fs/cifs/misc.c

   1 // SPDX-License-Identifier: LGPL-2.1
   2 /*
   3  *
   4  *   Copyright (C) International Business Machines  Corp., 2002,2008
   5  *   Author(s): Steve French (sfrench@us.ibm.com)
   6  *
   7  */
   8
   9 #include <linux/slab.h>
  10 #include <linux/ctype.h>
  11 #include <linux/mempool.h>
  12 #include <linux/vmalloc.h>
  13 #include "cifspdu.h"
  14 #include "cifsglob.h"
  15 #include "cifsproto.h"
  16 #include "cifs_debug.h"
  17 #include "smberr.h"
  18 #include "nterr.h"
  19 #include "cifs_unicode.h"
  20 #include "smb2pdu.h"
  21 #include "cifsfs.h"
  22 #ifdef CONFIG_CIFS_DFS_UPCALL
  23 #include "dns_resolve.h"
  24 #endif
  25 #include "fs_context.h"
  26 #include "cached_dir.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                 spin_lock_init(&ret_buf->ses_lock);
  74                 ret_buf->ses_status = SES_NEW;
  75                 ++ret_buf->ses_count;
  76                 INIT_LIST_HEAD(&ret_buf->smb_ses_list);
  77                 INIT_LIST_HEAD(&ret_buf->tcon_list);
  78                 mutex_init(&ret_buf->session_mutex);
  79                 spin_lock_init(&ret_buf->iface_lock);
  80                 INIT_LIST_HEAD(&ret_buf->iface_list);
  81                 spin_lock_init(&ret_buf->chan_lock);
  82         }
  83         return ret_buf;
  84 }
  85
  86 void
  87 sesInfoFree(struct cifs_ses *buf_to_free)
  88 {
  89         struct cifs_server_iface *iface = NULL, *niface = NULL;
  90
  91         if (buf_to_free == NULL) {
  92                 cifs_dbg(FYI, "Null buffer passed to sesInfoFree\n");
  93                 return;
  94         }
  95
  96         atomic_dec(&sesInfoAllocCount);
  97         kfree(buf_to_free->serverOS);
  98         kfree(buf_to_free->serverDomain);
  99         kfree(buf_to_free->serverNOS);
 100         kfree_sensitive(buf_to_free->password);
 101         kfree(buf_to_free->user_name);
 102         kfree(buf_to_free->domainName);
 103         kfree_sensitive(buf_to_free->auth_key.response);
 104         spin_lock(&buf_to_free->iface_lock);
 105         list_for_each_entry_safe(iface, niface, &buf_to_free->iface_list,
 106                                  iface_head)
 107                 kref_put(&iface->refcount, release_iface);
 108         spin_unlock(&buf_to_free->iface_lock);
 109         kfree_sensitive(buf_to_free);
 110 }
 111
 112 struct cifs_tcon *
 113 tconInfoAlloc(void)
 114 {
 115         struct cifs_tcon *ret_buf;
 116
 117         ret_buf = kzalloc(sizeof(*ret_buf), GFP_KERNEL);
 118         if (!ret_buf)
 119                 return NULL;
 120         ret_buf->cfids = init_cached_dirs();
 121         if (!ret_buf->cfids) {
 122                 kfree(ret_buf);
 123                 return NULL;
 124         }
 125
 126         atomic_inc(&tconInfoAllocCount);
 127         ret_buf->status = TID_NEW;
 128         ++ret_buf->tc_count;
 129         spin_lock_init(&ret_buf->tc_lock);
 130         INIT_LIST_HEAD(&ret_buf->openFileList);
 131         INIT_LIST_HEAD(&ret_buf->tcon_list);
 132         spin_lock_init(&ret_buf->open_file_lock);
 133         spin_lock_init(&ret_buf->stat_lock);
 134         atomic_set(&ret_buf->num_local_opens, 0);
 135         atomic_set(&ret_buf->num_remote_opens, 0);
 136
 137         return ret_buf;
 138 }
 139
 140 void
 141 tconInfoFree(struct cifs_tcon *tcon)
 142 {
 143         if (tcon == NULL) {
 144                 cifs_dbg(FYI, "Null buffer passed to tconInfoFree\n");
 145                 return;
 146         }
 147         free_cached_dirs(tcon->cfids);
 148         atomic_dec(&tconInfoAllocCount);
 149         kfree(tcon->nativeFileSystem);
 150         kfree_sensitive(tcon->password);
 151         kfree(tcon);
 152 }
 153
 154 struct smb_hdr *
 155 cifs_buf_get(void)
 156 {
 157         struct smb_hdr *ret_buf = NULL;
 158         /*
 159          * SMB2 header is bigger than CIFS one - no problems to clean some
 160          * more bytes for CIFS.
 161          */
 162         size_t buf_size = sizeof(struct smb2_hdr);
 163
 164         /*
 165          * We could use negotiated size instead of max_msgsize -
 166          * but it may be more efficient to always alloc same size
 167          * albeit slightly larger than necessary and maxbuffersize
 168          * defaults to this and can not be bigger.
