fs/ocfs2/dlm/userdlm.c

   1 /* -*- mode: c; c-basic-offset: 8; -*-
   2  * vim: noexpandtab sw=8 ts=8 sts=0:
   3  *
   4  * userdlm.c
   5  *
   6  * Code which implements the kernel side of a minimal userspace
   7  * interface to our DLM.
   8  *
   9  * Many of the functions here are pared down versions of dlmglue.c
  10  * functions.
  11  *
  12  * Copyright (C) 2003, 2004 Oracle.  All rights reserved.
  13  *
  14  * This program is free software; you can redistribute it and/or
  15  * modify it under the terms of the GNU General Public
  16  * License as published by the Free Software Foundation; either
  17  * version 2 of the License, or (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  22  * General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public
  25  * License along with this program; if not, write to the
  26  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  27  * Boston, MA 021110-1307, USA.
  28  */
  29
  30 #include <linux/signal.h>
  31
  32 #include <linux/module.h>
  33 #include <linux/fs.h>
  34 #include <linux/types.h>
  35 #include <linux/crc32.h>
  36
  37
  38 #include "cluster/nodemanager.h"
  39 #include "cluster/heartbeat.h"
  40 #include "cluster/tcp.h"
  41
  42 #include "dlmapi.h"
  43
  44 #include "userdlm.h"
  45
  46 #define MLOG_MASK_PREFIX ML_DLMFS
  47 #include "cluster/masklog.h"
  48
  49 static inline int user_check_wait_flag(struct user_lock_res *lockres,
  50                                        int flag)
  51 {
  52         int ret;
  53
  54         spin_lock(&lockres->l_lock);
  55         ret = lockres->l_flags & flag;
  56         spin_unlock(&lockres->l_lock);
  57
  58         return ret;
  59 }
  60
  61 static inline void user_wait_on_busy_lock(struct user_lock_res *lockres)
  62
  63 {
  64         wait_event(lockres->l_event,
  65                    !user_check_wait_flag(lockres, USER_LOCK_BUSY));
  66 }
  67
  68 static inline void user_wait_on_blocked_lock(struct user_lock_res *lockres)
  69
  70 {
  71         wait_event(lockres->l_event,
  72                    !user_check_wait_flag(lockres, USER_LOCK_BLOCKED));
  73 }
  74
  75 /* I heart container_of... */
  76 static inline struct dlm_ctxt *
  77 dlm_ctxt_from_user_lockres(struct user_lock_res *lockres)
  78 {
  79         struct dlmfs_inode_private *ip;
  80
  81         ip = container_of(lockres,
  82                           struct dlmfs_inode_private,
  83                           ip_lockres);
  84         return ip->ip_dlm;
  85 }
  86
  87 static struct inode *
  88 user_dlm_inode_from_user_lockres(struct user_lock_res *lockres)
  89 {
  90         struct dlmfs_inode_private *ip;
  91
  92         ip = container_of(lockres,
  93                           struct dlmfs_inode_private,
  94                           ip_lockres);
  95         return &ip->ip_vfs_inode;
  96 }
  97
  98 static inline void user_recover_from_dlm_error(struct user_lock_res *lockres)
  99 {
 100         spin_lock(&lockres->l_lock);
 101         lockres->l_flags &= ~USER_LOCK_BUSY;
 102         spin_unlock(&lockres->l_lock);
 103 }
 104
 105 #define user_log_dlm_error(_func, _stat, _lockres) do {         \
 106         mlog(ML_ERROR, "Dlm error \"%s\" while calling %s on "  \
 107                 "resource %s: %s\n", dlm_errname(_stat), _func, \
 108                 _lockres->l_name, dlm_errmsg(_stat));           \
 109 } while (0)
 110
 111 /* WARNING: This function lives in a world where the only three lock
 112  * levels are EX, PR, and NL. It *will* have to be adjusted when more
 113  * lock types are added. */
 114 static inline int user_highest_compat_lock_level(int level)
 115 {
 116         int new_level = LKM_EXMODE;
 117
 118         if (level == LKM_EXMODE)
 119                 new_level = LKM_NLMODE;
 120         else if (level == LKM_PRMODE)
 121                 new_level = LKM_PRMODE;
 122         return new_level;
 123 }
 124
 125 static void user_ast(void *opaque)
