fs/cifs/readdir.c

   1 /*
   2  *   fs/cifs/readdir.c
   3  *
   4  *   Directory search handling
   5  *
   6  *   Copyright (C) International Business Machines  Corp., 2004, 2008
   7  *   Copyright (C) Red Hat, Inc., 2011
   8  *   Author(s): Steve French (sfrench@us.ibm.com)
   9  *
  10  *   This library is free software; you can redistribute it and/or modify
  11  *   it under the terms of the GNU Lesser General Public License as published
  12  *   by the Free Software Foundation; either version 2.1 of the License, or
  13  *   (at your option) any later version.
  14  *
  15  *   This library is distributed in the hope that it will be useful,
  16  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  18  *   the GNU Lesser General Public License for more details.
  19  *
  20  *   You should have received a copy of the GNU Lesser General Public License
  21  *   along with this library; if not, write to the Free Software
  22  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  23  */
  24 #include <linux/fs.h>
  25 #include <linux/pagemap.h>
  26 #include <linux/slab.h>
  27 #include <linux/stat.h>
  28 #include "cifspdu.h"
  29 #include "cifsglob.h"
  30 #include "cifsproto.h"
  31 #include "cifs_unicode.h"
  32 #include "cifs_debug.h"
  33 #include "cifs_fs_sb.h"
  34 #include "cifsfs.h"
  35
  36 /*
  37  * To be safe - for UCS to UTF-8 with strings loaded with the rare long
  38  * characters alloc more to account for such multibyte target UTF-8
  39  * characters.
  40  */
  41 #define UNICODE_NAME_MAX ((4 * NAME_MAX) + 2)
  42
  43 #ifdef CONFIG_CIFS_DEBUG2
  44 static void dump_cifs_file_struct(struct file *file, char *label)
  45 {
  46         struct cifsFileInfo *cf;
  47
  48         if (file) {
  49                 cf = file->private_data;
  50                 if (cf == NULL) {
  51                         cifs_dbg(FYI, "empty cifs private file data\n");
  52                         return;
  53                 }
  54                 if (cf->invalidHandle)
  55                         cifs_dbg(FYI, "invalid handle\n");
  56                 if (cf->srch_inf.endOfSearch)
  57                         cifs_dbg(FYI, "end of search\n");
  58                 if (cf->srch_inf.emptyDir)
  59                         cifs_dbg(FYI, "empty dir\n");
  60         }
  61 }
  62 #else
  63 static inline void dump_cifs_file_struct(struct file *file, char *label)
  64 {
  65 }
  66 #endif /* DEBUG2 */
  67
  68 /*
  69  * Attempt to preload the dcache with the results from the FIND_FIRST/NEXT
  70  *
  71  * Find the dentry that matches "name". If there isn't one, create one. If it's
  72  * a negative dentry or the uniqueid changed, then drop it and recreate it.
  73  */
  74 static void
  75 cifs_prime_dcache(struct dentry *parent, struct qstr *name,
  76                     struct cifs_fattr *fattr)
  77 {
  78         struct dentry *dentry, *alias;
  79         struct inode *inode;
  80         struct super_block *sb = parent->d_inode->i_sb;
  81         struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
  82
  83         cifs_dbg(FYI, "%s: for %s\n", __func__, name->name);
  84
  85         dentry = d_hash_and_lookup(parent, name);
  86         if (unlikely(IS_ERR(dentry)))
  87                 return;
  88
  89         if (dentry) {
  90                 inode = dentry->d_inode;
  91                 if (inode) {
  92                         /*
  93                          * If we're generating inode numbers, then we don't
  94                          * want to clobber the existing one with the one that
  95                          * the readdir code created.
  96                          */
  97                         if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM))
  98                                 fattr->cf_uniqueid = CIFS_I(inode)->uniqueid;
  99
 100                         /* update inode in place if i_ino didn't change */
 101                         if (CIFS_I(inode)->uniqueid == fattr->cf_uniqueid) {
 102                                 cifs_fattr_to_inode(inode, fattr);
 103                                 goto out;
 104                         }
 105                 }
 106                 d_invalidate(dentry);
 107                 dput(dentry);
 108         }
 109
 110         /*
 111          * If we know that the inode will need to be revalidated immediately,
 112          * then don't create a new dentry for it. We'll end up doing an on
 113          * the wire call either way and this spares us an invalidation.