 169          */
 170         ret_buf = mempool_alloc(cifs_req_poolp, GFP_NOFS);
 171
 172         /* clear the first few header bytes */
 173         /* for most paths, more is cleared in header_assemble */
 174         memset(ret_buf, 0, buf_size + 3);
 175         atomic_inc(&buf_alloc_count);
 176 #ifdef CONFIG_CIFS_STATS2
 177         atomic_inc(&total_buf_alloc_count);
 178 #endif /* CONFIG_CIFS_STATS2 */
 179
 180         return ret_buf;
 181 }
 182
 183 void
 184 cifs_buf_release(void *buf_to_free)
 185 {
 186         if (buf_to_free == NULL) {
 187                 /* cifs_dbg(FYI, "Null buffer passed to cifs_buf_release\n");*/
 188                 return;
 189         }
 190         mempool_free(buf_to_free, cifs_req_poolp);
 191
 192         atomic_dec(&buf_alloc_count);
 193         return;
 194 }
 195
 196 struct smb_hdr *
 197 cifs_small_buf_get(void)
 198 {
 199         struct smb_hdr *ret_buf = NULL;
 200
 201 /* We could use negotiated size instead of max_msgsize -
 202    but it may be more efficient to always alloc same size
 203    albeit slightly larger than necessary and maxbuffersize
 204    defaults to this and can not be bigger */
 205         ret_buf = mempool_alloc(cifs_sm_req_poolp, GFP_NOFS);
 206         /* No need to clear memory here, cleared in header assemble */
 207         /*      memset(ret_buf, 0, sizeof(struct smb_hdr) + 27);*/
 208         atomic_inc(&small_buf_alloc_count);
 209 #ifdef CONFIG_CIFS_STATS2
 210         atomic_inc(&total_small_buf_alloc_count);
 211 #endif /* CONFIG_CIFS_STATS2 */
 212
 213         return ret_buf;
 214 }
 215
 216 void
 217 cifs_small_buf_release(void *buf_to_free)
 218 {
 219
 220         if (buf_to_free == NULL) {
 221                 cifs_dbg(FYI, "Null buffer passed to cifs_small_buf_release\n");
 222                 return;
 223         }
 224         mempool_free(buf_to_free, cifs_sm_req_poolp);
 225
 226         atomic_dec(&small_buf_alloc_count);
 227         return;
 228 }
 229
 230 void
 231 free_rsp_buf(int resp_buftype, void *rsp)
 232 {
 233         if (resp_buftype == CIFS_SMALL_BUFFER)
 234                 cifs_small_buf_release(rsp);
 235         else if (resp_buftype == CIFS_LARGE_BUFFER)
 236                 cifs_buf_release(rsp);
 237 }
 238
 239 /* NB: MID can not be set if treeCon not passed in, in that
 240    case it is responsbility of caller to set the mid */
 241 void
 242 header_assemble(struct smb_hdr *buffer, char smb_command /* command */ ,
 243                 const struct cifs_tcon *treeCon, int word_count
 244                 /* length of fixed section (word count) in two byte units  */)
 245 {
 246         char *temp = (char *) buffer;
 247
 248         memset(temp, 0, 256); /* bigger than MAX_CIFS_HDR_SIZE */
 249
 250         buffer->smb_buf_length = cpu_to_be32(
 251             (2 * word_count) + sizeof(struct smb_hdr) -
 252             4 /*  RFC 1001 length field does not count */  +
 253             2 /* for bcc field itself */) ;
 254
 255         buffer->Protocol[0] = 0xFF;
 256         buffer->Protocol[1] = 'S';
 257         buffer->Protocol[2] = 'M';
 258         buffer->Protocol[3] = 'B';
 259         buffer->Command = smb_command;
 260         buffer->Flags = 0x00;   /* case sensitive */
 261         buffer->Flags2 = SMBFLG2_KNOWS_LONG_NAMES;
 262         buffer->Pid = cpu_to_le16((__u16)current->tgid);
 263         buffer->PidHigh = cpu_to_le16((__u16)(current->tgid >> 16));
 264         if (treeCon) {
 265                 buffer->Tid = treeCon->tid;
 266                 if (treeCon->ses) {
 267                         if (treeCon->ses->capabilities & CAP_UNICODE)
 268                                 buffer->Flags2 |= SMBFLG2_UNICODE;
 269                         if (treeCon->ses->capabilities & CAP_STATUS32)
 270                                 buffer->Flags2 |= SMBFLG2_ERR_STATUS;
 271
 272                         /* Uid is not converted */
 273                         buffer->Uid = treeCon->ses->Suid;
 274                         if (treeCon->ses->server)
 275                                 buffer->Mid = get_next_mid(treeCon->ses->server);
 276                 }
 277                 if (treeCon->Flags & SMB_SHARE_IS_IN_DFS)
 278                         buffer->Flags2 |= SMBFLG2_DFS;
 279                 if (treeCon->nocase)
 280                         buffer->Flags  |= SMBFLG_CASELESS;
 281                 if ((treeCon->ses) && (treeCon->ses->server))
 282                         if (treeCon->ses->server->sign)
 283                                 buffer->Flags2 |= SMBFLG2_SECURITY_SIGNATURE;
 284         }
 285
 286 /*  endian conversion of flags is now done just before sending */
 287         buffer->WordCount = (char) word_count;
 288         return;
 289 }
 290
 291 static int
 292 check_smb_hdr(struct smb_hdr *smb)
 293 {
 294         /* does it have the right SMB "signature" ? */
 295         if (*(__le32 *) smb->Protocol != cpu_to_le32(0x424d53ff)) {
 296                 cifs_dbg(VFS, "Bad protocol string signature header 0x%x\n",
 297                          *(unsigned int *)smb->Protocol);
 298                 return 1;
 299         }
 300
 301         /* if it's a response then accept */
 302         if (smb->Flags & SMBFLG_RESPONSE)
 303                 return 0;
 304
 305         /* only one valid case where server sends us request */
 306         if (smb->Command == SMB_COM_LOCKING_ANDX)
 307                 return 0;
 308
 309         cifs_dbg(VFS, "Server sent request, not response. mid=%u\n",
 310                  get_mid(smb));
 311         return 1;
 312 }
 313
 314 int
 315 checkSMB(char *buf, unsigned int total_read, struct TCP_Server_Info *server)
 316 {
 317         struct smb_hdr *smb = (struct smb_hdr *)buf;
 318         __u32 rfclen = be32_to_cpu(smb->smb_buf_length);
 319         __u32 clc_len;  /* calculated length */
 320         cifs_dbg(FYI, "checkSMB Length: 0x%x, smb_buf_length: 0x%x\n",
 321                  total_read, rfclen);
 322
 323         /* is this frame too small to even get to a BCC? */
 324         if (total_read < 2 + sizeof(struct smb_hdr)) {
 325                 if ((total_read >= sizeof(struct smb_hdr) - 1)
 326                             && (smb->Status.CifsError != 0)) {
 327                         /* it's an error return */
 328                         smb->WordCount = 0;
 329                         /* some error cases do not return wct and bcc */
 330                         return 0;
 331                 } else if ((total_read == sizeof(struct smb_hdr) + 1) &&
 332                                 (smb->WordCount == 0)) {
 333                         char *tmp = (char *)smb;
