fs/cifs/misc.c

   1 // SPDX-License-Identifier: LGPL-2.1
   2 /*
   3  *   fs/cifs/misc.c
   4  *
   5  *   Copyright (C) International Business Machines  Corp., 2002,2008
   6  *   Author(s): Steve French (sfrench@us.ibm.com)
   7  *
   8  */
   9
  10 #include <linux/slab.h>
  11 #include <linux/ctype.h>
  12 #include <linux/mempool.h>
  13 #include <linux/vmalloc.h>
  14 #include "cifspdu.h"
  15 #include "cifsglob.h"
  16 #include "cifsproto.h"
  17 #include "cifs_debug.h"
  18 #include "smberr.h"
  19 #include "nterr.h"
  20 #include "cifs_unicode.h"
  21 #include "smb2pdu.h"
  22 #include "cifsfs.h"
  23 #ifdef CONFIG_CIFS_DFS_UPCALL
  24 #include "dns_resolve.h"
  25 #endif
  26 #include "fs_context.h"
  27
  28 extern mempool_t *cifs_sm_req_poolp;
  29 extern mempool_t *cifs_req_poolp;
  30
  31 /* The xid serves as a useful identifier for each incoming vfs request,
  32    in a similar way to the mid which is useful to track each sent smb,
  33    and CurrentXid can also provide a running counter (although it
  34    will eventually wrap past zero) of the total vfs operations handled
  35    since the cifs fs was mounted */
  36
  37 unsigned int
  38 _get_xid(void)
  39 {
  40         unsigned int xid;
  41
  42         spin_lock(&GlobalMid_Lock);
  43         GlobalTotalActiveXid++;
  44
  45         /* keep high water mark for number of simultaneous ops in filesystem */
  46         if (GlobalTotalActiveXid > GlobalMaxActiveXid)
  47                 GlobalMaxActiveXid = GlobalTotalActiveXid;
  48         if (GlobalTotalActiveXid > 65000)
  49                 cifs_dbg(FYI, "warning: more than 65000 requests active\n");
  50         xid = GlobalCurrentXid++;
  51         spin_unlock(&GlobalMid_Lock);
  52         return xid;
  53 }
  54
  55 void
  56 _free_xid(unsigned int xid)
  57 {
  58         spin_lock(&GlobalMid_Lock);
  59         /* if (GlobalTotalActiveXid == 0)
  60                 BUG(); */
  61         GlobalTotalActiveXid--;
  62         spin_unlock(&GlobalMid_Lock);
  63 }
  64
  65 struct cifs_ses *
  66 sesInfoAlloc(void)
  67 {
  68         struct cifs_ses *ret_buf;
  69
  70         ret_buf = kzalloc(sizeof(struct cifs_ses), GFP_KERNEL);
  71         if (ret_buf) {
  72                 atomic_inc(&sesInfoAllocCount);
  73                 ret_buf->status = CifsNew;
  74                 ++ret_buf->ses_count;
  75                 INIT_LIST_HEAD(&ret_buf->smb_ses_list);
  76                 INIT_LIST_HEAD(&ret_buf->tcon_list);
  77                 mutex_init(&ret_buf->session_mutex);
  78                 spin_lock_init(&ret_buf->iface_lock);
  79         }
  80         return ret_buf;
  81 }
  82
  83 void
  84 sesInfoFree(struct cifs_ses *buf_to_free)
  85 {
  86         if (buf_to_free == NULL) {
  87                 cifs_dbg(FYI, "Null buffer passed to sesInfoFree\n");
  88                 return;
  89         }
  90
  91         atomic_dec(&sesInfoAllocCount);
  92         kfree(buf_to_free->serverOS);
  93         kfree(buf_to_free->serverDomain);
  94         kfree(buf_to_free->serverNOS);
  95         kfree_sensitive(buf_to_free->password);
  96         kfree(buf_to_free->user_name);
  97         kfree(buf_to_free->domainName);
  98         kfree_sensitive(buf_to_free->auth_key.response);
  99         kfree(buf_to_free->iface_list);
 100         kfree_sensitive(buf_to_free);
 101 }
 102
 103 struct cifs_tcon *
 104 tconInfoAlloc(void)
 105 {
 106         struct cifs_tcon *ret_buf;
 107
 108         ret_buf = kzalloc(sizeof(*ret_buf), GFP_KERNEL);
 109         if (!ret_buf)
 110                 return NULL;
 111         ret_buf->crfid.fid = kzalloc(sizeof(*ret_buf->crfid.fid), GFP_KERNEL);
 112         if (!ret_buf->crfid.fid) {
 113                 kfree(ret_buf);
 114                 return NULL;
 115         }
 116
 117         atomic_inc(&tconInfoAllocCount);
 118         ret_buf->tidStatus = CifsNew;
 119         ++ret_buf->tc_count;
 120         INIT_LIST_HEAD(&ret_buf->openFileList);
 121         INIT_LIST_HEAD(&ret_buf->tcon_list);
 122         spin_lock_init(&ret_buf->open_file_lock);
 123         mutex_init(&ret_buf->crfid.fid_mutex);
 124         spin_lock_init(&ret_buf->stat_lock);
 125         atomic_set(&ret_buf->num_local_opens, 0);
 126         atomic_set(&ret_buf->num_remote_opens, 0);
 127
 128         return ret_buf;
 129 }
 130
 131 void
 132 tconInfoFree(struct cifs_tcon *buf_to_free)
 133 {
 134         if (buf_to_free == NULL) {
 135                 cifs_dbg(FYI, "Null buffer passed to tconInfoFree\n");
 136                 return;
 137         }
 138         atomic_dec(&tconInfoAllocCount);
 139         kfree(buf_to_free->nativeFileSystem);
 140         kfree_sensitive(buf_to_free->password);
 141         kfree(buf_to_free->crfid.fid);
 142 #ifdef CONFIG_CIFS_DFS_UPCALL
 143         kfree(buf_to_free->dfs_path);
 144 #endif
 145         kfree(buf_to_free);
 146 }
 147
 148 struct smb_hdr *
 149 cifs_buf_get(void)
 150 {
 151         struct smb_hdr *ret_buf = NULL;
 152         /*
 153          * SMB2 header is bigger than CIFS one - no problems to clean some
 154          * more bytes for CIFS.
