misc.c

   1 /*
   2  *   fs/cifs/misc.c
   3  *
   4  *   Copyright (C) International Business Machines  Corp., 2002,2008
   5  *   Author(s): Steve French (sfrench@us.ibm.com)
   6  *
   7  *   This library is free software; you can redistribute it and/or modify
   8  *   it under the terms of the GNU Lesser General Public License as published
   9  *   by the Free Software Foundation; either version 2.1 of the License, or
  10  *   (at your option) any later version.
  11  *
  12  *   This library is distributed in the hope that it will be useful,
  13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  15  *   the GNU Lesser General Public License for more details.
  16  *
  17  *   You should have received a copy of the GNU Lesser General Public License
  18  *   along with this library; if not, write to the Free Software
  19  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  20  */
  21
  22 #include <linux/slab.h>
  23 #include <linux/ctype.h>
  24 #include <linux/mempool.h>
  25 #include <linux/vmalloc.h>
  26 #include "cifspdu.h"
  27 #include "cifsglob.h"
  28 #include "cifsproto.h"
  29 #include "cifs_debug.h"
  30 #include "smberr.h"
  31 #include "nterr.h"
  32 #include "cifs_unicode.h"
  33 #include "smb2pdu.h"
  34 #include "cifsfs.h"
  35 #ifdef CONFIG_CIFS_DFS_UPCALL
  36 #include "dns_resolve.h"
  37 #endif
  38 #include "fs_context.h"
  39
  40 extern mempool_t *cifs_sm_req_poolp;
  41 extern mempool_t *cifs_req_poolp;
  42
  43 /* The xid serves as a useful identifier for each incoming vfs request,
  44    in a similar way to the mid which is useful to track each sent smb,
  45    and CurrentXid can also provide a running counter (although it
  46    will eventually wrap past zero) of the total vfs operations handled
  47    since the cifs fs was mounted */
  48
  49 unsigned int
  50 _get_xid(void)
  51 {
  52         unsigned int xid;
  53
  54         spin_lock(&GlobalMid_Lock);
  55         GlobalTotalActiveXid++;
  56
  57         /* keep high water mark for number of simultaneous ops in filesystem */
  58         if (GlobalTotalActiveXid > GlobalMaxActiveXid)
  59                 GlobalMaxActiveXid = GlobalTotalActiveXid;
  60         if (GlobalTotalActiveXid > 65000)
  61                 cifs_dbg(FYI, "warning: more than 65000 requests active\n");
  62         xid = GlobalCurrentXid++;
  63         spin_unlock(&GlobalMid_Lock);
  64         return xid;
  65 }
  66
  67 void
  68 _free_xid(unsigned int xid)
  69 {
  70         spin_lock(&GlobalMid_Lock);
  71         /* if (GlobalTotalActiveXid == 0)
  72                 BUG(); */
  73         GlobalTotalActiveXid--;
  74         spin_unlock(&GlobalMid_Lock);
  75 }
  76
  77 struct cifs_ses *
  78 sesInfoAlloc(void)
  79 {
  80         struct cifs_ses *ret_buf;
  81
  82         ret_buf = kzalloc(sizeof(struct cifs_ses), GFP_KERNEL);
  83         if (ret_buf) {
  84                 atomic_inc(&sesInfoAllocCount);
  85                 ret_buf->status = CifsNew;
  86                 ++ret_buf->ses_count;
  87                 INIT_LIST_HEAD(&ret_buf->smb_ses_list);
  88                 INIT_LIST_HEAD(&ret_buf->tcon_list);
  89                 mutex_init(&ret_buf->session_mutex);
  90                 spin_lock_init(&ret_buf->iface_lock);
  91         }
  92         return ret_buf;
  93 }
  94
  95 void
  96 sesInfoFree(struct cifs_ses *buf_to_free)
  97 {
  98         if (buf_to_free == NULL) {
  99                 cifs_dbg(FYI, "Null buffer passed to sesInfoFree\n");
 100                 return;
 101         }
 102
 103         atomic_dec(&sesInfoAllocCount);
 104         kfree(buf_to_free->serverOS);
 105         kfree(buf_to_free->serverDomain);
 106         kfree(buf_to_free->serverNOS);
 107         kfree_sensitive(buf_to_free->password);
 108         kfree(buf_to_free->user_name);
 109         kfree(buf_to_free->domainName);
 110         kfree_sensitive(buf_to_free->auth_key.response);
 111         kfree(buf_to_free->iface_list);
 112         kfree_sensitive(buf_to_free);
 113 }
 114
 115 struct cifs_tcon *
 116 tconInfoAlloc(void)
 117 {
 118         struct cifs_tcon *ret_buf;
 119
 120         ret_buf = kzalloc(sizeof(*ret_buf), GFP_KERNEL);
 121         if (!ret_buf)
 122                 return NULL;
 123         ret_buf->crfid.fid = kzalloc(sizeof(*ret_buf->crfid.fid), GFP_KERNEL);
 124         if (!ret_buf->crfid.fid) {
 125                 kfree(ret_buf);
 126                 return NULL;
 127         }
 128
 129         atomic_inc(&tconInfoAllocCount);
 130         ret_buf->tidStatus = CifsNew;
 131         ++ret_buf->tc_count;
 132         INIT_LIST_HEAD(&ret_buf->openFileList);
 133         INIT_LIST_HEAD(&ret_buf->tcon_list);
 134         spin_lock_init(&ret_buf->open_file_lock);
 135         mutex_init(&ret_buf->crfid.fid_mutex);
 136         spin_lock_init(&ret_buf->stat_lock);
 137         atomic_set(&ret_buf->num_local_opens, 0);
 138         atomic_set(&ret_buf->num_remote_opens, 0);
 139
 140         return ret_buf;
 141 }
 142
 143 void
 144 tconInfoFree(struct cifs_tcon *buf_to_free)
 145 {
 146         if (buf_to_free == NULL) {
 147                 cifs_dbg(FYI, "Null buffer passed to tconInfoFree\n");
 148                 return;
 149         }
 150         atomic_dec(&tconInfoAllocCount);
 151         kfree(buf_to_free->nativeFileSystem);
 152         kfree_sensitive(buf_to_free->password);
 153         kfree(buf_to_free->crfid.fid);
 154 #ifdef CONFIG_CIFS_DFS_UPCALL
 155         kfree(buf_to_free->dfs_path);
 156 #endif
 157         kfree(buf_to_free);
 158 }
 159
 160 struct smb_hdr *
 161 cifs_buf_get(void)
 162 {
 163         struct smb_hdr *ret_buf = NULL;
 164         /*
 165          * SMB2 header is bigger than CIFS one - no problems to clean some
 166          * more bytes for CIFS.
