source/ntvfs/posix/pvfs_lock.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    POSIX NTVFS backend - locking
   5
   6    Copyright (C) Andrew Tridgell 2004
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "includes.h"
  23 #include "vfs_posix.h"
  24 #include "system/time.h"
  25 #include "lib/util/dlinklist.h"
  26 #include "messaging/messaging.h"
  27
  28
  29 /*
  30   check if we can perform IO on a range that might be locked
  31 */
  32 NTSTATUS pvfs_check_lock(struct pvfs_state *pvfs,
  33                          struct pvfs_file *f,
  34                          uint16_t smbpid,
  35                          uint64_t offset, uint64_t count,
  36                          enum brl_type rw)
  37 {
  38         if (!(pvfs->flags & PVFS_FLAG_STRICT_LOCKING)) {
  39                 return NT_STATUS_OK;
  40         }
  41
  42         return brl_locktest(pvfs->brl_context,
  43                             f->brl_handle,
  44                             smbpid,
  45                             offset, count, rw);
  46 }
  47
  48 /* this state structure holds information about a lock we are waiting on */
  49 struct pvfs_pending_lock {
  50         struct pvfs_pending_lock *next, *prev;
  51         struct pvfs_state *pvfs;
  52         union smb_lock *lck;
  53         struct pvfs_file *f;
  54         struct ntvfs_request *req;
  55         int pending_lock;
  56         struct pvfs_wait *wait_handle;
  57         struct timeval end_time;
  58 };
  59
  60 /*
  61   a secondary attempt to setup a lock has failed - back out
  62   the locks we did get and send an error
  63 */
  64 static void pvfs_lock_async_failed(struct pvfs_state *pvfs,
  65                                    struct ntvfs_request *req,
  66                                    struct pvfs_file *f,
  67                                    struct smb_lock_entry *locks,
  68                                    int i,
  69                                    NTSTATUS status)
  70 {
  71         /* undo the locks we just did */
  72         for (i--;i>=0;i--) {
  73                 brl_unlock(pvfs->brl_context,
  74                            f->brl_handle,
  75                            locks[i].pid,
  76                            locks[i].offset,
  77                            locks[i].count);
  78                 f->lock_count--;
  79         }
  80         req->async_states->status = status;
  81         req->async_states->send_fn(req);
  82 }
  83
  84
  85 /*
  86   called when we receive a pending lock notification. It means that
  87   either our lock timed out or someone else has unlocked a overlapping
  88   range, so we should try the lock again. Note that on timeout we
  89   do retry the lock, giving it a last chance.
  90 */
  91 static void pvfs_pending_lock_continue(void *private, enum pvfs_wait_notice reason)
  92 {
  93         struct pvfs_pending_lock *pending = private;
  94         struct pvfs_state *pvfs = pending->pvfs;
  95         struct pvfs_file *f = pending->f;
  96         struct ntvfs_request *req = pending->req;
  97         union smb_lock *lck = pending->lck;
  98         struct smb_lock_entry *locks;
  99         enum brl_type rw;
 100         NTSTATUS status;
 101         int i;
 102         bool timed_out;
 103
 104         timed_out = (reason != PVFS_WAIT_EVENT);
 105
 106         locks = lck->lockx.in.locks + lck->lockx.in.ulock_cnt;
 107
 108         if (lck->lockx.in.mode & LOCKING_ANDX_SHARED_LOCK) {
 109                 rw = READ_LOCK;
 110         } else {
 111                 rw = WRITE_LOCK;
 112         }
 113
 114         DLIST_REMOVE(f->pending_list, pending);
 115
 116         /* we don't retry on a cancel */
 117         if (reason == PVFS_WAIT_CANCEL) {
 118                 status = NT_STATUS_FILE_LOCK_CONFLICT;
 119         } else {
 120                 /*
 121                  * here it's important to pass the pending pointer
 122                  * because with this we'll get the correct error code
 123                  * FILE_LOCK_CONFLICT in the error case
 124                  */
 125                 status = brl_lock(pvfs->brl_context,
 126                                   f->brl_handle,
 127                                   locks[pending->pending_lock].pid,