 155          */
 156         size_t buf_size = sizeof(struct smb2_sync_hdr);
 157
 158         /*
 159          * We could use negotiated size instead of max_msgsize -
 160          * but it may be more efficient to always alloc same size
 161          * albeit slightly larger than necessary and maxbuffersize
 162          * defaults to this and can not be bigger.
 163          */
 164         ret_buf = mempool_alloc(cifs_req_poolp, GFP_NOFS);
 165
 166         /* clear the first few header bytes */
 167         /* for most paths, more is cleared in header_assemble */
 168         memset(ret_buf, 0, buf_size + 3);
 169         atomic_inc(&bufAllocCount);
 170 #ifdef CONFIG_CIFS_STATS2
 171         atomic_inc(&totBufAllocCount);
 172 #endif /* CONFIG_CIFS_STATS2 */
 173
 174         return ret_buf;
 175 }
 176
 177 void
 178 cifs_buf_release(void *buf_to_free)
 179 {
 180         if (buf_to_free == NULL) {
 181                 /* cifs_dbg(FYI, "Null buffer passed to cifs_buf_release\n");*/
 182                 return;
 183         }
 184         mempool_free(buf_to_free, cifs_req_poolp);
 185
 186         atomic_dec(&bufAllocCount);
 187         return;
 188 }
 189
 190 struct smb_hdr *
 191 cifs_small_buf_get(void)
 192 {
 193         struct smb_hdr *ret_buf = NULL;
 194
 195 /* We could use negotiated size instead of max_msgsize -
 196    but it may be more efficient to always alloc same size
 197    albeit slightly larger than necessary and maxbuffersize
 198    defaults to this and can not be bigger */
 199         ret_buf = mempool_alloc(cifs_sm_req_poolp, GFP_NOFS);
 200         /* No need to clear memory here, cleared in header assemble */
 201         /*      memset(ret_buf, 0, sizeof(struct smb_hdr) + 27);*/
 202         atomic_inc(&smBufAllocCount);
 203 #ifdef CONFIG_CIFS_STATS2
 204         atomic_inc(&totSmBufAllocCount);
 205 #endif /* CONFIG_CIFS_STATS2 */
 206
 207         return ret_buf;
 208 }
 209
 210 void
 211 cifs_small_buf_release(void *buf_to_free)
 212 {
 213
 214         if (buf_to_free == NULL) {
 215                 cifs_dbg(FYI, "Null buffer passed to cifs_small_buf_release\n");
 216                 return;
 217         }
 218         mempool_free(buf_to_free, cifs_sm_req_poolp);
 219
 220         atomic_dec(&smBufAllocCount);
 221         return;
 222 }
 223
 224 void
 225 free_rsp_buf(int resp_buftype, void *rsp)
 226 {
 227         if (resp_buftype == CIFS_SMALL_BUFFER)
 228                 cifs_small_buf_release(rsp);
 229         else if (resp_buftype == CIFS_LARGE_BUFFER)
 230                 cifs_buf_release(rsp);
 231 }
 232
 233 /* NB: MID can not be set if treeCon not passed in, in that
 234    case it is responsbility of caller to set the mid */
 235 void
 236 header_assemble(struct smb_hdr *buffer, char smb_command /* command */ ,
 237                 const struct cifs_tcon *treeCon, int word_count
 238                 /* length of fixed section (word count) in two byte units  */)
 239 {
 240         char *temp = (char *) buffer;
 241
 242         memset(temp, 0, 256); /* bigger than MAX_CIFS_HDR_SIZE */
 243
 244         buffer->smb_buf_length = cpu_to_be32(
 245             (2 * word_count) + sizeof(struct smb_hdr) -
 246             4 /*  RFC 1001 length field does not count */  +
 247             2 /* for bcc field itself */) ;
 248
 249         buffer->Protocol[0] = 0xFF;
 250         buffer->Protocol[1] = 'S';
 251         buffer->Protocol[2] = 'M';
 252         buffer->Protocol[3] = 'B';
 253         buffer->Command = smb_command;
 254         buffer->Flags = 0x00;   /* case sensitive */
 255         buffer->Flags2 = SMBFLG2_KNOWS_LONG_NAMES;
 256         buffer->Pid = cpu_to_le16((__u16)current->tgid);
 257         buffer->PidHigh = cpu_to_le16((__u16)(current->tgid >> 16));
 258         if (treeCon) {
 259                 buffer->Tid = treeCon->tid;
 260                 if (treeCon->ses) {
 261                         if (treeCon->ses->capabilities & CAP_UNICODE)
 262                                 buffer->Flags2 |= SMBFLG2_UNICODE;
 263                         if (treeCon->ses->capabilities & CAP_STATUS32)
 264                                 buffer->Flags2 |= SMBFLG2_ERR_STATUS;
 265
 266                         /* Uid is not converted */
 267                         buffer->Uid = treeCon->ses->Suid;
 268                         buffer->Mid = get_next_mid(treeCon->ses->server);
 269                 }
 270                 if (treeCon->Flags & SMB_SHARE_IS_IN_DFS)
 271                         buffer->Flags2 |= SMBFLG2_DFS;
 272                 if (treeCon->nocase)
 273                         buffer->Flags  |= SMBFLG_CASELESS;
 274                 if ((treeCon->ses) && (treeCon->ses->server))
 275                         if (treeCon->ses->server->sign)
 276                                 buffer->Flags2 |= SMBFLG2_SECURITY_SIGNATURE;
 277         }
 278
 279 /*  endian conversion of flags is now done just before sending */
 280         buffer->WordCount = (char) word_count;
 281         return;
 282 }
 283
 284 static int
 285 check_smb_hdr(struct smb_hdr *smb)
 286 {
 287         /* does it have the right SMB "signature" ? */
 288         if (*(__le32 *) smb->Protocol != cpu_to_le32(0x424d53ff)) {
 289                 cifs_dbg(VFS, "Bad protocol string signature header 0x%x\n",
 290                          *(unsigned int *)smb->Protocol);
 291                 return 1;
 292         }
 293
 294         /* if it's a response then accept */
 295         if (smb->Flags & SMBFLG_RESPONSE)
 296                 return 0;
 297
 298         /* only one valid case where server sends us request */
 299         if (smb->Command == SMB_COM_LOCKING_ANDX)
 300                 return 0;
 301
 302         cifs_dbg(VFS, "Server sent request, not response. mid=%u\n",
 303                  get_mid(smb));
 304         return 1;
 305 }
 306
 307 int
 308 checkSMB(char *buf, unsigned int total_read, struct TCP_Server_Info *server)
 309 {
 310         struct smb_hdr *smb = (struct smb_hdr *)buf;
 311         __u32 rfclen = be32_to_cpu(smb->smb_buf_length);
 312         __u32 clc_len;  /* calculated length */
 313         cifs_dbg(FYI, "checkSMB Length: 0x%x, smb_buf_length: 0x%x\n",
 314                  total_read, rfclen);
 315
 316         /* is this frame too small to even get to a BCC? */
 317         if (total_read < 2 + sizeof(struct smb_hdr)) {
 318                 if ((total_read >= sizeof(struct smb_hdr) - 1)
 319                             && (smb->Status.CifsError != 0)) {
 320                         /* it's an error return */
 321                         smb->WordCount = 0;