 167          */
 168         size_t buf_size = sizeof(struct smb2_sync_hdr);
 169
 170         /*
 171          * We could use negotiated size instead of max_msgsize -
 172          * but it may be more efficient to always alloc same size
 173          * albeit slightly larger than necessary and maxbuffersize
 174          * defaults to this and can not be bigger.
 175          */
 176         ret_buf = mempool_alloc(cifs_req_poolp, GFP_NOFS);
 177
 178         /* clear the first few header bytes */
 179         /* for most paths, more is cleared in header_assemble */
 180         memset(ret_buf, 0, buf_size + 3);
 181         atomic_inc(&bufAllocCount);
 182 #ifdef CONFIG_CIFS_STATS2
 183         atomic_inc(&totBufAllocCount);
 184 #endif /* CONFIG_CIFS_STATS2 */
 185
 186         return ret_buf;
 187 }
 188
 189 void
 190 cifs_buf_release(void *buf_to_free)
 191 {
 192         if (buf_to_free == NULL) {
 193                 /* cifs_dbg(FYI, "Null buffer passed to cifs_buf_release\n");*/
 194                 return;
 195         }
 196         mempool_free(buf_to_free, cifs_req_poolp);
 197
 198         atomic_dec(&bufAllocCount);
 199         return;
 200 }
 201
 202 struct smb_hdr *
 203 cifs_small_buf_get(void)
 204 {
 205         struct smb_hdr *ret_buf = NULL;
 206
 207 /* We could use negotiated size instead of max_msgsize -
 208    but it may be more efficient to always alloc same size
 209    albeit slightly larger than necessary and maxbuffersize
 210    defaults to this and can not be bigger */
 211         ret_buf = mempool_alloc(cifs_sm_req_poolp, GFP_NOFS);
 212         /* No need to clear memory here, cleared in header assemble */
 213         /*      memset(ret_buf, 0, sizeof(struct smb_hdr) + 27);*/
 214         atomic_inc(&smBufAllocCount);
 215 #ifdef CONFIG_CIFS_STATS2
 216         atomic_inc(&totSmBufAllocCount);
 217 #endif /* CONFIG_CIFS_STATS2 */
 218
 219         return ret_buf;
 220 }
 221
 222 void
 223 cifs_small_buf_release(void *buf_to_free)
 224 {
 225
 226         if (buf_to_free == NULL) {
 227                 cifs_dbg(FYI, "Null buffer passed to cifs_small_buf_release\n");
 228                 return;
 229         }
 230         mempool_free(buf_to_free, cifs_sm_req_poolp);
 231
 232         atomic_dec(&smBufAllocCount);
 233         return;
 234 }
 235
 236 void
 237 free_rsp_buf(int resp_buftype, void *rsp)
 238 {
 239         if (resp_buftype == CIFS_SMALL_BUFFER)
 240                 cifs_small_buf_release(rsp);
 241         else if (resp_buftype == CIFS_LARGE_BUFFER)
 242                 cifs_buf_release(rsp);
 243 }
 244
 245 /* NB: MID can not be set if treeCon not passed in, in that
 246    case it is responsbility of caller to set the mid */
 247 void
 248 header_assemble(struct smb_hdr *buffer, char smb_command /* command */ ,
 249                 const struct cifs_tcon *treeCon, int word_count
 250                 /* length of fixed section (word count) in two byte units  */)
 251 {
 252         char *temp = (char *) buffer;
 253
 254         memset(temp, 0, 256); /* bigger than MAX_CIFS_HDR_SIZE */
 255
 256         buffer->smb_buf_length = cpu_to_be32(
 257             (2 * word_count) + sizeof(struct smb_hdr) -
 258             4 /*  RFC 1001 length field does not count */  +
 259             2 /* for bcc field itself */) ;
 260
 261         buffer->Protocol[0] = 0xFF;
 262         buffer->Protocol[1] = 'S';
 263         buffer->Protocol[2] = 'M';
 264         buffer->Protocol[3] = 'B';
 265         buffer->Command = smb_command;
 266         buffer->Flags = 0x00;   /* case sensitive */
 267         buffer->Flags2 = SMBFLG2_KNOWS_LONG_NAMES;
 268         buffer->Pid = cpu_to_le16((__u16)current->tgid);
 269         buffer->PidHigh = cpu_to_le16((__u16)(current->tgid >> 16));
 270         if (treeCon) {
 271                 buffer->Tid = treeCon->tid;
 272                 if (treeCon->ses) {
 273                         if (treeCon->ses->capabilities & CAP_UNICODE)
 274                                 buffer->Flags2 |= SMBFLG2_UNICODE;
 275                         if (treeCon->ses->capabilities & CAP_STATUS32)
 276                                 buffer->Flags2 |= SMBFLG2_ERR_STATUS;
 277
 278                         /* Uid is not converted */
 279                         buffer->Uid = treeCon->ses->Suid;
 280                         buffer->Mid = get_next_mid(treeCon->ses->server);
 281                 }
 282                 if (treeCon->Flags & SMB_SHARE_IS_IN_DFS)
 283                         buffer->Flags2 |= SMBFLG2_DFS;
 284                 if (treeCon->nocase)
 285                         buffer->Flags  |= SMBFLG_CASELESS;
 286                 if ((treeCon->ses) && (treeCon->ses->server))
 287                         if (treeCon->ses->server->sign)
 288                                 buffer->Flags2 |= SMBFLG2_SECURITY_SIGNATURE;
 289         }
 290
 291 /*  endian conversion of flags is now done just before sending */
 292         buffer->WordCount = (char) word_count;
 293         return;
 294 }
 295
 296 static int
 297 check_smb_hdr(struct smb_hdr *smb)
 298 {
 299         /* does it have the right SMB "signature" ? */
 300         if (*(__le32 *) smb->Protocol != cpu_to_le32(0x424d53ff)) {
 301                 cifs_dbg(VFS, "Bad protocol string signature header 0x%x\n",
 302                          *(unsigned int *)smb->Protocol);
 303                 return 1;
 304         }
 305
 306         /* if it's a response then accept */
 307         if (smb->Flags & SMBFLG_RESPONSE)
 308                 return 0;
 309
 310         /* only one valid case where server sends us request */
 311         if (smb->Command == SMB_COM_LOCKING_ANDX)
 312                 return 0;
 313
 314         cifs_dbg(VFS, "Server sent request, not response. mid=%u\n",
 315                  get_mid(smb));
 316         return 1;
 317 }
 318
 319 int
 320 checkSMB(char *buf, unsigned int total_read, struct TCP_Server_Info *server)
 321 {
 322         struct smb_hdr *smb = (struct smb_hdr *)buf;
 323         __u32 rfclen = be32_to_cpu(smb->smb_buf_length);
 324         __u32 clc_len;  /* calculated length */
 325         cifs_dbg(FYI, "checkSMB Length: 0x%x, smb_buf_length: 0x%x\n",
 326                  total_read, rfclen);
 327
 328         /* is this frame too small to even get to a BCC? */
 329         if (total_read < 2 + sizeof(struct smb_hdr)) {
 330                 if ((total_read >= sizeof(struct smb_hdr) - 1)
 331                             && (smb->Status.CifsError != 0)) {
 332                         /* it's an error return */
 333                         smb->WordCount = 0;
 334                         /* some error cases do not return wct and bcc */