 114          */
 115         if (fattr->cf_flags & CIFS_FATTR_NEED_REVAL)
 116                 return;
 117
 118         dentry = d_alloc(parent, name);
 119         if (!dentry)
 120                 return;
 121
 122         inode = cifs_iget(sb, fattr);
 123         if (!inode)
 124                 goto out;
 125
 126         alias = d_splice_alias(inode, dentry);
 127         if (alias && !IS_ERR(alias))
 128                 dput(alias);
 129 out:
 130         dput(dentry);
 131 }
 132
 133 static void
 134 cifs_fill_common_info(struct cifs_fattr *fattr, struct cifs_sb_info *cifs_sb)
 135 {
 136         fattr->cf_uid = cifs_sb->mnt_uid;
 137         fattr->cf_gid = cifs_sb->mnt_gid;
 138
 139         if (fattr->cf_cifsattrs & ATTR_DIRECTORY) {
 140                 fattr->cf_mode = S_IFDIR | cifs_sb->mnt_dir_mode;
 141                 fattr->cf_dtype = DT_DIR;
 142         } else {
 143                 fattr->cf_mode = S_IFREG | cifs_sb->mnt_file_mode;
 144                 fattr->cf_dtype = DT_REG;
 145         }
 146
 147         /*
 148          * We need to revalidate it further to make a decision about whether it
 149          * is a symbolic link, DFS referral or a reparse point with a direct
 150          * access like junctions, deduplicated files, NFS symlinks.
 151          */
 152         if (fattr->cf_cifsattrs & ATTR_REPARSE)
 153                 fattr->cf_flags |= CIFS_FATTR_NEED_REVAL;
 154
 155         /* non-unix readdir doesn't provide nlink */
 156         fattr->cf_flags |= CIFS_FATTR_UNKNOWN_NLINK;
 157
 158         if (fattr->cf_cifsattrs & ATTR_READONLY)
 159                 fattr->cf_mode &= ~S_IWUGO;
 160
 161         /*
 162          * We of course don't get ACL info in FIND_FIRST/NEXT results, so
 163          * mark it for revalidation so that "ls -l" will look right. It might
 164          * be super-slow, but if we don't do this then the ownership of files
 165          * may look wrong since the inodes may not have timed out by the time
 166          * "ls" does a stat() call on them.
 167          */
 168         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_ACL)
 169                 fattr->cf_flags |= CIFS_FATTR_NEED_REVAL;
 170
 171         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL &&
 172             fattr->cf_cifsattrs & ATTR_SYSTEM) {
 173                 if (fattr->cf_eof == 0)  {
 174                         fattr->cf_mode &= ~S_IFMT;
 175                         fattr->cf_mode |= S_IFIFO;
 176                         fattr->cf_dtype = DT_FIFO;
 177                 } else {
 178                         /*
 179                          * trying to get the type and mode via SFU can be slow,
 180                          * so just call those regular files for now, and mark
 181                          * for reval
 182                          */
 183                         fattr->cf_flags |= CIFS_FATTR_NEED_REVAL;
 184                 }
 185         }
 186 }
 187
 188 void
 189 cifs_dir_info_to_fattr(struct cifs_fattr *fattr, FILE_DIRECTORY_INFO *info,
 190                        struct cifs_sb_info *cifs_sb)
 191 {
 192         memset(fattr, 0, sizeof(*fattr));
 193         fattr->cf_cifsattrs = le32_to_cpu(info->ExtFileAttributes);
 194         fattr->cf_eof = le64_to_cpu(info->EndOfFile);
 195         fattr->cf_bytes = le64_to_cpu(info->AllocationSize);
 196         fattr->cf_createtime = le64_to_cpu(info->CreationTime);
 197         fattr->cf_atime = cifs_NTtimeToUnix(info->LastAccessTime);
 198         fattr->cf_ctime = cifs_NTtimeToUnix(info->ChangeTime);
 199         fattr->cf_mtime = cifs_NTtimeToUnix(info->LastWriteTime);
 200
 201         cifs_fill_common_info(fattr, cifs_sb);
 202 }
 203
 204 static void
 205 cifs_std_info_to_fattr(struct cifs_fattr *fattr, FIND_FILE_STANDARD_INFO *info,
 206                        struct cifs_sb_info *cifs_sb)
 207 {
 208         int offset = cifs_sb_master_tcon(cifs_sb)->ses->server->timeAdj;
 209
 210         memset(fattr, 0, sizeof(*fattr));
 211         fattr->cf_atime = cnvrtDosUnixTm(info->LastAccessDate,
 212                                             info->LastAccessTime, offset);
 213         fattr->cf_ctime = cnvrtDosUnixTm(info->LastWriteDate,
 214                                             info->LastWriteTime, offset);
 215         fattr->cf_mtime = cnvrtDosUnixTm(info->LastWriteDate,
 216                                             info->LastWriteTime, offset);
 217
 218         fattr->cf_cifsattrs = le16_to_cpu(info->Attributes);