 334                         /* Need to work around a bug in two servers here */
 335                         /* First, check if the part of bcc they sent was zero */
 336                         if (tmp[sizeof(struct smb_hdr)] == 0) {
 337                                 /* some servers return only half of bcc
 338                                  * on simple responses (wct, bcc both zero)
 339                                  * in particular have seen this on
 340                                  * ulogoffX and FindClose. This leaves
 341                                  * one byte of bcc potentially unitialized
 342                                  */
 343                                 /* zero rest of bcc */
 344                                 tmp[sizeof(struct smb_hdr)+1] = 0;
 345                                 return 0;
 346                         }
 347                         cifs_dbg(VFS, "rcvd invalid byte count (bcc)\n");
 348                 } else {
 349                         cifs_dbg(VFS, "Length less than smb header size\n");
 350                 }
 351                 return -EIO;
 352         }
 353
 354         /* otherwise, there is enough to get to the BCC */
 355         if (check_smb_hdr(smb))
 356                 return -EIO;
 357         clc_len = smbCalcSize(smb);
 358
 359         if (4 + rfclen != total_read) {
 360                 cifs_dbg(VFS, "Length read does not match RFC1001 length %d\n",
 361                          rfclen);
 362                 return -EIO;
 363         }
 364
 365         if (4 + rfclen != clc_len) {
 366                 __u16 mid = get_mid(smb);
 367                 /* check if bcc wrapped around for large read responses */
 368                 if ((rfclen > 64 * 1024) && (rfclen > clc_len)) {
 369                         /* check if lengths match mod 64K */
 370                         if (((4 + rfclen) & 0xFFFF) == (clc_len & 0xFFFF))
 371                                 return 0; /* bcc wrapped */
 372                 }
 373                 cifs_dbg(FYI, "Calculated size %u vs length %u mismatch for mid=%u\n",
 374                          clc_len, 4 + rfclen, mid);
 375
 376                 if (4 + rfclen < clc_len) {
 377                         cifs_dbg(VFS, "RFC1001 size %u smaller than SMB for mid=%u\n",
 378                                  rfclen, mid);
 379                         return -EIO;
 380                 } else if (rfclen > clc_len + 512) {
 381                         /*
 382                          * Some servers (Windows XP in particular) send more
 383                          * data than the lengths in the SMB packet would
 384                          * indicate on certain calls (byte range locks and
 385                          * trans2 find first calls in particular). While the
 386                          * client can handle such a frame by ignoring the
 387                          * trailing data, we choose limit the amount of extra
 388                          * data to 512 bytes.
 389                          */
 390                         cifs_dbg(VFS, "RFC1001 size %u more than 512 bytes larger than SMB for mid=%u\n",
 391                                  rfclen, mid);
 392                         return -EIO;
 393                 }
 394         }
 395         return 0;
 396 }
 397
 398 bool
 399 is_valid_oplock_break(char *buffer, struct TCP_Server_Info *srv)
 400 {
 401         struct smb_hdr *buf = (struct smb_hdr *)buffer;
 402         struct smb_com_lock_req *pSMB = (struct smb_com_lock_req *)buf;
 403         struct TCP_Server_Info *pserver;
 404         struct cifs_ses *ses;
 405         struct cifs_tcon *tcon;
 406         struct cifsInodeInfo *pCifsInode;
 407         struct cifsFileInfo *netfile;
 408
 409         cifs_dbg(FYI, "Checking for oplock break or dnotify response\n");
 410         if ((pSMB->hdr.Command == SMB_COM_NT_TRANSACT) &&
 411            (pSMB->hdr.Flags & SMBFLG_RESPONSE)) {
 412                 struct smb_com_transaction_change_notify_rsp *pSMBr =
 413                         (struct smb_com_transaction_change_notify_rsp *)buf;
 414                 struct file_notify_information *pnotify;
 415                 __u32 data_offset = 0;
 416                 size_t len = srv->total_read - sizeof(pSMBr->hdr.smb_buf_length);
 417
 418                 if (get_bcc(buf) > sizeof(struct file_notify_information)) {
 419                         data_offset = le32_to_cpu(pSMBr->DataOffset);
 420
 421                         if (data_offset >
 422                             len - sizeof(struct file_notify_information)) {
 423                                 cifs_dbg(FYI, "Invalid data_offset %u\n",
 424                                          data_offset);
 425                                 return true;
 426                         }
 427                         pnotify = (struct file_notify_information *)
 428                                 ((char *)&pSMBr->hdr.Protocol + data_offset);
 429                         cifs_dbg(FYI, "dnotify on %s Action: 0x%x\n",
 430                                  pnotify->FileName, pnotify->Action);
 431                         /*   cifs_dump_mem("Rcvd notify Data: ",buf,
 432                                 sizeof(struct smb_hdr)+60); */
 433                         return true;
 434                 }
 435                 if (pSMBr->hdr.Status.CifsError) {
 436                         cifs_dbg(FYI, "notify err 0x%x\n",
 437                                  pSMBr->hdr.Status.CifsError);
 438                         return true;
 439                 }
 440                 return false;
 441         }
 442         if (pSMB->hdr.Command != SMB_COM_LOCKING_ANDX)
 443                 return false;
 444         if (pSMB->hdr.Flags & SMBFLG_RESPONSE) {
 445                 /* no sense logging error on invalid handle on oplock
 446                    break - harmless race between close request and oplock
 447                    break response is expected from time to time writing out
 448                    large dirty files cached on the client */
 449                 if ((NT_STATUS_INVALID_HANDLE) ==
 450                    le32_to_cpu(pSMB->hdr.Status.CifsError)) {
 451                         cifs_dbg(FYI, "Invalid handle on oplock break\n");
 452                         return true;
 453                 } else if (ERRbadfid ==
 454                    le16_to_cpu(pSMB->hdr.Status.DosError.Error)) {
 455                         return true;
 456                 } else {
 457                         return false; /* on valid oplock brk we get "request" */
 458                 }
 459         }
 460         if (pSMB->hdr.WordCount != 8)
