244 lines
6.2 KiB
C
244 lines
6.2 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2005 Poul-Henning Kamp
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* All rights reserved.
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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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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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 <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/malloc.h>
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#include <sys/mount.h>
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#include <sys/rwlock.h>
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#include <sys/vnode.h>
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static MALLOC_DEFINE(M_VFS_HASH, "vfs_hash", "VFS hash table");
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static LIST_HEAD(vfs_hash_head, vnode) *vfs_hash_tbl;
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static LIST_HEAD(,vnode) vfs_hash_side;
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static u_long vfs_hash_mask;
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static struct rwlock __exclusive_cache_line vfs_hash_lock;
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static void
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vfs_hashinit(void *dummy __unused)
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{
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vfs_hash_tbl = hashinit(desiredvnodes, M_VFS_HASH, &vfs_hash_mask);
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rw_init(&vfs_hash_lock, "vfs hash");
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LIST_INIT(&vfs_hash_side);
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}
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/* Must be SI_ORDER_SECOND so desiredvnodes is available */
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SYSINIT(vfs_hash, SI_SUB_VFS, SI_ORDER_SECOND, vfs_hashinit, NULL);
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u_int
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vfs_hash_index(struct vnode *vp)
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{
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return (vp->v_hash + vp->v_mount->mnt_hashseed);
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}
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static struct vfs_hash_head *
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vfs_hash_bucket(const struct mount *mp, u_int hash)
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{
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return (&vfs_hash_tbl[(hash + mp->mnt_hashseed) & vfs_hash_mask]);
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}
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int
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vfs_hash_get(const struct mount *mp, u_int hash, int flags, struct thread *td,
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struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg)
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{
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struct vnode *vp;
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enum vgetstate vs;
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int error;
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while (1) {
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rw_rlock(&vfs_hash_lock);
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LIST_FOREACH(vp, vfs_hash_bucket(mp, hash), v_hashlist) {
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if (vp->v_hash != hash)
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continue;
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if (vp->v_mount != mp)
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continue;
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if (fn != NULL && fn(vp, arg))
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continue;
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vs = vget_prep(vp);
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rw_runlock(&vfs_hash_lock);
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error = vget_finish(vp, flags, vs);
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if (error == ENOENT && (flags & LK_NOWAIT) == 0)
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break;
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if (error != 0)
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return (error);
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if (vp->v_hash != hash ||
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(fn != NULL && fn(vp, arg))) {
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vput(vp);
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/* Restart the bucket walk. */
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break;
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}
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*vpp = vp;
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return (0);
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}
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if (vp == NULL) {
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rw_runlock(&vfs_hash_lock);
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*vpp = NULL;
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return (0);
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}
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}
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}
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void
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vfs_hash_ref(const struct mount *mp, u_int hash, struct thread *td,
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struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg)
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{
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struct vnode *vp;
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while (1) {
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rw_rlock(&vfs_hash_lock);
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LIST_FOREACH(vp, vfs_hash_bucket(mp, hash), v_hashlist) {
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if (vp->v_hash != hash)
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continue;
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if (vp->v_mount != mp)
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continue;
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if (fn != NULL && fn(vp, arg))
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continue;
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vhold(vp);
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rw_runlock(&vfs_hash_lock);
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vref(vp);
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vdrop(vp);
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*vpp = vp;
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return;
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}
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if (vp == NULL) {
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rw_runlock(&vfs_hash_lock);
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*vpp = NULL;
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return;
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}
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}
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}
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void
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vfs_hash_remove(struct vnode *vp)
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{
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rw_wlock(&vfs_hash_lock);
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LIST_REMOVE(vp, v_hashlist);
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rw_wunlock(&vfs_hash_lock);
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}
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int
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vfs_hash_insert(struct vnode *vp, u_int hash, int flags, struct thread *td,
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struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg)
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{
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struct vnode *vp2;
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enum vgetstate vs;
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int error;
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*vpp = NULL;
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while (1) {
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rw_wlock(&vfs_hash_lock);
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LIST_FOREACH(vp2,
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vfs_hash_bucket(vp->v_mount, hash), v_hashlist) {
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if (vp2->v_hash != hash)
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continue;
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if (vp2->v_mount != vp->v_mount)
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continue;
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if (fn != NULL && fn(vp2, arg))
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continue;
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vs = vget_prep(vp2);
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rw_wunlock(&vfs_hash_lock);
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error = vget_finish(vp2, flags, vs);
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if (error == ENOENT && (flags & LK_NOWAIT) == 0)
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break;
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rw_wlock(&vfs_hash_lock);
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LIST_INSERT_HEAD(&vfs_hash_side, vp, v_hashlist);
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rw_wunlock(&vfs_hash_lock);
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vgone(vp);
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vput(vp);
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if (!error)
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*vpp = vp2;
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return (error);
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}
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if (vp2 == NULL)
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break;
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}
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vp->v_hash = hash;
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LIST_INSERT_HEAD(vfs_hash_bucket(vp->v_mount, hash), vp, v_hashlist);
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rw_wunlock(&vfs_hash_lock);
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return (0);
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}
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void
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vfs_hash_rehash(struct vnode *vp, u_int hash)
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{
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ASSERT_VOP_ELOCKED(vp, "rehash requires excl lock");
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rw_wlock(&vfs_hash_lock);
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LIST_REMOVE(vp, v_hashlist);
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LIST_INSERT_HEAD(vfs_hash_bucket(vp->v_mount, hash), vp, v_hashlist);
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vp->v_hash = hash;
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rw_wunlock(&vfs_hash_lock);
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}
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void
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vfs_hash_changesize(u_long newmaxvnodes)
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{
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struct vfs_hash_head *vfs_hash_newtbl, *vfs_hash_oldtbl;
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u_long vfs_hash_newmask, vfs_hash_oldmask;
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struct vnode *vp;
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int i;
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vfs_hash_newtbl = hashinit(newmaxvnodes, M_VFS_HASH,
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&vfs_hash_newmask);
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/* If same hash table size, nothing to do */
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if (vfs_hash_mask == vfs_hash_newmask) {
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free(vfs_hash_newtbl, M_VFS_HASH);
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return;
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}
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/*
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* Move everything from the old hash table to the new table.
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* None of the vnodes in the table can be recycled because to
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* do so, they have to be removed from the hash table.
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*/
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rw_wlock(&vfs_hash_lock);
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vfs_hash_oldtbl = vfs_hash_tbl;
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vfs_hash_oldmask = vfs_hash_mask;
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vfs_hash_tbl = vfs_hash_newtbl;
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vfs_hash_mask = vfs_hash_newmask;
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for (i = 0; i <= vfs_hash_oldmask; i++) {
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while ((vp = LIST_FIRST(&vfs_hash_oldtbl[i])) != NULL) {
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LIST_REMOVE(vp, v_hashlist);
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LIST_INSERT_HEAD(
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vfs_hash_bucket(vp->v_mount, vp->v_hash),
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vp, v_hashlist);
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}
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}
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rw_wunlock(&vfs_hash_lock);
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free(vfs_hash_oldtbl, M_VFS_HASH);
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}
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