 219         fattr->cf_bytes = le32_to_cpu(info->AllocationSize);
 220         fattr->cf_eof = le32_to_cpu(info->DataSize);
 221
 222         cifs_fill_common_info(fattr, cifs_sb);
 223 }
 224
 225 /* BB eventually need to add the following helper function to
 226       resolve NT_STATUS_STOPPED_ON_SYMLINK return code when
 227       we try to do FindFirst on (NTFS) directory symlinks */
 228 /*
 229 int get_symlink_reparse_path(char *full_path, struct cifs_sb_info *cifs_sb,
 230                              unsigned int xid)
 231 {
 232         __u16 fid;
 233         int len;
 234         int oplock = 0;
 235         int rc;
 236         struct cifs_tcon *ptcon = cifs_sb_tcon(cifs_sb);
 237         char *tmpbuffer;
 238
 239         rc = CIFSSMBOpen(xid, ptcon, full_path, FILE_OPEN, GENERIC_READ,
 240                         OPEN_REPARSE_POINT, &fid, &oplock, NULL,
 241                         cifs_sb->local_nls,
 242                         cifs_remap(cifs_sb);
 243         if (!rc) {
 244                 tmpbuffer = kmalloc(maxpath);
 245                 rc = CIFSSMBQueryReparseLinkInfo(xid, ptcon, full_path,
 246                                 tmpbuffer,
 247                                 maxpath -1,
 248                                 fid,
 249                                 cifs_sb->local_nls);
 250                 if (CIFSSMBClose(xid, ptcon, fid)) {
 251                         cifs_dbg(FYI, "Error closing temporary reparsepoint open\n");
 252                 }
 253         }
 254 }
 255  */
 256
 257 static int
 258 initiate_cifs_search(const unsigned int xid, struct file *file)
 259 {
 260         __u16 search_flags;
 261         int rc = 0;
 262         char *full_path = NULL;
 263         struct cifsFileInfo *cifsFile;
 264         struct cifs_sb_info *cifs_sb = CIFS_FILE_SB(file);
 265         struct tcon_link *tlink = NULL;
 266         struct cifs_tcon *tcon;
 267         struct TCP_Server_Info *server;
 268
 269         if (file->private_data == NULL) {
 270                 tlink = cifs_sb_tlink(cifs_sb);
 271                 if (IS_ERR(tlink))
 272                         return PTR_ERR(tlink);
 273
 274                 cifsFile = kzalloc(sizeof(struct cifsFileInfo), GFP_KERNEL);
 275                 if (cifsFile == NULL) {
 276                         rc = -ENOMEM;
 277                         goto error_exit;
 278                 }
 279                 file->private_data = cifsFile;
 280                 cifsFile->tlink = cifs_get_tlink(tlink);
 281                 tcon = tlink_tcon(tlink);
 282         } else {
 283                 cifsFile = file->private_data;
 284                 tcon = tlink_tcon(cifsFile->tlink);
 285         }
 286
 287         server = tcon->ses->server;
 288
 289         if (!server->ops->query_dir_first) {
 290                 rc = -ENOSYS;
 291                 goto error_exit;
 292         }
 293
 294         cifsFile->invalidHandle = true;
 295         cifsFile->srch_inf.endOfSearch = false;
 296
 297         full_path = build_path_from_dentry(file->f_path.dentry);
 298         if (full_path == NULL) {
 299                 rc = -ENOMEM;
 300                 goto error_exit;
 301         }
 302
 303         cifs_dbg(FYI, "Full path: %s start at: %lld\n", full_path, file->f_pos);
 304
 305 ffirst_retry:
 306         /* test for Unix extensions */
 307         /* but now check for them on the share/mount not on the SMB session */
 308         /* if (cap_unix(tcon->ses) { */
 309         if (tcon->unix_ext)
 310                 cifsFile->srch_inf.info_level = SMB_FIND_FILE_UNIX;
 311         else if ((tcon->ses->capabilities &
 312                   tcon->ses->server->vals->cap_nt_find) == 0) {
 313                 cifsFile->srch_inf.info_level = SMB_FIND_FILE_INFO_STANDARD;
 314         } else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) {
 315                 cifsFile->srch_inf.info_level = SMB_FIND_FILE_ID_FULL_DIR_INFO;
 316         } else /* not srvinos - BB fixme add check for backlevel? */ {
 317                 cifsFile->srch_inf.info_level = SMB_FIND_FILE_DIRECTORY_INFO;
 318         }
 319
 320         search_flags = CIFS_SEARCH_CLOSE_AT_END | CIFS_SEARCH_RETURN_RESUME;
 321         if (backup_cred(cifs_sb))
 322                 search_flags |= CIFS_SEARCH_BACKUP_SEARCH;
 323
 324         rc = server->ops->query_dir_first(xid, tcon, full_path, cifs_sb,
 325                                           &cifsFile->fid, search_flags,