 322                         /* some error cases do not return wct and bcc */
 323                         return 0;
 324                 } else if ((total_read == sizeof(struct smb_hdr) + 1) &&
 325                                 (smb->WordCount == 0)) {
 326                         char *tmp = (char *)smb;
 327                         /* Need to work around a bug in two servers here */
 328                         /* First, check if the part of bcc they sent was zero */
 329                         if (tmp[sizeof(struct smb_hdr)] == 0) {
 330                                 /* some servers return only half of bcc
 331                                  * on simple responses (wct, bcc both zero)
 332                                  * in particular have seen this on
 333                                  * ulogoffX and FindClose. This leaves
 334                                  * one byte of bcc potentially unitialized
 335                                  */
 336                                 /* zero rest of bcc */
 337                                 tmp[sizeof(struct smb_hdr)+1] = 0;
 338                                 return 0;
 339                         }
 340                         cifs_dbg(VFS, "rcvd invalid byte count (bcc)\n");
 341                 } else {
 342                         cifs_dbg(VFS, "Length less than smb header size\n");
 343                 }
 344                 return -EIO;
 345         }
 346
 347         /* otherwise, there is enough to get to the BCC */
 348         if (check_smb_hdr(smb))
 349                 return -EIO;
 350         clc_len = smbCalcSize(smb, server);
 351
 352         if (4 + rfclen != total_read) {
 353                 cifs_dbg(VFS, "Length read does not match RFC1001 length %d\n",
 354                          rfclen);
 355                 return -EIO;
 356         }
 357
 358         if (4 + rfclen != clc_len) {
 359                 __u16 mid = get_mid(smb);
 360                 /* check if bcc wrapped around for large read responses */
 361                 if ((rfclen > 64 * 1024) && (rfclen > clc_len)) {
 362                         /* check if lengths match mod 64K */
 363                         if (((4 + rfclen) & 0xFFFF) == (clc_len & 0xFFFF))
 364                                 return 0; /* bcc wrapped */
 365                 }
 366                 cifs_dbg(FYI, "Calculated size %u vs length %u mismatch for mid=%u\n",
 367                          clc_len, 4 + rfclen, mid);
 368
 369                 if (4 + rfclen < clc_len) {
 370                         cifs_dbg(VFS, "RFC1001 size %u smaller than SMB for mid=%u\n",
 371                                  rfclen, mid);
 372                         return -EIO;
 373                 } else if (rfclen > clc_len + 512) {
 374                         /*
 375                          * Some servers (Windows XP in particular) send more
 376                          * data than the lengths in the SMB packet would
 377                          * indicate on certain calls (byte range locks and
 378                          * trans2 find first calls in particular). While the
 379                          * client can handle such a frame by ignoring the
 380                          * trailing data, we choose limit the amount of extra
 381                          * data to 512 bytes.
 382                          */
 383                         cifs_dbg(VFS, "RFC1001 size %u more than 512 bytes larger than SMB for mid=%u\n",
 384                                  rfclen, mid);
 385                         return -EIO;
 386                 }
 387         }
 388         return 0;
 389 }
 390
 391 bool
 392 is_valid_oplock_break(char *buffer, struct TCP_Server_Info *srv)
 393 {
 394         struct smb_hdr *buf = (struct smb_hdr *)buffer;
 395         struct smb_com_lock_req *pSMB = (struct smb_com_lock_req *)buf;
 396         struct list_head *tmp, *tmp1, *tmp2;
 397         struct cifs_ses *ses;
 398         struct cifs_tcon *tcon;
 399         struct cifsInodeInfo *pCifsInode;
 400         struct cifsFileInfo *netfile;
 401
 402         cifs_dbg(FYI, "Checking for oplock break or dnotify response\n");
 403         if ((pSMB->hdr.Command == SMB_COM_NT_TRANSACT) &&
 404            (pSMB->hdr.Flags & SMBFLG_RESPONSE)) {
 405                 struct smb_com_transaction_change_notify_rsp *pSMBr =
 406                         (struct smb_com_transaction_change_notify_rsp *)buf;
 407                 struct file_notify_information *pnotify;
 408                 __u32 data_offset = 0;
 409                 size_t len = srv->total_read - sizeof(pSMBr->hdr.smb_buf_length);
 410
 411                 if (get_bcc(buf) > sizeof(struct file_notify_information)) {
 412                         data_offset = le32_to_cpu(pSMBr->DataOffset);
 413
 414                         if (data_offset >
 415                             len - sizeof(struct file_notify_information)) {
 416                                 cifs_dbg(FYI, "Invalid data_offset %u\n",
 417                                          data_offset);
 418                                 return true;
 419                         }
 420                         pnotify = (struct file_notify_information *)
 421                                 ((char *)&pSMBr->hdr.Protocol + data_offset);
 422                         cifs_dbg(FYI, "dnotify on %s Action: 0x%x\n",
 423                                  pnotify->FileName, pnotify->Action);
 424                         /*   cifs_dump_mem("Rcvd notify Data: ",buf,
 425                                 sizeof(struct smb_hdr)+60); */
 426                         return true;
 427                 }
 428                 if (pSMBr->hdr.Status.CifsError) {
 429                         cifs_dbg(FYI, "notify err 0x%x\n",
 430                                  pSMBr->hdr.Status.CifsError);
 431                         return true;
 432                 }
 433                 return false;
 434         }
 435         if (pSMB->hdr.Command != SMB_COM_LOCKING_ANDX)
 436                 return false;
 437         if (pSMB->hdr.Flags & SMBFLG_RESPONSE) {
 438                 /* no sense logging error on invalid handle on oplock
 439                    break - harmless race between close request and oplock
 440                    break response is expected from time to time writing out
 441                    large dirty files cached on the client */
 442                 if ((NT_STATUS_INVALID_HANDLE) ==
 443                    le32_to_cpu(pSMB->hdr.Status.CifsError)) {
 444                         cifs_dbg(FYI, "Invalid handle on oplock break\n");
 445                         return true;
