source4/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 2 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, write to the Free Software
  20    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21 */
  22
  23 #include "includes.h"
  24 #include "vfs_posix.h"
  25 #include "system/time.h"
  26 #include "dlinklist.h"
  27 #include "messages.h"
  28
  29
  30 /*
  31   check if we can perform IO on a range that might be locked
  32 */
  33 NTSTATUS pvfs_check_lock(struct pvfs_state *pvfs,
  34                          struct pvfs_file *f,
  35                          uint16_t smbpid,
  36                          uint64_t offset, uint64_t count,
  37                          enum brl_type rw)
  38 {
  39         if (!(pvfs->flags & PVFS_FLAG_STRICT_LOCKING)) {
  40                 return NT_STATUS_OK;
  41         }
  42
  43         return brl_locktest(pvfs->brl_context,
  44                             &f->handle->locking_key,
  45                             f->fnum,
  46                             smbpid,
  47                             offset, count, rw);
  48 }
  49
  50 /* this state structure holds information about a lock we are waiting on */
  51 struct pvfs_pending_lock {
  52         struct pvfs_pending_lock *next, *prev;
  53         struct pvfs_state *pvfs;
  54         union smb_lock *lck;
  55         struct pvfs_file *f;
  56         struct smbsrv_request *req;
  57         int pending_lock;
  58         void *wait_handle;
  59         struct timeval end_time;
  60 };
  61
  62 /*
  63   a secondary attempt to setup a lock has failed - back out
  64   the locks we did get and send an error
  65 */
  66 static void pvfs_lock_async_failed(struct pvfs_state *pvfs,
  67                                    struct smbsrv_request *req,
  68                                    struct pvfs_file *f,
  69                                    struct smb_lock_entry *locks,
  70                                    int i,
  71                                    NTSTATUS status)
  72 {
  73         /* undo the locks we just did */
  74         for (i=i-1;i>=0;i--) {
  75                 brl_unlock(pvfs->brl_context,
  76                            &f->handle->locking_key,
  77                            locks[i].pid,
  78                            f->fnum,
  79                            locks[i].offset,
  80                            locks[i].count);
  81                 f->lock_count--;
  82         }
  83         req->async_states->status = status;
  84         req->async_states->send_fn(req);
  85 }
  86
  87
  88 /*
  89   called when we receive a pending lock notification. It means that
  90   either our lock timed out or somoene else has unlocked a overlapping
  91   range, so we should try the lock again. Note that on timeout we
  92   do retry the lock, giving it a last chance.
  93 */
  94 static void pvfs_pending_lock_continue(void *private, enum pvfs_wait_notice reason)
  95 {
  96         struct pvfs_pending_lock *pending = private;
  97         struct pvfs_state *pvfs = pending->pvfs;
  98         struct pvfs_file *f = pending->f;
  99         struct smbsrv_request *req = pending->req;
 100         union smb_lock *lck = pending->lck;
 101         struct smb_lock_entry *locks;
 102         enum brl_type rw;
 103         NTSTATUS status;
 104         int i;
 105         BOOL timed_out;
 106
 107         /* we consider a cancel to be a timeout */
 108         timed_out = (reason != PVFS_WAIT_EVENT);
 109
 110         locks = lck->lockx.in.locks + lck->lockx.in.ulock_cnt;
 111
 112         if (lck->lockx.in.mode & LOCKING_ANDX_SHARED_LOCK) {
 113                 rw = READ_LOCK;
 114         } else {
 115                 rw = WRITE_LOCK;
 116         }
 117
 118         DLIST_REMOVE(f->pending_list, pending);
 119
 120         status = brl_lock(pvfs->brl_context,
 121                           &f->handle->locking_key,
 122                           req->smbpid,
 123                           f->fnum,
 124                           locks[pending->pending_lock].offset,
 125                           locks[pending->pending_lock].count,
 126                           rw, NULL);
 127
 128         if (NT_STATUS_IS_OK(status)) {
 129                 f->lock_count++;
 130         }
 131
 132         /* if we have failed and timed out, or succeeded, then we
 133            don't need the pending lock any more */
 134         if (NT_STATUS_IS_OK(status) || timed_out) {
 135                 NTSTATUS status2;
 136                 status2 = brl_remove_pending(pvfs->brl_context,
 137                                              &f->handle->locking_key, pending);
 138                 if (!NT_STATUS_IS_OK(status2)) {
 139                         DEBUG(0,("pvfs_lock: failed to remove pending lock - %s\n", nt_errstr(status2)));
 140                 }
 141                 talloc_free(pending->wait_handle);
 142         }
 143
 144         if (!NT_STATUS_IS_OK(status)) {
 145                 if (timed_out) {
 146                         /* no more chances */
 147                         pvfs_lock_async_failed(pvfs, req, f, locks, pending->pending_lock, status);
 148                 } else {
 149                         /* we can try again */
 150                         DLIST_ADD(f->pending_list, pending);
 151                 }
 152                 return;
 153         }
 154
 155         /* if we haven't timed out yet, then we can do more pending locks */
 156         if (timed_out) {