 128                                   locks[pending->pending_lock].offset,
 129                                   locks[pending->pending_lock].count,
 130                                   rw, pending);
 131         }
 132         if (NT_STATUS_IS_OK(status)) {
 133                 f->lock_count++;
 134                 timed_out = false;
 135         }
 136
 137         /* if we have failed and timed out, or succeeded, then we
 138            don't need the pending lock any more */
 139         if (NT_STATUS_IS_OK(status) || timed_out) {
 140                 NTSTATUS status2;
 141                 status2 = brl_remove_pending(pvfs->brl_context,
 142                                              f->brl_handle, pending);
 143                 if (!NT_STATUS_IS_OK(status2)) {
 144                         DEBUG(0,("pvfs_lock: failed to remove pending lock - %s\n", nt_errstr(status2)));
 145                 }
 146                 talloc_free(pending->wait_handle);
 147         }
 148
 149         if (!NT_STATUS_IS_OK(status)) {
 150                 if (timed_out) {
 151                         /* no more chances */
 152                         pvfs_lock_async_failed(pvfs, req, f, locks, pending->pending_lock, status);
 153                         talloc_free(pending);
 154                 } else {
 155                         /* we can try again */
 156                         DLIST_ADD(f->pending_list, pending);
 157                 }
 158                 return;
 159         }
 160
 161         /* if we haven't timed out yet, then we can do more pending locks */
 162         if (rw == READ_LOCK) {
 163                 rw = PENDING_READ_LOCK;
 164         } else {
 165                 rw = PENDING_WRITE_LOCK;
 166         }
 167
 168         /* we've now got the pending lock. try and get the rest, which might
 169            lead to more pending locks */
 170         for (i=pending->pending_lock+1;i<lck->lockx.in.lock_cnt;i++) {
 171                 if (pending) {
 172                         pending->pending_lock = i;
 173                 }
 174
 175                 status = brl_lock(pvfs->brl_context,
 176                                   f->brl_handle,
 177                                   locks[i].pid,
 178                                   locks[i].offset,
 179                                   locks[i].count,
 180                                   rw, pending);
 181                 if (!NT_STATUS_IS_OK(status)) {
 182                         if (pending) {
 183                                 /* a timed lock failed - setup a wait message to handle
 184                                    the pending lock notification or a timeout */
 185                                 pending->wait_handle = pvfs_wait_message(pvfs, req, MSG_BRL_RETRY,
 186                                                                          pending->end_time,
 187                                                                          pvfs_pending_lock_continue,
 188                                                                          pending);
 189                                 if (pending->wait_handle == NULL) {
 190                                         pvfs_lock_async_failed(pvfs, req, f, locks, i, NT_STATUS_NO_MEMORY);
 191                                         talloc_free(pending);
 192                                 } else {
 193                                         talloc_steal(pending, pending->wait_handle);
 194                                         DLIST_ADD(f->pending_list, pending);
 195                                 }
 196                                 return;
 197                         }
 198                         pvfs_lock_async_failed(pvfs, req, f, locks, i, status);
 199                         talloc_free(pending);
 200                         return;
 201                 }
 202
 203                 f->lock_count++;
 204         }
 205
 206         /* we've managed to get all the locks. Tell the client */
 207         req->async_states->status = NT_STATUS_OK;
 208         req->async_states->send_fn(req);
 209         talloc_free(pending);
 210 }
 211
 212
 213 /*
 214   called when we close a file that might have locks
