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)
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>
32 #include <sys/limits.h>
33 #if __FreeBSD_version >= 1000030
34 #include <sys/rwlock.h>
38 * FreeBSD implementation notes:
39 * Most of these operations require us to frob vm_objects. Most
40 * functions require that the object be locked (with VM_OBJECT_*LOCK)
41 * on entry and leave it locked on exit. The locking protocol
42 * requires that we access vp->v_object with the heavy vnode lock
43 * held and the vnode interlock unlocked.
45 * The locking protocol for vnodes is defined in
46 * kern/vnode_if.src and sys/vnode.h; unfortunately, it is not *quite*
47 * constant from version to version so to be properly correct we must
48 * check the VCS history of those files.
51 #define lock_vnode(v, f) vn_lock((v), (f))
52 #define ilock_vnode(v) vn_lock((v), LK_INTERLOCK|LK_EXCLUSIVE|LK_RETRY)
53 #define unlock_vnode(v) VOP_UNLOCK((v), 0)
54 #define islocked_vnode(v) VOP_ISLOCKED((v))
56 #if __FreeBSD_version >= 1000030
57 #define AFS_VM_OBJECT_WLOCK(o) VM_OBJECT_WLOCK(o)
58 #define AFS_VM_OBJECT_WUNLOCK(o) VM_OBJECT_WUNLOCK(o)
60 #define AFS_VM_OBJECT_WLOCK(o) VM_OBJECT_LOCK(o)
61 #define AFS_VM_OBJECT_WUNLOCK(o) VM_OBJECT_UNLOCK(o)
64 /* Try to discard pages, in order to recycle a vcache entry.
66 * We also make some sanity checks: ref count, open count, held locks.
68 * We also do some non-VM-related chores, such as releasing the cred pointer
69 * (for AIX and Solaris) and releasing the gnode (for AIX).
71 * Locking: afs_xvcache lock is held. It must not be dropped.
75 osi_VM_FlushVCache(struct vcache *avc)
83 code = osi_fbsd_checkinuse(avc);
89 /* must hold the vnode before calling cache_purge()
90 * This code largely copied from vfs_subr.c:vlrureclaim() */
103 /* Try to store pages to cache, in order to store a file back to the server.
105 * Locking: the vcache entry's lock is held. It will usually be dropped and
109 osi_VM_StoreAllSegments(struct vcache *avc)
112 struct vm_object *obj;
115 ReleaseWriteLock(&avc->lock);
121 * I don't understand this. Why not just call vm_object_page_clean()
122 * and be done with it? I particularly don't understand why we're calling
123 * vget() here. Is there some reason to believe that the vnode might
124 * be being recycled at this point? I don't think there's any need for
125 * this loop, either -- if we keep the vnode locked all the time,
126 * that and the object lock will prevent any new pages from appearing.
127 * The loop is what causes the race condition. -GAW
133 if (obj != NULL && obj->flags & OBJ_MIGHTBEDIRTY) {
134 if (!vget(vp, LK_EXCLUSIVE | LK_RETRY, curthread)) {
137 AFS_VM_OBJECT_WLOCK(obj);
138 vm_object_page_clean(obj, 0, 0, OBJPC_SYNC);
139 AFS_VM_OBJECT_WUNLOCK(obj);
145 } while (anyio && (--tries > 0));
147 ObtainWriteLock(&avc->lock, 94);
150 /* Try to invalidate pages, for "fs flush" or "fs flushv"; or
151 * try to free pages, when deleting a file.
153 * Locking: the vcache entry's lock is held. It may be dropped and
156 * Since we drop and re-obtain the lock, we can't guarantee that there won't
157 * be some pages around when we return, newly created by concurrent activity.
160 osi_VM_TryToSmush(struct vcache *avc, afs_ucred_t *acred, int sync)
169 if (vp->v_iflag & VI_DOOMED) {
177 islocked = islocked_vnode(vp);
178 if (islocked == LK_EXCLOTHER)
179 panic("Trying to Smush over someone else's lock");
180 else if (islocked == LK_SHARED) {
181 afs_warn("Trying to Smush with a shared lock");
182 lock_vnode(vp, LK_UPGRADE);
183 } else if (!islocked)
184 lock_vnode(vp, LK_EXCLUSIVE);
186 if (vp->v_bufobj.bo_object != NULL) {
187 AFS_VM_OBJECT_WLOCK(vp->v_bufobj.bo_object);
189 * Do we really want OBJPC_SYNC? OBJPC_INVAL would be
190 * faster, if invalidation is really what we are being
191 * asked to do. (It would make more sense, too, since
192 * otherwise this function is practically identical to
193 * osi_VM_StoreAllSegments().) -GAW
197 * Dunno. We no longer resemble osi_VM_StoreAllSegments,
198 * though maybe that's wrong, now. And OBJPC_SYNC is the
199 * common thing in 70 file systems, it seems. Matt.
202 vm_object_page_clean(vp->v_bufobj.bo_object, 0, 0, OBJPC_SYNC);
203 AFS_VM_OBJECT_WUNLOCK(vp->v_bufobj.bo_object);
207 code = osi_vinvalbuf(vp, V_SAVE, PCATCH, 0);
208 while (code && (tries > 0)) {
209 afs_warn("TryToSmush retrying vinvalbuf");
210 code = osi_vinvalbuf(vp, V_SAVE, PCATCH, 0);
213 if (islocked == LK_SHARED)
214 lock_vnode(vp, LK_DOWNGRADE);
221 /* Purge VM for a file when its callback is revoked.
223 * Locking: No lock is held, not even the global lock.
226 osi_VM_FlushPages(struct vcache *avc, afs_ucred_t *credp)
229 struct vm_object *obj;
232 ASSERT_VOP_LOCKED(vp, __func__);
235 AFS_VM_OBJECT_WLOCK(obj);
236 vm_object_page_remove(obj, 0, 0, FALSE);
237 AFS_VM_OBJECT_WUNLOCK(obj);
239 osi_vinvalbuf(vp, 0, 0, 0);
242 /* Purge pages beyond end-of-file, when truncating a file.
244 * Locking: no lock is held, not even the global lock.
245 * activeV is raised. This is supposed to block pageins, but at present
246 * it only works on Solaris.
249 osi_VM_Truncate(struct vcache *avc, int alen, afs_ucred_t *acred)
251 vnode_pager_setsize(AFSTOV(avc), alen);