2 * Copyright (c) 2004 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * $DragonFly: src/sys/kern/vfs_lock.c,v 1.18 2006/05/24 03:23:31 dillon Exp $
38 * External virtual filesystem routines
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/kernel.h>
45 #include <sys/malloc.h>
46 #include <sys/mount.h>
48 #include <sys/vnode.h>
50 #include <sys/sysctl.h>
52 #include <machine/limits.h>
55 #include <vm/vm_object.h>
58 #include <sys/thread2.h>
61 static MALLOC_DEFINE(M_VNODE, "vnodes", "vnode structures");
63 static TAILQ_HEAD(freelst, vnode) vnode_free_list; /* vnode free list */
66 SYSCTL_INT(_debug, OID_AUTO, freevnodes, CTLFLAG_RD,
68 static int wantfreevnodes = 25;
69 SYSCTL_INT(_debug, OID_AUTO, wantfreevnodes, CTLFLAG_RW,
70 &wantfreevnodes, 0, "");
72 SYSCTL_INT(_kern, OID_AUTO, minvnodes, CTLFLAG_RW,
73 &minvnodes, 0, "Minimum number of vnodes");
76 * Called from vfsinit()
81 minvnodes = desiredvnodes / 4;
83 TAILQ_INIT(&vnode_free_list);
87 * Inline helper functions. vbusy() and vfree() must be called while in a
90 * Warning: must be callable if the caller holds a read spinlock to something
91 * else, meaning we can't use read spinlocks here.
95 __vbusy(struct vnode *vp)
97 KKASSERT(vp->v_flag & VFREE);
98 TAILQ_REMOVE(&vnode_free_list, vp, v_freelist);
100 vp->v_flag &= ~(VFREE|VAGE);
105 __vfree(struct vnode *vp)
107 KKASSERT((vp->v_flag & VFREE) == 0);
108 if (vp->v_flag & (VAGE|VRECLAIMED))
109 TAILQ_INSERT_HEAD(&vnode_free_list, vp, v_freelist);
111 TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
118 * Return 1 if we can immediately place the vnode on the freelist.
121 vshouldfree(struct vnode *vp, int usecount)
123 if (vp->v_holdcnt != 0 || vp->v_usecount != usecount)
124 return (0); /* other holderse */
126 (vp->v_object->ref_count || vp->v_object->resident_page_count)) {
133 * Reference a vnode or release the reference on a vnode. The vnode will
134 * be taken off the freelist if it is on it and cannot be recycled or
135 * deactivated while refd. The last release of a vnode will deactivate the
136 * vnode via VOP_INACTIVE().
138 * Special cases: refing a vnode does not clear VINACTIVE, you have to vget()
139 * the vnode shared or exclusive to do that.
141 * Warning: must be callable if the caller holds a read spinlock to something
142 * else, meaning we can't use read spinlocks here.
146 __vref(struct vnode *vp)
149 if (vp->v_flag & VFREE)
154 * This is a rare case where callers are allowed to hold spinlocks, so
155 * we can't ourselves. In such cases the vnode must already have at least
156 * one reference because we cannot get the spinlock required to move
157 * the vnode off the free list.
159 * If the usecount & holdcnt are 0 the caller must be holding the
160 * free list spinlock since we will be removing the vnode from the
161 * freelist in that case.
164 vref(struct vnode *vp)
172 vrele(struct vnode *vp)
175 if (vp->v_usecount == 1) {
176 KASSERT(lockcountnb(&vp->v_lock) == 0, ("last vrele vp %p still locked", vp));
179 * Deactivation requires an exclusive v_lock (vx_lock()), and
180 * only occurs if the usecount is still 1 after locking.
182 if ((vp->v_flag & VINACTIVE) == 0) {
183 if (vx_lock(vp) == 0) {
184 if ((vp->v_flag & VINACTIVE) == 0 &&
185 vp->v_usecount == 1) {
186 vp->v_flag |= VINACTIVE;
192 if (vshouldfree(vp, 1))
195 KKASSERT(vp->v_usecount > 0);
202 * Hold a vnode or drop the hold on a vnode. The vnode will be taken off
203 * the freelist if it is on it and cannot be recycled. However, the
204 * vnode can be deactivated and reactivated while held.
206 * Special cases: The last drop of a vnode does nothing special, allowing it
207 * to be called from an interrupt. vrele() on the otherhand cannot be called
211 vhold(struct vnode *vp)
215 if (vp->v_flag & VFREE)
221 vdrop(struct vnode *vp)
224 if (vp->v_holdcnt == 1) {
226 if (vshouldfree(vp, 0))
230 KKASSERT(vp->v_holdcnt > 0);
235 /****************************************************************
236 * VX LOCKING FUNCTIONS *
237 ****************************************************************
239 * These functions lock vnodes for reclamation and deactivation ops.
240 * Only vp->v_lock, the top layer of the VFS, is locked. You must be
241 * holding a normal reference in order to be able to safely call vx_lock()
242 * and vx_unlock(). vx_get() and vx_put() are combination functions which
243 * vref+vx_lock and vrele+vx_unlock.