 157                 pending = NULL;
 158         } else {
 159                 if (rw == READ_LOCK) {
 160                         rw = PENDING_READ_LOCK;
 161                 } else {
 162                         rw = PENDING_WRITE_LOCK;
 163                 }
 164         }
 165
 166         /* we've now got the pending lock. try and get the rest, which might
 167            lead to more pending locks */
 168         for (i=pending->pending_lock+1;i<lck->lockx.in.lock_cnt;i++) {
 169                 if (pending) {
 170                         pending->pending_lock = i;
 171                 }
 172
 173                 status = brl_lock(pvfs->brl_context,
 174                                   &f->handle->locking_key,
 175                                   req->smbpid,
 176                                   f->fnum,
 177                                   locks[i].offset,
 178                                   locks[i].count,
 179                                   rw, pending);
 180                 if (!NT_STATUS_IS_OK(status)) {
 181                         if (pending) {
 182                                 /* a timed lock failed - setup a wait message to handle
 183                                    the pending lock notification or a timeout */
 184                                 pending->wait_handle = pvfs_wait_message(pvfs, req, MSG_BRL_RETRY,
 185                                                                          pending->end_time,
 186                                                                          pvfs_pending_lock_continue,
 187                                                                          pending);
 188                                 if (pending->wait_handle == NULL) {
 189                                         pvfs_lock_async_failed(pvfs, req, f, locks, i, NT_STATUS_NO_MEMORY);
 190                                 } else {
 191                                         talloc_steal(pending, pending->wait_handle);
 192                                         DLIST_ADD(f->pending_list, pending);
 193                                 }
 194                                 return;
 195                         }
 196                         pvfs_lock_async_failed(pvfs, req, f, locks, i, status);
 197                         return;
 198                 }
 199
 200                 f->lock_count++;
 201         }
 202
 203         /* we've managed to get all the locks. Tell the client */
 204         req->async_states->status = NT_STATUS_OK;
 205         req->async_states->send_fn(req);
 206 }
 207
 208
 209 /*
 210   called when we close a file that might have locks
 211 */
 212 void pvfs_lock_close(struct pvfs_state *pvfs, struct pvfs_file *f)
 213 {
 214         struct pvfs_pending_lock *p, *next;
 215
 216         if (f->lock_count || f->pending_list) {
 217                 DEBUG(5,("pvfs_lock: removing %.0f locks on close\n",
 218                          (double)f->lock_count));
 219                 brl_close(f->pvfs->brl_context, &f->handle->locking_key, f->fnum);
 220                 f->lock_count = 0;
 221         }
 222
 223         /* reply to all the pending lock requests, telling them the
 224            lock failed */
 225         for (p=f->pending_list;p;p=next) {
 226                 next = p->next;
 227                 DLIST_REMOVE(f->pending_list, p);
 228                 p->req->async_states->status = NT_STATUS_RANGE_NOT_LOCKED;
 229                 p->req->async_states->send_fn(p->req);
 230         }
 231 }
 232
 233
 234 /*
 235   cancel a set of locks
 236 */
 237 static NTSTATUS pvfs_lock_cancel(struct pvfs_state *pvfs, struct smbsrv_request *req, union smb_lock *lck,
 238                                  struct pvfs_file *f)
 239 {
 240         struct pvfs_pending_lock *p;
 241
 242         for (p=f->pending_list;p;p=p->next) {
 243                 /* check if the lock request matches exactly - you can only cancel with exact matches */
 244                 if (p->lck->lockx.in.ulock_cnt == lck->lockx.in.ulock_cnt &&
 245                     p->lck->lockx.in.lock_cnt  == lck->lockx.in.lock_cnt &&
 246                     p->lck->lockx.in.fnum      == lck->lockx.in.fnum &&
 247                     p->lck->lockx.in.mode      == (lck->lockx.in.mode & ~LOCKING_ANDX_CANCEL_LOCK)) {
 248                         int i;
 249
 250                         for (i=0;i<lck->lockx.in.ulock_cnt + lck->lockx.in.lock_cnt;i++) {
 251                                 if (p->lck->lockx.in.locks[i].pid != lck->lockx.in.locks[i].pid ||
 252                                     p->lck->lockx.in.locks[i].offset != lck->lockx.in.locks[i].offset ||
 253                                     p->lck->lockx.in.locks[i].count != lck->lockx.in.locks[i].count) {
 254                                         break;
 255                                 }
 256                         }
 257                         if (i < lck->lockx.in.ulock_cnt) continue;
 258
 259                         /* an exact match! we can cancel it, which is equivalent
 260                            to triggering the timeout early */
 261                         pvfs_pending_lock_continue(p ,True);
 262                         return NT_STATUS_OK;
 263                 }
 264         }
 265
 266         return NT_STATUS_UNSUCCESSFUL;
 267 }
 268
 269
 270 /*
 271   lock or unlock a byte range
 272 */
 273 NTSTATUS pvfs_lock(struct ntvfs_module_context *ntvfs,