 335                         return 0;
 336                 } else if ((total_read == sizeof(struct smb_hdr) + 1) &&
 337                                 (smb->WordCount == 0)) {
 338                         char *tmp = (char *)smb;
 339                         /* Need to work around a bug in two servers here */
 340                         /* First, check if the part of bcc they sent was zero */
 341                         if (tmp[sizeof(struct smb_hdr)] == 0) {
 342                                 /* some servers return only half of bcc
 343                                  * on simple responses (wct, bcc both zero)
 344                                  * in particular have seen this on
 345                                  * ulogoffX and FindClose. This leaves
 346                                  * one byte of bcc potentially unitialized
 347                                  */
 348                                 /* zero rest of bcc */
 349                                 tmp[sizeof(struct smb_hdr)+1] = 0;
 350                                 return 0;
 351                         }
 352                         cifs_dbg(VFS, "rcvd invalid byte count (bcc)\n");
 353                 } else {
 354                         cifs_dbg(VFS, "Length less than smb header size\n");
 355                 }
 356                 return -EIO;
 357         }
 358
 359         /* otherwise, there is enough to get to the BCC */
 360         if (check_smb_hdr(smb))
 361                 return -EIO;
 362         clc_len = smbCalcSize(smb, server);
 363
 364         if (4 + rfclen != total_read) {
 365                 cifs_dbg(VFS, "Length read does not match RFC1001 length %d\n",
 366                          rfclen);
 367                 return -EIO;
 368         }
 369
 370         if (4 + rfclen != clc_len) {
 371                 __u16 mid = get_mid(smb);
 372                 /* check if bcc wrapped around for large read responses */
 373                 if ((rfclen > 64 * 1024) && (rfclen > clc_len)) {
 374                         /* check if lengths match mod 64K */
 375                         if (((4 + rfclen) & 0xFFFF) == (clc_len & 0xFFFF))
 376                                 return 0; /* bcc wrapped */
 377                 }
 378                 cifs_dbg(FYI, "Calculated size %u vs length %u mismatch for mid=%u\n",
 379                          clc_len, 4 + rfclen, mid);
 380
 381                 if (4 + rfclen < clc_len) {
 382                         cifs_dbg(VFS, "RFC1001 size %u smaller than SMB for mid=%u\n",
 383                                  rfclen, mid);
 384                         return -EIO;
 385                 } else if (rfclen > clc_len + 512) {
 386                         /*
 387                          * Some servers (Windows XP in particular) send more
 388                          * data than the lengths in the SMB packet would
 389                          * indicate on certain calls (byte range locks and
 390                          * trans2 find first calls in particular). While the
 391                          * client can handle such a frame by ignoring the
 392                          * trailing data, we choose limit the amount of extra
 393                          * data to 512 bytes.
 394                          */
 395                         cifs_dbg(VFS, "RFC1001 size %u more than 512 bytes larger than SMB for mid=%u\n",
 396                                  rfclen, mid);
 397                         return -EIO;
 398                 }
 399         }
 400         return 0;
 401 }
 402
 403 bool
 404 is_valid_oplock_break(char *buffer, struct TCP_Server_Info *srv)
 405 {
 406         struct smb_hdr *buf = (struct smb_hdr *)buffer;
 407         struct smb_com_lock_req *pSMB = (struct smb_com_lock_req *)buf;
 408         struct list_head *tmp, *tmp1, *tmp2;
 409         struct cifs_ses *ses;
 410         struct cifs_tcon *tcon;
 411         struct cifsInodeInfo *pCifsInode;
 412         struct cifsFileInfo *netfile;
 413
 414         cifs_dbg(FYI, "Checking for oplock break or dnotify response\n");
 415         if ((pSMB->hdr.Command == SMB_COM_NT_TRANSACT) &&
 416            (pSMB->hdr.Flags & SMBFLG_RESPONSE)) {
 417                 struct smb_com_transaction_change_notify_rsp *pSMBr =
 418                         (struct smb_com_transaction_change_notify_rsp *)buf;
 419                 struct file_notify_information *pnotify;
 420                 __u32 data_offset = 0;
 421                 size_t len = srv->total_read - sizeof(pSMBr->hdr.smb_buf_length);
 422
 423                 if (get_bcc(buf) > sizeof(struct file_notify_information)) {
 424                         data_offset = le32_to_cpu(pSMBr->DataOffset);
 425
 426                         if (data_offset >
 427                             len - sizeof(struct file_notify_information)) {
 428                                 cifs_dbg(FYI, "Invalid data_offset %u\n",
 429                                          data_offset);
 430                                 return true;
 431                         }
 432                         pnotify = (struct file_notify_information *)
 433                                 ((char *)&pSMBr->hdr.Protocol + data_offset);
 434                         cifs_dbg(FYI, "dnotify on %s Action: 0x%x\n",
 435                                  pnotify->FileName, pnotify->Action);
 436                         /*   cifs_dump_mem("Rcvd notify Data: ",buf,
 437                                 sizeof(struct smb_hdr)+60); */
 438                         return true;
 439                 }
 440                 if (pSMBr->hdr.Status.CifsError) {
 441                         cifs_dbg(FYI, "notify err 0x%x\n",
 442                                  pSMBr->hdr.Status.CifsError);
 443                         return true;
 444                 }
 445                 return false;
 446         }
 447         if (pSMB->hdr.Command != SMB_COM_LOCKING_ANDX)
 448                 return false;
 449         if (pSMB->hdr.Flags & SMBFLG_RESPONSE) {
 450                 /* no sense logging error on invalid handle on oplock
 451                    break - harmless race between close request and oplock
 452                    break response is expected from time to time writing out
 453                    large dirty files cached on the client */
 454                 if ((NT_STATUS_INVALID_HANDLE) ==
 455                    le32_to_cpu(pSMB->hdr.Status.CifsError)) {
 456                         cifs_dbg(FYI, "Invalid handle on oplock break\n");
 457                         return true;
 458                 } else if (ERRbadfid ==
