2 * Copyright 2000, International Business Machines Corporation and others.
5 * This software has been released under the terms of the IBM Public
6 * License. For details, see the LICENSE file in the top-level source
7 * directory or online at http://www.openafs.org/dl/license10.html
11 /* osi_vm.c implements:
13 * osi_VM_FlushVCache(avc, slept)
14 * osi_ubc_flush_dirty_and_wait(vp, flags)
15 * osi_VM_StoreAllSegments(avc)
16 * osi_VM_TryToSmush(avc, acred, sync)
17 * osi_VM_FlushPages(avc, credp)
18 * osi_VM_Truncate(avc, alen, acred)
21 #include <afsconfig.h>
22 #include "afs/param.h"
27 #include "afs/sysincludes.h" /* Standard vendor system headers */
28 #include "afsincludes.h" /* Afs-based standard headers */
29 #include "afs/afs_stats.h" /* statistics */
30 #include <vm/vm_object.h>
31 #include <vm/vm_map.h>
36 * FreeBSD implementation notes:
37 * Most of these operations require us to frob vm_objects. Most
38 * functions require that the object be locked (with VM_OBJECT_LOCK)
39 * on entry and leave it locked on exit. In order to get the
40 * vm_object itself we call VOP_GETVOBJECT on the vnode; the
41 * locking protocol requires that we do so with the heavy vnode lock
42 * held and the vnode interlock unlocked, and it returns the same
45 * The locking protocol for vnodes is defined in
46 * kern/vnode_if.src and sys/vnode.h; the locking is still a work in
47 * progress, so some fields are (as of 5.1) still protected by Giant
48 * rather than an explicit lock.
52 #define lock_vnode(v) vn_lock((v), LK_EXCLUSIVE | LK_RETRY, curthread)
53 #define unlock_vnode(v) VOP_UNLOCK((v), 0, curthread)
55 #define lock_vnode(v) vn_lock((v), LK_EXCLUSIVE | LK_RETRY, curproc)
56 #define unlock_vnode(v) VOP_UNLOCK((v), 0, curproc)
57 /* need splvm() protection? */
58 #define VM_OBJECT_LOCK(o)
59 #define VM_OBJECT_UNLOCK(o)
62 /* Try to discard pages, in order to recycle a vcache entry.
64 * We also make some sanity checks: ref count, open count, held locks.
66 * We also do some non-VM-related chores, such as releasing the cred pointer
67 * (for AIX and Solaris) and releasing the gnode (for AIX).
69 * Locking: afs_xvcache lock is held. If it is dropped and re-acquired,
70 * *slept should be set to warn the caller.
72 * Formerly, afs_xvcache was dropped and re-acquired for Solaris, but now it
73 * is not dropped and re-acquired for any platform. It may be that *slept is
74 * therefore obsolescent.
76 * OSF/1 Locking: VN_LOCK has been called.
77 * XXX - should FreeBSD have done this, too? Certainly looks like it.
78 * Maybe better to just call vnode_pager_setsize()?
81 osi_VM_FlushVCache(struct vcache *avc, int *slept)
83 struct vm_object *obj;
85 if (VREFCOUNT(avc) > 1)
91 /* if a lock is held, give up */
92 if (CheckLock(&avc->lock))
98 if (VOP_GETVOBJECT(vp, &obj) == 0) {
100 vm_object_page_remove(obj, 0, 0, FALSE);
102 if (obj->ref_count == 0) {
104 simple_lock(&vp->v_interlock);
109 VM_OBJECT_UNLOCK(obj);
117 /* Try to store pages to cache, in order to store a file back to the server.
119 * Locking: the vcache entry's lock is held. It will usually be dropped and
123 osi_VM_StoreAllSegments(struct vcache *avc)
126 struct vm_object *obj;
129 ReleaseWriteLock(&avc->lock);
135 * I don't understand this. Why not just call vm_object_page_clean()
136 * and be done with it? I particularly don't understand why we're calling
137 * vget() here. Is there some reason to believe that the vnode might
138 * be being recycled at this point? I don't think there's any need for
139 * this loop, either -- if we keep the vnode locked all the time,
140 * that and the object lock will prevent any new pages from appearing.
