root/fs/9p/vfs_inode.c

DEFINITIONS

1. unixmode2p9mode
2. p9mode2perm
3. p9mode2unixmode
4. v9fs_uflags2omode
5. v9fs_blank_wstat
6. v9fs_alloc_inode
7. v9fs_free_inode
8. v9fs_init_inode
9. v9fs_get_inode
10. v9fs_evict_inode
11. v9fs_test_inode
12. v9fs_test_new_inode
13. v9fs_set_inode
14. v9fs_qid_iget
15. v9fs_inode_from_fid
16. v9fs_at_to_dotl_flags
17. v9fs_dec_count
18. v9fs_remove
19. v9fs_create
20. v9fs_vfs_create
21. v9fs_vfs_mkdir
22. v9fs_vfs_lookup
23. v9fs_vfs_atomic_open
24. v9fs_vfs_unlink
25. v9fs_vfs_rmdir
26. v9fs_vfs_rename
27. v9fs_vfs_getattr
28. v9fs_vfs_setattr
29. v9fs_stat2inode
30. v9fs_qid2ino
31. v9fs_vfs_get_link
32. v9fs_vfs_mkspecial
33. v9fs_vfs_symlink
34. v9fs_vfs_link
35. v9fs_vfs_mknod
36. v9fs_refresh_inode

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/fs/9p/vfs_inode.c
   4  *
   5  * This file contains vfs inode ops for the 9P2000 protocol.
   6  *
   7  *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
   8  *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
   9  */
  10 
  11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  12 
  13 #include <linux/module.h>
  14 #include <linux/errno.h>
  15 #include <linux/fs.h>
  16 #include <linux/file.h>
  17 #include <linux/pagemap.h>
  18 #include <linux/stat.h>
  19 #include <linux/string.h>
  20 #include <linux/inet.h>
  21 #include <linux/namei.h>
  22 #include <linux/idr.h>
  23 #include <linux/sched.h>
  24 #include <linux/slab.h>
  25 #include <linux/xattr.h>
  26 #include <linux/posix_acl.h>
  27 #include <net/9p/9p.h>
  28 #include <net/9p/client.h>
  29 
  30 #include "v9fs.h"
  31 #include "v9fs_vfs.h"
  32 #include "fid.h"
  33 #include "cache.h"
  34 #include "xattr.h"
  35 #include "acl.h"
  36 
  37 static const struct inode_operations v9fs_dir_inode_operations;
  38 static const struct inode_operations v9fs_dir_inode_operations_dotu;
  39 static const struct inode_operations v9fs_file_inode_operations;
  40 static const struct inode_operations v9fs_symlink_inode_operations;
  41 
  42 /**
  43  * unixmode2p9mode - convert unix mode bits to plan 9
  44  * @v9ses: v9fs session information
  45  * @mode: mode to convert
  46  *
  47  */
  48 
  49 static u32 unixmode2p9mode(struct v9fs_session_info *v9ses, umode_t mode)
  50 {
  51         int res;
  52         res = mode & 0777;
  53         if (S_ISDIR(mode))
  54                 res |= P9_DMDIR;
  55         if (v9fs_proto_dotu(v9ses)) {
  56                 if (v9ses->nodev == 0) {
  57                         if (S_ISSOCK(mode))
  58                                 res |= P9_DMSOCKET;
  59                         if (S_ISFIFO(mode))
  60                                 res |= P9_DMNAMEDPIPE;
  61                         if (S_ISBLK(mode))
  62                                 res |= P9_DMDEVICE;
  63                         if (S_ISCHR(mode))
  64                                 res |= P9_DMDEVICE;
  65                 }
  66 
  67                 if ((mode & S_ISUID) == S_ISUID)
  68                         res |= P9_DMSETUID;
  69                 if ((mode & S_ISGID) == S_ISGID)
  70                         res |= P9_DMSETGID;
  71                 if ((mode & S_ISVTX) == S_ISVTX)
  72                         res |= P9_DMSETVTX;
  73         }
  74         return res;
  75 }
  76 
  77 /**
  78  * p9mode2perm- convert plan9 mode bits to unix permission bits
  79  * @v9ses: v9fs session information
  80  * @stat: p9_wstat from which mode need to be derived
  81  *
  82  */
  83 static int p9mode2perm(struct v9fs_session_info *v9ses,
  84                        struct p9_wstat *stat)
  85 {
  86         int res;
  87         int mode = stat->mode;
  88 
  89         res = mode & S_IALLUGO;
  90         if (v9fs_proto_dotu(v9ses)) {
  91                 if ((mode & P9_DMSETUID) == P9_DMSETUID)
  92                         res |= S_ISUID;
  93 
  94                 if ((mode & P9_DMSETGID) == P9_DMSETGID)
  95                         res |= S_ISGID;
  96 
  97                 if ((mode & P9_DMSETVTX) == P9_DMSETVTX)
  98                         res |= S_ISVTX;
  99         }
 100         return res;
 101 }
 102 
 103 /**
 104  * p9mode2unixmode- convert plan9 mode bits to unix mode bits
 105  * @v9ses: v9fs session information
 106  * @stat: p9_wstat from which mode need to be derived
 107  * @rdev: major number, minor number in case of device files.