 126 {
 127         struct user_lock_res *lockres = opaque;
 128         struct dlm_lockstatus *lksb;
 129
 130         mlog(0, "AST fired for lockres %s\n", lockres->l_name);
 131
 132         spin_lock(&lockres->l_lock);
 133
 134         lksb = &(lockres->l_lksb);
 135         if (lksb->status != DLM_NORMAL) {
 136                 mlog(ML_ERROR, "lksb status value of %u on lockres %s\n",
 137                      lksb->status, lockres->l_name);
 138                 spin_unlock(&lockres->l_lock);
 139                 return;
 140         }
 141
 142         /* we're downconverting. */
 143         if (lockres->l_requested < lockres->l_level) {
 144                 if (lockres->l_requested <=
 145                     user_highest_compat_lock_level(lockres->l_blocking)) {
 146                         lockres->l_blocking = LKM_NLMODE;
 147                         lockres->l_flags &= ~USER_LOCK_BLOCKED;
 148                 }
 149         }
 150
 151         lockres->l_level = lockres->l_requested;
 152         lockres->l_requested = LKM_IVMODE;
 153         lockres->l_flags |= USER_LOCK_ATTACHED;
 154         lockres->l_flags &= ~USER_LOCK_BUSY;
 155
 156         spin_unlock(&lockres->l_lock);
 157
 158         wake_up(&lockres->l_event);
 159 }
 160
 161 static inline void user_dlm_grab_inode_ref(struct user_lock_res *lockres)
 162 {
 163         struct inode *inode;
 164         inode = user_dlm_inode_from_user_lockres(lockres);
 165         if (!igrab(inode))
 166                 BUG();
 167 }
 168
 169 static void user_dlm_unblock_lock(void *opaque);
 170
 171 static void __user_dlm_queue_lockres(struct user_lock_res *lockres)
 172 {
 173         if (!(lockres->l_flags & USER_LOCK_QUEUED)) {
 174                 user_dlm_grab_inode_ref(lockres);
 175
 176                 INIT_WORK(&lockres->l_work, user_dlm_unblock_lock,
 177                           lockres);
 178
 179                 queue_work(user_dlm_worker, &lockres->l_work);
 180                 lockres->l_flags |= USER_LOCK_QUEUED;
 181         }
 182 }
 183
 184 static void __user_dlm_cond_queue_lockres(struct user_lock_res *lockres)
 185 {
 186         int queue = 0;
 187
 188         if (!(lockres->l_flags & USER_LOCK_BLOCKED))
 189                 return;
 190
 191         switch (lockres->l_blocking) {
 192         case LKM_EXMODE:
 193                 if (!lockres->l_ex_holders && !lockres->l_ro_holders)
 194                         queue = 1;
 195                 break;
 196         case LKM_PRMODE:
 197                 if (!lockres->l_ex_holders)
 198                         queue = 1;
 199                 break;
 200         default:
 201                 BUG();
 202         }
 203
 204         if (queue)
 205                 __user_dlm_queue_lockres(lockres);
 206 }
 207
 208 static void user_bast(void *opaque, int level)
 209 {
 210         struct user_lock_res *lockres = opaque;
 211
 212         mlog(0, "Blocking AST fired for lockres %s. Blocking level %d\n",
 213                 lockres->l_name, level);
 214
 215         spin_lock(&lockres->l_lock);
 216         lockres->l_flags |= USER_LOCK_BLOCKED;
 217         if (level > lockres->l_blocking)
 218                 lockres->l_blocking = level;
 219
 220         __user_dlm_queue_lockres(lockres);
 221         spin_unlock(&lockres->l_lock);
 222
 223         wake_up(&lockres->l_event);
 224 }
 225
 226 static void user_unlock_ast(void *opaque, enum dlm_status status)
 227 {
 228         struct user_lock_res *lockres = opaque;
 229
 230         mlog(0, "UNLOCK AST called on lock %s\n", lockres->l_name);
 231
 232         if (status != DLM_NORMAL)
 233                 mlog(ML_ERROR, "Dlm returns status %d\n", status);
 234
 235         spin_lock(&lockres->l_lock);
 236         if (lockres->l_flags & USER_LOCK_IN_TEARDOWN)
 237                 lockres->l_level = LKM_IVMODE;
 238         else {
 239                 lockres->l_requested = LKM_IVMODE; /* cancel an