 459                    le16_to_cpu(pSMB->hdr.Status.DosError.Error)) {
 460                         return true;
 461                 } else {
 462                         return false; /* on valid oplock brk we get "request" */
 463                 }
 464         }
 465         if (pSMB->hdr.WordCount != 8)
 466                 return false;
 467
 468         cifs_dbg(FYI, "oplock type 0x%x level 0x%x\n",
 469                  pSMB->LockType, pSMB->OplockLevel);
 470         if (!(pSMB->LockType & LOCKING_ANDX_OPLOCK_RELEASE))
 471                 return false;
 472
 473         /* look up tcon based on tid & uid */
 474         spin_lock(&cifs_tcp_ses_lock);
 475         list_for_each(tmp, &srv->smb_ses_list) {
 476                 ses = list_entry(tmp, struct cifs_ses, smb_ses_list);
 477                 list_for_each(tmp1, &ses->tcon_list) {
 478                         tcon = list_entry(tmp1, struct cifs_tcon, tcon_list);
 479                         if (tcon->tid != buf->Tid)
 480                                 continue;
 481
 482                         cifs_stats_inc(&tcon->stats.cifs_stats.num_oplock_brks);
 483                         spin_lock(&tcon->open_file_lock);
 484                         list_for_each(tmp2, &tcon->openFileList) {
 485                                 netfile = list_entry(tmp2, struct cifsFileInfo,
 486                                                      tlist);
 487                                 if (pSMB->Fid != netfile->fid.netfid)
 488                                         continue;
 489
 490                                 cifs_dbg(FYI, "file id match, oplock break\n");
 491                                 pCifsInode = CIFS_I(d_inode(netfile->dentry));
 492
 493                                 set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK,
 494                                         &pCifsInode->flags);
 495
 496                                 netfile->oplock_epoch = 0;
 497                                 netfile->oplock_level = pSMB->OplockLevel;
 498                                 netfile->oplock_break_cancelled = false;
 499                                 cifs_queue_oplock_break(netfile);
 500
 501                                 spin_unlock(&tcon->open_file_lock);
 502                                 spin_unlock(&cifs_tcp_ses_lock);
 503                                 return true;
 504                         }
 505                         spin_unlock(&tcon->open_file_lock);
 506                         spin_unlock(&cifs_tcp_ses_lock);
 507                         cifs_dbg(FYI, "No matching file for oplock break\n");
 508                         return true;
 509                 }
 510         }
 511         spin_unlock(&cifs_tcp_ses_lock);
 512         cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");
 513         return true;
 514 }
 515
 516 void
 517 dump_smb(void *buf, int smb_buf_length)
 518 {
 519         if (traceSMB == 0)
 520                 return;
 521
 522         print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_NONE, 8, 2, buf,
 523                        smb_buf_length, true);
 524 }
 525
 526 void
 527 cifs_autodisable_serverino(struct cifs_sb_info *cifs_sb)
 528 {
 529         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) {
 530                 struct cifs_tcon *tcon = NULL;
 531
 532                 if (cifs_sb->master_tlink)
 533                         tcon = cifs_sb_master_tcon(cifs_sb);
 534
 535                 cifs_sb->mnt_cifs_flags &= ~CIFS_MOUNT_SERVER_INUM;
 536                 cifs_sb->mnt_cifs_serverino_autodisabled = true;
 537                 cifs_dbg(VFS, "Autodisabling the use of server inode numbers on %s\n",
 538                          tcon ? tcon->treeName : "new server");
 539                 cifs_dbg(VFS, "The server doesn't seem to support them properly or the files might be on different servers (DFS)\n");
 540                 cifs_dbg(VFS, "Hardlinks will not be recognized on this mount. Consider mounting with the \"noserverino\" option to silence this message.\n");
 541
 542         }
 543 }
 544
 545 void cifs_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock)
 546 {
 547         oplock &= 0xF;
 548
 549         if (oplock == OPLOCK_EXCLUSIVE) {
 550                 cinode->oplock = CIFS_CACHE_WRITE_FLG | CIFS_CACHE_READ_FLG;
 551                 cifs_dbg(FYI, "Exclusive Oplock granted on inode %p\n",
 552                          &cinode->vfs_inode);
 553         } else if (oplock == OPLOCK_READ) {
 554                 cinode->oplock = CIFS_CACHE_READ_FLG;
 555                 cifs_dbg(FYI, "Level II Oplock granted on inode %p\n",
 556                          &cinode->vfs_inode);
 557         } else
 558                 cinode->oplock = 0;
 559 }
 560
 561 /*
 562  * We wait for oplock breaks to be processed before we attempt to perform
 563  * writes.
 564  */
 565 int cifs_get_writer(struct cifsInodeInfo *cinode)
 566 {
 567         int rc;
 568
 569 start:
 570         rc = wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK,
 571                          TASK_KILLABLE);
 572         if (rc)
 573                 return rc;
 574
 575         spin_lock(&cinode->writers_lock);
 576         if (!cinode->writers)
 577                 set_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 578         cinode->writers++;
 579         /* Check to see if we have started servicing an oplock break */
 580         if (test_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags)) {
 581                 cinode->writers--;
 582                 if (cinode->writers == 0) {
 583                         clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 584                         wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
 585                 }
 586                 spin_unlock(&cinode->writers_lock);
 587                 goto start;
 588         }
 589         spin_unlock(&cinode->writers_lock);
 590         return 0;
 591 }
 592
 593 void cifs_put_writer(struct cifsInodeInfo *cinode)
 594 {
 595         spin_lock(&cinode->writers_lock);
 596         cinode->writers--;
 597         if (cinode->writers == 0) {
 598                 clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
 599                 wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
 600         }
 601         spin_unlock(&cinode->writers_lock);
 602 }
 603
 604 /**
 605  * cifs_queue_oplock_break - queue the oplock break handler for cfile
 606  *
 607  * This function is called from the demultiplex thread when it
 608  * receives an oplock break for @cfile.
 609  *
 610  * Assumes the tcon->open_file_lock is held.
 611  * Assumes cfile->file_info_lock is NOT held.