141 * The loop is what causes the race condition. -GAW
146 if (VOP_GETVOBJECT(vp, &obj) == 0 && (obj->flags & OBJ_MIGHTBEDIRTY)) {
147 /* XXX - obj locking? */
149 #ifdef AFS_FBSD50_ENV
150 if (!vget(vp, LK_EXCLUSIVE | LK_RETRY, curthread)) {
152 if (!vget(vp, LK_EXCLUSIVE | LK_RETRY | LK_NOOBJ, curproc)) {
154 if (VOP_GETVOBJECT(vp, &obj) == 0) {
156 vm_object_page_clean(obj, 0, 0, OBJPC_SYNC);
157 VM_OBJECT_UNLOCK(obj);
164 } while (anyio && (--tries > 0));
166 ObtainWriteLock(&avc->lock, 94);
169 /* Try to invalidate pages, for "fs flush" or "fs flushv"; or
170 * try to free pages, when deleting a file.
172 * Locking: the vcache entry's lock is held. It may be dropped and
175 * Since we drop and re-obtain the lock, we can't guarantee that there won't
176 * be some pages around when we return, newly created by concurrent activity.
179 osi_VM_TryToSmush(struct vcache *avc, struct AFS_UCRED *acred, int sync)
182 struct vm_object *obj;
185 ReleaseWriteLock(&avc->lock);
192 /* See the comments above. */
193 if (VOP_GETVOBJECT(vp, &obj) == 0 && (obj->flags & OBJ_MIGHTBEDIRTY)) {
194 /* XXX - obj locking */
196 #ifdef AFS_FBSD50_ENV
197 if (!vget(vp, LK_EXCLUSIVE | LK_RETRY, curthread)) {
199 if (!vget(vp, LK_EXCLUSIVE | LK_RETRY | LK_NOOBJ, curproc)) {
201 if (VOP_GETVOBJECT(vp, &obj) == 0) {
204 * Do we really want OBJPC_SYNC? OBJPC_INVAL would be
205 * faster, if invalidation is really what we are being
206 * asked to do. (It would make more sense, too, since
207 * otherwise this function is practically identical to
208 * osi_VM_StoreAllSegments().) -GAW
210 vm_object_page_clean(obj, 0, 0, OBJPC_SYNC);
211 VM_OBJECT_UNLOCK(obj);
218 } while (anyio && (--tries > 0));
220 if (VOP_GETVOBJECT(vp, &obj) == 0) {
222 vm_object_page_remove(obj, 0, 0, FALSE);
223 VM_OBJECT_UNLOCK(obj);
226 /*vinvalbuf(AFSTOV(avc),0, NOCRED, curproc, 0,0); */
228 ObtainWriteLock(&avc->lock, 59);
231 /* Purge VM for a file when its callback is revoked.
233 * Locking: No lock is held, not even the global lock.
236 osi_VM_FlushPages(struct vcache *avc, struct AFS_UCRED *credp)
239 struct vm_object *obj;
242 ASSERT_VOP_LOCKED(vp, __func__);
243 if (VOP_GETVOBJECT(vp, &obj) == 0) {
245 vm_object_page_remove(obj, 0, 0, FALSE);
246 VM_OBJECT_UNLOCK(obj);
248 /*vinvalbuf(AFSTOV(avc),0, NOCRED, curproc, 0,0); */
251 /* Purge pages beyond end-of-file, when truncating a file.
253 * Locking: no lock is held, not even the global lock.
254 * activeV is raised. This is supposed to block pageins, but at present
255 * it only works on Solaris.
258 osi_VM_Truncate(struct vcache *avc, int alen, struct AFS_UCRED *acred)
260 vnode_pager_setsize(AFSTOV(avc), alen);