 240                                                     * upconvert
 241                                                     * request. */
 242                 lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
 243                 /* we want the unblock thread to look at it again
 244                  * now. */
 245                 __user_dlm_queue_lockres(lockres);
 246         }
 247
 248         lockres->l_flags &= ~USER_LOCK_BUSY;
 249         spin_unlock(&lockres->l_lock);
 250
 251         wake_up(&lockres->l_event);
 252 }
 253
 254 static inline void user_dlm_drop_inode_ref(struct user_lock_res *lockres)
 255 {
 256         struct inode *inode;
 257         inode = user_dlm_inode_from_user_lockres(lockres);
 258         iput(inode);
 259 }
 260
 261 static void user_dlm_unblock_lock(void *opaque)
 262 {
 263         int new_level, status;
 264         struct user_lock_res *lockres = (struct user_lock_res *) opaque;
 265         struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
 266
 267         mlog(0, "processing lockres %s\n", lockres->l_name);
 268
 269         spin_lock(&lockres->l_lock);
 270
 271         BUG_ON(!(lockres->l_flags & USER_LOCK_BLOCKED));
 272         BUG_ON(!(lockres->l_flags & USER_LOCK_QUEUED));
 273
 274         /* notice that we don't clear USER_LOCK_BLOCKED here. That's
 275          * for user_ast to do. */
 276         lockres->l_flags &= ~USER_LOCK_QUEUED;
 277
 278         if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
 279                 mlog(0, "lock is in teardown so we do nothing\n");
 280                 spin_unlock(&lockres->l_lock);
 281                 goto drop_ref;
 282         }
 283
 284         if (lockres->l_flags & USER_LOCK_BUSY) {
 285                 mlog(0, "BUSY flag detected...\n");
 286                 if (lockres->l_flags & USER_LOCK_IN_CANCEL) {
 287                         spin_unlock(&lockres->l_lock);
 288                         goto drop_ref;
 289                 }
 290
 291                 lockres->l_flags |= USER_LOCK_IN_CANCEL;
 292                 spin_unlock(&lockres->l_lock);
 293
 294                 status = dlmunlock(dlm,
 295                                    &lockres->l_lksb,
 296                                    LKM_CANCEL,
 297                                    user_unlock_ast,
 298                                    lockres);
 299                 if (status == DLM_CANCELGRANT) {
 300                         /* If we got this, then the ast was fired
 301                          * before we could cancel. We cleanup our
 302                          * state, and restart the function. */
 303                         spin_lock(&lockres->l_lock);
 304                         lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
 305                         spin_unlock(&lockres->l_lock);
 306                 } else if (status != DLM_NORMAL)
 307                         user_log_dlm_error("dlmunlock", status, lockres);
 308                 goto drop_ref;
 309         }
 310
 311         /* If there are still incompat holders, we can exit safely
 312          * without worrying about re-queueing this lock as that will
 313          * happen on the last call to user_cluster_unlock. */
 314         if ((lockres->l_blocking == LKM_EXMODE)
 315             && (lockres->l_ex_holders || lockres->l_ro_holders)) {
 316                 spin_unlock(&lockres->l_lock);
 317                 mlog(0, "can't downconvert for ex: ro = %u, ex = %u\n",
 318                         lockres->l_ro_holders, lockres->l_ex_holders);
 319                 goto drop_ref;
 320         }
 321
 322         if ((lockres->l_blocking == LKM_PRMODE)
 323             && lockres->l_ex_holders) {
 324                 spin_unlock(&lockres->l_lock);
 325                 mlog(0, "can't downconvert for pr: ex = %u\n",
 326                         lockres->l_ex_holders);
 327                 goto drop_ref;
 328         }
 329