 612  */
 613 void cifs_queue_oplock_break(struct cifsFileInfo *cfile)
 614 {
 615         /*
 616          * Bump the handle refcount now while we hold the
 617          * open_file_lock to enforce the validity of it for the oplock
 618          * break handler. The matching put is done at the end of the
 619          * handler.
 620          */
 621         cifsFileInfo_get(cfile);
 622
 623         queue_work(cifsoplockd_wq, &cfile->oplock_break);
 624 }
 625
 626 void cifs_done_oplock_break(struct cifsInodeInfo *cinode)
 627 {
 628         clear_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags);
 629         wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK);
 630 }
 631
 632 bool
 633 backup_cred(struct cifs_sb_info *cifs_sb)
 634 {
 635         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPUID) {
 636                 if (uid_eq(cifs_sb->ctx->backupuid, current_fsuid()))
 637                         return true;
 638         }
 639         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPGID) {
 640                 if (in_group_p(cifs_sb->ctx->backupgid))
 641                         return true;
 642         }
 643
 644         return false;
 645 }
 646
 647 void
 648 cifs_del_pending_open(struct cifs_pending_open *open)
 649 {
 650         spin_lock(&tlink_tcon(open->tlink)->open_file_lock);
 651         list_del(&open->olist);
 652         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 653 }
 654
 655 void
 656 cifs_add_pending_open_locked(struct cifs_fid *fid, struct tcon_link *tlink,
 657                              struct cifs_pending_open *open)
 658 {
 659         memcpy(open->lease_key, fid->lease_key, SMB2_LEASE_KEY_SIZE);
 660         open->oplock = CIFS_OPLOCK_NO_CHANGE;
 661         open->tlink = tlink;
 662         fid->pending_open = open;
 663         list_add_tail(&open->olist, &tlink_tcon(tlink)->pending_opens);
 664 }
 665
 666 void
 667 cifs_add_pending_open(struct cifs_fid *fid, struct tcon_link *tlink,
 668                       struct cifs_pending_open *open)
 669 {
 670         spin_lock(&tlink_tcon(tlink)->open_file_lock);
 671         cifs_add_pending_open_locked(fid, tlink, open);
 672         spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 673 }
 674
 675 /*
 676  * Critical section which runs after acquiring deferred_lock.
 677  * As there is no reference count on cifs_deferred_close, pdclose
 678  * should not be used outside deferred_lock.
 679  */
 680 bool
 681 cifs_is_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close **pdclose)
 682 {
 683         struct cifs_deferred_close *dclose;
 684
 685         list_for_each_entry(dclose, &CIFS_I(d_inode(cfile->dentry))->deferred_closes, dlist) {
 686                 if ((dclose->netfid == cfile->fid.netfid) &&
 687                         (dclose->persistent_fid == cfile->fid.persistent_fid) &&
 688                         (dclose->volatile_fid == cfile->fid.volatile_fid)) {
 689                         *pdclose = dclose;
 690                         return true;
 691                 }
 692         }
 693         return false;
 694 }
 695
 696 /*
 697  * Critical section which runs after acquiring deferred_lock.
 698  */
 699 void
 700 cifs_add_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close *dclose)
 701 {
 702         bool is_deferred = false;
 703         struct cifs_deferred_close *pdclose;
 704
 705         is_deferred = cifs_is_deferred_close(cfile, &pdclose);
 706         if (is_deferred) {
 707                 kfree(dclose);
 708                 return;
 709         }
 710
 711         dclose->tlink = cfile->tlink;
 712         dclose->netfid = cfile->fid.netfid;
 713         dclose->persistent_fid = cfile->fid.persistent_fid;
 714         dclose->volatile_fid = cfile->fid.volatile_fid;
 715         list_add_tail(&dclose->dlist, &CIFS_I(d_inode(cfile->dentry))->deferred_closes);
 716 }
 717
 718 /*
 719  * Critical section which runs after acquiring deferred_lock.
 720  */
 721 void
 722 cifs_del_deferred_close(struct cifsFileInfo *cfile)
 723 {
 724         bool is_deferred = false;
 725         struct cifs_deferred_close *dclose;
 726
 727         is_deferred = cifs_is_deferred_close(cfile, &dclose);
 728         if (!is_deferred)
 729                 return;
 730         list_del(&dclose->dlist);
 731         kfree(dclose);
 732 }
 733
 734 void
 735 cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode)
 736 {
 737         struct cifsFileInfo *cfile = NULL;
 738         struct file_list *tmp_list, *tmp_next_list;
 739         struct list_head file_head;
 740
 741         if (cifs_inode == NULL)
 742                 return;
 743
 744         INIT_LIST_HEAD(&file_head);
 745         spin_lock(&cifs_inode->open_file_lock);
 746         list_for_each_entry(cfile, &cifs_inode->openFileList, flist) {
 747                 if (delayed_work_pending(&cfile->deferred)) {
 748                         if (cancel_delayed_work(&cfile->deferred)) {
 749                                 tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 750                                 if (tmp_list == NULL)
 751                                         continue;
 752                                 tmp_list->cfile = cfile;
 753                                 list_add_tail(&tmp_list->list, &file_head);
 754                         }
 755                 }
 756         }
 757         spin_unlock(&cifs_inode->open_file_lock);
 758
 759         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 760                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 761                 list_del(&tmp_list->list);
 762                 kfree(tmp_list);
 763         }
 764 }
 765
 766 void
 767 cifs_close_all_deferred_files(struct cifs_tcon *tcon)
 768 {
 769         struct cifsFileInfo *cfile;
 770         struct list_head *tmp;
 771         struct file_list *tmp_list, *tmp_next_list;
 772         struct list_head file_head;
 773
 774         INIT_LIST_HEAD(&file_head);
 775         spin_lock(&tcon->open_file_lock);
 776         list_for_each(tmp, &tcon->openFileList) {
 777                 cfile = list_entry(tmp, struct cifsFileInfo, tlist);
 778                 if (delayed_work_pending(&cfile->deferred)) {
 779                         if (cancel_delayed_work(&cfile->deferred)) {
 780                                 tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
 781                                 if (tmp_list == NULL)
