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"
14 #include "afs/sysincludes.h" /* Standard vendor system headers */
15 #include "afsincludes.h" /* Afs-based standard headers */
16 #include "afs/afs_stats.h" /* afs statistics */
18 #include <sys/adspace.h> /* for vm_att(), vm_det() */
22 osi_Active(struct vcache *avc)
24 AFS_STATCNT(osi_Active);
25 #if defined(AFS_AIX_ENV) || defined(AFS_SUN5_ENV) || (AFS_LINUX20_ENV) || defined(AFS_DARWIN_ENV) || defined(AFS_XBSD_ENV)
26 if ((avc->opens > 0) || (avc->f.states & CMAPPED))
27 return 1; /* XXX: Warning, verify this XXX */
28 #elif defined(AFS_SGI_ENV)
29 if ((avc->opens > 0) || AFS_VN_MAPPED(AFSTOV(avc)))
32 if (avc->opens > 0 || (AFSTOV(avc)->v_flag & VTEXT))
38 /* this call, unlike osi_FlushText, is supposed to discard caches that may
39 contain invalid information if a file is written remotely, but that may
40 contain valid information that needs to be written back if the file is
41 being written locally. It doesn't subsume osi_FlushText, since the latter
42 function may be needed to flush caches that are invalidated by local writes.
44 avc->pvnLock is already held, avc->lock is guaranteed not to be held (by
48 osi_FlushPages(struct vcache *avc, afs_ucred_t *credp)
51 #if defined(AFS_CACHE_BYPASS)
52 /* The optimization to check DV under read lock below is identical a
53 * change in CITI cache bypass work. The problem CITI found in 1999
54 * was that this code and background daemon doing prefetching competed
55 * for the vcache entry shared lock. It's not clear to me from the
56 * tech report, but it looks like CITI fixed the general prefetch code
57 * path as a bonus when experimenting on prefetch for cache bypass, see
61 ObtainReadLock(&avc->lock);
62 /* If we've already purged this version, or if we're the ones
63 * writing this version, don't flush it (could lose the
64 * data we're writing). */
65 if ((hcmp((avc->f.m.DataVersion), (avc->mapDV)) <= 0)
66 || ((avc->execsOrWriters > 0) && afs_DirtyPages(avc))) {
67 ReleaseReadLock(&avc->lock);
70 ReleaseReadLock(&avc->lock);
71 ObtainWriteLock(&avc->lock, 10);
73 if ((hcmp((avc->f.m.DataVersion), (avc->mapDV)) <= 0)
74 || ((avc->execsOrWriters > 0) && afs_DirtyPages(avc))) {
75 ReleaseWriteLock(&avc->lock);
78 if (hiszero(avc->mapDV)) {
79 hset(avc->mapDV, avc->f.m.DataVersion);
80 ReleaseWriteLock(&avc->lock);
84 AFS_STATCNT(osi_FlushPages);
85 hset(origDV, avc->f.m.DataVersion);
86 afs_Trace3(afs_iclSetp, CM_TRACE_FLUSHPAGES, ICL_TYPE_POINTER, avc,
87 ICL_TYPE_INT32, origDV.low, ICL_TYPE_INT32, avc->f.m.Length);
89 ReleaseWriteLock(&avc->lock);
90 #ifndef AFS_FBSD70_ENV
93 osi_VM_FlushPages(avc, credp);
94 #ifndef AFS_FBSD70_ENV
97 ObtainWriteLock(&avc->lock, 88);
99 /* do this last, and to original version, since stores may occur
100 * while executing above PUTPAGE call */
101 hset(avc->mapDV, origDV);
102 ReleaseWriteLock(&avc->lock);
107 /* This call is supposed to flush all caches that might be invalidated
108 * by either a local write operation or a write operation done on
109 * another client. This call may be called repeatedly on the same
110 * version of a file, even while a file is being written, so it
111 * shouldn't do anything that would discard newly written data before
112 * it is written to the file system. */
115 osi_FlushText_really(struct vcache *vp)
117 afs_hyper_t fdv; /* version before which we'll flush */
119 AFS_STATCNT(osi_FlushText);
120 /* see if we've already flushed this data version */
121 if (hcmp(vp->f.m.DataVersion, vp->flushDV) <= 0)
124 ObtainWriteLock(&afs_ftf, 317);
125 hset(fdv, vp->f.m.DataVersion);
127 /* why this disgusting code below?