 461                 return false;
 462
 463         cifs_dbg(FYI, "oplock type 0x%x level 0x%x\n",
 464                  pSMB->LockType, pSMB->OplockLevel);
 465         if (!(pSMB->LockType & LOCKING_ANDX_OPLOCK_RELEASE))
 466                 return false;
 467
 468         /* If server is a channel, select the primary channel */
 469         pserver = CIFS_SERVER_IS_CHAN(srv) ? srv->primary_server : srv;
 470
 471         /* look up tcon based on tid & uid */
 472         spin_lock(&cifs_tcp_ses_lock);
 473         list_for_each_entry(ses, &pserver->smb_ses_list, smb_ses_list) {
 474                 list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
 475                         if (tcon->tid != buf->Tid)
 476                                 continue;
 477
 478                         cifs_stats_inc(&tcon->stats.cifs_stats.num_oplock_brks);
 479                         spin_lock(&tcon->open_file_lock);
 480                         list_for_each_entry(netfile, &tcon->openFileList, tlist) {
 481                                 if (pSMB->Fid != netfile->fid.netfid)
 482                                         continue;
 483
 484                                 cifs_dbg(FYI, "file id match, oplock break\n");
 485                                 pCifsInode = CIFS_I(d_inode(netfile->dentry));
 486
 487                                 set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK,
 488                                         &pCifsInode->flags);
 489
 490                                 netfile->oplock_epoch = 0;
 491                                 netfile->oplock_level = pSMB->OplockLevel;
 492                                 netfile->oplock_break_cancelled = false;
 493                                 cifs_queue_oplock_break(netfile);
 494
 495                                 spin_unlock(&tcon->open_file_lock);
 496                                 spin_unlock(&cifs_tcp_ses_lock);
 497                                 return true;
 498                         }
 499                         spin_unlock(&tcon->open_file_lock);
 500                         spin_unlock(&cifs_tcp_ses_lock);
 501                         cifs_dbg(FYI, "No matching file for oplock break\n");
 502                         return true;
 503                 }
 504         }
 505         spin_unlock(&cifs_tcp_ses_lock);
 506         cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");
 507         return true;
 508 }
 509
 510 void
 511 dump_smb(void *buf, int smb_buf_length)
 512 {
 513         if (traceSMB == 0)
 514                 return;
 515
 516         print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_NONE, 8, 2, buf,
 517                        smb_buf_length, true);
 518 }
 519
 520 void
 521 cifs_autodisable_serverino(struct cifs_sb_info *cifs_sb)
 522 {
 523         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) {
 524                 struct cifs_tcon *tcon = NULL;
 525
 526                 if (cifs_sb->master_tlink)
 527                         tcon = cifs_sb_master_tcon(cifs_sb);
 528
 529                 cifs_sb->mnt_cifs_flags &= ~CIFS_MOUNT_SERVER_INUM;
 530                 cifs_sb->mnt_cifs_serverino_autodisabled = true;
 531                 cifs_dbg(VFS, "Autodisabling the use of server inode numbers on %s\n",
 532                          tcon ? tcon->tree_name : "new server");
 533                 cifs_dbg(VFS, "The server doesn't seem to support them properly or the files might be on different servers (DFS)\n");
 534                 cifs_dbg(VFS, "Hardlinks will not be recognized on this mount. Consider mounting with the \"noserverino\" option to silence this message.\n");
 535
 536         }
 537 }
 538
 539 void cifs_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock)
 540 {
 541         oplock &= 0xF;
 542
 543         if (oplock == OPLOCK_EXCLUSIVE) {
 544                 cinode->oplock = CIFS_CACHE_WRITE_FLG | CIFS_CACHE_READ_FLG;
 545                 cifs_dbg(FYI, "Exclusive Oplock granted on inode %p\n",
 546                          &cinode->netfs.inode);
 547         } else if (oplock == OPLOCK_READ) {
 548                 cinode->oplock = CIFS_CACHE_READ_FLG;
 549                 cifs_dbg(FYI, "Level II Oplock granted on inode %p\n",
 550                          &cinode->netfs.inode);
 551         } else
 552                 cinode->oplock = 0;
 553 }
 554
 555 /*
 556  * We wait for oplock breaks to be processed before we attempt to perform
 557  * writes.
 558  */
 559 int cifs_get_writer(struct cifsInodeInfo *cinode)
 560 {
 561         int rc;
 562
 563 start:
 564         rc = wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK,
 565                          TASK_KILLABLE);
 566         if (rc)
 567                 return rc;
 568
 569         spin_lock(&cinode->writers_lock);
 570         if (!cinode->writers)
 571                 set_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 572         cinode->writers++;
 573         /* Check to see if we have started servicing an oplock break */
 574         if (test_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags)) {
 575                 cinode->writers--;
 576                 if (cinode->writers == 0) {
 577                         clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 578                         wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
 579                 }
 580                 spin_unlock(&cinode->writers_lock);
 581                 goto start;
 582         }
 583         spin_unlock(&cinode->writers_lock);
 584         return 0;
 585 }
 586
 587 void cifs_put_writer(struct cifsInodeInfo *cinode)
 588 {
 589         spin_lock(&cinode->writers_lock);
 590         cinode->writers--;
 591         if (cinode->writers == 0) {
 592                 clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 593                 wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
 594         }
 595         spin_unlock(&cinode->writers_lock);
 596 }
 597
 598 /**
 599  * cifs_queue_oplock_break - queue the oplock break handler for cfile
 600  * @cfile: The file to break the oplock on
 601  *
 602  * This function is called from the demultiplex thread when it
 603  * receives an oplock break for @cfile.
 604  *
 605  * Assumes the tcon->open_file_lock is held.
 606  * Assumes cfile->file_info_lock is NOT held.
 607  */
 608 void cifs_queue_oplock_break(struct cifsFileInfo *cfile)
 609 {
 610         /*
 611          * Bump the handle refcount now while we hold the
 612          * open_file_lock to enforce the validity of it for the oplock
 613          * break handler. The matching put is done at the end of the
 614          * handler.