 782                                         continue;
 783                                 tmp_list->cfile = cfile;
 784                                 list_add_tail(&tmp_list->list, &file_head);
 785                         }
 786                 }
 787         }
 788         spin_unlock(&tcon->open_file_lock);
 789
 790         list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
 791                 _cifsFileInfo_put(tmp_list->cfile, true, false);
 792                 list_del(&tmp_list->list);
 793                 kfree(tmp_list);
 794         }
 795 }
 796
 797 /* parses DFS refferal V3 structure
 798  * caller is responsible for freeing target_nodes
 799  * returns:
 800  * - on success - 0
 801  * - on failure - errno
 802  */
 803 int
 804 parse_dfs_referrals(struct get_dfs_referral_rsp *rsp, u32 rsp_size,
 805                     unsigned int *num_of_nodes,
 806                     struct dfs_info3_param **target_nodes,
 807                     const struct nls_table *nls_codepage, int remap,
 808                     const char *searchName, bool is_unicode)
 809 {
 810         int i, rc = 0;
 811         char *data_end;
 812         struct dfs_referral_level_3 *ref;
 813
 814         *num_of_nodes = le16_to_cpu(rsp->NumberOfReferrals);
 815
 816         if (*num_of_nodes < 1) {
 817                 cifs_dbg(VFS, "num_referrals: must be at least > 0, but we get num_referrals = %d\n",
 818                          *num_of_nodes);
 819                 rc = -EINVAL;
 820                 goto parse_DFS_referrals_exit;
 821         }
 822
 823         ref = (struct dfs_referral_level_3 *) &(rsp->referrals);
 824         if (ref->VersionNumber != cpu_to_le16(3)) {
 825                 cifs_dbg(VFS, "Referrals of V%d version are not supported, should be V3\n",
 826                          le16_to_cpu(ref->VersionNumber));
 827                 rc = -EINVAL;
 828                 goto parse_DFS_referrals_exit;
 829         }
 830
 831         /* get the upper boundary of the resp buffer */
 832         data_end = (char *)rsp + rsp_size;
 833
 834         cifs_dbg(FYI, "num_referrals: %d dfs flags: 0x%x ...\n",
 835                  *num_of_nodes, le32_to_cpu(rsp->DFSFlags));
 836
 837         *target_nodes = kcalloc(*num_of_nodes, sizeof(struct dfs_info3_param),
 838                                 GFP_KERNEL);
 839         if (*target_nodes == NULL) {
 840                 rc = -ENOMEM;
 841                 goto parse_DFS_referrals_exit;
 842         }
 843
 844         /* collect necessary data from referrals */
 845         for (i = 0; i < *num_of_nodes; i++) {
 846                 char *temp;
 847                 int max_len;
 848                 struct dfs_info3_param *node = (*target_nodes)+i;
 849
 850                 node->flags = le32_to_cpu(rsp->DFSFlags);
 851                 if (is_unicode) {
 852                         __le16 *tmp = kmalloc(strlen(searchName)*2 + 2,
 853                                                 GFP_KERNEL);
 854                         if (tmp == NULL) {
 855                                 rc = -ENOMEM;
 856                                 goto parse_DFS_referrals_exit;
 857                         }
 858                         cifsConvertToUTF16((__le16 *) tmp, searchName,
 859                                            PATH_MAX, nls_codepage, remap);
 860                         node->path_consumed = cifs_utf16_bytes(tmp,
 861                                         le16_to_cpu(rsp->PathConsumed),
 862                                         nls_codepage);
 863                         kfree(tmp);
 864                 } else
 865                         node->path_consumed = le16_to_cpu(rsp->PathConsumed);
 866
 867                 node->server_type = le16_to_cpu(ref->ServerType);
 868                 node->ref_flag = le16_to_cpu(ref->ReferralEntryFlags);
 869
 870                 /* copy DfsPath */
 871                 temp = (char *)ref + le16_to_cpu(ref->DfsPathOffset);
 872                 max_len = data_end - temp;
 873                 node->path_name = cifs_strndup_from_utf16(temp, max_len,
 874                                                 is_unicode, nls_codepage);
 875                 if (!node->path_name) {
 876                         rc = -ENOMEM;
 877                         goto parse_DFS_referrals_exit;
 878                 }
 879
 880                 /* copy link target UNC */
 881                 temp = (char *)ref + le16_to_cpu(ref->NetworkAddressOffset);
 882                 max_len = data_end - temp;
 883                 node->node_name = cifs_strndup_from_utf16(temp, max_len,
 884                                                 is_unicode, nls_codepage);
 885                 if (!node->node_name) {
 886                         rc = -ENOMEM;
 887                         goto parse_DFS_referrals_exit;
 888                 }
 889
 890                 node->ttl = le32_to_cpu(ref->TimeToLive);
 891
 892                 ref++;
 893         }
 894
 895 parse_DFS_referrals_exit:
 896         if (rc) {
 897                 free_dfs_info_array(*target_nodes, *num_of_nodes);
 898                 *target_nodes = NULL;
 899                 *num_of_nodes = 0;
 900         }
 901         return rc;
 902 }
 903
 904 struct cifs_aio_ctx *
 905 cifs_aio_ctx_alloc(void)
 906 {
 907         struct cifs_aio_ctx *ctx;
 908
 909         /*
 910          * Must use kzalloc to initialize ctx->bv to NULL and ctx->direct_io
 911          * to false so that we know when we have to unreference pages within
 912          * cifs_aio_ctx_release()
 913          */
 914         ctx = kzalloc(sizeof(struct cifs_aio_ctx), GFP_KERNEL);
 915         if (!ctx)
 916                 return NULL;
 917
 918         INIT_LIST_HEAD(&ctx->list);
 919         mutex_init(&ctx->aio_mutex);
 920         init_completion(&ctx->done);
 921         kref_init(&ctx->refcount);
 922         return ctx;
 923 }
 924
 925 void
 926 cifs_aio_ctx_release(struct kref *refcount)
 927 {
 928         struct cifs_aio_ctx *ctx = container_of(refcount,
 929                                         struct cifs_aio_ctx, refcount);
 930
 931         cifsFileInfo_put(ctx->cfile);
 932
 933         /*
 934          * ctx->bv is only set if setup_aio_ctx_iter() was call successfuly
 935          * which means that iov_iter_get_pages() was a success and thus that
 936          * we have taken reference on pages.