 326                                           &cifsFile->srch_inf);
 327
 328         if (rc == 0)
 329                 cifsFile->invalidHandle = false;
 330         /* BB add following call to handle readdir on new NTFS symlink errors
 331         else if STATUS_STOPPED_ON_SYMLINK
 332                 call get_symlink_reparse_path and retry with new path */
 333         else if ((rc == -EOPNOTSUPP) &&
 334                 (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM)) {
 335                 cifs_sb->mnt_cifs_flags &= ~CIFS_MOUNT_SERVER_INUM;
 336                 goto ffirst_retry;
 337         }
 338 error_exit:
 339         kfree(full_path);
 340         cifs_put_tlink(tlink);
 341         return rc;
 342 }
 343
 344 /* return length of unicode string in bytes */
 345 static int cifs_unicode_bytelen(const char *str)
 346 {
 347         int len;
 348         const __le16 *ustr = (const __le16 *)str;
 349
 350         for (len = 0; len <= PATH_MAX; len++) {
 351                 if (ustr[len] == 0)
 352                         return len << 1;
 353         }
 354         cifs_dbg(FYI, "Unicode string longer than PATH_MAX found\n");
 355         return len << 1;
 356 }
 357
 358 static char *nxt_dir_entry(char *old_entry, char *end_of_smb, int level)
 359 {
 360         char *new_entry;
 361         FILE_DIRECTORY_INFO *pDirInfo = (FILE_DIRECTORY_INFO *)old_entry;
 362
 363         if (level == SMB_FIND_FILE_INFO_STANDARD) {
 364                 FIND_FILE_STANDARD_INFO *pfData;
 365                 pfData = (FIND_FILE_STANDARD_INFO *)pDirInfo;
 366
 367                 new_entry = old_entry + sizeof(FIND_FILE_STANDARD_INFO) +
 368                                 pfData->FileNameLength;
 369         } else
 370                 new_entry = old_entry + le32_to_cpu(pDirInfo->NextEntryOffset);
 371         cifs_dbg(FYI, "new entry %p old entry %p\n", new_entry, old_entry);
 372         /* validate that new_entry is not past end of SMB */
 373         if (new_entry >= end_of_smb) {
 374                 cifs_dbg(VFS, "search entry %p began after end of SMB %p old entry %p\n",
 375                          new_entry, end_of_smb, old_entry);
 376                 return NULL;
 377         } else if (((level == SMB_FIND_FILE_INFO_STANDARD) &&
 378                     (new_entry + sizeof(FIND_FILE_STANDARD_INFO) > end_of_smb))
 379                   || ((level != SMB_FIND_FILE_INFO_STANDARD) &&
 380                    (new_entry + sizeof(FILE_DIRECTORY_INFO) > end_of_smb)))  {
 381                 cifs_dbg(VFS, "search entry %p extends after end of SMB %p\n",
 382                          new_entry, end_of_smb);
 383                 return NULL;
 384         } else
 385                 return new_entry;
 386
 387 }
 388
 389 struct cifs_dirent {
 390         const char      *name;
 391         size_t          namelen;
 392         u32             resume_key;
 393         u64             ino;
 394 };
 395
 396 static void cifs_fill_dirent_unix(struct cifs_dirent *de,
 397                 const FILE_UNIX_INFO *info, bool is_unicode)
 398 {
 399         de->name = &info->FileName[0];
 400         if (is_unicode)
 401                 de->namelen = cifs_unicode_bytelen(de->name);
 402         else
 403                 de->namelen = strnlen(de->name, PATH_MAX);
 404         de->resume_key = info->ResumeKey;
 405         de->ino = le64_to_cpu(info->basic.UniqueId);
 406 }
 407
 408 static void cifs_fill_dirent_dir(struct cifs_dirent *de,
 409                 const FILE_DIRECTORY_INFO *info)
 410 {
 411         de->name = &info->FileName[0];
 412         de->namelen = le32_to_cpu(info->FileNameLength);
 413         de->resume_key = info->FileIndex;
 414 }
 415
 416 static void cifs_fill_dirent_full(struct cifs_dirent *de,
 417                 const FILE_FULL_DIRECTORY_INFO *info)
 418 {
 419         de->name = &info->FileName[0];
 420         de->namelen = le32_to_cpu(info->FileNameLength);
 421         de->resume_key = info->FileIndex;
 422 }
 423
 424 static void cifs_fill_dirent_search(struct cifs_dirent *de,
 425                 const SEARCH_ID_FULL_DIR_INFO *info)
 426 {
 427         de->name = &info->FileName[0];
 428         de->namelen = le32_to_cpu(info->FileNameLength);
 429         de->resume_key = info->FileIndex;
 430         de->ino = le64_to_cpu(info->UniqueId);
 431 }
 432
 433 static void cifs_fill_dirent_both(struct cifs_dirent *de,
 434                 const FILE_BOTH_DIRECTORY_INFO *info)
 435 {
 436         de->name = &info->FileName[0];
