src/afs/LINUX/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 #include "osi_compat.h"
  17
  18 static void
  19 TryEvictDirDentries(struct inode *inode)
  20 {
  21     struct dentry *dentry;
  22 #if defined(D_ALIAS_IS_HLIST) && !defined(HLIST_ITERATOR_NO_NODE)
  23     struct hlist_node *p;
  24 #endif
  25
  26     afs_d_alias_lock(inode);
  27
  28 restart:
  29 #if defined(D_ALIAS_IS_HLIST)
  30 # if defined(HLIST_ITERATOR_NO_NODE)
  31     hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) {
  32 # else
  33     hlist_for_each_entry(dentry, p, &inode->i_dentry, d_alias) {
  34 # endif
  35 #else
  36     list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
  37 #endif
  38         spin_lock(&dentry->d_lock);
  39         if (d_unhashed(dentry)) {
  40             spin_unlock(&dentry->d_lock);
  41             continue;
  42         }
  43         spin_unlock(&dentry->d_lock);
  44         afs_linux_dget(dentry);
  45
  46         afs_d_alias_unlock(inode);
  47
  48         /*
  49          * Once we have dropped the d_alias lock (above), it is no longer safe
  50          * to 'continue' our iteration over d_alias because the list may change
  51          * out from under us.  Therefore, we must either leave the loop, or
  52          * restart from the beginning.  To avoid looping forever, we must only
  53          * restart if we know we've d_drop'd an alias.  In all other cases we
  54          * must leave the loop.
  55          */
  56
  57         /*
  58          * For a long time we used d_invalidate() for this purpose, but
  59          * using shrink_dcache_parent() and checking the refcount ourselves is
  60          * better, for two reasons: it avoids causing ENOENT issues for the
  61          * CWD in linux versions since 3.11, and it avoids dropping Linux
  62          * submounts.
  63          *
  64          * For non-fakestat, AFS mountpoints look like directories and end up here.
  65          */
  66
  67         shrink_dcache_parent(dentry);
  68         spin_lock(&dentry->d_lock);
  69         if (afs_dentry_count(dentry) > 1)       /* still has references */ {
  70             if (dentry->d_inode != NULL) /* is not a negative dentry */ {
  71                 spin_unlock(&dentry->d_lock);
  72                 dput(dentry);
  73                 goto inuse;
  74             }
  75         }
  76         /*
  77          * This is either a negative dentry, or a dentry with no references.
  78          * Either way, it is okay to unhash it now.
  79          * Do so under the d_lock (that is, via __d_drop() instead of d_drop())
  80          * to avoid a race with another process picking up a reference.
  81          */
  82         __d_drop(dentry);
  83         spin_unlock(&dentry->d_lock);
  84
  85         dput(dentry);
  86         afs_d_alias_lock(inode);
  87         goto restart;
  88     }
  89     afs_d_alias_unlock(inode);
  90
  91 inuse:
  92     return;
  93 }
  94
  95
  96 int
  97 osi_TryEvictVCache(struct vcache *avc, int *slept, int defersleep)
  98 {
  99     int code;
 100
 101     /* First, see if we can evict the inode from the dcache */
 102     if (defersleep && avc != afs_globalVp && VREFCOUNT(avc) > 1
 103         && avc->opens == 0) {
 104         struct inode *ip = AFSTOV(avc);
 105
 106         *slept = 1;
 107         AFS_FAST_HOLD(avc);
 108         ReleaseWriteLock(&afs_xvcache);