 937          */
 938         if (ctx->bv) {
 939                 unsigned i;
 940
 941                 for (i = 0; i < ctx->npages; i++) {
 942                         if (ctx->should_dirty)
 943                                 set_page_dirty(ctx->bv[i].bv_page);
 944                         put_page(ctx->bv[i].bv_page);
 945                 }
 946                 kvfree(ctx->bv);
 947         }
 948
 949         kfree(ctx);
 950 }
 951
 952 #define CIFS_AIO_KMALLOC_LIMIT (1024 * 1024)
 953
 954 int
 955 setup_aio_ctx_iter(struct cifs_aio_ctx *ctx, struct iov_iter *iter, int rw)
 956 {
 957         ssize_t rc;
 958         unsigned int cur_npages;
 959         unsigned int npages = 0;
 960         unsigned int i;
 961         size_t len;
 962         size_t count = iov_iter_count(iter);
 963         unsigned int saved_len;
 964         size_t start;
 965         unsigned int max_pages = iov_iter_npages(iter, INT_MAX);
 966         struct page **pages = NULL;
 967         struct bio_vec *bv = NULL;
 968
 969         if (iov_iter_is_kvec(iter)) {
 970                 memcpy(&ctx->iter, iter, sizeof(*iter));
 971                 ctx->len = count;
 972                 iov_iter_advance(iter, count);
 973                 return 0;
 974         }
 975
 976         if (array_size(max_pages, sizeof(*bv)) <= CIFS_AIO_KMALLOC_LIMIT)
 977                 bv = kmalloc_array(max_pages, sizeof(*bv), GFP_KERNEL);
 978
 979         if (!bv) {
 980                 bv = vmalloc(array_size(max_pages, sizeof(*bv)));
 981                 if (!bv)
 982                         return -ENOMEM;
 983         }
 984
 985         if (array_size(max_pages, sizeof(*pages)) <= CIFS_AIO_KMALLOC_LIMIT)
 986                 pages = kmalloc_array(max_pages, sizeof(*pages), GFP_KERNEL);
 987
 988         if (!pages) {
 989                 pages = vmalloc(array_size(max_pages, sizeof(*pages)));
 990                 if (!pages) {
 991                         kvfree(bv);
 992                         return -ENOMEM;
 993                 }
 994         }
 995
 996         saved_len = count;
 997
 998         while (count && npages < max_pages) {
 999                 rc = iov_iter_get_pages(iter, pages, count, max_pages, &start);
1000                 if (rc < 0) {
1001                         cifs_dbg(VFS, "Couldn't get user pages (rc=%zd)\n", rc);
1002                         break;
1003                 }
1004
1005                 if (rc > count) {
1006                         cifs_dbg(VFS, "get pages rc=%zd more than %zu\n", rc,
1007                                  count);
1008                         break;
1009                 }
1010
1011                 iov_iter_advance(iter, rc);
1012                 count -= rc;
1013                 rc += start;
1014                 cur_npages = DIV_ROUND_UP(rc, PAGE_SIZE);
1015
1016                 if (npages + cur_npages > max_pages) {
1017                         cifs_dbg(VFS, "out of vec array capacity (%u vs %u)\n",
1018                                  npages + cur_npages, max_pages);
1019                         break;
1020                 }
1021
1022                 for (i = 0; i < cur_npages; i++) {
1023                         len = rc > PAGE_SIZE ? PAGE_SIZE : rc;
1024                         bv[npages + i].bv_page = pages[i];
1025                         bv[npages + i].bv_offset = start;
1026                         bv[npages + i].bv_len = len - start;
1027                         rc -= len;
1028                         start = 0;
1029                 }
1030
1031                 npages += cur_npages;
1032         }
1033
1034         kvfree(pages);
1035         ctx->bv = bv;
1036         ctx->len = saved_len - count;
1037         ctx->npages = npages;
1038         iov_iter_bvec(&ctx->iter, rw, ctx->bv, npages, ctx->len);
1039         return 0;
1040 }
1041
1042 /**
1043  * cifs_alloc_hash - allocate hash and hash context together
1044  *
1045  * The caller has to make sure @sdesc is initialized to either NULL or
1046  * a valid context. Both can be freed via cifs_free_hash().
1047  */
1048 int
1049 cifs_alloc_hash(const char *name,
1050                 struct crypto_shash **shash, struct sdesc **sdesc)
1051 {
1052         int rc = 0;
1053         size_t size;
1054
1055         if (*sdesc != NULL)
1056                 return 0;
1057
1058         *shash = crypto_alloc_shash(name, 0, 0);
1059         if (IS_ERR(*shash)) {
1060                 cifs_dbg(VFS, "Could not allocate crypto %s\n", name);
1061                 rc = PTR_ERR(*shash);
1062                 *shash = NULL;
1063                 *sdesc = NULL;
1064                 return rc;
1065         }
1066
1067         size = sizeof(struct shash_desc) + crypto_shash_descsize(*shash);
1068         *sdesc = kmalloc(size, GFP_KERNEL);
1069         if (*sdesc == NULL) {
1070                 cifs_dbg(VFS, "no memory left to allocate crypto %s\n", name);
1071                 crypto_free_shash(*shash);
1072                 *shash = NULL;
1073                 return -ENOMEM;
1074         }
1075
1076         (*sdesc)->shash.tfm = *shash;
1077         return 0;
1078 }
1079
1080 /**
1081  * cifs_free_hash - free hash and hash context together
1082  *
1083  * Freeing a NULL hash or context is safe.
