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"
25 #include "afs/sysincludes.h" /* Standard vendor system headers */
26 #include "afsincludes.h" /* Afs-based standard headers */
27 #include "afs/afs_stats.h" /* statistics */
28 /* #include <vm/vm_ubc.h> */
32 /* Try to discard pages, in order to recycle a vcache entry.
34 * We also make some sanity checks: ref count, open count, held locks.
36 * We also do some non-VM-related chores, such as releasing the cred pointer
37 * (for AIX and Solaris) and releasing the gnode (for AIX).
39 * Locking: afs_xvcache lock is held. If it is dropped and re-acquired,
40 * *slept should be set to warn the caller.
42 * Formerly, afs_xvcache was dropped and re-acquired for Solaris, but now it
43 * is not dropped and re-acquired for any platform. It may be that *slept is
44 * therefore obsolescent.
46 * OSF/1 Locking: VN_LOCK has been called.
49 osi_VM_FlushVCache(struct vcache *avc, int *slept)
52 if (avc->vrefCount > 1)
58 /* if a lock is held, give up */
59 if (CheckLock(&avc->lock))
63 ubc_invalidate(((struct vnode *)avc)->v_object, 0, 0, B_INVAL);
65 #endif /* SECRETLY_OSF1 */
71 * osi_ubc_flush_dirty_and_wait -- ensure all dirty pages cleaned
73 * Alpha OSF/1 doesn't make it easy to wait for all dirty pages to be cleaned.
74 * NFS tries to do this by calling waitforio(), which waits for v_numoutput
75 * to go to zero. But that isn't good enough, because afs_putpage() doesn't
76 * increment v_numoutput until it has obtained the vcache entry lock. Suppose
77 * that Process A, trying to flush a page, is waiting for that lock, and
78 * Process B tries to close the file. Process B calls waitforio() which thinks
79 * that everything is cool because v_numoutput is still zero. Process B then
80 * proceeds to call afs_StoreAllSegments(). Finally when B is finished, A gets
81 * to proceed and flush its page. But then it's too late because the file is
84 * (I suspect that waitforio() is not adequate for NFS, just as it isn't
85 * adequate for us. But that's not my problem.)
87 * The only way we can be sure that there are no more dirty pages is if there
88 * are no more pages with pg_busy set. We look for them on the cleanpl.
90 * For some reason, ubc_flush_dirty() only looks at the dirtypl, not the
91 * dirtywpl. I don't know why this is good enough, but I assume it is. By
92 * the same token, I only look for busy pages on the cleanpl, not the cleanwpl.
94 * Called with the global lock NOT held.
97 osi_ubc_flush_dirty_and_wait(struct vnode *vp, int flags)
105 struct vm_ubc_object *vop;
106 vop = (struct vm_ubc_object *)(vp->v_object);
107 ubc_flush_dirty(vop, flags);
111 /* shouldn't happen, but who knows */
115 if (vop->vu_cleanpl) {
116 for (first = 1, pp = vop->vu_cleanpl;
117 first || pp != vop->vu_cleanpl;
118 first = 0, pp = pp->pg_onext) {
122 assert_wait_mesg((vm_offset_t) pp, FALSE, "pg_wait");
123 vm_object_unlock(vop);
132 vm_object_unlock(vop);
134 #endif /* SECRETLY_OSF1 */
137 /* Try to store pages to cache, in order to store a file back to the server.
139 * Locking: the vcache entry's lock is held. It will usually be dropped and
143 osi_VM_StoreAllSegments(struct vcache *avc)
146 ReleaseWriteLock(&avc->lock);
148 osi_ubc_flush_dirty_and_wait((struct vnode *)avc, 0);
150 ObtainWriteLock(&avc->lock, 94);
151 #endif /* SECRETLY_OSF1 */
154 /* Try to invalidate pages, for "fs flush" or "fs flushv"; or
155 * try to free pages, when deleting a file.
157 * Locking: the vcache entry's lock is held. It may be dropped and
160 * Since we drop and re-obtain the lock, we can't guarantee that there won't
161 * be some pages around when we return, newly created by concurrent activity.
164 osi_VM_TryToSmush(struct vcache *avc, AFS_UCRED *acred, int sync)
167 ReleaseWriteLock(&avc->lock);
169 osi_ubc_flush_dirty_and_wait((struct vnode *)avc, 0);
170 ubc_invalidate(((struct vnode *)avc)->v_object, 0, 0, B_INVAL);
172 ObtainWriteLock(&avc->lock, 59);
173 #endif /* SECRETLY_OSF1 */
176 /* Purge VM for a file when its callback is revoked.
178 * Locking: No lock is held, not even the global lock.
181 osi_VM_FlushPages(struct vcache *avc, AFS_UCRED *credp)
184 ubc_flush_dirty(((struct vnode *)avc)->v_object, 0);
185 ubc_invalidate(((struct vnode *)avc)->v_object, 0, 0, B_INVAL);
186 #endif /* SECRETLY_OSF1 */
189 /* Purge pages beyond end-of-file, when truncating a file.
191 * Locking: no lock is held, not even the global lock.
192 * activeV is raised. This is supposed to block pageins, but at present
193 * it only works on Solaris.
196 osi_VM_Truncate(struct vcache *avc, int alen, AFS_UCRED *acred)
199 ubc_invalidate(((struct vnode *)avc)->v_object, alen, MAXINT - alen,
201 #endif /* SECRETLY_OSF1 */