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
10 #include <afsconfig.h>
11 #include "afs/param.h"
16 #include "afs/sysincludes.h" /* Standard vendor system headers */
17 #include "afsincludes.h" /* Afs-based standard headers */
18 #include "afs/afs_stats.h" /* statistics */
19 #include <vm/vm_ubc.h>
22 /* Try to discard pages, in order to recycle a vcache entry.
24 * We also make some sanity checks: ref count, open count, held locks.
26 * We also do some non-VM-related chores, such as releasing the cred pointer
27 * (for AIX and Solaris) and releasing the gnode (for AIX).
29 * Locking: afs_xvcache lock is held. If it is dropped and re-acquired,
30 * *slept should be set to warn the caller.
32 * Formerly, afs_xvcache was dropped and re-acquired for Solaris, but now it
33 * is not dropped and re-acquired for any platform. It may be that *slept is
34 * therefore obsolescent.
36 * OSF/1 Locking: VN_LOCK has been called.
39 osi_VM_FlushVCache(struct vcache *avc, int *slept)
41 if (avc->vrefCount > 1)
47 /* if a lock is held, give up */
48 if (CheckLock(&avc->lock) || afs_CheckBozonLock(&avc->pvnLock))
52 ubc_invalidate(AFSTOV(avc)->v_object, 0, 0, B_INVAL);
59 * osi_ubc_flush_dirty_and_wait -- ensure all dirty pages cleaned
61 * Alpha OSF/1 doesn't make it easy to wait for all dirty pages to be cleaned.
62 * NFS tries to do this by calling waitforio(), which waits for v_numoutput
63 * to go to zero. But that isn't good enough, because afs_putpage() doesn't
64 * increment v_numoutput until it has obtained the vcache entry lock. Suppose
65 * that Process A, trying to flush a page, is waiting for that lock, and
66 * Process B tries to close the file. Process B calls waitforio() which thinks
67 * that everything is cool because v_numoutput is still zero. Process B then
68 * proceeds to call afs_StoreAllSegments(). Finally when B is finished, A gets
69 * to proceed and flush its page. But then it's too late because the file is
72 * (I suspect that waitforio() is not adequate for NFS, just as it isn't
73 * adequate for us. But that's not my problem.)
75 * The only way we can be sure that there are no more dirty pages is if there
76 * are no more pages with pg_busy set. We look for them on the cleanpl.
78 * For some reason, ubc_flush_dirty() only looks at the dirtypl, not the
79 * dirtywpl. I don't know why this is good enough, but I assume it is. By
80 * the same token, I only look for busy pages on the cleanpl, not the cleanwpl.
82 * Called with the global lock NOT held.
85 osi_ubc_flush_dirty_and_wait(struct vnode *vp, int flags)
92 struct vm_ubc_object *vop;
93 vop = (struct vm_ubc_object *)(vp->v_object);
94 ubc_flush_dirty(vop, flags);
98 /* shouldn't happen, but who knows */
102 if (vop->vu_cleanpl) {
103 for (first = 1, pp = vop->vu_cleanpl;
104 first || pp != vop->vu_cleanpl;
105 first = 0, pp = pp->pg_onext) {
109 assert_wait_mesg((vm_offset_t) pp, FALSE, "pg_wait");
110 vm_object_unlock(vop);
119 vm_object_unlock(vop);
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)
131 ReleaseWriteLock(&avc->lock);
133 osi_ubc_flush_dirty_and_wait(AFSTOV(avc), 0);
135 ObtainWriteLock(&avc->lock, 94);
138 /* Try to invalidate pages, for "fs flush" or "fs flushv"; or
139 * try to free pages, when deleting a file.
141 * Locking: the vcache entry's lock is held. It may be dropped and
144 * Since we drop and re-obtain the lock, we can't guarantee that there won't
145 * be some pages around when we return, newly created by concurrent activity.
148 osi_VM_TryToSmush(struct vcache *avc, struct AFS_UCRED *acred, int sync)
150 ReleaseWriteLock(&avc->lock);
152 osi_ubc_flush_dirty_and_wait(AFSTOV(avc), 0);
153 ubc_invalidate(AFSTOV(avc)->v_object, 0, 0, B_INVAL);
155 ObtainWriteLock(&avc->lock, 59);
158 /* Purge VM for a file when its callback is revoked.
160 * Locking: No lock is held, not even the global lock.
163 osi_VM_FlushPages(struct vcache *avc, struct AFS_UCRED *credp)
165 ubc_flush_dirty(AFSTOV(avc)->v_object, 0);
166 ubc_invalidate(AFSTOV(avc)->v_object, 0, 0, B_INVAL);
169 /* Purge pages beyond end-of-file, when truncating a file.
171 * Locking: no lock is held, not even the global lock.
172 * activeV is raised. This is supposed to block pageins, but at present
173 * it only works on Solaris.
176 osi_VM_Truncate(struct vcache *avc, int alen, struct AFS_UCRED *acred)
178 ubc_invalidate(AFSTOV(avc)->v_object, alen, MAXINT - alen, B_INVAL);