 108  *
 109  */
 110 static umode_t p9mode2unixmode(struct v9fs_session_info *v9ses,
 111                                struct p9_wstat *stat, dev_t *rdev)
 112 {
 113         int res;
 114         u32 mode = stat->mode;
 115 
 116         *rdev = 0;
 117         res = p9mode2perm(v9ses, stat);
 118 
 119         if ((mode & P9_DMDIR) == P9_DMDIR)
 120                 res |= S_IFDIR;
 121         else if ((mode & P9_DMSYMLINK) && (v9fs_proto_dotu(v9ses)))
 122                 res |= S_IFLNK;
 123         else if ((mode & P9_DMSOCKET) && (v9fs_proto_dotu(v9ses))
 124                  && (v9ses->nodev == 0))
 125                 res |= S_IFSOCK;
 126         else if ((mode & P9_DMNAMEDPIPE) && (v9fs_proto_dotu(v9ses))
 127                  && (v9ses->nodev == 0))
 128                 res |= S_IFIFO;
 129         else if ((mode & P9_DMDEVICE) && (v9fs_proto_dotu(v9ses))
 130                  && (v9ses->nodev == 0)) {
 131                 char type = 0, ext[32];
 132                 int major = -1, minor = -1;
 133 
 134                 strlcpy(ext, stat->extension, sizeof(ext));
 135                 sscanf(ext, "%c %i %i", &type, &major, &minor);
 136                 switch (type) {
 137                 case 'c':
 138                         res |= S_IFCHR;
 139                         break;
 140                 case 'b':
 141                         res |= S_IFBLK;
 142                         break;
 143                 default:
 144                         p9_debug(P9_DEBUG_ERROR, "Unknown special type %c %s\n",
 145                                  type, stat->extension);
 146                 };
 147                 *rdev = MKDEV(major, minor);
 148         } else
 149                 res |= S_IFREG;
 150 
 151         return res;
 152 }
 153 
 154 /**
 155  * v9fs_uflags2omode- convert posix open flags to plan 9 mode bits
 156  * @uflags: flags to convert
 157  * @extended: if .u extensions are active
 158  */
 159 
 160 int v9fs_uflags2omode(int uflags, int extended)
 161 {
 162         int ret;
 163 
 164         ret = 0;
 165         switch (uflags&3) {
 166         default:
 167         case O_RDONLY:
 168                 ret = P9_OREAD;
 169                 break;
 170 
 171         case O_WRONLY:
 172                 ret = P9_OWRITE;
 173                 break;
 174 
 175         case O_RDWR:
 176                 ret = P9_ORDWR;
 177                 break;
 178         }
 179 
 180         if (extended) {
 181                 if (uflags & O_EXCL)
 182                         ret |= P9_OEXCL;
 183 
 184                 if (uflags & O_APPEND)
 185                         ret |= P9_OAPPEND;
 186         }
 187 
 188         return ret;
 189 }
 190 
 191 /**
 192  * v9fs_blank_wstat - helper function to setup a 9P stat structure
 193  * @wstat: structure to initialize
 194  *
 195  */
 196 
 197 void
 198 v9fs_blank_wstat(struct p9_wstat *wstat)
 199 {
 200         wstat->type = ~0;
 201         wstat->dev = ~0;
 202         wstat->qid.type = ~0;
 203         wstat->qid.version = ~0;
 204         *((long long *)&wstat->qid.path) = ~0;
 205         wstat->mode = ~0;
 206         wstat->atime = ~0;
 207         wstat->mtime = ~0;
 208         wstat->length = ~0;
 209         wstat->name = NULL;
 210         wstat->uid = NULL;
 211         wstat->gid = NULL;
 212         wstat->muid = NULL;
 213         wstat->n_uid = INVALID_UID;
 214         wstat->n_gid = INVALID_GID;
 215         wstat->n_muid = INVALID_UID;
 216         wstat->extension = NULL;
 217 }
 218 
 219 /**
 220  * v9fs_alloc_inode - helper function to allocate an inode
 221  *
 222  */
 223 struct inode *v9fs_alloc_inode(struct super_block *sb)
 224 {
 225         struct v9fs_inode *v9inode;
 226         v9inode = (struct v9fs_inode *)kmem_cache_alloc(v9fs_inode_cache,
 227                                                         GFP_KERNEL);
 228         if (!v9inode)
 229                 return NULL;
 230 #ifdef CONFIG_9P_FSCACHE
 231         v9inode->fscache = NULL;
 232         mutex_init(&v9inode->fscache_lock);
 233 #endif
 234         v9inode->writeback_fid = NULL;