 109         AFS_GUNLOCK();
 110
 111         if (S_ISDIR(ip->i_mode))
 112             TryEvictDirDentries(ip);
 113         else
 114             d_prune_aliases(ip);
 115
 116         AFS_GLOCK();
 117         ObtainWriteLock(&afs_xvcache, 733);
 118         AFS_FAST_RELE(avc);
 119     }
 120
 121     /* See if we can evict it from the VLRUQ */
 122     if (VREFCOUNT_GT(avc, 0) && !VREFCOUNT_GT(avc, 1) && avc->opens == 0
 123         && (avc->f.states & CUnlinkedDel) == 0) {
 124         int didsleep = *slept;
 125
 126         code = afs_FlushVCache(avc, slept);
 127         /* flushvcache wipes slept; restore slept if we did before */
 128         if (didsleep)
 129             *slept = didsleep;
 130
 131         if (code == 0)
 132             return 1;
 133     }
 134
 135     return 0;
 136 }
 137
 138 struct vcache *
 139 osi_NewVnode(void)
 140 {
 141     struct inode *ip;
 142     struct vcache *tvc;
 143
 144     AFS_GUNLOCK();
 145     ip = new_inode(afs_globalVFS);
 146     if (!ip)
 147         osi_Panic("afs_NewVCache: no more inodes");
 148     AFS_GLOCK();
 149 #if defined(STRUCT_SUPER_OPERATIONS_HAS_ALLOC_INODE)
 150     tvc = VTOAFS(ip);
 151 #else
 152     tvc = afs_osi_Alloc(sizeof(struct vcache));
 153     ip->u.generic_ip = tvc;
 154     tvc->v = ip;
 155 #endif
 156
 157     INIT_LIST_HEAD(&tvc->pagewriters);
 158     spin_lock_init(&tvc->pagewriter_lock);
 159
 160     return tvc;
 161 }
 162
 163 void
 164 osi_PrePopulateVCache(struct vcache *avc)
 165 {
 166     avc->uncred = 0;
 167     memset(&(avc->f), 0, sizeof(struct fvcache));
 168     avc->cred = NULL;
 169 }
 170
 171 void
 172 osi_AttachVnode(struct vcache *avc, int seq)
 173 {
 174     /* Nada */
 175 }
 176
 177 void
 178 osi_PostPopulateVCache(struct vcache *avc)
 179 {
 180     vSetType(avc, VREG);
 181 }
 182
 183 /**
 184  * osi_ResetRootVCache - Reset the root vcache
 185  * Reset the dentry associated with the afs root.
 186  * Called from afs_CheckRootVolume when we notice that
 187  * the root volume ID has changed.
 188  *
 189  * @volid: volume ID for the afs root
 190  */
 191 void
 192 osi_ResetRootVCache(afs_uint32 volid)
 193 {
 194     struct vrequest *treq = NULL;
 195     struct vattr vattr;
 196     cred_t *credp;
 197     struct dentry *dp;
 198     struct vcache *vcp;
 199     struct inode *root = AFSTOV(afs_globalVp);
 200
 201     afs_rootFid.Fid.Volume = volid;
 202     afs_rootFid.Fid.Vnode = 1;
 203     afs_rootFid.Fid.Unique = 1;
 204
 205     credp = crref();
 206     if (afs_CreateReq(&treq, credp))
 207         goto out;
 208     vcp = afs_GetVCache(&afs_rootFid, treq, NULL, NULL);
 209     if (!vcp)
 210         goto out;
 211     afs_getattr(vcp, &vattr, credp);
 212     afs_fill_inode(AFSTOV(vcp), &vattr);
 213
 214     dp = d_find_alias(root);
 215
 216     afs_d_alias_lock(AFSTOV(vcp));
 217
 218     spin_lock(&dp->d_lock);
 219 #if defined(D_ALIAS_IS_HLIST)
 220     hlist_del_init(&dp->d_alias);
 221     hlist_add_head(&dp->d_alias, &(AFSTOV(vcp)->i_dentry));
 222 #else
 223     list_del_init(&dp->d_alias);
 224     list_add(&dp->d_alias, &(AFSTOV(vcp)->i_dentry));
 225 #endif
 226     dp->d_inode = AFSTOV(vcp);
 227     spin_unlock(&dp->d_lock);
 228
 229     afs_d_alias_unlock(AFSTOV(vcp));
 230
 231     dput(dp);
 232
 233     AFS_RELE(root);
 234     afs_globalVp = vcp;
 235 out:
 236     crfree(credp);
 237     afs_DestroyReq(treq);
 238 }