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 if (vType(avc) == VDIR) {
62 /* not applicable to directories; they're never mapped or stored in
66 ObtainReadLock(&avc->lock);
67 /* If we've already purged this version, or if we're the ones
68 * writing this version, don't flush it (could lose the
69 * data we're writing). */
70 if ((hcmp((avc->f.m.DataVersion), (avc->mapDV)) <= 0)
71 || ((avc->execsOrWriters > 0) && afs_DirtyPages(avc))) {
72 ReleaseReadLock(&avc->lock);
75 ReleaseReadLock(&avc->lock);
76 ObtainWriteLock(&avc->lock, 10);
78 if ((hcmp((avc->f.m.DataVersion), (avc->mapDV)) <= 0)
79 || ((avc->execsOrWriters > 0) && afs_DirtyPages(avc))) {
80 ReleaseWriteLock(&avc->lock);
84 /* At this point, you might think that we can skip trying to flush pages
85 * if mapDV is zero, since a file with a zero DV will not have any data in
86 * it. However, some platforms (notably Linux 2.6.22+) will keep a page
87 * full of zeroes around for an empty file. So play it safe and always
90 AFS_STATCNT(osi_FlushPages);
91 hset(origDV, avc->f.m.DataVersion);
92 afs_Trace3(afs_iclSetp, CM_TRACE_FLUSHPAGES, ICL_TYPE_POINTER, avc,
93 ICL_TYPE_INT32, origDV.low, ICL_TYPE_INT32, avc->f.m.Length);
95 ReleaseWriteLock(&avc->lock);
97 osi_VM_FlushPages(avc, credp);
99 ObtainWriteLock(&avc->lock, 88);
101 /* do this last, and to original version, since stores may occur
102 * while executing above PUTPAGE call */
103 hset(avc->mapDV, origDV);
104 ReleaseWriteLock(&avc->lock);
109 /* This call is supposed to flush all caches that might be invalidated
110 * by either a local write operation or a write operation done on
111 * another client. This call may be called repeatedly on the same
112 * version of a file, even while a file is being written, so it
113 * shouldn't do anything that would discard newly written data before
114 * it is written to the file system. */
117 osi_FlushText_really(struct vcache *vp)
119 afs_hyper_t fdv; /* version before which we'll flush */
121 AFS_STATCNT(osi_FlushText);
122 /* see if we've already flushed this data version */
123 if (hcmp(vp->f.m.DataVersion, vp->flushDV) <= 0)
126 ObtainWriteLock(&afs_ftf, 317);
127 hset(fdv, vp->f.m.DataVersion);
129 /* why this disgusting code below?
130 * xuntext, called by xrele, doesn't notice when it is called
131 * with a freed text object. Sun continually calls xrele or xuntext
132 * without any locking, as long as VTEXT is set on the
133 * corresponding vnode.
134 * But, if the text object is locked when you check the VTEXT
135 * flag, several processes can wait in xuntext, waiting for the
136 * text lock; when the second one finally enters xuntext's
137 * critical region, the text object is already free, but the check
138 * was already done by xuntext's caller.
139 * Even worse, it turns out that xalloc locks the text object
140 * before reading or stating a file via the vnode layer. Thus, we
141 * could end up in getdcache, being asked to bring in a new
142 * version of a file, but the corresponding text object could be
143 * locked. We can't flush the text object without causing
144 * deadlock, so now we just don't try to lock the text object
145 * unless it is guaranteed to work. And we try to flush the text
146 * when we need to a bit more often at the vnode layer. Sun
147 * really blew the vm-cache flushing interface.
150 #if defined (AFS_HPUX_ENV)
151 if (vp->v.v_flag & VTEXT) {
154 if (vp->v.v_flag & VTEXT) { /* still has a text object? */
155 ReleaseWriteLock(&afs_ftf);
161 /* next do the stuff that need not check for deadlock problems */
164 /* finally, record that we've done it */
165 hset(vp->flushDV, fdv);
166 ReleaseWriteLock(&afs_ftf);
169 #endif /* AFS_TEXT_ENV */
172 * Solaris osi_ReleaseVM should not drop and re-obtain the vcache entry lock.
173 * This leads to bad races when osi_ReleaseVM() is called from
174 * afs_InvalidateAllSegments().
176 * We can do this because Solaris osi_VM_Truncate() doesn't care whether the
177 * vcache entry lock is held or not.
179 * For other platforms, in some cases osi_VM_Truncate() doesn't care, but
180 * there may be cases where it does care. If so, it would be good to fix
181 * them so they don't care. Until then, we assume the worst.
183 * Locking: the vcache entry lock is held. It is dropped and re-obtained.
186 osi_ReleaseVM(struct vcache *avc, afs_ucred_t *acred)
190 osi_VM_Truncate(avc, 0, acred);
193 ReleaseWriteLock(&avc->lock);
195 osi_VM_Truncate(avc, 0, acred);
197 ObtainWriteLock(&avc->lock, 80);