 437         de->namelen = le32_to_cpu(info->FileNameLength);
 438         de->resume_key = info->FileIndex;
 439 }
 440
 441 static void cifs_fill_dirent_std(struct cifs_dirent *de,
 442                 const FIND_FILE_STANDARD_INFO *info)
 443 {
 444         de->name = &info->FileName[0];
 445         /* one byte length, no endianess conversion */
 446         de->namelen = info->FileNameLength;
 447         de->resume_key = info->ResumeKey;
 448 }
 449
 450 static int cifs_fill_dirent(struct cifs_dirent *de, const void *info,
 451                 u16 level, bool is_unicode)
 452 {
 453         memset(de, 0, sizeof(*de));
 454
 455         switch (level) {
 456         case SMB_FIND_FILE_UNIX:
 457                 cifs_fill_dirent_unix(de, info, is_unicode);
 458                 break;
 459         case SMB_FIND_FILE_DIRECTORY_INFO:
 460                 cifs_fill_dirent_dir(de, info);
 461                 break;
 462         case SMB_FIND_FILE_FULL_DIRECTORY_INFO:
 463                 cifs_fill_dirent_full(de, info);
 464                 break;
 465         case SMB_FIND_FILE_ID_FULL_DIR_INFO:
 466                 cifs_fill_dirent_search(de, info);
 467                 break;
 468         case SMB_FIND_FILE_BOTH_DIRECTORY_INFO:
 469                 cifs_fill_dirent_both(de, info);
 470                 break;
 471         case SMB_FIND_FILE_INFO_STANDARD:
 472                 cifs_fill_dirent_std(de, info);
 473                 break;
 474         default:
 475                 cifs_dbg(FYI, "Unknown findfirst level %d\n", level);
 476                 return -EINVAL;
 477         }
 478
 479         return 0;
 480 }
 481
 482 #define UNICODE_DOT cpu_to_le16(0x2e)
 483
 484 /* return 0 if no match and 1 for . (current directory) and 2 for .. (parent) */
 485 static int cifs_entry_is_dot(struct cifs_dirent *de, bool is_unicode)
 486 {
 487         int rc = 0;
 488
 489         if (!de->name)
 490                 return 0;
 491
 492         if (is_unicode) {
 493                 __le16 *ufilename = (__le16 *)de->name;
 494                 if (de->namelen == 2) {
 495                         /* check for . */
 496                         if (ufilename[0] == UNICODE_DOT)
 497                                 rc = 1;
 498                 } else if (de->namelen == 4) {
 499                         /* check for .. */
 500                         if (ufilename[0] == UNICODE_DOT &&
 501                             ufilename[1] == UNICODE_DOT)
 502                                 rc = 2;
 503                 }
 504         } else /* ASCII */ {
 505                 if (de->namelen == 1) {
 506                         if (de->name[0] == '.')
 507                                 rc = 1;
 508                 } else if (de->namelen == 2) {
 509                         if (de->name[0] == '.' && de->name[1] == '.')
 510                                 rc = 2;
 511                 }
 512         }
 513
 514         return rc;
 515 }
 516
 517 /* Check if directory that we are searching has changed so we can decide
 518    whether we can use the cached search results from the previous search */
 519 static int is_dir_changed(struct file *file)
 520 {
 521         struct inode *inode = file_inode(file);
 522         struct cifsInodeInfo *cifsInfo = CIFS_I(inode);
 523
 524         if (cifsInfo->time == 0)
 525                 return 1; /* directory was changed, perhaps due to unlink */
 526         else
 527                 return 0;
 528
 529 }
 530
 531 static int cifs_save_resume_key(const char *current_entry,
 532         struct cifsFileInfo *file_info)
 533 {
 534         struct cifs_dirent de;
 535         int rc;
 536
 537         rc = cifs_fill_dirent(&de, current_entry, file_info->srch_inf.info_level,
 538                               file_info->srch_inf.unicode);
 539         if (!rc) {
 540                 file_info->srch_inf.presume_name = de.name;
 541                 file_info->srch_inf.resume_name_len = de.namelen;
 542                 file_info->srch_inf.resume_key = de.resume_key;
 543         }
 544         return rc;
 545 }
 546
 547 /*
 548  * Find the corresponding entry in the search. Note that the SMB server returns
 549  * search entries for . and .. which complicates logic here if we choose to
 550  * parse for them and we do not assume that they are located in the findfirst
 551  * return buffer. We start counting in the buffer with entry 2 and increment for
 552  * every entry (do not increment for . or .. entry).