 615          */
 616         cifsFileInfo_get(cfile);
 617
 618         queue_work(cifsoplockd_wq, &cfile->oplock_break);
 619 }
 620
 621 void cifs_done_oplock_break(struct cifsInodeInfo *cinode)
 622 {
 623         clear_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags);
 624         wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK);
 625 }
 626
 627 bool
 628 backup_cred(struct cifs_sb_info *cifs_sb)
 629 {
 630         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPUID) {
 631                 if (uid_eq(cifs_sb->ctx->backupuid, current_fsuid()))
 632                         return true;
 633         }
 634         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPGID) {
 635                 if (in_group_p(cifs_sb->ctx->backupgid))
 636                         return true;
 637         }
 638
 639         return false;
 640 }
 641
 642 void
 643 cifs_del_pending_open(struct cifs_pending_open *open)
 644 {
 645         spin_lock(&tlink_tcon(open->tlink)->open_file_lock);
 646         list_del(&open->olist);
 647         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 648 }
 649
 650 void
 651 cifs_add_pending_open_locked(struct cifs_fid *fid, struct tcon_link *tlink,
 652                              struct cifs_pending_open *open)
 653 {
 654         memcpy(open->lease_key, fid->lease_key, SMB2_LEASE_KEY_SIZE);
 655         open->oplock = CIFS_OPLOCK_NO_CHANGE;
 656         open->tlink = tlink;
 657         fid->pending_open = open;
 658         list_add_tail(&open->olist, &tlink_tcon(tlink)->pending_opens);
 659 }
 660
 661 void
 662 cifs_add_pending_open(struct cifs_fid *fid, struct tcon_link *tlink,
 663                       struct cifs_pending_open *open)
 664 {
 665         spin_lock(&tlink_tcon(tlink)->open_file_lock);
 666         cifs_add_pending_open_locked(fid, tlink, open);
 667         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 668 }
 669
 670 /*
 671  * Critical section which runs after acquiring deferred_lock.
 672  * As there is no reference count on cifs_deferred_close, pdclose
 673  * should not be used outside deferred_lock.
 674  */
 675 bool
 676 cifs_is_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close **pdclose)
 677 {
 678         struct cifs_deferred_close *dclose;
 679
 680         list_for_each_entry(dclose, &CIFS_I(d_inode(cfile->dentry))->deferred_closes, dlist) {
 681                 if ((dclose->netfid == cfile->fid.netfid) &&
 682                         (dclose->persistent_fid == cfile->fid.persistent_fid) &&
 683                         (dclose->volatile_fid == cfile->fid.volatile_fid)) {
 684                         *pdclose = dclose;
 685                         return true;
 686                 }
 687         }
 688         return false;
 689 }
 690
 691 /*
 692  * Critical section which runs after acquiring deferred_lock.
 693  */
 694 void
 695 cifs_add_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close *dclose)
 696 {
 697         bool is_deferred = false;
 698         struct cifs_deferred_close *pdclose;
 699
 700         is_deferred = cifs_is_deferred_close(cfile, &pdclose);
 701         if (is_deferred) {
 702                 kfree(dclose);
 703                 return;
 704         }
 705
 706         dclose->tlink = cfile->tlink;
 707         dclose->netfid = cfile->fid.netfid;
 708         dclose->persistent_fid = cfile->fid.persistent_fid;
 709         dclose->volatile_fid = cfile->fid.volatile_fid;
 710         list_add_tail(&dclose->dlist, &CIFS_I(d_inode(cfile->dentry))->deferred_closes);
 711 }
 712
 713 /*
 714  * Critical section which runs after acquiring deferred_lock.
 715  */
 716 void
 717 cifs_del_deferred_close(struct cifsFileInfo *cfile)
 718 {
 719         bool is_deferred = false;
 720         struct cifs_deferred_close *dclose;
 721
 722         is_deferred = cifs_is_deferred_close(cfile, &dclose);
 723         if (!is_deferred)
 724                 return;
 725         list_del(&dclose->dlist);
 726         kfree(dclose);
 727 }
 728
 729 void
 730 cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode)
 731 {
 732         struct cifsFileInfo *cfile = NULL;
 733         struct file_list *tmp_list, *tmp_next_list;
 734         struct list_head file_head;
 735
 736         if (cifs_inode == NULL)
 737                 return;
 738
 739         INIT_LIST_HEAD(&file_head);
 740         spin_lock(&cifs_inode->open_file_lock);
 741         list_for_each_entry(cfile, &cifs_inode->openFileList, flist) {
 742                 if (delayed_work_pending(&cfile->deferred)) {
 743                         if (cancel_delayed_work(&cfile->deferred)) {
 744                                 cifs_del_deferred_close(cfile);
 745
 746                                 tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 747                                 if (tmp_list == NULL)
 748                                         break;
 749                                 tmp_list->cfile = cfile;
 750                                 list_add_tail(&tmp_list->list, &file_head);
 751                         }
 752                 }
 753         }
 754         spin_unlock(&cifs_inode->open_file_lock);
 755
 756         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 757                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 758                 list_del(&tmp_list->list);
 759                 kfree(tmp_list);
 760         }
 761 }
 762
 763 void
 764 cifs_close_all_deferred_files(struct cifs_tcon *tcon)
 765 {
 766         struct cifsFileInfo *cfile;
 767         struct file_list *tmp_list, *tmp_next_list;
 768         struct list_head file_head;
 769
 770         INIT_LIST_HEAD(&file_head);
 771         spin_lock(&tcon->open_file_lock);
 772         list_for_each_entry(cfile, &tcon->openFileList, tlist) {
 773                 if (delayed_work_pending(&cfile->deferred)) {
 774                         if (cancel_delayed_work(&cfile->deferred)) {
 775                                 cifs_del_deferred_close(cfile);
 776
 777                                 tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 778                                 if (tmp_list == NULL)
 779                                         break;
 780                                 tmp_list->cfile = cfile;
 781                                 list_add_tail(&tmp_list->list, &file_head);
 782                         }
 783                 }
 784         }
 785         spin_unlock(&tcon->open_file_lock);
 786
 787         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 788                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 789                 list_del(&tmp_list->list);
 790                 kfree(tmp_list);
 791         }
 792 }
 793 void
 794 cifs_close_deferred_file_under_dentry(struct cifs_tcon *tcon, const char *path)
 795 {
 796         struct cifsFileInfo *cfile;
 797         struct file_list *tmp_list, *tmp_next_list;
 798         struct list_head file_head;
 799         void *page;
 800         const char *full_path;
 801
 802         INIT_LIST_HEAD(&file_head);
 803         page = alloc_dentry_path();