 446                 } else if (ERRbadfid ==
 447                    le16_to_cpu(pSMB->hdr.Status.DosError.Error)) {
 448                         return true;
 449                 } else {
 450                         return false; /* on valid oplock brk we get "request" */
 451                 }
 452         }
 453         if (pSMB->hdr.WordCount != 8)
 454                 return false;
 455
 456         cifs_dbg(FYI, "oplock type 0x%x level 0x%x\n",
 457                  pSMB->LockType, pSMB->OplockLevel);
 458         if (!(pSMB->LockType & LOCKING_ANDX_OPLOCK_RELEASE))
 459                 return false;
 460
 461         /* look up tcon based on tid & uid */
 462         spin_lock(&cifs_tcp_ses_lock);
 463         list_for_each(tmp, &srv->smb_ses_list) {
 464                 ses = list_entry(tmp, struct cifs_ses, smb_ses_list);
 465                 list_for_each(tmp1, &ses->tcon_list) {
 466                         tcon = list_entry(tmp1, struct cifs_tcon, tcon_list);
 467                         if (tcon->tid != buf->Tid)
 468                                 continue;
 469
 470                         cifs_stats_inc(&tcon->stats.cifs_stats.num_oplock_brks);
 471                         spin_lock(&tcon->open_file_lock);
 472                         list_for_each(tmp2, &tcon->openFileList) {
 473                                 netfile = list_entry(tmp2, struct cifsFileInfo,
 474                                                      tlist);
 475                                 if (pSMB->Fid != netfile->fid.netfid)
 476                                         continue;
 477
 478                                 cifs_dbg(FYI, "file id match, oplock break\n");
 479                                 pCifsInode = CIFS_I(d_inode(netfile->dentry));
 480
 481                                 set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK,
 482                                         &pCifsInode->flags);
 483
 484                                 netfile->oplock_epoch = 0;
 485                                 netfile->oplock_level = pSMB->OplockLevel;
 486                                 netfile->oplock_break_cancelled = false;
 487                                 cifs_queue_oplock_break(netfile);
 488
 489                                 spin_unlock(&tcon->open_file_lock);
 490                                 spin_unlock(&cifs_tcp_ses_lock);
 491                                 return true;
 492                         }
 493                         spin_unlock(&tcon->open_file_lock);
 494                         spin_unlock(&cifs_tcp_ses_lock);
 495                         cifs_dbg(FYI, "No matching file for oplock break\n");
 496                         return true;
 497                 }
 498         }
 499         spin_unlock(&cifs_tcp_ses_lock);
 500         cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");
 501         return true;
 502 }
 503
 504 void
 505 dump_smb(void *buf, int smb_buf_length)
 506 {
 507         if (traceSMB == 0)
 508                 return;
 509
 510         print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_NONE, 8, 2, buf,
 511                        smb_buf_length, true);
 512 }
 513
 514 void
 515 cifs_autodisable_serverino(struct cifs_sb_info *cifs_sb)
 516 {
 517         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) {
 518                 struct cifs_tcon *tcon = NULL;
 519
 520                 if (cifs_sb->master_tlink)
 521                         tcon = cifs_sb_master_tcon(cifs_sb);
 522
 523                 cifs_sb->mnt_cifs_flags &= ~CIFS_MOUNT_SERVER_INUM;
 524                 cifs_sb->mnt_cifs_serverino_autodisabled = true;
 525                 cifs_dbg(VFS, "Autodisabling the use of server inode numbers on %s\n",
 526                          tcon ? tcon->treeName : "new server");
 527                 cifs_dbg(VFS, "The server doesn't seem to support them properly or the files might be on different servers (DFS)\n");
 528                 cifs_dbg(VFS, "Hardlinks will not be recognized on this mount. Consider mounting with the \"noserverino\" option to silence this message.\n");
 529
 530         }
 531 }
 532
 533 void cifs_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock)
 534 {
 535         oplock &= 0xF;
 536
 537         if (oplock == OPLOCK_EXCLUSIVE) {
 538                 cinode->oplock = CIFS_CACHE_WRITE_FLG | CIFS_CACHE_READ_FLG;
 539                 cifs_dbg(FYI, "Exclusive Oplock granted on inode %p\n",
 540                          &cinode->vfs_inode);
 541         } else if (oplock == OPLOCK_READ) {
 542                 cinode->oplock = CIFS_CACHE_READ_FLG;
 543                 cifs_dbg(FYI, "Level II Oplock granted on inode %p\n",
 544                          &cinode->vfs_inode);
 545         } else
 546                 cinode->oplock = 0;
 547 }
 548
 549 /*
 550  * We wait for oplock breaks to be processed before we attempt to perform
 551  * writes.
 552  */
 553 int cifs_get_writer(struct cifsInodeInfo *cinode)
 554 {
 555         int rc;
 556
 557 start:
 558         rc = wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK,
 559                          TASK_KILLABLE);
 560         if (rc)
 561                 return rc;
 562
 563         spin_lock(&cinode->writers_lock);
 564         if (!cinode->writers)
 565                 set_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 566         cinode->writers++;
 567         /* Check to see if we have started servicing an oplock break */
 568         if (test_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags)) {
 569                 cinode->writers--;
 570                 if (cinode->writers == 0) {
 571                         clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 572                         wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
 573                 }
 574                 spin_unlock(&cinode->writers_lock);
 575                 goto start;
 576         }
 577         spin_unlock(&cinode->writers_lock);
 578         return 0;
 579 }
 580
 581 void cifs_put_writer(struct cifsInodeInfo *cinode)
 582 {
 583         spin_lock(&cinode->writers_lock);
 584         cinode->writers--;
 585         if (cinode->writers == 0) {
 586                 clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 587                 wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
 588         }
 589         spin_unlock(&cinode->writers_lock);
 590 }
 591
 592 /**
 593  * cifs_queue_oplock_break - queue the oplock break handler for cfile
 594  *
 595  * This function is called from the demultiplex thread when it
 596  * receives an oplock break for @cfile.
