src/afs/FBSD/osi_vcache.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 #include "afs/sysincludes.h"    /*Standard vendor system headers */
  14 #include "afsincludes.h"        /*AFS-based standard headers */
  15
  16 int
  17 osi_TryEvictVCache(struct vcache *avc, int *slept, int defersleep)
  18 {
  19     struct vnode *vp;
  20     int code;
  21
  22     vp = AFSTOV(avc);
  23
  24     if (!VI_TRYLOCK(vp))
  25         return 0;
  26     code = osi_fbsd_checkinuse(avc);
  27     if (code != 0) {
  28         VI_UNLOCK(vp);
  29         return 0;
  30     }
  31
  32     if ((vp->v_iflag & VI_DOOMED) != 0) {
  33         VI_UNLOCK(vp);
  34         return 1;
  35     }
  36
  37     /* must hold the vnode before calling vgone()
  38      * This code largely copied from vfs_subr.c:vlrureclaim() */
  39     vholdl(vp);
  40
  41     ReleaseWriteLock(&afs_xvcache);
  42     AFS_GUNLOCK();
  43
  44     *slept = 1;
  45     /* use the interlock while locking, so no one else can DOOM this */
  46     vn_lock(vp, LK_INTERLOCK|LK_EXCLUSIVE|LK_RETRY);
  47     vgone(vp);
  48     VOP_UNLOCK(vp, 0);
  49     vdrop(vp);
  50
  51     AFS_GLOCK();
  52     ObtainWriteLock(&afs_xvcache, 340);
  53     return 1;
  54 }
  55
  56 struct vcache *
  57 osi_NewVnode(void) {
  58     struct vcache *tvc;
  59
  60     tvc = afs_osi_Alloc(sizeof(struct vcache));
  61     tvc->v = NULL; /* important to clean this, or use memset 0 */
  62
  63     return tvc;
  64 }
  65
  66 void
  67 osi_PrePopulateVCache(struct vcache *avc) {
  68     memset(avc, 0, sizeof(struct vcache));
  69 }
  70
  71 void
  72 osi_AttachVnode(struct vcache *avc, int seq) {
  73     struct vnode *vp;
  74
  75     ReleaseWriteLock(&afs_xvcache);
  76     AFS_GUNLOCK();
  77     if (getnewvnode(MOUNT_AFS, afs_globalVFS, &afs_vnodeops, &vp))
  78         panic("afs getnewvnode");       /* can't happen */
  79     /* XXX verified on 80--TODO check on 7x */
  80     if (!vp->v_mount) {
  81         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); /* !glocked */
  82         insmntque(vp, afs_globalVFS);
  83         VOP_UNLOCK(vp, 0);
  84     }
  85     AFS_GLOCK();
  86     ObtainWriteLock(&afs_xvcache,339);
  87     if (avc->v != NULL) {
  88         /* I'd like to know if this ever happens...
  89          * We don't drop global for the rest of this function,
  90          * so if we do lose the race, the other thread should
  91          * have found the same vnode and finished initializing
  92          * the vcache entry.  Is it conceivable that this vcache
  93          * entry could be recycled during this interval?  If so,
  94          * then there probably needs to be some sort of additional
  95          * mutual exclusion (an Embryonic flag would suffice).
  96          * -GAW */
  97         afs_warn("afs_NewVCache: lost the race\n");
  98         return;
  99     }
 100     avc->v = vp;
 101     avc->v->v_data = avc;
 102     lockinit(&avc->rwlock, PINOD, "vcache", 0, 0);
 103 }
 104
 105 void
 106 osi_PostPopulateVCache(struct vcache *avc) {
 107     avc->v->v_mount = afs_globalVFS;
 108     vSetType(avc, VREG);
 109 }
 110