uap, register_t *retva
* Do the actual file system unmount. File system is assumed to have
* been locked by the caller.
*
* => Caller gain reference to the mount, explicility for unmount.
* => Reference will be dropped in all cases.
* => Caller hold reference to the mount, explicility for dounmount().
*/
int
dounmount(struct mount *mp, int flags, struct lwp *l)
@ -728,7 +728,6 @@ dounmount(struct mount *mp, int flags, struct lwp *l)
if ((mp->mnt_iflag & IMNT_GONE) != 0) {
rw_exit(&mp->mnt_unmounting);
mutex_exit(&syncer_mutex);
vfs_destroy(mp);
return ENOENT;
}
@ -787,8 +786,7 @@ dounmount(struct mount *mp, int flags, struct lwp *l)
mutex_exit(&syncer_mutex);
vfs_hooks_unmount(mp);
rw_exit(&mp->mnt_unmounting);
vfs_destroy(mp); /* caller provided reference */
vfs_destroy(mp); /* from mount(), final nail in coffin */
vfs_destroy(mp); /* reference from mount() */
if (coveredvp != NULLVP)
vrele(coveredvp);
return (0);