 597  *
 598  * Assumes the tcon->open_file_lock is held.
 599  * Assumes cfile->file_info_lock is NOT held.
 600  */
 601 void cifs_queue_oplock_break(struct cifsFileInfo *cfile)
 602 {
 603         /*
 604          * Bump the handle refcount now while we hold the
 605          * open_file_lock to enforce the validity of it for the oplock
 606          * break handler. The matching put is done at the end of the
 607          * handler.
 608          */
 609         cifsFileInfo_get(cfile);
 610
 611         queue_work(cifsoplockd_wq, &cfile->oplock_break);
 612 }
 613
 614 void cifs_done_oplock_break(struct cifsInodeInfo *cinode)
 615 {
 616         clear_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags);
 617         wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK);
 618 }
 619
 620 bool
 621 backup_cred(struct cifs_sb_info *cifs_sb)
 622 {
 623         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPUID) {
 624                 if (uid_eq(cifs_sb->ctx->backupuid, current_fsuid()))
 625                         return true;
 626         }
 627         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPGID) {
 628                 if (in_group_p(cifs_sb->ctx->backupgid))
 629                         return true;
 630         }
 631
 632         return false;
 633 }
 634
 635 void
 636 cifs_del_pending_open(struct cifs_pending_open *open)
 637 {
 638         spin_lock(&tlink_tcon(open->tlink)->open_file_lock);
 639         list_del(&open->olist);
 640         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 641 }
 642
 643 void
 644 cifs_add_pending_open_locked(struct cifs_fid *fid, struct tcon_link *tlink,
 645                              struct cifs_pending_open *open)
 646 {
 647         memcpy(open->lease_key, fid->lease_key, SMB2_LEASE_KEY_SIZE);
 648         open->oplock = CIFS_OPLOCK_NO_CHANGE;
 649         open->tlink = tlink;
 650         fid->pending_open = open;
 651         list_add_tail(&open->olist, &tlink_tcon(tlink)->pending_opens);
 652 }
 653
 654 void
 655 cifs_add_pending_open(struct cifs_fid *fid, struct tcon_link *tlink,
 656                       struct cifs_pending_open *open)
 657 {
 658         spin_lock(&tlink_tcon(tlink)->open_file_lock);
 659         cifs_add_pending_open_locked(fid, tlink, open);
 660         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 661 }
 662
 663 /*
 664  * Critical section which runs after acquiring deferred_lock.
 665  * As there is no reference count on cifs_deferred_close, pdclose
 666  * should not be used outside deferred_lock.
 667  */
 668 bool
 669 cifs_is_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close **pdclose)
 670 {
 671         struct cifs_deferred_close *dclose;
 672
 673         list_for_each_entry(dclose, &CIFS_I(d_inode(cfile->dentry))->deferred_closes, dlist) {
 674                 if ((dclose->netfid == cfile->fid.netfid) &&
 675                         (dclose->persistent_fid == cfile->fid.persistent_fid) &&
 676                         (dclose->volatile_fid == cfile->fid.volatile_fid)) {
 677                         *pdclose = dclose;
 678                         return true;
 679                 }
 680         }
 681         return false;
 682 }
 683
 684 /*
 685  * Critical section which runs after acquiring deferred_lock.
 686  */
 687 void
 688 cifs_add_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close *dclose)
 689 {
 690         bool is_deferred = false;
 691         struct cifs_deferred_close *pdclose;
 692
 693         is_deferred = cifs_is_deferred_close(cfile, &pdclose);
 694         if (is_deferred) {
 695                 kfree(dclose);
 696                 return;
 697         }
 698
 699         dclose->tlink = cfile->tlink;
 700         dclose->netfid = cfile->fid.netfid;
 701         dclose->persistent_fid = cfile->fid.persistent_fid;
 702         dclose->volatile_fid = cfile->fid.volatile_fid;
 703         list_add_tail(&dclose->dlist, &CIFS_I(d_inode(cfile->dentry))->deferred_closes);
 704 }
 705
 706 /*
 707  * Critical section which runs after acquiring deferred_lock.
 708  */
 709 void
 710 cifs_del_deferred_close(struct cifsFileInfo *cfile)
 711 {
 712         bool is_deferred = false;
 713         struct cifs_deferred_close *dclose;
 714
 715         is_deferred = cifs_is_deferred_close(cfile, &dclose);
 716         if (!is_deferred)
 717                 return;
 718         list_del(&dclose->dlist);
 719         kfree(dclose);
 720 }
 721
 722 void
 723 cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode)
 724 {
 725         struct cifsFileInfo *cfile = NULL;
 726         struct cifs_deferred_close *dclose;
 727
 728         list_for_each_entry(cfile, &cifs_inode->openFileList, flist) {
 729                 spin_lock(&cifs_inode->deferred_lock);
 730                 if (cifs_is_deferred_close(cfile, &dclose))
 731                         mod_delayed_work(deferredclose_wq, &cfile->deferred, 0);
 732                 spin_unlock(&cifs_inode->deferred_lock);
 733         }
 734 }
 735
 736 void
 737 cifs_close_all_deferred_files(struct cifs_tcon *tcon)
 738 {
 739         struct cifsFileInfo *cfile;
 740         struct list_head *tmp;
 741
 742         spin_lock(&tcon->open_file_lock);
 743         list_for_each(tmp, &tcon->openFileList) {
 744                 cfile = list_entry(tmp, struct cifsFileInfo, tlist);
 745                 if (delayed_work_pending(&cfile->deferred)) {
 746                         /*
 747                          * If there is no pending work, mod_delayed_work queues new work.
 748                          * So, Increase the ref count to avoid use-after-free.