246 #define VXLOCKFLAGS (LK_EXCLUSIVE|LK_RETRY)
247 #define VXLOCKFLAGS_NB (LK_EXCLUSIVE|LK_NOWAIT)
250 __vxlock(struct vnode *vp, int flags)
252 return(lockmgr(&vp->v_lock, flags));
256 __vxunlock(struct vnode *vp)
258 lockmgr(&vp->v_lock, LK_RELEASE);
262 vx_lock(struct vnode *vp)
264 return(__vxlock(vp, VXLOCKFLAGS));
268 vx_unlock(struct vnode *vp)
274 vx_get(struct vnode *vp)
279 if ((error = __vxlock(vp, VXLOCKFLAGS)) != 0)
285 vx_get_nonblock(struct vnode *vp)
290 if ((error = __vxlock(vp, VXLOCKFLAGS_NB)) != 0)
296 vx_put(struct vnode *vp)
302 /****************************************************************
303 * VNODE ACQUISITION FUNCTIONS *
304 ****************************************************************
306 * vget() and vput() access a vnode for the intent of executing an
307 * operation other then a reclamation or deactivation. vget() will ref
308 * and lock the vnode, vput() will unlock and deref the vnode.
309 * The VOP_*() locking functions are used.
311 * CALLING VGET IS MANDATORY PRIOR TO ANY MODIFYING OPERATION ON A VNODE.
312 * This is because vget handles the VINACTIVE interlock and is responsible
313 * for clearing the bit. If the bit is not cleared inode updates may not
316 * Special cases: If vget()'s locking operation fails the vrele() call may
317 * cause the vnode to be deactivated (VOP_INACTIVE called). However, this
318 * never occurs if the vnode is in a reclaimed state. Vnodes in reclaimed
319 * states always return an error code of ENOENT.
321 * Special cases: vput() will unlock and, if it is the last reference,
322 * deactivate the vnode. The deactivation uses a separate non-layered
323 * VX lock after the normal unlock. XXX make it more efficient.
326 vget(struct vnode *vp, int flags)
332 if (flags & LK_TYPE_MASK) {
333 if ((error = vn_lock(vp, flags)) != 0) {
335 } else if (vp->v_flag & VRECLAIMED) {
340 vp->v_flag &= ~VINACTIVE;
344 panic("vget() called with no lock specified!");
345 error = ENOENT; /* not reached, compiler opt */
352 vput(struct vnode *vp)
359 vsetflags(struct vnode *vp, int flags)
367 vclrflags(struct vnode *vp, int flags)
370 vp->v_flag &= ~flags;
375 * Obtain a new vnode from the freelist, allocating more if necessary.
376 * The returned vnode is VX locked & refd.
379 allocvnode(int lktimeout, int lkflags)
385 * Try to reuse vnodes if we hit the max. This situation only
386 * occurs in certain large-memory (2G+) situations. We cannot
387 * attempt to directly reclaim vnodes due to nasty recursion
390 while (numvnodes - freevnodes > desiredvnodes)
397 * Attempt to reuse a vnode already on the free list, allocating
398 * a new vnode if we can't find one or if we have not reached a
399 * good minimum for good LRU performance.
401 if (freevnodes >= wantfreevnodes && numvnodes >= minvnodes) {
404 for (count = 0; count < freevnodes; count++) {
408 * Pull the next vnode off the free list and do some
409 * sanity checks. Note that regardless of how we
410 * block, if freevnodes is non-zero there had better
411 * be something on the list.
413 vp = TAILQ_FIRST(&vnode_free_list);
415 panic("getnewvnode: free vnode isn't");
418 * Note the lack of a critical section. We vx_get()
419 * the vnode before we check it for validity, reducing
420 * the number of checks we have to make. The vx_get()
421 * will pull it off the freelist.
429 * Can this vnode be recycled? It must be in a
430 * VINACTIVE state with only our reference to it.
431 * (vx_get(), unlike vget(), does not reactivate
432 * the vnode). vx_put() will recycle it onto the
433 * end of the freelist.
435 if ((vp->v_flag & VINACTIVE) == 0 ||
436 vp->v_holdcnt || vp->v_usecount != 1) {
443 * Ok, we can reclaim the vnode if it isn't already
444 * in a reclaimed state. If the reclamation fails,
445 * or if someone else is referencing the vnode after
446 * we have vgone()'d it, we recycle the vnode on the
447 * freelist or hold it (by calling vx_put()).
449 if ((vp->v_flag & VRECLAIMED) == 0) {
451 if ((vp->v_flag & VRECLAIMED) == 0 ||
452 vp->v_holdcnt || vp->v_usecount != 1) {
458 KKASSERT(vp->v_flag & VINACTIVE);
468 * If we have a vp it will be refd and VX locked.
473 panic("cleaned vnode isn't");
474 if (vp->v_track_read.bk_active + vp->v_track_write.bk_active)
475 panic("Clean vnode has pending I/O's");
476 KKASSERT(vp->v_mount == NULL);
485 vp->v_writecount = 0; /* XXX */
486 lockreinit(&vp->v_lock, "vnode", lktimeout, lkflags);
487 KKASSERT(TAILQ_FIRST(&vp->v_namecache) == NULL);
490 * A brand-new vnode (we could use malloc() here I think) XXX
492 vp = malloc(sizeof(struct vnode), M_VNODE, M_WAITOK|M_ZERO);
493 lwkt_token_init(&vp->v_pollinfo.vpi_token);
494 lockinit(&vp->v_lock, "vnode", lktimeout, lkflags);
495 TAILQ_INIT(&vp->v_namecache);
498 * short cut around vfreeing it and looping, just set it up
499 * as if we had pulled a reclaimed vnode off the freelist
500 * and reinitialized it.
503 if (__vxlock(vp, VXLOCKFLAGS))
504 panic("getnewvnode: __vxlock failed");
508 RB_INIT(&vp->v_rbclean_tree);
509 RB_INIT(&vp->v_rbdirty_tree);
510 RB_INIT(&vp->v_rbhash_tree);
511 vp->v_filesize = NOOFFSET;
516 KKASSERT(vp->v_mount == NULL);