src/vol/vnode_inline.h

   1 /*
   2  * Copyright 2007-2008, Sine Nomine Associates 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 #ifndef _AFS_VOL_VNODE_INLINE_H
  11 #define _AFS_VOL_VNODE_INLINE_H 1
  12
  13 #include "vnode.h"
  14
  15 /***************************************************/
  16 /* demand attach vnode state machine routines      */
  17 /***************************************************/
  18
  19 /**
  20  * get a reference to a vnode object.
  21  *
  22  * @param[in] vnp  vnode object pointer
  23  *
  24  * @internal vnode package internal use only
  25  *
  26  * @pre VOL_LOCK must be held
  27  *
  28  * @post vnode refcount incremented
  29  *
  30  * @see VnCancelReservation_r
  31  */
  32 static_inline void
  33 VnCreateReservation_r(Vnode * vnp)
  34 {
  35     Vn_refcount(vnp)++;
  36     if (Vn_refcount(vnp) == 1) {
  37         DeleteFromVnLRU(Vn_class(vnp), vnp);
  38     }
  39 }
  40
  41 extern int TrustVnodeCacheEntry;
  42
  43 /**
  44  * release a reference to a vnode object.
  45  *
  46  * @param[in] vnp  vnode object pointer
  47  *
  48  * @pre VOL_LOCK held
  49  *
  50  * @post refcount decremented; possibly re-added to vn lru
  51  *
  52  * @internal vnode package internal use only
  53  *
  54  * @see VnCreateReservation_r
  55  */
  56 static_inline void
  57 VnCancelReservation_r(Vnode * vnp)
  58 {
  59     if (--Vn_refcount(vnp) == 0) {
  60         AddToVnLRU(Vn_class(vnp), vnp);
  61
  62         /* If caching is turned off,
  63          * disassociate vnode cache entry from volume object */
  64         if (!TrustVnodeCacheEntry) {
  65             DeleteFromVVnList(vnp);
  66         }
  67     }
  68 }
  69
  70 #ifdef AFS_PTHREAD_ENV
  71 #define VN_SET_WRITER_THREAD_ID(v)  (((v)->writer) = pthread_self())
  72 #else
  73 #define VN_SET_WRITER_THREAD_ID(v)  (LWP_CurrentProcess(&((v)->writer)))
  74 #endif
  75
  76 #define VOL_LOCK_NOT_HELD 0
  77 #define VOL_LOCK_HELD 1
  78 #define MIGHT_DEADLOCK 0
  79 #define WILL_NOT_DEADLOCK 1
  80
  81 /**
  82  * acquire a lock on a vnode object.
  83  *
  84  * @param[in] vnp   vnode object pointer
  85  * @param[in] type  lock type
  86  * @param[in] held  whether or not vol glock is held
  87  * @param[in] safe  whether it it is safe to acquire without dropping vol glock
  88  *
  89  * @note caller must guarantee deadlock will not occur
  90  *
  91  * @post lock acquired.
  92  *       for write case, thread owner field set.
  93  *
  94  * @note for DAFS, this is a no-op
  95  *
  96  * @internal vnode package internal use only
  97  */
  98 static_inline void
  99 VnLock(Vnode * vnp, int type, int held, int safe)
 100 {
 101 #ifdef AFS_DEMAND_ATTACH_FS
 102     if (type == WRITE_LOCK) {
 103         VN_SET_WRITER_THREAD_ID(vnp);
 104     }
 105 #else /* !AFS_DEMAND_ATTACH_FS */
 106     if (held && !safe) {
 107         VOL_UNLOCK;
 108     }
 109     if (type == READ_LOCK) {
 110         ObtainReadLock(&vnp->lock);
 111     } else {
 112         ObtainWriteLock(&vnp->lock);
 113         VN_SET_WRITER_THREAD_ID(vnp);
 114     }
 115     if (held && !safe) {
 116         VOL_LOCK;
 117     }
 118 #endif /* !AFS_DEMAND_ATTACH_FS */
 119 }
 120
 121 /**
 122  * release a lock on a vnode object.