 553  */
 554 static int
 555 find_cifs_entry(const unsigned int xid, struct cifs_tcon *tcon, loff_t pos,
 556                 struct file *file, char **current_entry, int *num_to_ret)
 557 {
 558         __u16 search_flags;
 559         int rc = 0;
 560         int pos_in_buf = 0;
 561         loff_t first_entry_in_buffer;
 562         loff_t index_to_find = pos;
 563         struct cifsFileInfo *cfile = file->private_data;
 564         struct cifs_sb_info *cifs_sb = CIFS_FILE_SB(file);
 565         struct TCP_Server_Info *server = tcon->ses->server;
 566         /* check if index in the buffer */
 567
 568         if (!server->ops->query_dir_first || !server->ops->query_dir_next)
 569                 return -ENOSYS;
 570
 571         if ((cfile == NULL) || (current_entry == NULL) || (num_to_ret == NULL))
 572                 return -ENOENT;
 573
 574         *current_entry = NULL;
 575         first_entry_in_buffer = cfile->srch_inf.index_of_last_entry -
 576                                         cfile->srch_inf.entries_in_buffer;
 577
 578         /*
 579          * If first entry in buf is zero then is first buffer
 580          * in search response data which means it is likely . and ..
 581          * will be in this buffer, although some servers do not return
 582          * . and .. for the root of a drive and for those we need
 583          * to start two entries earlier.
 584          */
 585
 586         dump_cifs_file_struct(file, "In fce ");
 587         if (((index_to_find < cfile->srch_inf.index_of_last_entry) &&
 588              is_dir_changed(file)) || (index_to_find < first_entry_in_buffer)) {
 589                 /* close and restart search */
 590                 cifs_dbg(FYI, "search backing up - close and restart search\n");
 591                 spin_lock(&cifs_file_list_lock);
 592                 if (server->ops->dir_needs_close(cfile)) {
 593                         cfile->invalidHandle = true;
 594                         spin_unlock(&cifs_file_list_lock);
 595                         if (server->ops->close_dir)
 596                                 server->ops->close_dir(xid, tcon, &cfile->fid);
 597                 } else
 598                         spin_unlock(&cifs_file_list_lock);
 599                 if (cfile->srch_inf.ntwrk_buf_start) {
 600                         cifs_dbg(FYI, "freeing SMB ff cache buf on search rewind\n");
 601                         if (cfile->srch_inf.smallBuf)
 602                                 cifs_small_buf_release(cfile->srch_inf.
 603                                                 ntwrk_buf_start);
 604                         else
 605                                 cifs_buf_release(cfile->srch_inf.
 606                                                 ntwrk_buf_start);
 607                         cfile->srch_inf.ntwrk_buf_start = NULL;
 608                 }
 609                 rc = initiate_cifs_search(xid, file);
 610                 if (rc) {
 611                         cifs_dbg(FYI, "error %d reinitiating a search on rewind\n",
 612                                  rc);
 613                         return rc;
 614                 }
 615                 /* FindFirst/Next set last_entry to NULL on malformed reply */
 616                 if (cfile->srch_inf.last_entry)
 617                         cifs_save_resume_key(cfile->srch_inf.last_entry, cfile);
 618         }
 619
 620         search_flags = CIFS_SEARCH_CLOSE_AT_END | CIFS_SEARCH_RETURN_RESUME;
 621         if (backup_cred(cifs_sb))
 622                 search_flags |= CIFS_SEARCH_BACKUP_SEARCH;
 623
 624         while ((index_to_find >= cfile->srch_inf.index_of_last_entry) &&
 625                (rc == 0) && !cfile->srch_inf.endOfSearch) {
 626                 cifs_dbg(FYI, "calling findnext2\n");
 627                 rc = server->ops->query_dir_next(xid, tcon, &cfile->fid,
 628                                                  search_flags,
 629                                                  &cfile->srch_inf);
 630                 /* FindFirst/Next set last_entry to NULL on malformed reply */
 631                 if (cfile->srch_inf.last_entry)
 632                         cifs_save_resume_key(cfile->srch_inf.last_entry, cfile);
 633                 if (rc)
 634                         return -ENOENT;
 635         }
 636         if (index_to_find < cfile->srch_inf.index_of_last_entry) {
 637                 /* we found the buffer that contains the entry */
 638                 /* scan and find it */
 639                 int i;
 640                 char *cur_ent;
 641                 char *end_of_smb = cfile->srch_inf.ntwrk_buf_start +
 642                         server->ops->calc_smb_size(
 643                                         cfile->srch_inf.ntwrk_buf_start);
 644
 645                 cur_ent = cfile->srch_inf.srch_entries_start;
 646                 first_entry_in_buffer = cfile->srch_inf.index_of_last_entry
 647                                         - cfile->srch_inf.entries_in_buffer;
 648                 pos_in_buf = index_to_find - first_entry_in_buffer;
 649                 cifs_dbg(FYI, "found entry - pos_in_buf %d\n", pos_in_buf);
 650
 651                 for (i = 0; (i < (pos_in_buf)) && (cur_ent != NULL); i++) {
 652                         /* go entry by entry figuring out which is first */
 653                         cur_ent = nxt_dir_entry(cur_ent, end_of_smb,