 804         spin_lock(&tcon->open_file_lock);
 805         list_for_each_entry(cfile, &tcon->openFileList, tlist) {
 806                 full_path = build_path_from_dentry(cfile->dentry, page);
 807                 if (strstr(full_path, path)) {
 808                         if (delayed_work_pending(&cfile->deferred)) {
 809                                 if (cancel_delayed_work(&cfile->deferred)) {
 810                                         cifs_del_deferred_close(cfile);
 811
 812                                         tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 813                                         if (tmp_list == NULL)
 814                                                 break;
 815                                         tmp_list->cfile = cfile;
 816                                         list_add_tail(&tmp_list->list, &file_head);
 817                                 }
 818                         }
 819                 }
 820         }
 821         spin_unlock(&tcon->open_file_lock);
 822
 823         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 824                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 825                 list_del(&tmp_list->list);
 826                 kfree(tmp_list);
 827         }
 828         free_dentry_path(page);
 829 }
 830
 831 /* parses DFS referral V3 structure
 832  * caller is responsible for freeing target_nodes
 833  * returns:
 834  * - on success - 0
 835  * - on failure - errno
 836  */
 837 int
 838 parse_dfs_referrals(struct get_dfs_referral_rsp *rsp, u32 rsp_size,
 839                     unsigned int *num_of_nodes,
 840                     struct dfs_info3_param **target_nodes,
 841                     const struct nls_table *nls_codepage, int remap,
 842                     const char *searchName, bool is_unicode)
 843 {
 844         int i, rc = 0;
 845         char *data_end;
 846         struct dfs_referral_level_3 *ref;
 847
 848         *num_of_nodes = le16_to_cpu(rsp->NumberOfReferrals);
 849
 850         if (*num_of_nodes < 1) {
 851                 cifs_dbg(VFS, "num_referrals: must be at least > 0, but we get num_referrals = %d\n",
 852                          *num_of_nodes);
 853                 rc = -EINVAL;
 854                 goto parse_DFS_referrals_exit;
 855         }
 856
 857         ref = (struct dfs_referral_level_3 *) &(rsp->referrals);
 858         if (ref->VersionNumber != cpu_to_le16(3)) {
 859                 cifs_dbg(VFS, "Referrals of V%d version are not supported, should be V3\n",
 860                          le16_to_cpu(ref->VersionNumber));
 861                 rc = -EINVAL;
 862                 goto parse_DFS_referrals_exit;
 863         }
 864
 865         /* get the upper boundary of the resp buffer */
 866         data_end = (char *)rsp + rsp_size;
 867
 868         cifs_dbg(FYI, "num_referrals: %d dfs flags: 0x%x ...\n",
 869                  *num_of_nodes, le32_to_cpu(rsp->DFSFlags));
 870
 871         *target_nodes = kcalloc(*num_of_nodes, sizeof(struct dfs_info3_param),
 872                                 GFP_KERNEL);
 873         if (*target_nodes == NULL) {
 874                 rc = -ENOMEM;
 875                 goto parse_DFS_referrals_exit;
 876         }
 877
 878         /* collect necessary data from referrals */
 879         for (i = 0; i < *num_of_nodes; i++) {
 880                 char *temp;
 881                 int max_len;
 882                 struct dfs_info3_param *node = (*target_nodes)+i;
 883
 884                 node->flags = le32_to_cpu(rsp->DFSFlags);
 885                 if (is_unicode) {
 886                         __le16 *tmp = kmalloc(strlen(searchName)*2 + 2,
 887                                                 GFP_KERNEL);
 888                         if (tmp == NULL) {
 889                                 rc = -ENOMEM;
 890                                 goto parse_DFS_referrals_exit;
 891                         }
 892                         cifsConvertToUTF16((__le16 *) tmp, searchName,
 893                                            PATH_MAX, nls_codepage, remap);
 894                         node->path_consumed = cifs_utf16_bytes(tmp,
 895                                         le16_to_cpu(rsp->PathConsumed),
 896                                         nls_codepage);
 897                         kfree(tmp);
 898                 } else
 899                         node->path_consumed = le16_to_cpu(rsp->PathConsumed);
 900
 901                 node->server_type = le16_to_cpu(ref->ServerType);
 902                 node->ref_flag = le16_to_cpu(ref->ReferralEntryFlags);
 903
 904                 /* copy DfsPath */
 905                 temp = (char *)ref + le16_to_cpu(ref->DfsPathOffset);
 906                 max_len = data_end - temp;
 907                 node->path_name = cifs_strndup_from_utf16(temp, max_len,
 908                                                 is_unicode, nls_codepage);
 909                 if (!node->path_name) {
 910                         rc = -ENOMEM;
 911                         goto parse_DFS_referrals_exit;
 912                 }
 913
 914                 /* copy link target UNC */
 915                 temp = (char *)ref + le16_to_cpu(ref->NetworkAddressOffset);
 916                 max_len = data_end - temp;
 917                 node->node_name = cifs_strndup_from_utf16(temp, max_len,
 918                                                 is_unicode, nls_codepage);
 919                 if (!node->node_name) {
 920                         rc = -ENOMEM;
 921                         goto parse_DFS_referrals_exit;
 922                 }
 923
 924                 node->ttl = le32_to_cpu(ref->TimeToLive);
 925
 926                 ref++;
 927         }
 928
 929 parse_DFS_referrals_exit:
 930         if (rc) {
 931                 free_dfs_info_array(*target_nodes, *num_of_nodes);
 932                 *target_nodes = NULL;
 933                 *num_of_nodes = 0;
 934         }
 935         return rc;
 936 }
 937
 938 struct cifs_aio_ctx *
 939 cifs_aio_ctx_alloc(void)
 940 {
 941         struct cifs_aio_ctx *ctx;
 942
 943         /*
 944          * Must use kzalloc to initialize ctx->bv to NULL and ctx->direct_io
 945          * to false so that we know when we have to unreference pages within
 946          * cifs_aio_ctx_release()
 947          */
 948         ctx = kzalloc(sizeof(struct cifs_aio_ctx), GFP_KERNEL);
 949         if (!ctx)
 950                 return NULL;
 951
 952         INIT_LIST_HEAD(&ctx->list);
 953         mutex_init(&ctx->aio_mutex);
 954         init_completion(&ctx->done);
 955         kref_init(&ctx->refcount);
 956         return ctx;
 957 }
 958
 959 void
 960 cifs_aio_ctx_release(struct kref *refcount)
 961 {
 962         struct cifs_aio_ctx *ctx = container_of(refcount,
 963                                         struct cifs_aio_ctx, refcount);
 964
 965         cifsFileInfo_put(ctx->cfile);
 966
 967         /*
 968          * ctx->bv is only set if setup_aio_ctx_iter() was call successfuly
 969          * which means that iov_iter_get_pages() was a success and thus that
 970          * we have taken reference on pages.
