Current Path : /sys/fs/pseudofs/ |
FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
Current File : //sys/fs/pseudofs/pseudofs_vncache.c |
/*- * Copyright (c) 2001 Dag-Erling Coïdan Smørgrav * All rights reserved. * * 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 * in this position and unchanged. * 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. * 3. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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. */ #include <sys/cdefs.h> __FBSDID("$FreeBSD: release/9.1.0/sys/fs/pseudofs/pseudofs_vncache.c 211531 2010-08-20 19:46:50Z jhb $"); #include "opt_pseudofs.h" #include <sys/param.h> #include <sys/kernel.h> #include <sys/systm.h> #include <sys/eventhandler.h> #include <sys/lock.h> #include <sys/malloc.h> #include <sys/mutex.h> #include <sys/proc.h> #include <sys/sysctl.h> #include <sys/vnode.h> #include <fs/pseudofs/pseudofs.h> #include <fs/pseudofs/pseudofs_internal.h> static MALLOC_DEFINE(M_PFSVNCACHE, "pfs_vncache", "pseudofs vnode cache"); static struct mtx pfs_vncache_mutex; static struct pfs_vdata *pfs_vncache; static eventhandler_tag pfs_exit_tag; static void pfs_exit(void *arg, struct proc *p); SYSCTL_NODE(_vfs_pfs, OID_AUTO, vncache, CTLFLAG_RW, 0, "pseudofs vnode cache"); static int pfs_vncache_entries; SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, entries, CTLFLAG_RD, &pfs_vncache_entries, 0, "number of entries in the vnode cache"); static int pfs_vncache_maxentries; SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, maxentries, CTLFLAG_RD, &pfs_vncache_maxentries, 0, "highest number of entries in the vnode cache"); static int pfs_vncache_hits; SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, hits, CTLFLAG_RD, &pfs_vncache_hits, 0, "number of cache hits since initialization"); static int pfs_vncache_misses; SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, misses, CTLFLAG_RD, &pfs_vncache_misses, 0, "number of cache misses since initialization"); extern struct vop_vector pfs_vnodeops; /* XXX -> .h file */ /* * Initialize vnode cache */ void pfs_vncache_load(void) { mtx_assert(&Giant, MA_OWNED); mtx_init(&pfs_vncache_mutex, "pfs_vncache", NULL, MTX_DEF); pfs_exit_tag = EVENTHANDLER_REGISTER(process_exit, pfs_exit, NULL, EVENTHANDLER_PRI_ANY); } /* * Tear down vnode cache */ void pfs_vncache_unload(void) { mtx_assert(&Giant, MA_OWNED); EVENTHANDLER_DEREGISTER(process_exit, pfs_exit_tag); KASSERT(pfs_vncache_entries == 0, ("%d vncache entries remaining", pfs_vncache_entries)); mtx_destroy(&pfs_vncache_mutex); } /* * Allocate a vnode */ int pfs_vncache_alloc(struct mount *mp, struct vnode **vpp, struct pfs_node *pn, pid_t pid) { struct pfs_vdata *pvd, *pvd2; struct vnode *vp; int error; /* * See if the vnode is in the cache. * XXX linear search is not very efficient. */ retry: mtx_lock(&pfs_vncache_mutex); for (pvd = pfs_vncache; pvd; pvd = pvd->pvd_next) { if (pvd->pvd_pn == pn && pvd->pvd_pid == pid && pvd->pvd_vnode->v_mount == mp) { vp = pvd->pvd_vnode; VI_LOCK(vp); mtx_unlock(&pfs_vncache_mutex); if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, curthread) == 0) { ++pfs_vncache_hits; *vpp = vp; /* * Some callers cache_enter(vp) later, so * we have to make sure it's not in the * VFS cache so it doesn't get entered * twice. A better solution would be to * make pfs_vncache_alloc() responsible * for entering the vnode in the VFS * cache. */ cache_purge(vp); return (0); } goto retry; } } mtx_unlock(&pfs_vncache_mutex); /* nope, get a new one */ pvd = malloc(sizeof *pvd, M_PFSVNCACHE, M_WAITOK); pvd->pvd_next = pvd->pvd_prev = NULL; error = getnewvnode("pseudofs", mp, &pfs_vnodeops, vpp); if (error) { free(pvd, M_PFSVNCACHE); return (error); } pvd->pvd_pn = pn; pvd->pvd_pid = pid; (*vpp)->v_data = pvd; switch (pn->pn_type) { case pfstype_root: (*vpp)->v_vflag = VV_ROOT; #if 0 printf("root vnode allocated\n"); #endif /* fall through */ case pfstype_dir: case pfstype_this: case pfstype_parent: case pfstype_procdir: (*vpp)->v_type = VDIR; break; case pfstype_file: (*vpp)->v_type = VREG; break; case pfstype_symlink: (*vpp)->v_type = VLNK; break; case pfstype_none: KASSERT(0, ("pfs_vncache_alloc called for null node\n")); default: panic("%s has unexpected type: %d", pn->pn_name, pn->pn_type); } /* * Propagate flag through to vnode so users know it can change * if the process changes (i.e. execve) */ if ((pn->pn_flags & PFS_PROCDEP) != 0) (*vpp)->v_vflag |= VV_PROCDEP; pvd->pvd_vnode = *vpp; vn_lock(*vpp, LK_EXCLUSIVE | LK_RETRY); VN_LOCK_AREC(*vpp); error = insmntque(*vpp, mp); if (error != 0) { free(pvd, M_PFSVNCACHE); *vpp = NULLVP; return (error); } retry2: mtx_lock(&pfs_vncache_mutex); /* * Other thread may race with us, creating the entry we are * going to insert into the cache. Recheck after * pfs_vncache_mutex is reacquired. */ for (pvd2 = pfs_vncache; pvd2; pvd2 = pvd2->pvd_next) { if (pvd2->pvd_pn == pn && pvd2->pvd_pid == pid && pvd2->pvd_vnode->v_mount == mp) { vp = pvd2->pvd_vnode; VI_LOCK(vp); mtx_unlock(&pfs_vncache_mutex); if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, curthread) == 0) { ++pfs_vncache_hits; vgone(*vpp); vput(*vpp); *vpp = vp; cache_purge(vp); return (0); } goto retry2; } } ++pfs_vncache_misses; if (++pfs_vncache_entries > pfs_vncache_maxentries) pfs_vncache_maxentries = pfs_vncache_entries; pvd->pvd_prev = NULL; pvd->pvd_next = pfs_vncache; if (pvd->pvd_next) pvd->pvd_next->pvd_prev = pvd; pfs_vncache = pvd; mtx_unlock(&pfs_vncache_mutex); return (0); } /* * Free a vnode */ int pfs_vncache_free(struct vnode *vp) { struct pfs_vdata *pvd; mtx_lock(&pfs_vncache_mutex); pvd = (struct pfs_vdata *)vp->v_data; KASSERT(pvd != NULL, ("pfs_vncache_free(): no vnode data\n")); if (pvd->pvd_next) pvd->pvd_next->pvd_prev = pvd->pvd_prev; if (pvd->pvd_prev) { pvd->pvd_prev->pvd_next = pvd->pvd_next; --pfs_vncache_entries; } else if (pfs_vncache == pvd) { pfs_vncache = pvd->pvd_next; --pfs_vncache_entries; } mtx_unlock(&pfs_vncache_mutex); free(pvd, M_PFSVNCACHE); vp->v_data = NULL; return (0); } /* * Purge the cache of dead entries * * This is extremely inefficient due to the fact that vgone() not only * indirectly modifies the vnode cache, but may also sleep. We can * neither hold pfs_vncache_mutex across a vgone() call, nor make any * assumptions about the state of the cache after vgone() returns. In * consequence, we must start over after every vgone() call, and keep * trying until we manage to traverse the entire cache. * * The only way to improve this situation is to change the data structure * used to implement the cache. */ static void pfs_purge_locked(struct pfs_node *pn) { struct pfs_vdata *pvd; struct vnode *vnp; mtx_assert(&pfs_vncache_mutex, MA_OWNED); pvd = pfs_vncache; while (pvd != NULL) { if (pvd->pvd_dead || (pn != NULL && pvd->pvd_pn == pn)) { vnp = pvd->pvd_vnode; vhold(vnp); mtx_unlock(&pfs_vncache_mutex); VOP_LOCK(vnp, LK_EXCLUSIVE); vgone(vnp); VOP_UNLOCK(vnp, 0); mtx_lock(&pfs_vncache_mutex); vdrop(vnp); pvd = pfs_vncache; } else { pvd = pvd->pvd_next; } } } void pfs_purge(struct pfs_node *pn) { mtx_lock(&pfs_vncache_mutex); pfs_purge_locked(pn); mtx_unlock(&pfs_vncache_mutex); } /* * Free all vnodes associated with a defunct process */ static void pfs_exit(void *arg, struct proc *p) { struct pfs_vdata *pvd; int dead; if (pfs_vncache == NULL) return; mtx_lock(&pfs_vncache_mutex); for (pvd = pfs_vncache, dead = 0; pvd != NULL; pvd = pvd->pvd_next) if (pvd->pvd_pid == p->p_pid) dead = pvd->pvd_dead = 1; if (dead) pfs_purge_locked(NULL); mtx_unlock(&pfs_vncache_mutex); }