 654                                                 cfile->srch_inf.info_level);
 655                 }
 656                 if ((cur_ent == NULL) && (i < pos_in_buf)) {
 657                         /* BB fixme - check if we should flag this error */
 658                         cifs_dbg(VFS, "reached end of buf searching for pos in buf %d index to find %lld rc %d\n",
 659                                  pos_in_buf, index_to_find, rc);
 660                 }
 661                 rc = 0;
 662                 *current_entry = cur_ent;
 663         } else {
 664                 cifs_dbg(FYI, "index not in buffer - could not findnext into it\n");
 665                 return 0;
 666         }
 667
 668         if (pos_in_buf >= cfile->srch_inf.entries_in_buffer) {
 669                 cifs_dbg(FYI, "can not return entries pos_in_buf beyond last\n");
 670                 *num_to_ret = 0;
 671         } else
 672                 *num_to_ret = cfile->srch_inf.entries_in_buffer - pos_in_buf;
 673
 674         return rc;
 675 }
 676
 677 static int cifs_filldir(char *find_entry, struct file *file,
 678                 struct dir_context *ctx,
 679                 char *scratch_buf, unsigned int max_len)
 680 {
 681         struct cifsFileInfo *file_info = file->private_data;
 682         struct super_block *sb = file_inode(file)->i_sb;
 683         struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
 684         struct cifs_dirent de = { NULL, };
 685         struct cifs_fattr fattr;
 686         struct qstr name;
 687         int rc = 0;
 688         ino_t ino;
 689
 690         rc = cifs_fill_dirent(&de, find_entry, file_info->srch_inf.info_level,
 691                               file_info->srch_inf.unicode);
 692         if (rc)
 693                 return rc;
 694
 695         if (de.namelen > max_len) {
 696                 cifs_dbg(VFS, "bad search response length %zd past smb end\n",
 697                          de.namelen);
 698                 return -EINVAL;
 699         }
 700
 701         /* skip . and .. since we added them first */
 702         if (cifs_entry_is_dot(&de, file_info->srch_inf.unicode))
 703                 return 0;
 704
 705         if (file_info->srch_inf.unicode) {
 706                 struct nls_table *nlt = cifs_sb->local_nls;
 707                 int map_type;
 708
 709                 map_type = cifs_remap(cifs_sb);
 710                 name.name = scratch_buf;
 711                 name.len =
 712                         cifs_from_utf16((char *)name.name, (__le16 *)de.name,
 713                                         UNICODE_NAME_MAX,
 714                                         min_t(size_t, de.namelen,
 715                                               (size_t)max_len), nlt, map_type);
 716                 name.len -= nls_nullsize(nlt);
 717         } else {
 718                 name.name = de.name;
 719                 name.len = de.namelen;
 720         }
 721
 722         switch (file_info->srch_inf.info_level) {
 723         case SMB_FIND_FILE_UNIX:
 724                 cifs_unix_basic_to_fattr(&fattr,
 725                                          &((FILE_UNIX_INFO *)find_entry)->basic,
 726                                          cifs_sb);
 727                 break;
 728         case SMB_FIND_FILE_INFO_STANDARD:
 729                 cifs_std_info_to_fattr(&fattr,
 730                                        (FIND_FILE_STANDARD_INFO *)find_entry,
 731                                        cifs_sb);
 732                 break;
 733         default:
 734                 cifs_dir_info_to_fattr(&fattr,
 735                                        (FILE_DIRECTORY_INFO *)find_entry,
 736                                        cifs_sb);
 737                 break;
 738         }
 739
 740         if (de.ino && (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM)) {
 741                 fattr.cf_uniqueid = de.ino;
 742         } else {
 743                 fattr.cf_uniqueid = iunique(sb, ROOT_I);
 744                 cifs_autodisable_serverino(cifs_sb);
 745         }
 746
 747         if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS) &&
 748             couldbe_mf_symlink(&fattr))
 749                 /*
 750                  * trying to get the type and mode can be slow,
 751                  * so just call those regular files for now, and mark
 752                  * for reval
 753                  */
 754                 fattr.cf_flags |= CIFS_FATTR_NEED_REVAL;
 755
 756         cifs_prime_dcache(file->f_path.dentry, &name, &fattr);
 757
 758         ino = cifs_uniqueid_to_ino_t(fattr.cf_uniqueid);
 759         return !dir_emit(ctx, name.name, name.len, ino, fattr.cf_dtype);
 760 }
 761
 762
 763 int cifs_readdir(struct file *file, struct dir_context *ctx)
 764 {
 765         int rc = 0;
 766         unsigned int xid;
 767         int i;
 768         struct cifs_tcon *tcon;
 769         struct cifsFileInfo *cifsFile = NULL;
 770         char *current_entry;
 771         int num_to_fill = 0;
 772         char *tmp_buf = NULL;
 773         char *end_of_smb;
 774         unsigned int max_len;
 775
 776         xid = get_xid();
 777
 778         /*
 779          * Ensure FindFirst doesn't fail before doing filldir() for '.' and
 780          * '..'. Otherwise we won't be able to notify VFS in case of failure.