128 * xuntext, called by xrele, doesn't notice when it is called
129 * with a freed text object. Sun continually calls xrele or xuntext
130 * without any locking, as long as VTEXT is set on the
131 * corresponding vnode.
132 * But, if the text object is locked when you check the VTEXT
133 * flag, several processes can wait in xuntext, waiting for the
134 * text lock; when the second one finally enters xuntext's
135 * critical region, the text object is already free, but the check
136 * was already done by xuntext's caller.
137 * Even worse, it turns out that xalloc locks the text object
138 * before reading or stating a file via the vnode layer. Thus, we
139 * could end up in getdcache, being asked to bring in a new
140 * version of a file, but the corresponding text object could be
141 * locked. We can't flush the text object without causing
142 * deadlock, so now we just don't try to lock the text object
143 * unless it is guaranteed to work. And we try to flush the text
144 * when we need to a bit more often at the vnode layer. Sun
145 * really blew the vm-cache flushing interface.
148 #if defined (AFS_HPUX_ENV)
149 if (vp->v.v_flag & VTEXT) {
152 if (vp->v.v_flag & VTEXT) { /* still has a text object? */
153 ReleaseWriteLock(&afs_ftf);
159 /* next do the stuff that need not check for deadlock problems */
162 /* finally, record that we've done it */
163 hset(vp->flushDV, fdv);
164 ReleaseWriteLock(&afs_ftf);
167 #endif /* AFS_TEXT_ENV */
169 /* ? is it moderately likely that there are dirty VM pages associated with
172 * Prereqs: avc must be write-locked
174 * System Dependencies: - *must* support each type of system for which
175 * memory mapped files are supported, even if all
176 * it does is return TRUE;
178 * NB: this routine should err on the side of caution for ProcessFS to work
179 * correctly (or at least, not to introduce worse bugs than already exist)
183 osi_VMDirty_p(struct vcache *avc)
187 if (avc->execsOrWriters <= 0)
188 return 0; /* can't be many dirty pages here, I guess */
190 #if defined (AFS_AIX32_ENV)
192 /* because of the level of hardware involvment with VM and all the
193 * warnings about "This routine must be called at VMM interrupt
194 * level", I thought it would be safest to disable interrupts while
195 * looking at the software page fault table. */
197 /* convert vm handle into index into array: I think that stoinio is
198 * always zero... Look into this XXX */
199 #define VMHASH(handle) ( \
200 ( ((handle) & ~vmker.stoinio) \
201 ^ ((((handle) & ~vmker.stoinio) & vmker.stoimask) << vmker.stoihash) \
205 unsigned int pagef, pri, index, next;
207 index = VMHASH(avc->segid);
208 if (scb_valid(index)) { /* could almost be an ASSERT */
210 pri = disable_ints();
211 for (pagef = scb_sidlist(index); pagef >= 0; pagef = next) {
212 next = pft_sidfwd(pagef);
213 if (pft_modbit(pagef)) { /* has page frame been modified? */
223 #endif /* AFS_AIX32_ENV */
225 #if defined (AFS_SUN5_ENV)
226 if (avc->f.states & CMAPPED) {
228 for (pg = avc->v.v_s.v_Pages; pg; pg = pg->p_vpnext) {
241 * Solaris osi_ReleaseVM should not drop and re-obtain the vcache entry lock.
242 * This leads to bad races when osi_ReleaseVM() is called from
243 * afs_InvalidateAllSegments().
245 * We can do this because Solaris osi_VM_Truncate() doesn't care whether the
246 * vcache entry lock is held or not.
248 * For other platforms, in some cases osi_VM_Truncate() doesn't care, but
249 * there may be cases where it does care. If so, it would be good to fix
250 * them so they don't care. Until then, we assume the worst.
252 * Locking: the vcache entry lock is held. It is dropped and re-obtained.
255 osi_ReleaseVM(struct vcache *avc, afs_ucred_t *acred)
259 osi_VM_Truncate(avc, 0, acred);
262 ReleaseWriteLock(&avc->lock);
264 osi_VM_Truncate(avc, 0, acred);
266 ObtainWriteLock(&avc->lock, 80);