 235         v9inode->cache_validity = 0;
 236         mutex_init(&v9inode->v_mutex);
 237         return &v9inode->vfs_inode;
 238 }
 239 
 240 /**
 241  * v9fs_free_inode - destroy an inode
 242  *
 243  */
 244 
 245 void v9fs_free_inode(struct inode *inode)
 246 {
 247         kmem_cache_free(v9fs_inode_cache, V9FS_I(inode));
 248 }
 249 
 250 int v9fs_init_inode(struct v9fs_session_info *v9ses,
 251                     struct inode *inode, umode_t mode, dev_t rdev)
 252 {
 253         int err = 0;
 254 
 255         inode_init_owner(inode, NULL, mode);
 256         inode->i_blocks = 0;
 257         inode->i_rdev = rdev;
 258         inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
 259         inode->i_mapping->a_ops = &v9fs_addr_operations;
 260 
 261         switch (mode & S_IFMT) {
 262         case S_IFIFO:
 263         case S_IFBLK:
 264         case S_IFCHR:
 265         case S_IFSOCK:
 266                 if (v9fs_proto_dotl(v9ses)) {
 267                         inode->i_op = &v9fs_file_inode_operations_dotl;
 268                 } else if (v9fs_proto_dotu(v9ses)) {
 269                         inode->i_op = &v9fs_file_inode_operations;
 270                 } else {
 271                         p9_debug(P9_DEBUG_ERROR,
 272                                  "special files without extended mode\n");
 273                         err = -EINVAL;
 274                         goto error;
 275                 }
 276                 init_special_inode(inode, inode->i_mode, inode->i_rdev);
 277                 break;
 278         case S_IFREG:
 279                 if (v9fs_proto_dotl(v9ses)) {
 280                         inode->i_op = &v9fs_file_inode_operations_dotl;
 281                         if (v9ses->cache == CACHE_LOOSE ||
 282                             v9ses->cache == CACHE_FSCACHE)
 283                                 inode->i_fop =
 284                                         &v9fs_cached_file_operations_dotl;
 285                         else if (v9ses->cache == CACHE_MMAP)
 286                                 inode->i_fop = &v9fs_mmap_file_operations_dotl;
 287                         else
 288                                 inode->i_fop = &v9fs_file_operations_dotl;
 289                 } else {
 290                         inode->i_op = &v9fs_file_inode_operations;
 291                         if (v9ses->cache == CACHE_LOOSE ||
 292                             v9ses->cache == CACHE_FSCACHE)
 293                                 inode->i_fop =
 294                                         &v9fs_cached_file_operations;
 295                         else if (v9ses->cache == CACHE_MMAP)
 296                                 inode->i_fop = &v9fs_mmap_file_operations;
 297                         else
 298                                 inode->i_fop = &v9fs_file_operations;
 299                 }
 300 
 301                 break;
 302         case S_IFLNK:
 303                 if (!v9fs_proto_dotu(v9ses) && !v9fs_proto_dotl(v9ses)) {
 304                         p9_debug(P9_DEBUG_ERROR,
 305                                  "extended modes used with legacy protocol\n");
 306                         err = -EINVAL;
 307                         goto error;
 308                 }
 309 
 310                 if (v9fs_proto_dotl(v9ses))
 311                         inode->i_op = &v9fs_symlink_inode_operations_dotl;
 312                 else
 313                         inode->i_op = &v9fs_symlink_inode_operations;
 314 
 315                 break;
 316         case S_IFDIR:
 317                 inc_nlink(inode);
 318                 if (v9fs_proto_dotl(v9ses))
 319                         inode->i_op = &v9fs_dir_inode_operations_dotl;
 320                 else if (v9fs_proto_dotu(v9ses))
 321                         inode->i_op = &v9fs_dir_inode_operations_dotu;
 322                 else
 323                         inode->i_op = &v9fs_dir_inode_operations;
 324 
 325                 if (v9fs_proto_dotl(v9ses))
 326                         inode->i_fop = &v9fs_dir_operations_dotl;
 327                 else