 123  *
 124  * @param[in] vnp   vnode object pointer
 125  * @param[in] type  lock type
 126  *
 127  * @note for DAFS, this is a no-op
 128  *
 129  * @internal vnode package internal use only
 130  */
 131 static_inline void
 132 VnUnlock(Vnode * vnp, int type)
 133 {
 134     if (type == READ_LOCK) {
 135 #ifndef AFS_DEMAND_ATTACH_FS
 136         ReleaseReadLock(&vnp->lock);
 137 #endif
 138     } else {
 139         vnp->writer = 0;
 140 #ifndef AFS_DEMAND_ATTACH_FS
 141         ReleaseWriteLock(&vnp->lock);
 142 #endif
 143     }
 144 }
 145
 146
 147 #ifdef AFS_DEMAND_ATTACH_FS
 148 /**
 149  * change state, and notify other threads,
 150  * return previous state to caller.
 151  *
 152  * @param[in] vnp        pointer to vnode object
 153  * @param[in] new_state  new vnode state value
 154  *
 155  * @pre VOL_LOCK held
 156  *
 157  * @post vnode state changed
 158  *
 159  * @return previous vnode state
 160  *
 161  * @note DEMAND_ATTACH_FS only
 162  *
 163  * @internal vnode package internal use only
 164  */
 165 static_inline VnState
 166 VnChangeState_r(Vnode * vnp, VnState new_state)
 167 {
 168     VnState old_state = Vn_state(vnp);
 169
 170     Vn_state(vnp) = new_state;
 171     opr_cv_broadcast(&Vn_stateCV(vnp));
 172     return old_state;
 173 }
 174
 175 /**
 176  * tells caller whether or not the current state requires
 177  * exclusive access without holding glock.
 178  *
 179  * @param[in] state  vnode state enumeration
 180  *
 181  * @return whether vnode state is a mutually exclusive state
 182  *   @retval 0  no, state is re-entrant
 183  *   @retval 1  yes, state is mutually exclusive
 184  *
 185  * @note DEMAND_ATTACH_FS only
 186  */
 187 static_inline int
 188 VnIsExclusiveState(VnState state)
 189 {
 190     switch (state) {
 191     case VN_STATE_RELEASING:
 192     case VN_STATE_CLOSING:
 193     case VN_STATE_ALLOC:
 194     case VN_STATE_LOAD:
 195     case VN_STATE_EXCLUSIVE:
 196     case VN_STATE_STORE:
 197         return 1;
 198     default:
 199         return 0;
 200     }
 201 }
 202
 203 /**
 204  * tell caller whether vnode state is an error condition.
 205  *
 206  * @param[in] state  vnode state enumeration
 207  *
 208  * @return whether vnode state is in error state
 209  *   @retval 0  state is not an error state
 210  *   @retval 1  state is an error state
 211  *
 212  * @note DEMAND_ATTACH_FS only
 213  */
 214 static_inline int
 215 VnIsErrorState(VnState state)
 216 {
 217     switch (state) {
 218     case VN_STATE_ERROR:
 219         return 1;
 220     default:
 221         return 0;
 222     }
 223 }
 224
 225 /**
 226  * tell caller whether vnode state is valid.
 227  *
 228  * @param[in] state  vnode state enumeration
 229  *
 230  * @return whether vnode state is a mutually exclusive state
 231  *   @retval 0  no, state is not valid
 232  *   @retval 1  yes, state is a valid enumeration member
 233  *
 234  * @note DEMAND_ATTACH_FS only
 235  */
 236 static_inline int
 237 VnIsValidState(VnState state)
 238 {
 239     if (((int) state >= 0) &&
 240         (state < VN_STATE_COUNT)) {
 241         return 1;
 242     }
 243     return 0;
 244 }
 245
 246 /**
 247  * wait for the vnode to change states.
 248  *
 249  * @param[in] vnp  vnode object pointer
 250  *
 251  * @pre VOL_LOCK held; ref held on vnode
 252  *
 253  * @post VOL_LOCK held; vnode state has changed from previous value
 254  *
 255  * @note DEMAND_ATTACH_FS only
 256  */
 257 static_inline void
 258 VnWaitStateChange_r(Vnode * vnp)
 259 {
 260     VnState state_save = Vn_state(vnp);
 261
 262     opr_Assert(Vn_refcount(vnp));
 263     do {
 264         VOL_CV_WAIT(&Vn_stateCV(vnp));
 265     } while (Vn_state(vnp) == state_save);
 266     opr_Assert(!(Vn_stateFlags(vnp) & VN_ON_LRU));
 267 }
 268
 269 /**
 270  * wait for blocking ops to end.