 971          */
 972         if (ctx->bv) {
 973                 unsigned i;
 974
 975                 for (i = 0; i < ctx->npages; i++) {
 976                         if (ctx->should_dirty)
 977                                 set_page_dirty(ctx->bv[i].bv_page);
 978                         put_page(ctx->bv[i].bv_page);
 979                 }
 980                 kvfree(ctx->bv);
 981         }
 982
 983         kfree(ctx);
 984 }
 985
 986 #define CIFS_AIO_KMALLOC_LIMIT (1024 * 1024)
 987
 988 int
 989 setup_aio_ctx_iter(struct cifs_aio_ctx *ctx, struct iov_iter *iter, int rw)
 990 {
 991         ssize_t rc;
 992         unsigned int cur_npages;
 993         unsigned int npages = 0;
 994         unsigned int i;
 995         size_t len;
 996         size_t count = iov_iter_count(iter);
 997         unsigned int saved_len;
 998         size_t start;
 999         unsigned int max_pages = iov_iter_npages(iter, INT_MAX);
1000         struct page **pages = NULL;
1001         struct bio_vec *bv = NULL;
1002
1003         if (iov_iter_is_kvec(iter)) {
1004                 memcpy(&ctx->iter, iter, sizeof(*iter));
1005                 ctx->len = count;
1006                 iov_iter_advance(iter, count);
1007                 return 0;
1008         }
1009
1010         if (array_size(max_pages, sizeof(*bv)) <= CIFS_AIO_KMALLOC_LIMIT)
1011                 bv = kmalloc_array(max_pages, sizeof(*bv), GFP_KERNEL);
1012
1013         if (!bv) {
1014                 bv = vmalloc(array_size(max_pages, sizeof(*bv)));
1015                 if (!bv)
1016                         return -ENOMEM;
1017         }
1018
1019         if (array_size(max_pages, sizeof(*pages)) <= CIFS_AIO_KMALLOC_LIMIT)
1020                 pages = kmalloc_array(max_pages, sizeof(*pages), GFP_KERNEL);
1021
1022         if (!pages) {
1023                 pages = vmalloc(array_size(max_pages, sizeof(*pages)));
1024                 if (!pages) {
1025                         kvfree(bv);
1026                         return -ENOMEM;
1027                 }
1028         }
1029
1030         saved_len = count;
1031
1032         while (count && npages < max_pages) {
1033                 rc = iov_iter_get_pages2(iter, pages, count, max_pages, &start);
1034                 if (rc < 0) {
1035                         cifs_dbg(VFS, "Couldn't get user pages (rc=%zd)\n", rc);
1036                         break;
1037                 }
1038
1039                 if (rc > count) {
1040                         cifs_dbg(VFS, "get pages rc=%zd more than %zu\n", rc,
1041                                  count);
1042                         break;
1043                 }
1044
1045                 count -= rc;
1046                 rc += start;
1047                 cur_npages = DIV_ROUND_UP(rc, PAGE_SIZE);
1048
1049                 if (npages + cur_npages > max_pages) {
1050                         cifs_dbg(VFS, "out of vec array capacity (%u vs %u)\n",
1051                                  npages + cur_npages, max_pages);
1052                         break;
1053                 }
1054
1055                 for (i = 0; i < cur_npages; i++) {
1056                         len = rc > PAGE_SIZE ? PAGE_SIZE : rc;
1057                         bv[npages + i].bv_page = pages[i];
1058                         bv[npages + i].bv_offset = start;
1059                         bv[npages + i].bv_len = len - start;
1060                         rc -= len;
1061                         start = 0;
1062                 }
1063
1064                 npages += cur_npages;
1065         }
1066
1067         kvfree(pages);
1068         ctx->bv = bv;
1069         ctx->len = saved_len - count;
1070         ctx->npages = npages;
1071         iov_iter_bvec(&ctx->iter, rw, ctx->bv, npages, ctx->len);
1072         return 0;
1073 }
1074
1075 /**
1076  * cifs_alloc_hash - allocate hash and hash context together
1077  * @name: The name of the crypto hash algo
1078  * @sdesc: SHASH descriptor where to put the pointer to the hash TFM
1079  *
1080  * The caller has to make sure @sdesc is initialized to either NULL or
1081  * a valid context. It can be freed via cifs_free_hash().
1082  */
1083 int
1084 cifs_alloc_hash(const char *name, struct shash_desc **sdesc)
1085 {
1086         int rc = 0;
1087         struct crypto_shash *alg = NULL;
1088
1089         if (*sdesc)
1090                 return 0;
1091
1092         alg = crypto_alloc_shash(name, 0, 0);
1093         if (IS_ERR(alg)) {
1094                 cifs_dbg(VFS, "Could not allocate shash TFM '%s'\n", name);
1095                 rc = PTR_ERR(alg);
1096                 *sdesc = NULL;
1097                 return rc;
1098         }
1099
1100         *sdesc = kmalloc(sizeof(struct shash_desc) + crypto_shash_descsize(alg), GFP_KERNEL);
1101         if (*sdesc == NULL) {
1102                 cifs_dbg(VFS, "no memory left to allocate shash TFM '%s'\n", name);
1103                 crypto_free_shash(alg);
1104                 return -ENOMEM;
1105         }
1106
1107         (*sdesc)->tfm = alg;
1108         return 0;
1109 }
1110
1111 /**
1112  * cifs_free_hash - free hash and hash context together
1113  * @sdesc: Where to find the pointer to the hash TFM
1114  *
1115  * Freeing a NULL descriptor is safe.