 330         /* yay, we can downconvert now. */
 331         new_level = user_highest_compat_lock_level(lockres->l_blocking);
 332         lockres->l_requested = new_level;
 333         lockres->l_flags |= USER_LOCK_BUSY;
 334         mlog(0, "Downconvert lock from %d to %d\n",
 335                 lockres->l_level, new_level);
 336         spin_unlock(&lockres->l_lock);
 337
 338         /* need lock downconvert request now... */
 339         status = dlmlock(dlm,
 340                          new_level,
 341                          &lockres->l_lksb,
 342                          LKM_CONVERT|LKM_VALBLK,
 343                          lockres->l_name,
 344                          user_ast,
 345                          lockres,
 346                          user_bast);
 347         if (status != DLM_NORMAL) {
 348                 user_log_dlm_error("dlmlock", status, lockres);
 349                 user_recover_from_dlm_error(lockres);
 350         }
 351
 352 drop_ref:
 353         user_dlm_drop_inode_ref(lockres);
 354 }
 355
 356 static inline void user_dlm_inc_holders(struct user_lock_res *lockres,
 357                                         int level)
 358 {
 359         switch(level) {
 360         case LKM_EXMODE:
 361                 lockres->l_ex_holders++;
 362                 break;
 363         case LKM_PRMODE:
 364                 lockres->l_ro_holders++;
 365                 break;
 366         default:
 367                 BUG();
 368         }
 369 }
 370
 371 /* predict what lock level we'll be dropping down to on behalf
 372  * of another node, and return true if the currently wanted
 373  * level will be compatible with it. */
 374 static inline int
 375 user_may_continue_on_blocked_lock(struct user_lock_res *lockres,
 376                                   int wanted)
 377 {
 378         BUG_ON(!(lockres->l_flags & USER_LOCK_BLOCKED));
 379
 380         return wanted <= user_highest_compat_lock_level(lockres->l_blocking);
 381 }
 382
 383 int user_dlm_cluster_lock(struct user_lock_res *lockres,
 384                           int level,
 385                           int lkm_flags)
 386 {
 387         int status, local_flags;
 388         struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
 389
 390         if (level != LKM_EXMODE &&
 391             level != LKM_PRMODE) {
 392                 mlog(ML_ERROR, "lockres %s: invalid request!\n",
 393                      lockres->l_name);
 394                 status = -EINVAL;
 395                 goto bail;
 396         }
 397
 398         mlog(0, "lockres %s: asking for %s lock, passed flags = 0x%x\n",
 399                 lockres->l_name,
 400                 (level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE",
 401                 lkm_flags);
 402
 403 again:
 404         if (signal_pending(current)) {
 405                 status = -ERESTARTSYS;
 406                 goto bail;
 407         }
 408
 409         spin_lock(&lockres->l_lock);
 410
 411         /* We only compare against the currently granted level
 412          * here. If the lock is blocked waiting on a downconvert,
 413          * we'll get caught below. */
 414         if ((lockres->l_flags & USER_LOCK_BUSY) &&
 415             (level > lockres->l_level)) {
 416                 /* is someone sitting in dlm_lock? If so, wait on
 417                  * them. */
 418                 spin_unlock(&lockres->l_lock);
 419
 420                 user_wait_on_busy_lock(lockres);
 421                 goto again;
 422         }
 423
 424         if ((lockres->l_flags & USER_LOCK_BLOCKED) &&
 425             (!user_may_continue_on_blocked_lock(lockres, level))) {
 426                 /* is the lock is currently blocked on behalf of
 427                  * another node */
 428                 spin_unlock(&lockres->l_lock);
 429
 430                 user_wait_on_blocked_lock(lockres);
 431                 goto again;
 432         }
 433
 434         if (level > lockres->l_level) {