 271  *
 272  * @pre VOL_LOCK held; ref held on vnode
 273  *
 274  * @post VOL_LOCK held; vnode not in exclusive state
 275  *
 276  * @param[in] vnp  vnode object pointer
 277  *
 278  * @note DEMAND_ATTACH_FS only
 279  */
 280 static_inline void
 281 VnWaitExclusiveState_r(Vnode * vnp)
 282 {
 283     opr_Assert(Vn_refcount(vnp));
 284     while (VnIsExclusiveState(Vn_state(vnp))) {
 285         VOL_CV_WAIT(&Vn_stateCV(vnp));
 286     }
 287     opr_Assert(!(Vn_stateFlags(vnp) & VN_ON_LRU));
 288 }
 289
 290 /**
 291  * wait until vnode is in non-exclusive state, and there are no active readers.
 292  *
 293  * @param[in] vnp  vnode object pointer
 294  *
 295  * @pre VOL_LOCK held; ref held on vnode
 296  *
 297  * @post VOL_LOCK held; vnode is in non-exclusive state and has no active readers
 298  *
 299  * @note DEMAND_ATTACH_FS only
 300  */
 301 static_inline void
 302 VnWaitQuiescent_r(Vnode * vnp)
 303 {
 304     opr_Assert(Vn_refcount(vnp));
 305     while (VnIsExclusiveState(Vn_state(vnp)) ||
 306            Vn_readers(vnp)) {
 307         VOL_CV_WAIT(&Vn_stateCV(vnp));
 308     }
 309     opr_Assert(!(Vn_stateFlags(vnp) & VN_ON_LRU));
 310 }
 311
 312 /**
 313  * register a new reader on a vnode.
 314  *
 315  * @param[in] vnp  vnode object pointer
 316  *
 317  * @pre VOL_LOCK held.
 318  *      ref held on vnode.
 319  *      vnode in VN_STATE_READ or VN_STATE_ONLINE
 320  *
 321  * @post refcount incremented.
 322  *       state set to VN_STATE_READ.
 323  *
 324  * @note DEMAND_ATTACH_FS only
 325  *
 326  * @internal vnode package internal use only
 327  */
 328 static_inline void
 329 VnBeginRead_r(Vnode * vnp)
 330 {
 331     if (!Vn_readers(vnp)) {
 332         opr_Assert(Vn_state(vnp) == VN_STATE_ONLINE);
 333         VnChangeState_r(vnp, VN_STATE_READ);
 334     }
 335     Vn_readers(vnp)++;
 336     opr_Assert(Vn_state(vnp) == VN_STATE_READ);
 337 }
 338
 339 /**
 340  * deregister a reader on a vnode.
 341  *
 342  * @param[in] vnp  vnode object pointer
 343  *
 344  * @pre VOL_LOCK held.
 345  *      ref held on vnode.
 346  *      read ref held on vnode.
 347  *      vnode in VN_STATE_READ.
 348  *
 349  * @post refcount decremented.
 350  *       when count reaches zero, state set to VN_STATE_ONLINE.
 351  *
 352  * @note DEMAND_ATTACH_FS only
 353  *
 354  * @internal vnode package internal use only
 355  */
 356 static_inline void
 357 VnEndRead_r(Vnode * vnp)
 358 {
 359     opr_Assert(Vn_readers(vnp) > 0);
 360     Vn_readers(vnp)--;
 361     if (!Vn_readers(vnp)) {
 362         opr_cv_broadcast(&Vn_stateCV(vnp));
 363         VnChangeState_r(vnp, VN_STATE_ONLINE);
 364     }
 365 }
 366
 367 #endif /* AFS_DEMAND_ATTACH_FS */
 368
 369 #endif /* _AFS_VOL_VNODE_INLINE_H */