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c746ed724d
In certain emergency cases such as media failure or removal, UFS will initiate a forced unmount in order to prevent dirty buffers from accumulating against the no-longer-usable filesystem. The presence of a stacked filesystem such as nullfs or unionfs above the UFS mount will prevent this forced unmount from succeeding. This change addreses the situation by allowing stacked filesystems to be recursively unmounted on a taskqueue thread when the MNT_RECURSE flag is specified to dounmount(). This call will block until all upper mounts have been removed unless the caller specifies the MNT_DEFERRED flag to indicate the base filesystem should also be unmounted from the taskqueue. To achieve this, the recently-added vfs_pin_from_vp()/vfs_unpin() KPIs have been combined with the existing 'mnt_uppers' list used by nullfs and renamed to vfs_register_upper_from_vp()/vfs_unregister_upper(). The format of the mnt_uppers list has also been changed to accommodate filesystems such as unionfs in which a given mount may be stacked atop more than one lower mount. Additionally, management of lower FS reclaim/unlink notifications has been split into a separate list managed by a separate set of KPIs, as registration of an upper FS no longer implies interest in these notifications. Reviewed by: kib, mckusick Tested by: pho Differential Revision: https://reviews.freebsd.org/D31016
99 lines
3.3 KiB
C
99 lines
3.3 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1992, 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 donated to Berkeley by
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* Jan-Simon Pendry.
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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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* @(#)null.h 8.3 (Berkeley) 8/20/94
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*
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* $FreeBSD$
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*/
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#ifndef FS_NULL_H
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#define FS_NULL_H
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#define NULLM_CACHE 0x0001
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struct null_mount {
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struct mount *nullm_vfs;
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struct vnode *nullm_lowerrootvp; /* Ref to lower root vnode */
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uint64_t nullm_flags;
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struct mount_upper_node upper_node;
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struct mount_upper_node notify_node;
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};
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#ifdef _KERNEL
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/*
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* A cache of vnode references
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*/
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struct null_node {
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LIST_ENTRY(null_node) null_hash; /* Hash list */
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struct vnode *null_lowervp; /* VREFed once */
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struct vnode *null_vnode; /* Back pointer */
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u_int null_flags;
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};
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#define NULLV_NOUNLOCK 0x0001
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#define NULLV_DROP 0x0002
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#define MOUNTTONULLMOUNT(mp) ((struct null_mount *)((mp)->mnt_data))
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#define VTONULL(vp) ((struct null_node *)(vp)->v_data)
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#define NULLTOV(xp) ((xp)->null_vnode)
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int nullfs_init(struct vfsconf *vfsp);
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int nullfs_uninit(struct vfsconf *vfsp);
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int null_nodeget(struct mount *mp, struct vnode *target, struct vnode **vpp);
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struct vnode *null_hashget(struct mount *mp, struct vnode *lowervp);
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void null_hashrem(struct null_node *xp);
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int null_bypass(struct vop_generic_args *ap);
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#ifdef DIAGNOSTIC
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struct vnode *null_checkvp(struct vnode *vp, char *fil, int lno);
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#define NULLVPTOLOWERVP(vp) null_checkvp((vp), __FILE__, __LINE__)
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#else
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#define NULLVPTOLOWERVP(vp) (VTONULL(vp)->null_lowervp)
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#endif
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extern struct vop_vector null_vnodeops;
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#ifdef MALLOC_DECLARE
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MALLOC_DECLARE(M_NULLFSNODE);
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#endif
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#ifdef NULLFS_DEBUG
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#define NULLFSDEBUG(format, args...) printf(format ,## args)
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#else
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#define NULLFSDEBUG(format, args...)
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#endif /* NULLFS_DEBUG */
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#endif /* _KERNEL */
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#endif
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