 215 */
 216 void pvfs_lock_close(struct pvfs_state *pvfs, struct pvfs_file *f)
 217 {
 218         struct pvfs_pending_lock *p, *next;
 219
 220         if (f->lock_count || f->pending_list) {
 221                 DEBUG(5,("pvfs_lock: removing %.0f locks on close\n",
 222                          (double)f->lock_count));
 223                 brl_close(f->pvfs->brl_context, f->brl_handle);
 224                 f->lock_count = 0;
 225         }
 226
 227         /* reply to all the pending lock requests, telling them the
 228            lock failed */
 229         for (p=f->pending_list;p;p=next) {
 230                 next = p->next;
 231                 DLIST_REMOVE(f->pending_list, p);
 232                 p->req->async_states->status = NT_STATUS_RANGE_NOT_LOCKED;
 233                 p->req->async_states->send_fn(p->req);
 234         }
 235 }
 236
 237
 238 /*
 239   cancel a set of locks
 240 */
 241 static NTSTATUS pvfs_lock_cancel(struct pvfs_state *pvfs, struct ntvfs_request *req, union smb_lock *lck,
 242                                  struct pvfs_file *f)
 243 {
 244         struct pvfs_pending_lock *p;
 245
 246         for (p=f->pending_list;p;p=p->next) {
 247                 /* check if the lock request matches exactly - you can only cancel with exact matches */
 248                 if (p->lck->lockx.in.ulock_cnt == lck->lockx.in.ulock_cnt &&
 249                     p->lck->lockx.in.lock_cnt  == lck->lockx.in.lock_cnt &&
 250                     p->lck->lockx.in.file.ntvfs== lck->lockx.in.file.ntvfs &&
 251                     p->lck->lockx.in.mode      == (lck->lockx.in.mode & ~LOCKING_ANDX_CANCEL_LOCK)) {
 252                         int i;
 253
 254                         for (i=0;i<lck->lockx.in.ulock_cnt + lck->lockx.in.lock_cnt;i++) {
 255                                 if (p->lck->lockx.in.locks[i].pid != lck->lockx.in.locks[i].pid ||
 256                                     p->lck->lockx.in.locks[i].offset != lck->lockx.in.locks[i].offset ||
 257                                     p->lck->lockx.in.locks[i].count != lck->lockx.in.locks[i].count) {
 258                                         break;
 259                                 }
 260                         }
 261                         if (i < lck->lockx.in.ulock_cnt) continue;
 262
 263                         /* an exact match! we can cancel it, which is equivalent
 264                            to triggering the timeout early */
 265                         pvfs_pending_lock_continue(p, PVFS_WAIT_TIMEOUT);
 266                         return NT_STATUS_OK;
 267                 }
 268         }
 269
 270         return NT_STATUS_DOS(ERRDOS, ERRcancelviolation);
 271 }
 272
 273
 274 /*
 275   lock or unlock a byte range
 276 */
 277 NTSTATUS pvfs_lock(struct ntvfs_module_context *ntvfs,
 278                    struct ntvfs_request *req, union smb_lock *lck)
 279 {
 280         struct pvfs_state *pvfs = ntvfs->private_data;
 281         struct pvfs_file *f;
 282         struct smb_lock_entry *locks;
 283         int i;
 284         enum brl_type rw;
 285         struct pvfs_pending_lock *pending = NULL;
 286         NTSTATUS status;
 287
 288         if (lck->generic.level != RAW_LOCK_GENERIC) {
 289                 return ntvfs_map_lock(ntvfs, req, lck);
 290         }
 291
 292         if (lck->lockx.in.mode & LOCKING_ANDX_OPLOCK_RELEASE) {
 293                 return pvfs_oplock_release(ntvfs, req, lck);
 294         }
 295
 296         f = pvfs_find_fd(pvfs, req, lck->lockx.in.file.ntvfs);
 297         if (!f) {
 298                 return NT_STATUS_INVALID_HANDLE;
 299         }
 300
 301         if (f->handle->fd == -1) {
 302                 return NT_STATUS_FILE_IS_A_DIRECTORY;
 303         }
 304
 305         status = pvfs_break_level2_oplocks(f);
 306         NT_STATUS_NOT_OK_RETURN(status);
 307
 308         if (lck->lockx.in.timeout != 0 &&
 309             (req->async_states->state & NTVFS_ASYNC_STATE_MAY_ASYNC)) {
 310                 pending = talloc(f, struct pvfs_pending_lock);
 311                 if (pending == NULL) {
 312                         return NT_STATUS_NO_MEMORY;
 313                 }
 314
 315                 pending->pvfs = pvfs;