 328                         inode->i_fop = &v9fs_dir_operations;
 329 
 330                 break;
 331         default:
 332                 p9_debug(P9_DEBUG_ERROR, "BAD mode 0x%hx S_IFMT 0x%x\n",
 333                          mode, mode & S_IFMT);
 334                 err = -EINVAL;
 335                 goto error;
 336         }
 337 error:
 338         return err;
 339 
 340 }
 341 
 342 /**
 343  * v9fs_get_inode - helper function to setup an inode
 344  * @sb: superblock
 345  * @mode: mode to setup inode with
 346  *
 347  */
 348 
 349 struct inode *v9fs_get_inode(struct super_block *sb, umode_t mode, dev_t rdev)
 350 {
 351         int err;
 352         struct inode *inode;
 353         struct v9fs_session_info *v9ses = sb->s_fs_info;
 354 
 355         p9_debug(P9_DEBUG_VFS, "super block: %p mode: %ho\n", sb, mode);
 356 
 357         inode = new_inode(sb);
 358         if (!inode) {
 359                 pr_warn("%s (%d): Problem allocating inode\n",
 360                         __func__, task_pid_nr(current));
 361                 return ERR_PTR(-ENOMEM);
 362         }
 363         err = v9fs_init_inode(v9ses, inode, mode, rdev);
 364         if (err) {
 365                 iput(inode);
 366                 return ERR_PTR(err);
 367         }
 368         return inode;
 369 }
 370 
 371 /*
 372 static struct v9fs_fid*
 373 v9fs_clone_walk(struct v9fs_session_info *v9ses, u32 fid, struct dentry *dentry)
 374 {
 375         int err;
 376         int nfid;
 377         struct v9fs_fid *ret;
 378         struct v9fs_fcall *fcall;
 379 
 380         nfid = v9fs_get_idpool(&v9ses->fidpool);
 381         if (nfid < 0) {
 382                 eprintk(KERN_WARNING, "no free fids available\n");
 383                 return ERR_PTR(-ENOSPC);
 384         }
 385 
 386         err = v9fs_t_walk(v9ses, fid, nfid, (char *) dentry->d_name.name,
 387                 &fcall);
 388 
 389         if (err < 0) {
 390                 if (fcall && fcall->id == RWALK)
 391                         goto clunk_fid;
 392 
 393                 PRINT_FCALL_ERROR("walk error", fcall);
 394                 v9fs_put_idpool(nfid, &v9ses->fidpool);
 395                 goto error;
 396         }
 397 
 398         kfree(fcall);
 399         fcall = NULL;
 400         ret = v9fs_fid_create(v9ses, nfid);
 401         if (!ret) {
 402                 err = -ENOMEM;
 403                 goto clunk_fid;
 404         }
 405 
 406         err = v9fs_fid_insert(ret, dentry);
 407         if (err < 0) {
 408                 v9fs_fid_destroy(ret);
 409                 goto clunk_fid;
 410         }
 411 
 412         return ret;
 413 
 414 clunk_fid:
 415         v9fs_t_clunk(v9ses, nfid);
 416 
 417 error:
 418         kfree(fcall);
 419         return ERR_PTR(err);
 420 }
 421 */
 422 
 423 
 424 /**
 425  * v9fs_clear_inode - release an inode
 426  * @inode: inode to release
 427  *
 428  */
 429 void v9fs_evict_inode(struct inode *inode)
 430 {
 431         struct v9fs_inode *v9inode = V9FS_I(inode);
 432 
 433         truncate_inode_pages_final(&inode->i_data);
 434         clear_inode(inode);
 435         filemap_fdatawrite(&inode->i_data);
 436 
 437         v9fs_cache_inode_put_cookie(inode);
 438         /* clunk the fid stashed in writeback_fid */
 439         if (v9inode->writeback_fid) {
 440                 p9_client_clunk(v9inode->writeback_fid);
 441                 v9inode->writeback_fid = NULL;
 442         }
 443 }
 444 
 445 static int v9fs_test_inode(struct inode *inode, void *data)
 446 {
 447         int umode;
 448         dev_t rdev;
 449         struct v9fs_inode *v9inode = V9FS_I(inode);
 450         struct p9_wstat *st = (struct p9_wstat *)data;
 451         struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
 452 
 453         umode = p9mode2unixmode(v9ses, st, &rdev);
 454         /* don't match inode of different type */
 455         if ((inode->i_mode & S_IFMT) != (umode & S_IFMT))
 456                 return 0;
 457 
 458         /* compare qid details */
 459         if (memcmp(&v9inode->qid.version,
 460                    &st->qid.version, sizeof(v9inode->qid.version)))
