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"
26 #include "../afs/sysincludes.h" /* Standard vendor system headers */
27 #include "../afs/afsincludes.h" /* Afs-based standard headers */
28 #include "../afs/afs_stats.h" /* statistics */
29 /* #include <vm/vm_ubc.h> */
33 /* Try to discard pages, in order to recycle a vcache entry.
35 * We also make some sanity checks: ref count, open count, held locks.
37 * We also do some non-VM-related chores, such as releasing the cred pointer
38 * (for AIX and Solaris) and releasing the gnode (for AIX).
40 * Locking: afs_xvcache lock is held. If it is dropped and re-acquired,
41 * *slept should be set to warn the caller.
43 * Formerly, afs_xvcache was dropped and re-acquired for Solaris, but now it
44 * is not dropped and re-acquired for any platform. It may be that *slept is
45 * therefore obsolescent.
47 * OSF/1 Locking: VN_LOCK has been called.
50 osi_VM_FlushVCache(avc, slept)
55 if (avc->vrefCount > 1)
61 /* if a lock is held, give up */
62 if (CheckLock(&avc->lock) || afs_CheckBozonLock(&avc->pvnLock))
66 ubc_invalidate(((struct vnode *)avc)->v_object, 0, 0, B_INVAL);
68 #endif /* SECRETLY_OSF1 */
74 * osi_ubc_flush_dirty_and_wait -- ensure all dirty pages cleaned
76 * Alpha OSF/1 doesn't make it easy to wait for all dirty pages to be cleaned.
77 * NFS tries to do this by calling waitforio(), which waits for v_numoutput
78 * to go to zero. But that isn't good enough, because afs_putpage() doesn't
79 * increment v_numoutput until it has obtained the vcache entry lock. Suppose
80 * that Process A, trying to flush a page, is waiting for that lock, and
81 * Process B tries to close the file. Process B calls waitforio() which thinks
82 * that everything is cool because v_numoutput is still zero. Process B then
83 * proceeds to call afs_StoreAllSegments(). Finally when B is finished, A gets
84 * to proceed and flush its page. But then it's too late because the file is
87 * (I suspect that waitforio() is not adequate for NFS, just as it isn't
88 * adequate for us. But that's not my problem.)
90 * The only way we can be sure that there are no more dirty pages is if there
91 * are no more pages with pg_busy set. We look for them on the cleanpl.
93 * For some reason, ubc_flush_dirty() only looks at the dirtypl, not the
94 * dirtywpl. I don't know why this is good enough, but I assume it is. By
95 * the same token, I only look for busy pages on the cleanpl, not the cleanwpl.
97 * Called with the global lock NOT held.
100 osi_ubc_flush_dirty_and_wait(vp, flags)
109 struct vm_ubc_object* vop;
110 vop = (struct vm_ubc_object*)(vp->v_object);
111 ubc_flush_dirty(vop, flags);
115 /* shouldn't happen, but who knows */
119 if (vop->vu_cleanpl) {
120 for (first = 1, pp = vop->vu_cleanpl;
121 first || pp != vop->vu_cleanpl;
122 first = 0, pp = pp->pg_onext) {
126 assert_wait_mesg((vm_offset_t)pp, FALSE, "pg_wait");
127 vm_object_unlock(vop);
135 vm_object_unlock(vop);
137 #endif /* SECRETLY_OSF1 */
140 /* Try to store pages to cache, in order to store a file back to the server.
142 * Locking: the vcache entry's lock is held. It will usually be dropped and
146 osi_VM_StoreAllSegments(avc)
150 ReleaseWriteLock(&avc->lock);
152 osi_ubc_flush_dirty_and_wait((struct vnode *)avc, 0);
154 ObtainWriteLock(&avc->lock,94);
155 #endif /* SECRETLY_OSF1 */
158 /* Try to invalidate pages, for "fs flush" or "fs flushv"; or
159 * try to free pages, when deleting a file.
161 * Locking: the vcache entry's lock is held. It may be dropped and
164 * Since we drop and re-obtain the lock, we can't guarantee that there won't
165 * be some pages around when we return, newly created by concurrent activity.
168 osi_VM_TryToSmush(avc, acred, sync)
170 struct AFS_UCRED *acred;
174 ReleaseWriteLock(&avc->lock);
176 osi_ubc_flush_dirty_and_wait((struct vnode *)avc, 0);
177 ubc_invalidate(((struct vnode *)avc)->v_object, 0, 0, B_INVAL);
179 ObtainWriteLock(&avc->lock,59);
180 #endif /* SECRETLY_OSF1 */
183 /* Purge VM for a file when its callback is revoked.
185 * Locking: No lock is held, not even the global lock.
188 osi_VM_FlushPages(avc, credp)
190 struct AFS_UCRED *credp;
193 ubc_flush_dirty(((struct vnode *)avc)->v_object, 0);
194 ubc_invalidate(((struct vnode *)avc)->v_object, 0, 0, B_INVAL);
195 #endif /* SECRETLY_OSF1 */
198 /* Purge pages beyond end-of-file, when truncating a file.
200 * Locking: no lock is held, not even the global lock.
201 * activeV is raised. This is supposed to block pageins, but at present
202 * it only works on Solaris.
205 osi_VM_Truncate(avc, alen, acred)
208 struct AFS_UCRED *acred;
211 ubc_invalidate(((struct vnode *)avc)->v_object, alen,
212 MAXINT - alen, B_INVAL);
213 #endif /* SECRETLY_OSF1 */