 781          */
 782         if (file->private_data == NULL) {
 783                 rc = initiate_cifs_search(xid, file);
 784                 cifs_dbg(FYI, "initiate cifs search rc %d\n", rc);
 785                 if (rc)
 786                         goto rddir2_exit;
 787         }
 788
 789         if (!dir_emit_dots(file, ctx))
 790                 goto rddir2_exit;
 791
 792         /* 1) If search is active,
 793                 is in current search buffer?
 794                 if it before then restart search
 795                 if after then keep searching till find it */
 796
 797         cifsFile = file->private_data;
 798         if (cifsFile->srch_inf.endOfSearch) {
 799                 if (cifsFile->srch_inf.emptyDir) {
 800                         cifs_dbg(FYI, "End of search, empty dir\n");
 801                         rc = 0;
 802                         goto rddir2_exit;
 803                 }
 804         } /* else {
 805                 cifsFile->invalidHandle = true;
 806                 tcon->ses->server->close(xid, tcon, &cifsFile->fid);
 807         } */
 808
 809         tcon = tlink_tcon(cifsFile->tlink);
 810         rc = find_cifs_entry(xid, tcon, ctx->pos, file, &current_entry,
 811                              &num_to_fill);
 812         if (rc) {
 813                 cifs_dbg(FYI, "fce error %d\n", rc);
 814                 goto rddir2_exit;
 815         } else if (current_entry != NULL) {
 816                 cifs_dbg(FYI, "entry %lld found\n", ctx->pos);
 817         } else {
 818                 cifs_dbg(FYI, "could not find entry\n");
 819                 goto rddir2_exit;
 820         }
 821         cifs_dbg(FYI, "loop through %d times filling dir for net buf %p\n",
 822                  num_to_fill, cifsFile->srch_inf.ntwrk_buf_start);
 823         max_len = tcon->ses->server->ops->calc_smb_size(
 824                         cifsFile->srch_inf.ntwrk_buf_start);
 825         end_of_smb = cifsFile->srch_inf.ntwrk_buf_start + max_len;
 826
 827         tmp_buf = kmalloc(UNICODE_NAME_MAX, GFP_KERNEL);
 828         if (tmp_buf == NULL) {
 829                 rc = -ENOMEM;
 830                 goto rddir2_exit;
 831         }
 832
 833         for (i = 0; i < num_to_fill; i++) {
 834                 if (current_entry == NULL) {
 835                         /* evaluate whether this case is an error */
 836                         cifs_dbg(VFS, "past SMB end,  num to fill %d i %d\n",
 837                                  num_to_fill, i);
 838                         break;
 839                 }
 840                 /*
 841                  * if buggy server returns . and .. late do we want to
 842                  * check for that here?
 843                  */
 844                 rc = cifs_filldir(current_entry, file, ctx,
 845                                   tmp_buf, max_len);
 846                 if (rc) {
 847                         if (rc > 0)
 848                                 rc = 0;
 849                         break;
 850                 }
 851
 852                 ctx->pos++;
 853                 if (ctx->pos ==
 854                         cifsFile->srch_inf.index_of_last_entry) {
 855                         cifs_dbg(FYI, "last entry in buf at pos %lld %s\n",
 856                                  ctx->pos, tmp_buf);
 857                         cifs_save_resume_key(current_entry, cifsFile);
 858                         break;
 859                 } else
 860                         current_entry =
 861                                 nxt_dir_entry(current_entry, end_of_smb,
 862                                         cifsFile->srch_inf.info_level);
 863         }
 864         kfree(tmp_buf);
 865
 866 rddir2_exit:
 867         free_xid(xid);
 868         return rc;
 869 }