1116  */
1117 void
1118 cifs_free_hash(struct shash_desc **sdesc)
1119 {
1120         if (unlikely(!sdesc) || !*sdesc)
1121                 return;
1122
1123         if ((*sdesc)->tfm) {
1124                 crypto_free_shash((*sdesc)->tfm);
1125                 (*sdesc)->tfm = NULL;
1126         }
1127
1128         kfree_sensitive(*sdesc);
1129         *sdesc = NULL;
1130 }
1131
1132 /**
1133  * rqst_page_get_length - obtain the length and offset for a page in smb_rqst
1134  * @rqst: The request descriptor
1135  * @page: The index of the page to query
1136  * @len: Where to store the length for this page:
1137  * @offset: Where to store the offset for this page
1138  */
1139 void rqst_page_get_length(const struct smb_rqst *rqst, unsigned int page,
1140                           unsigned int *len, unsigned int *offset)
1141 {
1142         *len = rqst->rq_pagesz;
1143         *offset = (page == 0) ? rqst->rq_offset : 0;
1144
1145         if (rqst->rq_npages == 1 || page == rqst->rq_npages-1)
1146                 *len = rqst->rq_tailsz;
1147         else if (page == 0)
1148                 *len = rqst->rq_pagesz - rqst->rq_offset;
1149 }
1150
1151 void extract_unc_hostname(const char *unc, const char **h, size_t *len)
1152 {
1153         const char *end;
1154
1155         /* skip initial slashes */
1156         while (*unc && (*unc == '\\' || *unc == '/'))
1157                 unc++;
1158
1159         end = unc;
1160
1161         while (*end && !(*end == '\\' || *end == '/'))
1162                 end++;
1163
1164         *h = unc;
1165         *len = end - unc;
1166 }
1167
1168 /**
1169  * copy_path_name - copy src path to dst, possibly truncating
1170  * @dst: The destination buffer
1171  * @src: The source name
1172  *
1173  * returns number of bytes written (including trailing nul)
1174  */
1175 int copy_path_name(char *dst, const char *src)
1176 {
1177         int name_len;
1178
1179         /*
1180          * PATH_MAX includes nul, so if strlen(src) >= PATH_MAX it
1181          * will truncate and strlen(dst) will be PATH_MAX-1
1182          */
1183         name_len = strscpy(dst, src, PATH_MAX);
1184         if (WARN_ON_ONCE(name_len < 0))
1185                 name_len = PATH_MAX-1;
1186
1187         /* we count the trailing nul */
1188         name_len++;
1189         return name_len;
1190 }
1191
1192 struct super_cb_data {
1193         void *data;
1194         struct super_block *sb;
1195 };
1196
1197 static void tcp_super_cb(struct super_block *sb, void *arg)
1198 {
1199         struct super_cb_data *sd = arg;
1200         struct TCP_Server_Info *server = sd->data;
1201         struct cifs_sb_info *cifs_sb;
1202         struct cifs_tcon *tcon;
1203
1204         if (sd->sb)
1205                 return;
1206
1207         cifs_sb = CIFS_SB(sb);
1208         tcon = cifs_sb_master_tcon(cifs_sb);
1209         if (tcon->ses->server == server)
1210                 sd->sb = sb;
1211 }
1212
1213 static struct super_block *__cifs_get_super(void (*f)(struct super_block *, void *),
1214                                             void *data)
1215 {
1216         struct super_cb_data sd = {
1217                 .data = data,
1218                 .sb = NULL,
1219         };
1220         struct file_system_type **fs_type = (struct file_system_type *[]) {
1221                 &cifs_fs_type, &smb3_fs_type, NULL,
1222         };
1223
1224         for (; *fs_type; fs_type++) {
1225                 iterate_supers_type(*fs_type, f, &sd);
1226                 if (sd.sb) {
1227                         /*
1228                          * Grab an active reference in order to prevent automounts (DFS links)
1229                          * of expiring and then freeing up our cifs superblock pointer while
1230                          * we're doing failover.
1231                          */
1232                         cifs_sb_active(sd.sb);
1233                         return sd.sb;
1234                 }
1235         }
1236         return ERR_PTR(-EINVAL);
1237 }
1238
1239 static void __cifs_put_super(struct super_block *sb)
1240 {
1241         if (!IS_ERR_OR_NULL(sb))
1242                 cifs_sb_deactive(sb);
1243 }
1244
1245 struct super_block *cifs_get_tcp_super(struct TCP_Server_Info *server)
1246 {
1247         return __cifs_get_super(tcp_super_cb, server);
1248 }
1249
1250 void cifs_put_tcp_super(struct super_block *sb)
1251 {
1252         __cifs_put_super(sb);
1253 }
1254
1255 #ifdef CONFIG_CIFS_DFS_UPCALL
1256 int match_target_ip(struct TCP_Server_Info *server,
1257                     const char *share, size_t share_len,
1258                     bool *result)
1259 {
1260         int rc;
1261         char *target;
1262         struct sockaddr_storage ss;
1263
1264         *result = false;
1265
1266         target = kzalloc(share_len + 3, GFP_KERNEL);
1267         if (!target)
1268                 return -ENOMEM;
1269
1270         scnprintf(target, share_len + 3, "\\\\%.*s", (int)share_len, share);
1271
1272         cifs_dbg(FYI, "%s: target name: %s\n", __func__, target + 2);
1273
1274         rc = dns_resolve_server_name_to_ip(target, (struct sockaddr *)&ss, NULL);
1275         kfree(target);
1276
1277         if (rc < 0)
1278                 return rc;
1279
1280         spin_lock(&server->srv_lock);
1281         *result = cifs_match_ipaddr((struct sockaddr *)&server->dstaddr, (struct sockaddr *)&ss);
1282         spin_unlock(&server->srv_lock);
1283         cifs_dbg(FYI, "%s: ip addresses match: %u\n", __func__, *result);
1284         return 0;
1285 }
1286
1287 int cifs_update_super_prepath(struct cifs_sb_info *cifs_sb, char *prefix)
1288 {
1289         kfree(cifs_sb->prepath);
1290
1291         if (prefix && *prefix) {
1292                 cifs_sb->prepath = kstrdup(prefix, GFP_ATOMIC);
1293                 if (!cifs_sb->prepath)
1294                         return -ENOMEM;
1295
1296                 convert_delimiter(cifs_sb->prepath, CIFS_DIR_SEP(cifs_sb));
1297         } else
1298                 cifs_sb->prepath = NULL;
1299
1300         cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
1301         return 0;
1302 }
1303 #endif