 435                 local_flags = lkm_flags | LKM_VALBLK;
 436                 if (lockres->l_level != LKM_IVMODE)
 437                         local_flags |= LKM_CONVERT;
 438
 439                 lockres->l_requested = level;
 440                 lockres->l_flags |= USER_LOCK_BUSY;
 441                 spin_unlock(&lockres->l_lock);
 442
 443                 BUG_ON(level == LKM_IVMODE);
 444                 BUG_ON(level == LKM_NLMODE);
 445
 446                 mlog(0, "lock %s, get lock from %d to level = %d\n",
 447                         lockres->l_name, lockres->l_level, level);
 448
 449                 /* call dlm_lock to upgrade lock now */
 450                 status = dlmlock(dlm,
 451                                  level,
 452                                  &lockres->l_lksb,
 453                                  local_flags,
 454                                  lockres->l_name,
 455                                  user_ast,
 456                                  lockres,
 457                                  user_bast);
 458                 if (status != DLM_NORMAL) {
 459                         if ((lkm_flags & LKM_NOQUEUE) &&
 460                             (status == DLM_NOTQUEUED))
 461                                 status = -EAGAIN;
 462                         else {
 463                                 user_log_dlm_error("dlmlock", status, lockres);
 464                                 status = -EINVAL;
 465                         }
 466                         user_recover_from_dlm_error(lockres);
 467                         goto bail;
 468                 }
 469
 470                 mlog(0, "lock %s, successfull return from dlmlock\n",
 471                         lockres->l_name);
 472
 473                 user_wait_on_busy_lock(lockres);
 474                 goto again;
 475         }
 476
 477         user_dlm_inc_holders(lockres, level);
 478         spin_unlock(&lockres->l_lock);
 479
 480         mlog(0, "lockres %s: Got %s lock!\n", lockres->l_name,
 481                 (level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE");
 482
 483         status = 0;
 484 bail:
 485         return status;
 486 }
 487
 488 static inline void user_dlm_dec_holders(struct user_lock_res *lockres,
 489                                         int level)
 490 {
 491         switch(level) {
 492         case LKM_EXMODE:
 493                 BUG_ON(!lockres->l_ex_holders);
 494                 lockres->l_ex_holders--;
 495                 break;
 496         case LKM_PRMODE:
 497                 BUG_ON(!lockres->l_ro_holders);
 498                 lockres->l_ro_holders--;
 499                 break;
 500         default:
 501                 BUG();
 502         }
 503 }
 504
 505 void user_dlm_cluster_unlock(struct user_lock_res *lockres,
 506                              int level)
 507 {
 508         if (level != LKM_EXMODE &&
 509             level != LKM_PRMODE) {
 510                 mlog(ML_ERROR, "lockres %s: invalid request!\n", lockres->l_name);
 511                 return;
 512         }
 513
 514         mlog(0, "lockres %s: dropping %s lock\n", lockres->l_name,
 515                 (level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE");
 516
 517         spin_lock(&lockres->l_lock);
 518         user_dlm_dec_holders(lockres, level);
 519         __user_dlm_cond_queue_lockres(lockres);
 520         spin_unlock(&lockres->l_lock);
 521 }
 522
 523 void user_dlm_write_lvb(struct inode *inode,
 524                         const char *val,
 525                         unsigned int len)
 526 {
 527         struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
 528         char *lvb = lockres->l_lksb.lvb;
 529
 530         BUG_ON(len > DLM_LVB_LEN);
 531
 532         spin_lock(&lockres->l_lock);
 533
 534         BUG_ON(lockres->l_level < LKM_EXMODE);
 535         memcpy(lvb, val, len);
 536
 537         spin_unlock(&lockres->l_lock);
 538 }
 539