1084  */
1085 void
1086 cifs_free_hash(struct crypto_shash **shash, struct sdesc **sdesc)
1087 {
1088         kfree(*sdesc);
1089         *sdesc = NULL;
1090         if (*shash)
1091                 crypto_free_shash(*shash);
1092         *shash = NULL;
1093 }
1094
1095 /**
1096  * rqst_page_get_length - obtain the length and offset for a page in smb_rqst
1097  * Input: rqst - a smb_rqst, page - a page index for rqst
1098  * Output: *len - the length for this page, *offset - the offset for this page
1099  */
1100 void rqst_page_get_length(struct smb_rqst *rqst, unsigned int page,
1101                                 unsigned int *len, unsigned int *offset)
1102 {
1103         *len = rqst->rq_pagesz;
1104         *offset = (page == 0) ? rqst->rq_offset : 0;
1105
1106         if (rqst->rq_npages == 1 || page == rqst->rq_npages-1)
1107                 *len = rqst->rq_tailsz;
1108         else if (page == 0)
1109                 *len = rqst->rq_pagesz - rqst->rq_offset;
1110 }
1111
1112 void extract_unc_hostname(const char *unc, const char **h, size_t *len)
1113 {
1114         const char *end;
1115
1116         /* skip initial slashes */
1117         while (*unc && (*unc == '\\' || *unc == '/'))
1118                 unc++;
1119
1120         end = unc;
1121
1122         while (*end && !(*end == '\\' || *end == '/'))
1123                 end++;
1124
1125         *h = unc;
1126         *len = end - unc;
1127 }
1128
1129 /**
1130  * copy_path_name - copy src path to dst, possibly truncating
1131  *
1132  * returns number of bytes written (including trailing nul)
1133  */
1134 int copy_path_name(char *dst, const char *src)
1135 {
1136         int name_len;
1137
1138         /*
1139          * PATH_MAX includes nul, so if strlen(src) >= PATH_MAX it
1140          * will truncate and strlen(dst) will be PATH_MAX-1
1141          */
1142         name_len = strscpy(dst, src, PATH_MAX);
1143         if (WARN_ON_ONCE(name_len < 0))
1144                 name_len = PATH_MAX-1;
1145
1146         /* we count the trailing nul */
1147         name_len++;
1148         return name_len;
1149 }
1150
1151 struct super_cb_data {
1152         void *data;
1153         struct super_block *sb;
1154 };
1155
1156 static void tcp_super_cb(struct super_block *sb, void *arg)
1157 {
1158         struct super_cb_data *sd = arg;
1159         struct TCP_Server_Info *server = sd->data;
1160         struct cifs_sb_info *cifs_sb;
1161         struct cifs_tcon *tcon;
1162
1163         if (sd->sb)
1164                 return;
1165
1166         cifs_sb = CIFS_SB(sb);
1167         tcon = cifs_sb_master_tcon(cifs_sb);
1168         if (tcon->ses->server == server)
1169                 sd->sb = sb;
1170 }
1171
1172 static struct super_block *__cifs_get_super(void (*f)(struct super_block *, void *),
1173                                             void *data)
1174 {
1175         struct super_cb_data sd = {
1176                 .data = data,
1177                 .sb = NULL,
1178         };
1179
1180         iterate_supers_type(&cifs_fs_type, f, &sd);
1181
1182         if (!sd.sb)
1183                 return ERR_PTR(-EINVAL);
1184         /*
1185          * Grab an active reference in order to prevent automounts (DFS links)
1186          * of expiring and then freeing up our cifs superblock pointer while
1187          * we're doing failover.
1188          */
1189         cifs_sb_active(sd.sb);
1190         return sd.sb;
1191 }
1192
1193 static void __cifs_put_super(struct super_block *sb)
1194 {
1195         if (!IS_ERR_OR_NULL(sb))
1196                 cifs_sb_deactive(sb);
1197 }
1198
1199 struct super_block *cifs_get_tcp_super(struct TCP_Server_Info *server)
1200 {
1201         return __cifs_get_super(tcp_super_cb, server);
1202 }
1203
1204 void cifs_put_tcp_super(struct super_block *sb)
1205 {
1206         __cifs_put_super(sb);
1207 }
1208
1209 #ifdef CONFIG_CIFS_DFS_UPCALL
1210 int match_target_ip(struct TCP_Server_Info *server,
1211                     const char *share, size_t share_len,
1212                     bool *result)
1213 {
1214         int rc;
1215         char *target, *tip = NULL;
1216         struct sockaddr tipaddr;
1217
1218         *result = false;
1219
1220         target = kzalloc(share_len + 3, GFP_KERNEL);
1221         if (!target) {
1222                 rc = -ENOMEM;
1223                 goto out;
1224         }
1225
1226         scnprintf(target, share_len + 3, "\\\\%.*s", (int)share_len, share);
1227
1228         cifs_dbg(FYI, "%s: target name: %s\n", __func__, target + 2);
1229
1230         rc = dns_resolve_server_name_to_ip(target, &tip, NULL);
1231         if (rc < 0)
1232                 goto out;
1233
1234         cifs_dbg(FYI, "%s: target ip: %s\n", __func__, tip);
1235
1236         if (!cifs_convert_address(&tipaddr, tip, strlen(tip))) {
1237                 cifs_dbg(VFS, "%s: failed to convert target ip address\n",
1238                          __func__);
1239                 rc = -EINVAL;
1240                 goto out;
1241         }
1242
1243         *result = cifs_match_ipaddr((struct sockaddr *)&server->dstaddr,
1244                                     &tipaddr);
1245         cifs_dbg(FYI, "%s: ip addresses match: %u\n", __func__, *result);
1246         rc = 0;
1247
1248 out:
1249         kfree(target);
1250         kfree(tip);
1251
1252         return rc;
1253 }
1254
1255 static void tcon_super_cb(struct super_block *sb, void *arg)
1256 {
1257         struct super_cb_data *sd = arg;
1258         struct cifs_tcon *tcon = sd->data;
1259         struct cifs_sb_info *cifs_sb;
1260
1261         if (sd->sb)
1262                 return;
1263
1264         cifs_sb = CIFS_SB(sb);
1265         if (tcon->dfs_path && cifs_sb->origin_fullpath &&
1266             !strcasecmp(tcon->dfs_path, cifs_sb->origin_fullpath))
1267                 sd->sb = sb;
1268 }
1269
1270 static inline struct super_block *cifs_get_tcon_super(struct cifs_tcon *tcon)
1271 {
1272         return __cifs_get_super(tcon_super_cb, tcon);
1273 }
1274
1275 static inline void cifs_put_tcon_super(struct super_block *sb)
1276 {
1277         __cifs_put_super(sb);
1278 }
1279 #else
1280 static inline struct super_block *cifs_get_tcon_super(struct cifs_tcon *tcon)
1281 {
1282         return ERR_PTR(-EOPNOTSUPP);
1283 }
1284
1285 static inline void cifs_put_tcon_super(struct super_block *sb)
1286 {
1287 }
1288 #endif
1289
1290 int update_super_prepath(struct cifs_tcon *tcon, char *prefix)
1291 {
1292         struct super_block *sb;
1293         struct cifs_sb_info *cifs_sb;
1294         int rc = 0;
1295
1296         sb = cifs_get_tcon_super(tcon);
1297         if (IS_ERR(sb))
1298                 return PTR_ERR(sb);
1299
1300         cifs_sb = CIFS_SB(sb);
1301
1302         kfree(cifs_sb->prepath);
1303
1304         if (prefix && *prefix) {
1305                 cifs_sb->prepath = kstrdup(prefix, GFP_ATOMIC);
1306                 if (!cifs_sb->prepath) {
1307                         rc = -ENOMEM;
1308                         goto out;
1309                 }
1310
1311                 convert_delimiter(cifs_sb->prepath, CIFS_DIR_SEP(cifs_sb));
1312         } else
1313                 cifs_sb->prepath = NULL;
1314
1315         cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
1316
1317 out:
1318         cifs_put_tcon_super(sb);
1319         return rc;
1320 }