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mntfs_vnops.c
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Editing: mntfs_vnops.c
/*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2020 Netflix, Inc. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * $FreeBSD$ */ #include <sys/param.h> #include <sys/conf.h> #include <sys/mount.h> #include <sys/vnode.h> /* * The "mntfs" VCHR vnodes implemented here provide a safe way for file systems * to access their disk devices. Using the normal devfs vnode has the problem * that if the device disappears, the devfs vnode is vgone'd as part of * removing it from the application-visible namespace, and some file systems * (notably FFS with softdep) get very unhappy if their dirty buffers are * invalidated out from under them. By using a separate, private vnode, * file systems are able to clean up their buffer state in a controlled fashion * when the underlying device disappears. */ static int mntfs_reclaim(struct vop_reclaim_args *ap) { struct vnode *vp = ap->a_vp; dev_rel(vp->v_rdev); return (0); } struct vop_vector mntfs_vnodeops = { .vop_default = &default_vnodeops, .vop_fsync = vop_stdfsync, .vop_strategy = VOP_PANIC, .vop_reclaim = mntfs_reclaim, }; VFS_VOP_VECTOR_REGISTER(mntfs_vnodeops); /* * Allocate a private VCHR vnode for use by a mounted fs. * The underlying device will be the same as for the given vnode. * This mntfs vnode must be freed with mntfs_freevp() rather than just * releasing the reference. */ struct vnode * mntfs_allocvp(struct mount *mp, struct vnode *ovp) { struct vnode *vp; struct cdev *dev; ASSERT_VOP_ELOCKED(ovp, __func__); dev = ovp->v_rdev; getnewvnode("mntfs", mp, &mntfs_vnodeops, &vp); vp->v_type = VCHR; vp->v_data = NULL; dev_ref(dev); vp->v_rdev = dev; return (vp); } void mntfs_freevp(struct vnode *vp) { vgone(vp); vrele(vp); }
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