 540 void user_dlm_read_lvb(struct inode *inode,
 541                        char *val,
 542                        unsigned int len)
 543 {
 544         struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
 545         char *lvb = lockres->l_lksb.lvb;
 546
 547         BUG_ON(len > DLM_LVB_LEN);
 548
 549         spin_lock(&lockres->l_lock);
 550
 551         BUG_ON(lockres->l_level < LKM_PRMODE);
 552         memcpy(val, lvb, len);
 553
 554         spin_unlock(&lockres->l_lock);
 555 }
 556
 557 void user_dlm_lock_res_init(struct user_lock_res *lockres,
 558                             struct dentry *dentry)
 559 {
 560         memset(lockres, 0, sizeof(*lockres));
 561
 562         spin_lock_init(&lockres->l_lock);
 563         init_waitqueue_head(&lockres->l_event);
 564         lockres->l_level = LKM_IVMODE;
 565         lockres->l_requested = LKM_IVMODE;
 566         lockres->l_blocking = LKM_IVMODE;
 567
 568         /* should have been checked before getting here. */
 569         BUG_ON(dentry->d_name.len >= USER_DLM_LOCK_ID_MAX_LEN);
 570
 571         memcpy(lockres->l_name,
 572                dentry->d_name.name,
 573                dentry->d_name.len);
 574 }
 575
 576 int user_dlm_destroy_lock(struct user_lock_res *lockres)
 577 {
 578         int status = -EBUSY;
 579         struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
 580
 581         mlog(0, "asked to destroy %s\n", lockres->l_name);
 582
 583         spin_lock(&lockres->l_lock);
 584         while (lockres->l_flags & USER_LOCK_BUSY) {
 585                 spin_unlock(&lockres->l_lock);
 586
 587                 mlog(0, "lock %s is busy\n", lockres->l_name);
 588
 589                 user_wait_on_busy_lock(lockres);
 590
 591                 spin_lock(&lockres->l_lock);
 592         }
 593
 594         if (lockres->l_ro_holders || lockres->l_ex_holders) {
 595                 spin_unlock(&lockres->l_lock);
 596                 mlog(0, "lock %s has holders\n", lockres->l_name);
 597                 goto bail;
 598         }
 599
 600         status = 0;
 601         if (!(lockres->l_flags & USER_LOCK_ATTACHED)) {
 602                 spin_unlock(&lockres->l_lock);
 603                 mlog(0, "lock %s is not attached\n", lockres->l_name);
 604                 goto bail;
 605         }
 606
 607         lockres->l_flags &= ~USER_LOCK_ATTACHED;
 608         lockres->l_flags |= USER_LOCK_BUSY;
 609         lockres->l_flags |= USER_LOCK_IN_TEARDOWN;
 610         spin_unlock(&lockres->l_lock);
 611
 612         mlog(0, "unlocking lockres %s\n", lockres->l_name);
 613         status = dlmunlock(dlm,
 614                            &lockres->l_lksb,
 615                            LKM_VALBLK,
 616                            user_unlock_ast,
 617                            lockres);
 618         if (status != DLM_NORMAL) {
 619                 user_log_dlm_error("dlmunlock", status, lockres);
 620                 status = -EINVAL;
 621                 goto bail;
 622         }
 623
 624         user_wait_on_busy_lock(lockres);
 625
 626         status = 0;
 627 bail:
 628         return status;
 629 }
 630
 631 struct dlm_ctxt *user_dlm_register_context(struct qstr *name)
 632 {
 633         struct dlm_ctxt *dlm;
 634         u32 dlm_key;
 635         char *domain;
 636
 637         domain = kmalloc(name->len + 1, GFP_KERNEL);
 638         if (!domain) {
 639                 mlog_errno(-ENOMEM);
 640                 return ERR_PTR(-ENOMEM);
 641         }
 642
 643         dlm_key = crc32_le(0, name->name, name->len);
 644
 645         snprintf(domain, name->len + 1, "%.*s", name->len, name->name);
 646
 647         dlm = dlm_register_domain(domain, dlm_key);
 648         if (IS_ERR(dlm))
 649                 mlog_errno(PTR_ERR(dlm));
 650
 651         kfree(domain);
 652         return dlm;
 653 }
 654
 655 void user_dlm_unregister_context(struct dlm_ctxt *dlm)
 656 {
 657         dlm_unregister_domain(dlm);
 658 }