 749                          */
 750                         if (!mod_delayed_work(deferredclose_wq, &cfile->deferred, 0))
 751                                 cifsFileInfo_get(cfile);
 752                 }
 753         }
 754         spin_unlock(&tcon->open_file_lock);
 755 }
 756
 757 /* parses DFS refferal V3 structure
 758  * caller is responsible for freeing target_nodes
 759  * returns:
 760  * - on success - 0
 761  * - on failure - errno
 762  */
 763 int
 764 parse_dfs_referrals(struct get_dfs_referral_rsp *rsp, u32 rsp_size,
 765                     unsigned int *num_of_nodes,
 766                     struct dfs_info3_param **target_nodes,
 767                     const struct nls_table *nls_codepage, int remap,
 768                     const char *searchName, bool is_unicode)
 769 {
 770         int i, rc = 0;
 771         char *data_end;
 772         struct dfs_referral_level_3 *ref;
 773
 774         *num_of_nodes = le16_to_cpu(rsp->NumberOfReferrals);
 775
 776         if (*num_of_nodes < 1) {
 777                 cifs_dbg(VFS, "num_referrals: must be at least > 0, but we get num_referrals = %d\n",
 778                          *num_of_nodes);
 779                 rc = -EINVAL;
 780                 goto parse_DFS_referrals_exit;
 781         }
 782
 783         ref = (struct dfs_referral_level_3 *) &(rsp->referrals);
 784         if (ref->VersionNumber != cpu_to_le16(3)) {
 785                 cifs_dbg(VFS, "Referrals of V%d version are not supported, should be V3\n",
 786                          le16_to_cpu(ref->VersionNumber));
 787                 rc = -EINVAL;
 788                 goto parse_DFS_referrals_exit;
 789         }
 790
 791         /* get the upper boundary of the resp buffer */
 792         data_end = (char *)rsp + rsp_size;
 793
 794         cifs_dbg(FYI, "num_referrals: %d dfs flags: 0x%x ...\n",
 795                  *num_of_nodes, le32_to_cpu(rsp->DFSFlags));
 796
 797         *target_nodes = kcalloc(*num_of_nodes, sizeof(struct dfs_info3_param),
 798                                 GFP_KERNEL);
 799         if (*target_nodes == NULL) {
 800                 rc = -ENOMEM;
 801                 goto parse_DFS_referrals_exit;
 802         }
 803
 804         /* collect necessary data from referrals */
 805         for (i = 0; i < *num_of_nodes; i++) {
 806                 char *temp;
 807                 int max_len;
 808                 struct dfs_info3_param *node = (*target_nodes)+i;
 809
 810                 node->flags = le32_to_cpu(rsp->DFSFlags);
 811                 if (is_unicode) {
 812                         __le16 *tmp = kmalloc(strlen(searchName)*2 + 2,
 813                                                 GFP_KERNEL);
 814                         if (tmp == NULL) {
 815                                 rc = -ENOMEM;
 816                                 goto parse_DFS_referrals_exit;
 817                         }
 818                         cifsConvertToUTF16((__le16 *) tmp, searchName,
 819                                            PATH_MAX, nls_codepage, remap);
 820                         node->path_consumed = cifs_utf16_bytes(tmp,
 821                                         le16_to_cpu(rsp->PathConsumed),
 822                                         nls_codepage);
 823                         kfree(tmp);
 824                 } else
 825                         node->path_consumed = le16_to_cpu(rsp->PathConsumed);
 826
 827                 node->server_type = le16_to_cpu(ref->ServerType);
 828                 node->ref_flag = le16_to_cpu(ref->ReferralEntryFlags);
 829
 830                 /* copy DfsPath */
 831                 temp = (char *)ref + le16_to_cpu(ref->DfsPathOffset);
 832                 max_len = data_end - temp;
 833                 node->path_name = cifs_strndup_from_utf16(temp, max_len,
 834                                                 is_unicode, nls_codepage);
 835                 if (!node->path_name) {
 836                         rc = -ENOMEM;
 837                         goto parse_DFS_referrals_exit;
 838                 }
 839
 840                 /* copy link target UNC */
 841                 temp = (char *)ref + le16_to_cpu(ref->NetworkAddressOffset);
 842                 max_len = data_end - temp;
 843                 node->node_name = cifs_strndup_from_utf16(temp, max_len,
 844                                                 is_unicode, nls_codepage);
 845                 if (!node->node_name) {
 846                         rc = -ENOMEM;
 847                         goto parse_DFS_referrals_exit;
 848                 }
 849
 850                 node->ttl = le32_to_cpu(ref->TimeToLive);
 851
 852                 ref++;
 853         }
 854
 855 parse_DFS_referrals_exit:
 856         if (rc) {
 857                 free_dfs_info_array(*target_nodes, *num_of_nodes);
 858                 *target_nodes = NULL;
 859                 *num_of_nodes = 0;
 860         }
 861         return rc;
 862 }
 863
 864 struct cifs_aio_ctx *
 865 cifs_aio_ctx_alloc(void)
 866 {
 867         struct cifs_aio_ctx *ctx;
 868
 869         /*
 870          * Must use kzalloc to initialize ctx->bv to NULL and ctx->direct_io
 871          * to false so that we know when we have to unreference pages within
 872          * cifs_aio_ctx_release()
 873          */
 874         ctx = kzalloc(sizeof(struct cifs_aio_ctx), GFP_KERNEL);
 875         if (!ctx)
 876                 return NULL;
 877
 878         INIT_LIST_HEAD(&ctx->list);
 879         mutex_init(&ctx->aio_mutex);
 880         init_completion(&ctx->done);
 881         kref_init(&ctx->refcount);
 882         return ctx;
 883 }
 884
 885 void
 886 cifs_aio_ctx_release(struct kref *refcount)
 887 {
 888         struct cifs_aio_ctx *ctx = container_of(refcount,
 889                                         struct cifs_aio_ctx, refcount);
 890
 891         cifsFileInfo_put(ctx->cfile);
 892
 893         /*
 894          * ctx->bv is only set if setup_aio_ctx_iter() was call successfuly
 895          * which means that iov_iter_get_pages() was a success and thus that
 896          * we have taken reference on pages.
