src/afs/AIX/osi_vm.c

   1 /*
   2  * Copyright 2000, International Business Machines Corporation and others.
   3  * All Rights Reserved.
   4  *
   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
   8  */
   9
  10 #include <afsconfig.h>
  11 #include "afs/param.h"
  12
  13
  14 #include "afs/sysincludes.h"    /* Standard vendor system headers */
  15 #include "afsincludes.h"        /* Afs-based standard headers */
  16 #include "afs/afs_stats.h"      /* statistics */
  17
  18 /* Try to discard pages, in order to recycle a vcache entry.
  19  *
  20  * We also make some sanity checks:  ref count, open count, held locks.
  21  *
  22  * We also do some non-VM-related chores, such as releasing the cred pointer
  23  * (for AIX and Solaris) and releasing the gnode (for AIX).
  24  *
  25  * Locking:  afs_xvcache lock is held. It must not be dropped.
  26  */
  27 int
  28 osi_VM_FlushVCache(struct vcache *avc)
  29 {
  30     if (avc->vrefCount != 0)
  31         return EBUSY;
  32
  33     if (avc->opens)
  34         return EBUSY;
  35
  36     /* Just in case someone is still referring to the vnode we
  37      * give up trying to get rid of this guy */
  38     if (avc->vrefCount || CheckLock(&avc->lock) || LockWaiters(&avc->lock))
  39         return EBUSY;
  40
  41     if (avc->segid) {
  42         AFS_GUNLOCK();
  43         vms_delete(avc->segid);
  44         AFS_GLOCK();
  45         avc->segid = avc->vmh = NULL;
  46     }
  47
  48     if (avc->credp) {
  49         crfree(avc->credp);
  50         avc->credp = NULL;
  51     }
  52
  53     /* Free the alloced gnode that was accompanying the vcache's vnode */
  54     aix_gnode_rele(AFSTOV(avc));
  55
  56     return 0;
  57 }
  58
  59 /* Try to store pages to cache, in order to store a file back to the server.
  60  *
  61  * Locking:  the vcache entry's lock is held.  It will usually be dropped and
  62  * re-obtained.
  63  */
  64 void
  65 osi_VM_StoreAllSegments(struct vcache *avc)
  66 {
  67     if (avc->segid) {
  68         /*
  69          * The execsOrWriters test is done so that we don't thrash on
  70          * the vm_writep call below. We only initiate a pageout of the
  71          * dirty vm pages on the last store...
  72          * this is strictly a pragmatic decision, and _does_ break the
  73          * advertised AFS consistency semantics.  Without this hack,
  74          * AIX systems panic under heavy load.  I consider the current
  75          * behavior a bug introduced to hack around a worse bug. XXX
  76          *
  77          * Removed do_writep governing sync'ing behavior.
  78          */
  79         ReleaseWriteLock(&avc->lock);   /* XXX */
  80         AFS_GUNLOCK();
  81         vm_writep(avc->segid, 0, MAXFSIZE / PAGESIZE - 1);
  82         vms_iowait(avc->segid);
  83         AFS_GLOCK();
  84         ObtainWriteLock(&avc->lock, 93);        /* XXX */
  85         /*
  86          * The following is necessary because of the following
  87          * asynchronicity: We open a file, write to it and
  88          * close the file
  89          * if CCore flag is set, we clear it and do the extra
  90          * decrement ourselves now.
  91          * If we're called by the CCore clearer, the CCore flag
  92          * will already be clear, so we don't have to worry about
  93          * clearing it twice.
  94          * avc was "VN_HELD" and "crheld" when CCore was set in
  95          * afs_FakeClose
  96          */
  97         if (avc->f.states & CCore) {
  98             avc->f.states &= ~CCore;
  99             avc->opens--;
 100             avc->execsOrWriters--;
 101             AFS_RELE(AFSTOV(avc));
 102             crfree((struct ucred *)avc->linkData);
 103             avc->linkData = NULL;
 104         }
 105     }
 106 }
 107
 108 /* Try to invalidate pages, for "fs flush" or "fs flushv"; or
 109  * try to free pages, when deleting a file.
 110  *
 111  * Locking:  the vcache entry's lock is held.  It may be dropped and
 112  * re-obtained.
 113  *
 114  * Since we drop and re-obtain the lock, we can't guarantee that there won't
 115  * be some pages around when we return, newly created by concurrent activity.
 116  */
 117 void
 118 osi_VM_TryToSmush(struct vcache *avc, afs_ucred_t *acred, int sync)
 119 {
 120     if (avc->segid) {
 121         ReleaseWriteLock(&avc->lock);
 122         AFS_GUNLOCK();
 123         vm_flushp(avc->segid, 0, MAXFSIZE / PAGESIZE - 1);
 124         vms_iowait(avc->segid); /* XXX Wait?? XXX */
 125         AFS_GLOCK();
 126         ObtainWriteLock(&avc->lock, 60);
 127     }
 128 }
 129
 130 /* Purge VM for a file when its callback is revoked.
 131  *
 132  * Locking:  No lock is held, not even the global lock.
 133  */
 134 void
 135 osi_VM_FlushPages(struct vcache *avc, afs_ucred_t *credp)
 136 {
 137     if (avc->segid) {
 138         vm_flushp(avc->segid, 0, MAXFSIZE / PAGESIZE - 1);
 139         /*
 140          * XXX We probably don't need to wait but better be safe XXX
 141          */
 142         vms_iowait(avc->segid);
 143     }
 144 }
 145
 146 /* Purge pages beyond end-of-file, when truncating a file.
 147  *
 148  * Locking:  no lock is held, not even the global lock.
 149  * activeV is raised.  This is supposed to block pageins, but at present
 150  * it only works on Solaris.
 151  */
 152 void
 153 osi_VM_Truncate(struct vcache *avc, int alen, afs_ucred_t *acred)
 154 {
 155     if (avc->segid) {
 156         int firstpage = (alen + PAGESIZE - 1) / PAGESIZE;
 157         vm_releasep(avc->segid, firstpage, MAXFSIZE / PAGESIZE - firstpage);
 158         vms_iowait(avc->segid); /* Do we need this? */
 159     }
 160 }