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"
23 #include <sys/param.h>
24 #include <sys/vnode.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>
35 * FreeBSD implementation notes:
36 * Most of these operations require us to frob vm_objects. Most
37 * functions require that the object be locked (with VM_OBJECT_LOCK)
38 * on entry and leave it locked on exit. The locking protocol
39 * requires that we access vp->v_object with the heavy vnode lock
40 * held and the vnode interlock unlocked.
42 * The locking protocol for vnodes is defined in
43 * kern/vnode_if.src and sys/vnode.h; unfortunately, it is not *quite*
44 * constant from version to version so to be properly correct we must
45 * check the VCS history of those files.
48 #if defined(AFS_FBSD80_ENV)
49 #define lock_vnode(v, f) vn_lock((v), (f))
50 #define ilock_vnode(v) vn_lock((v), LK_INTERLOCK|LK_EXCLUSIVE|LK_RETRY);
51 #define unlock_vnode(v) VOP_UNLOCK((v), 0)
52 #define islocked_vnode(v) VOP_ISLOCKED((v))
54 #define lock_vnode(v, f) vn_lock((v), (f), curthread)
55 #define ilock_vnode(v) vn_lock((v), LK_INTERLOCK|LK_EXCLUSIVE|LK_RETRY, curthread);
56 #define unlock_vnode(v) VOP_UNLOCK((v), 0, curthread)
57 #define islocked_vnode(v) VOP_ISLOCKED((v), curthread)
60 /* Try to discard pages, in order to recycle a vcache entry.
62 * We also make some sanity checks: ref count, open count, held locks.
64 * We also do some non-VM-related chores, such as releasing the cred pointer
65 * (for AIX and Solaris) and releasing the gnode (for AIX).
67 * Locking: afs_xvcache lock is held. If it is dropped and re-acquired,
68 * *slept should be set to warn the caller.
70 * Formerly, afs_xvcache was dropped and re-acquired for Solaris, but now it
71 * is not dropped and re-acquired for any platform. It may be that *slept is
72 * therefore obsolescent.
76 osi_VM_FlushVCache(struct vcache *avc, int *slept)
78 struct vnode *vp = AFSTOV(avc);
80 if (!VI_TRYLOCK(vp)) /* need interlock to check usecount */
83 if (vp->v_usecount > 0) {
89 * The value of avc->opens here came to be, at some point,
90 * typically -1. This was caused by incorrectly performing afs_close
91 * processing on vnodes being recycled */
97 /* if a lock is held, give up */
98 if (CheckLock(&avc->lock)) {
103 if ((vp->v_iflag & VI_DOOMED) != 0) {
108 /* must hold the vnode before calling vgone()
109 * This code largely copied from vfs_subr.c:vlrureclaim() */
113 /* use the interlock while locking, so no one else can DOOM this */
123 /* Try to store pages to cache, in order to store a file back to the server.
125 * Locking: the vcache entry's lock is held. It will usually be dropped and
129 osi_VM_StoreAllSegments(struct vcache *avc)
132 struct vm_object *obj;
135 ReleaseWriteLock(&avc->lock);
141 * I don't understand this. Why not just call vm_object_page_clean()
142 * and be done with it? I particularly don't understand why we're calling
143 * vget() here. Is there some reason to believe that the vnode might
144 * be being recycled at this point? I don't think there's any need for
145 * this loop, either -- if we keep the vnode locked all the time,
146 * that and the object lock will prevent any new pages from appearing.
147 * The loop is what causes the race condition. -GAW
153 if (obj != NULL && obj->flags & OBJ_MIGHTBEDIRTY) {
154 if (!vget(vp, LK_EXCLUSIVE | LK_RETRY, curthread)) {
158 vm_object_page_clean(obj, 0, 0, OBJPC_SYNC);
159 VM_OBJECT_UNLOCK(obj);
165 } while (anyio && (--tries > 0));
167 ObtainWriteLock(&avc->lock, 94);
170 /* Try to invalidate pages, for "fs flush" or "fs flushv"; or
171 * try to free pages, when deleting a file.
173 * Locking: the vcache entry's lock is held. It may be dropped and
176 * Since we drop and re-obtain the lock, we can't guarantee that there won't
177 * be some pages around when we return, newly created by concurrent activity.
180 osi_VM_TryToSmush(struct vcache *avc, afs_ucred_t *acred, int sync)
189 if (vp->v_iflag & VI_DOOMED) {
195 islocked = islocked_vnode(vp);
196 if (islocked == LK_EXCLOTHER)
197 panic("Trying to Smush over someone else's lock");
198 else if (islocked == LK_SHARED) {
199 afs_warn("Trying to Smush with a shared lock");
200 lock_vnode(vp, LK_UPGRADE);
201 } else if (!islocked)
202 lock_vnode(vp, LK_EXCLUSIVE);
204 if (vp->v_bufobj.bo_object != NULL) {
205 VM_OBJECT_LOCK(vp->v_bufobj.bo_object);
207 * Do we really want OBJPC_SYNC? OBJPC_INVAL would be
208 * faster, if invalidation is really what we are being
209 * asked to do. (It would make more sense, too, since
210 * otherwise this function is practically identical to
211 * osi_VM_StoreAllSegments().) -GAW
215 * Dunno. We no longer resemble osi_VM_StoreAllSegments,
216 * though maybe that's wrong, now. And OBJPC_SYNC is the
217 * common thing in 70 file systems, it seems. Matt.
220 vm_object_page_clean(vp->v_bufobj.bo_object, 0, 0, OBJPC_SYNC);
221 VM_OBJECT_UNLOCK(vp->v_bufobj.bo_object);
225 code = osi_vinvalbuf(vp, V_SAVE, PCATCH, 0);
226 while (code && (tries > 0)) {
227 afs_warn("TryToSmush retrying vinvalbuf");
228 code = osi_vinvalbuf(vp, V_SAVE, PCATCH, 0);
231 if (islocked == LK_SHARED)
232 lock_vnode(vp, LK_DOWNGRADE);
237 /* Purge VM for a file when its callback is revoked.
239 * Locking: No lock is held, not even the global lock.
242 osi_VM_FlushPages(struct vcache *avc, afs_ucred_t *credp)
245 struct vm_object *obj;
248 ASSERT_VOP_LOCKED(vp, __func__);
252 vm_object_page_remove(obj, 0, 0, FALSE);
253 VM_OBJECT_UNLOCK(obj);
255 osi_vinvalbuf(vp, 0, 0, 0);
258 /* Purge pages beyond end-of-file, when truncating a file.
260 * Locking: no lock is held, not even the global lock.
261 * activeV is raised. This is supposed to block pageins, but at present
262 * it only works on Solaris.
265 osi_VM_Truncate(struct vcache *avc, int alen, afs_ucred_t *acred)
267 vnode_pager_setsize(AFSTOV(avc), alen);