 897          */
 898         if (ctx->bv) {
 899                 unsigned i;
 900
 901                 for (i = 0; i < ctx->npages; i++) {
 902                         if (ctx->should_dirty)
 903                                 set_page_dirty(ctx->bv[i].bv_page);
 904                         put_page(ctx->bv[i].bv_page);
 905                 }
 906                 kvfree(ctx->bv);
 907         }
 908
 909         kfree(ctx);
 910 }
 911
 912 #define CIFS_AIO_KMALLOC_LIMIT (1024 * 1024)
 913
 914 int
 915 setup_aio_ctx_iter(struct cifs_aio_ctx *ctx, struct iov_iter *iter, int rw)
 916 {
 917         ssize_t rc;
 918         unsigned int cur_npages;
 919         unsigned int npages = 0;
 920         unsigned int i;
 921         size_t len;
 922         size_t count = iov_iter_count(iter);
 923         unsigned int saved_len;
 924         size_t start;
 925         unsigned int max_pages = iov_iter_npages(iter, INT_MAX);
 926         struct page **pages = NULL;
 927         struct bio_vec *bv = NULL;
 928
 929         if (iov_iter_is_kvec(iter)) {
 930                 memcpy(&ctx->iter, iter, sizeof(*iter));
 931                 ctx->len = count;
 932                 iov_iter_advance(iter, count);
 933                 return 0;
 934         }
 935
 936         if (array_size(max_pages, sizeof(*bv)) <= CIFS_AIO_KMALLOC_LIMIT)
 937                 bv = kmalloc_array(max_pages, sizeof(*bv), GFP_KERNEL);
 938
 939         if (!bv) {
 940                 bv = vmalloc(array_size(max_pages, sizeof(*bv)));
 941                 if (!bv)
 942                         return -ENOMEM;
 943         }
 944
 945         if (array_size(max_pages, sizeof(*pages)) <= CIFS_AIO_KMALLOC_LIMIT)
 946                 pages = kmalloc_array(max_pages, sizeof(*pages), GFP_KERNEL);
 947
 948         if (!pages) {
 949                 pages = vmalloc(array_size(max_pages, sizeof(*pages)));
 950                 if (!pages) {
 951                         kvfree(bv);
 952                         return -ENOMEM;
 953                 }
 954         }
 955
 956         saved_len = count;
 957
 958         while (count && npages < max_pages) {
 959                 rc = iov_iter_get_pages(iter, pages, count, max_pages, &start);
 960                 if (rc < 0) {
 961                         cifs_dbg(VFS, "Couldn't get user pages (rc=%zd)\n", rc);
 962                         break;
 963                 }
 964
 965                 if (rc > count) {
 966                         cifs_dbg(VFS, "get pages rc=%zd more than %zu\n", rc,
 967                                  count);
 968                         break;
 969                 }
 970
 971                 iov_iter_advance(iter, rc);
 972                 count -= rc;
 973                 rc += start;
 974                 cur_npages = DIV_ROUND_UP(rc, PAGE_SIZE);
 975
 976                 if (npages + cur_npages > max_pages) {
 977                         cifs_dbg(VFS, "out of vec array capacity (%u vs %u)\n",
 978                                  npages + cur_npages, max_pages);
 979                         break;
 980                 }
 981
 982                 for (i = 0; i < cur_npages; i++) {
 983                         len = rc > PAGE_SIZE ? PAGE_SIZE : rc;
 984                         bv[npages + i].bv_page = pages[i];
 985                         bv[npages + i].bv_offset = start;
 986                         bv[npages + i].bv_len = len - start;
 987                         rc -= len;
 988                         start = 0;
 989                 }
 990
 991                 npages += cur_npages;
 992         }
 993
 994         kvfree(pages);
 995         ctx->bv = bv;
 996         ctx->len = saved_len - count;
 997         ctx->npages = npages;
 998         iov_iter_bvec(&ctx->iter, rw, ctx->bv, npages, ctx->len);
 999         return 0;
1000 }
1001
1002 /**
1003  * cifs_alloc_hash - allocate hash and hash context together
1004  *
1005  * The caller has to make sure @sdesc is initialized to either NULL or
1006  * a valid context. Both can be freed via cifs_free_hash().
1007  */
1008 int
1009 cifs_alloc_hash(const char *name,
1010                 struct crypto_shash **shash, struct sdesc **sdesc)
1011 {
1012         int rc = 0;
1013         size_t size;
1014
1015         if (*sdesc != NULL)
1016                 return 0;
1017
1018         *shash = crypto_alloc_shash(name, 0, 0);
1019         if (IS_ERR(*shash)) {
1020                 cifs_dbg(VFS, "Could not allocate crypto %s\n", name);
1021                 rc = PTR_ERR(*shash);
1022                 *shash = NULL;
1023                 *sdesc = NULL;
1024                 return rc;
1025         }
1026
1027         size = sizeof(struct shash_desc) + crypto_shash_descsize(*shash);
1028         *sdesc = kmalloc(size, GFP_KERNEL);
1029         if (*sdesc == NULL) {
1030                 cifs_dbg(VFS, "no memory left to allocate crypto %s\n", name);
1031                 crypto_free_shash(*shash);
1032                 *shash = NULL;
1033                 return -ENOMEM;
1034         }
1035
1036         (*sdesc)->shash.tfm = *shash;
1037         return 0;
1038 }
1039
1040 /**
1041  * cifs_free_hash - free hash and hash context together
1042  *
1043  * Freeing a NULL hash or context is safe.