 316                 pending->lck = lck;
 317                 pending->f = f;
 318                 pending->req = req;
 319
 320                 pending->end_time =
 321                         timeval_current_ofs(lck->lockx.in.timeout/1000,
 322                                             1000*(lck->lockx.in.timeout%1000));
 323         }
 324
 325         if (lck->lockx.in.mode & LOCKING_ANDX_SHARED_LOCK) {
 326                 rw = pending? PENDING_READ_LOCK : READ_LOCK;
 327         } else {
 328                 rw = pending? PENDING_WRITE_LOCK : WRITE_LOCK;
 329         }
 330
 331         if (lck->lockx.in.mode & LOCKING_ANDX_CANCEL_LOCK) {
 332                 talloc_free(pending);
 333                 return pvfs_lock_cancel(pvfs, req, lck, f);
 334         }
 335
 336         if (lck->lockx.in.mode & LOCKING_ANDX_CHANGE_LOCKTYPE) {
 337                 /* this seems to not be supported by any windows server,
 338                    or used by any clients */
 339                 talloc_free(pending);
 340                 return NT_STATUS_DOS(ERRDOS, ERRnoatomiclocks);
 341         }
 342
 343         /* the unlocks happen first */
 344         locks = lck->lockx.in.locks;
 345
 346         for (i=0;i<lck->lockx.in.ulock_cnt;i++) {
 347                 status = brl_unlock(pvfs->brl_context,
 348                                     f->brl_handle,
 349                                     locks[i].pid,
 350                                     locks[i].offset,
 351                                     locks[i].count);
 352                 if (!NT_STATUS_IS_OK(status)) {
 353                         talloc_free(pending);
 354                         return status;
 355                 }
 356                 f->lock_count--;
 357         }
 358
 359         locks += i;
 360
 361         for (i=0;i<lck->lockx.in.lock_cnt;i++) {
 362                 if (pending) {
 363                         pending->pending_lock = i;
 364                 }
 365
 366                 status = brl_lock(pvfs->brl_context,
 367                                   f->brl_handle,
 368                                   locks[i].pid,
 369                                   locks[i].offset,
 370                                   locks[i].count,
 371                                   rw, pending);
 372                 if (!NT_STATUS_IS_OK(status)) {
 373                         if (pending) {
 374                                 /* a timed lock failed - setup a wait message to handle
 375                                    the pending lock notification or a timeout */
 376                                 pending->wait_handle = pvfs_wait_message(pvfs, req, MSG_BRL_RETRY,
 377                                                                          pending->end_time,
 378                                                                          pvfs_pending_lock_continue,
 379                                                                          pending);
 380                                 if (pending->wait_handle == NULL) {
 381                                         talloc_free(pending);
 382                                         return NT_STATUS_NO_MEMORY;
 383                                 }
 384                                 talloc_steal(pending, pending->wait_handle);
 385                                 DLIST_ADD(f->pending_list, pending);
 386                                 return NT_STATUS_OK;
 387                         }
 388
 389                         /* undo the locks we just did */
 390                         for (i--;i>=0;i--) {
 391                                 brl_unlock(pvfs->brl_context,
 392                                            f->brl_handle,
 393                                            locks[i].pid,
 394                                            locks[i].offset,
 395                                            locks[i].count);
 396                                 f->lock_count--;
 397                         }
 398                         talloc_free(pending);
 399                         return status;
 400                 }
 401                 f->lock_count++;
 402         }
 403
 404         talloc_free(pending);
 405         return NT_STATUS_OK;
 406 }