 274                    struct smbsrv_request *req, union smb_lock *lck)
 275 {
 276         struct pvfs_state *pvfs = ntvfs->private_data;
 277         struct pvfs_file *f;
 278         struct smb_lock_entry *locks;
 279         int i;
 280         enum brl_type rw;
 281         struct pvfs_pending_lock *pending = NULL;
 282         NTSTATUS status;
 283
 284         if (lck->generic.level != RAW_LOCK_GENERIC) {
 285                 return ntvfs_map_lock(req, lck, ntvfs);
 286         }
 287
 288         f = pvfs_find_fd(pvfs, req, lck->lockx.in.fnum);
 289         if (!f) {
 290                 return NT_STATUS_INVALID_HANDLE;
 291         }
 292
 293         if (f->handle->fd == -1) {
 294                 return NT_STATUS_FILE_IS_A_DIRECTORY;
 295         }
 296
 297         if (lck->lockx.in.timeout != 0 &&
 298             (req->async_states->state & NTVFS_ASYNC_STATE_MAY_ASYNC)) {
 299                 pending = talloc_p(f, struct pvfs_pending_lock);
 300                 if (pending == NULL) {
 301                         return NT_STATUS_NO_MEMORY;
 302                 }
 303
 304                 pending->pvfs = pvfs;
 305                 pending->lck = lck;
 306                 pending->f = f;
 307                 pending->req = req;
 308
 309                 pending->end_time =
 310                         timeval_current_ofs(lck->lockx.in.timeout/1000,
 311                                             1000*(lck->lockx.in.timeout%1000));
 312         }
 313
 314         if (lck->lockx.in.mode & LOCKING_ANDX_SHARED_LOCK) {
 315                 rw = pending? PENDING_READ_LOCK : READ_LOCK;
 316         } else {
 317                 rw = pending? PENDING_WRITE_LOCK : WRITE_LOCK;
 318         }
 319
 320         if (lck->lockx.in.mode & LOCKING_ANDX_CANCEL_LOCK) {
 321                 return pvfs_lock_cancel(pvfs, req, lck, f);
 322         }
 323
 324         if (lck->lockx.in.mode & LOCKING_ANDX_CHANGE_LOCKTYPE) {
 325                 /* this seems to not be supported by any windows server,
 326                    or used by any clients */
 327                 return NT_STATUS_UNSUCCESSFUL;
 328         }
 329
 330         if (lck->lockx.in.mode & LOCKING_ANDX_OPLOCK_RELEASE) {
 331                 DEBUG(0,("received unexpected oplock break\n"));
 332                 return NT_STATUS_NOT_IMPLEMENTED;
 333         }
 334
 335
 336         /* the unlocks happen first */
 337         locks = lck->lockx.in.locks;
 338
 339         for (i=0;i<lck->lockx.in.ulock_cnt;i++) {
 340                 status = brl_unlock(pvfs->brl_context,
 341                                     &f->handle->locking_key,
 342                                     locks[i].pid,
 343                                     f->fnum,
 344                                     locks[i].offset,
 345                                     locks[i].count);
 346                 if (!NT_STATUS_IS_OK(status)) {
 347                         return status;
 348                 }
 349                 f->lock_count--;
 350         }
 351
 352         locks += i;
 353
 354         for (i=0;i<lck->lockx.in.lock_cnt;i++) {
 355                 if (pending) {
 356                         pending->pending_lock = i;
 357                 }
 358
 359                 status = brl_lock(pvfs->brl_context,
 360                                   &f->handle->locking_key,
 361                                   locks[i].pid,
 362                                   f->fnum,
 363                                   locks[i].offset,
 364                                   locks[i].count,
 365                                   rw, pending);
 366                 if (!NT_STATUS_IS_OK(status)) {
 367                         if (pending) {
 368                                 /* a timed lock failed - setup a wait message to handle
 369                                    the pending lock notification or a timeout */
 370                                 pending->wait_handle = pvfs_wait_message(pvfs, req, MSG_BRL_RETRY,
 371                                                                          pending->end_time,
 372                                                                          pvfs_pending_lock_continue,
 373                                                                          pending);
 374                                 if (pending->wait_handle == NULL) {
 375                                         return NT_STATUS_NO_MEMORY;
 376                                 }
 377                                 talloc_steal(pending, pending->wait_handle);
 378                                 DLIST_ADD(f->pending_list, pending);
 379                                 return NT_STATUS_OK;
 380                         }
 381                         /* undo the locks we just did */
 382                         for (i=i-1;i>=0;i--) {
 383                                 brl_unlock(pvfs->brl_context,
 384                                            &f->handle->locking_key,
 385                                            locks[i].pid,
 386                                            f->fnum,
 387                                            locks[i].offset,
 388                                            locks[i].count);
 389                                 f->lock_count--;
 390                         }
 391                         return status;
 392                 }
 393                 f->lock_count++;
 394         }
 395
 396         return NT_STATUS_OK;
 397 }
 398