1044  */
1045 void
1046 cifs_free_hash(struct crypto_shash **shash, struct sdesc **sdesc)
1047 {
1048         kfree(*sdesc);
1049         *sdesc = NULL;
1050         if (*shash)
1051                 crypto_free_shash(*shash);
1052         *shash = NULL;
1053 }
1054
1055 /**
1056  * rqst_page_get_length - obtain the length and offset for a page in smb_rqst
1057  * Input: rqst - a smb_rqst, page - a page index for rqst
1058  * Output: *len - the length for this page, *offset - the offset for this page
1059  */
1060 void rqst_page_get_length(struct smb_rqst *rqst, unsigned int page,
1061                                 unsigned int *len, unsigned int *offset)
1062 {
1063         *len = rqst->rq_pagesz;
1064         *offset = (page == 0) ? rqst->rq_offset : 0;
1065
1066         if (rqst->rq_npages == 1 || page == rqst->rq_npages-1)
1067                 *len = rqst->rq_tailsz;
1068         else if (page == 0)
1069                 *len = rqst->rq_pagesz - rqst->rq_offset;
1070 }
1071
1072 void extract_unc_hostname(const char *unc, const char **h, size_t *len)
1073 {
1074         const char *end;
1075
1076         /* skip initial slashes */
1077         while (*unc && (*unc == '\\' || *unc == '/'))
1078                 unc++;
1079
1080         end = unc;
1081
1082         while (*end && !(*end == '\\' || *end == '/'))
1083                 end++;
1084
1085         *h = unc;
1086         *len = end - unc;
1087 }
1088
1089 /**
1090  * copy_path_name - copy src path to dst, possibly truncating
1091  *
1092  * returns number of bytes written (including trailing nul)
1093  */
1094 int copy_path_name(char *dst, const char *src)
1095 {
1096         int name_len;
1097
1098         /*
1099          * PATH_MAX includes nul, so if strlen(src) >= PATH_MAX it
1100          * will truncate and strlen(dst) will be PATH_MAX-1
1101          */
1102         name_len = strscpy(dst, src, PATH_MAX);
1103         if (WARN_ON_ONCE(name_len < 0))
1104                 name_len = PATH_MAX-1;
1105
1106         /* we count the trailing nul */
1107         name_len++;
1108         return name_len;
1109 }
1110
1111 struct super_cb_data {
1112         void *data;
1113         struct super_block *sb;
1114 };
1115
1116 static void tcp_super_cb(struct super_block *sb, void *arg)
1117 {
1118         struct super_cb_data *sd = arg;
1119         struct TCP_Server_Info *server = sd->data;
1120         struct cifs_sb_info *cifs_sb;
1121         struct cifs_tcon *tcon;
1122
1123         if (sd->sb)
1124                 return;
1125
1126         cifs_sb = CIFS_SB(sb);
1127         tcon = cifs_sb_master_tcon(cifs_sb);
1128         if (tcon->ses->server == server)
1129                 sd->sb = sb;
1130 }
1131
1132 static struct super_block *__cifs_get_super(void (*f)(struct super_block *, void *),
1133                                             void *data)
1134 {
1135         struct super_cb_data sd = {
1136                 .data = data,
1137                 .sb = NULL,
1138         };
1139
1140         iterate_supers_type(&cifs_fs_type, f, &sd);
1141
1142         if (!sd.sb)
1143                 return ERR_PTR(-EINVAL);
1144         /*
1145          * Grab an active reference in order to prevent automounts (DFS links)
1146          * of expiring and then freeing up our cifs superblock pointer while
1147          * we're doing failover.
1148          */
1149         cifs_sb_active(sd.sb);
1150         return sd.sb;
1151 }
1152
1153 static void __cifs_put_super(struct super_block *sb)
1154 {
1155         if (!IS_ERR_OR_NULL(sb))
1156                 cifs_sb_deactive(sb);
1157 }
1158
1159 struct super_block *cifs_get_tcp_super(struct TCP_Server_Info *server)
1160 {
1161         return __cifs_get_super(tcp_super_cb, server);
1162 }
1163
1164 void cifs_put_tcp_super(struct super_block *sb)
1165 {
1166         __cifs_put_super(sb);
1167 }
1168
1169 #ifdef CONFIG_CIFS_DFS_UPCALL
1170 int match_target_ip(struct TCP_Server_Info *server,
1171                     const char *share, size_t share_len,
1172                     bool *result)
1173 {
1174         int rc;
1175         char *target, *tip = NULL;
1176         struct sockaddr tipaddr;
1177
1178         *result = false;
1179
1180         target = kzalloc(share_len + 3, GFP_KERNEL);
1181         if (!target) {
1182                 rc = -ENOMEM;
1183                 goto out;
1184         }
1185
1186         scnprintf(target, share_len + 3, "\\\\%.*s", (int)share_len, share);
1187
1188         cifs_dbg(FYI, "%s: target name: %s\n", __func__, target + 2);
1189
1190         rc = dns_resolve_server_name_to_ip(target, &tip);
1191         if (rc < 0)
1192                 goto out;
1193
1194         cifs_dbg(FYI, "%s: target ip: %s\n", __func__, tip);
1195
1196         if (!cifs_convert_address(&tipaddr, tip, strlen(tip))) {
1197                 cifs_dbg(VFS, "%s: failed to convert target ip address\n",
1198                          __func__);
1199                 rc = -EINVAL;
1200                 goto out;
1201         }
1202
1203         *result = cifs_match_ipaddr((struct sockaddr *)&server->dstaddr,
1204                                     &tipaddr);
1205         cifs_dbg(FYI, "%s: ip addresses match: %u\n", __func__, *result);
1206         rc = 0;
1207
1208 out:
1209         kfree(target);
1210         kfree(tip);
1211
1212         return rc;
1213 }
1214
1215 static void tcon_super_cb(struct super_block *sb, void *arg)
1216 {
1217         struct super_cb_data *sd = arg;
1218         struct cifs_tcon *tcon = sd->data;
1219         struct cifs_sb_info *cifs_sb;
1220
1221         if (sd->sb)
1222                 return;
1223
1224         cifs_sb = CIFS_SB(sb);
1225         if (tcon->dfs_path && cifs_sb->origin_fullpath &&
1226             !strcasecmp(tcon->dfs_path, cifs_sb->origin_fullpath))
1227                 sd->sb = sb;
1228 }
1229
1230 static inline struct super_block *cifs_get_tcon_super(struct cifs_tcon *tcon)
1231 {
1232         return __cifs_get_super(tcon_super_cb, tcon);
1233 }
1234
1235 static inline void cifs_put_tcon_super(struct super_block *sb)
1236 {
1237         __cifs_put_super(sb);
1238 }
1239 #else
1240 static inline struct super_block *cifs_get_tcon_super(struct cifs_tcon *tcon)
1241 {
1242         return ERR_PTR(-EOPNOTSUPP);
1243 }
1244
1245 static inline void cifs_put_tcon_super(struct super_block *sb)
1246 {
1247 }
1248 #endif
1249
1250 int update_super_prepath(struct cifs_tcon *tcon, char *prefix)
1251 {
1252         struct super_block *sb;
1253         struct cifs_sb_info *cifs_sb;
1254         int rc = 0;
1255
1256         sb = cifs_get_tcon_super(tcon);
1257         if (IS_ERR(sb))
1258                 return PTR_ERR(sb);
1259
1260         cifs_sb = CIFS_SB(sb);
1261
1262         kfree(cifs_sb->prepath);
1263
1264         if (prefix && *prefix) {
1265                 cifs_sb->prepath = kstrdup(prefix, GFP_ATOMIC);
1266                 if (!cifs_sb->prepath) {
1267                         rc = -ENOMEM;
1268                         goto out;
1269                 }
1270
1271                 convert_delimiter(cifs_sb->prepath, CIFS_DIR_SEP(cifs_sb));
1272         } else
1273                 cifs_sb->prepath = NULL;
1274
1275         cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
1276
1277 out:
1278         cifs_put_tcon_super(sb);
1279         return rc;
1280 }