 461                 return 0;
 462 
 463         if (v9inode->qid.type != st->qid.type)
 464                 return 0;
 465 
 466         if (v9inode->qid.path != st->qid.path)
 467                 return 0;
 468         return 1;
 469 }
 470 
 471 static int v9fs_test_new_inode(struct inode *inode, void *data)
 472 {
 473         return 0;
 474 }
 475 
 476 static int v9fs_set_inode(struct inode *inode,  void *data)
 477 {
 478         struct v9fs_inode *v9inode = V9FS_I(inode);
 479         struct p9_wstat *st = (struct p9_wstat *)data;
 480 
 481         memcpy(&v9inode->qid, &st->qid, sizeof(st->qid));
 482         return 0;
 483 }
 484 
 485 static struct inode *v9fs_qid_iget(struct super_block *sb,
 486                                    struct p9_qid *qid,
 487                                    struct p9_wstat *st,
 488                                    int new)
 489 {
 490         dev_t rdev;
 491         int retval;
 492         umode_t umode;
 493         unsigned long i_ino;
 494         struct inode *inode;
 495         struct v9fs_session_info *v9ses = sb->s_fs_info;
 496         int (*test)(struct inode *, void *);
 497 
 498         if (new)
 499                 test = v9fs_test_new_inode;
 500         else
 501                 test = v9fs_test_inode;
 502 
 503         i_ino = v9fs_qid2ino(qid);
 504         inode = iget5_locked(sb, i_ino, test, v9fs_set_inode, st);
 505         if (!inode)
 506                 return ERR_PTR(-ENOMEM);
 507         if (!(inode->i_state & I_NEW))
 508                 return inode;
 509         /*
 510          * initialize the inode with the stat info
 511          * FIXME!! we may need support for stale inodes
 512          * later.
 513          */
 514         inode->i_ino = i_ino;
 515         umode = p9mode2unixmode(v9ses, st, &rdev);
 516         retval = v9fs_init_inode(v9ses, inode, umode, rdev);
 517         if (retval)
 518                 goto error;
 519 
 520         v9fs_stat2inode(st, inode, sb, 0);
 521         v9fs_cache_inode_get_cookie(inode);
 522         unlock_new_inode(inode);
 523         return inode;
 524 error:
 525         iget_failed(inode);
 526         return ERR_PTR(retval);
 527 
 528 }
 529 
 530 struct inode *
 531 v9fs_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
 532                     struct super_block *sb, int new)
 533 {
 534         struct p9_wstat *st;
 535         struct inode *inode = NULL;
 536 
 537         st = p9_client_stat(fid);
 538         if (IS_ERR(st))
 539                 return ERR_CAST(st);
 540 
 541         inode = v9fs_qid_iget(sb, &st->qid, st, new);
 542         p9stat_free(st);
 543         kfree(st);
 544         return inode;
 545 }
 546 
 547 /**
 548  * v9fs_at_to_dotl_flags- convert Linux specific AT flags to
 549  * plan 9 AT flag.
 550  * @flags: flags to convert
 551  */
 552 static int v9fs_at_to_dotl_flags(int flags)
 553 {
 554         int rflags = 0;
 555         if (flags & AT_REMOVEDIR)
 556                 rflags |= P9_DOTL_AT_REMOVEDIR;
 557         return rflags;
 558 }
 559 
 560 /**
 561  * v9fs_dec_count - helper functon to drop i_nlink.
 562  *
 563  * If a directory had nlink <= 2 (including . and ..), then we should not drop
 564  * the link count, which indicates the underlying exported fs doesn't maintain
 565  * nlink accurately. e.g.
 566  * - overlayfs sets nlink to 1 for merged dir
 567  * - ext4 (with dir_nlink feature enabled) sets nlink to 1 if a dir has more
 568  *   than EXT4_LINK_MAX (65000) links.
 569  *
 570  * @inode: inode whose nlink is being dropped
 571  */
 572 static void v9fs_dec_count(struct inode *inode)
 573 {
 574         if (!S_ISDIR(inode->i_mode) || inode->i_nlink > 2)
 575                 drop_nlink(inode);
 576 }
 577 
 578 /**
 579  * v9fs_remove - helper function to remove files and directories
 580  * @dir: directory inode that is being deleted
 581  * @dentry:  dentry that is being deleted
 582  * @flags: removing a directory
 583  *
 584  */
 585 
 586 static int v9fs_remove(struct inode *dir, struct dentry *dentry, int flags)
 587 {
 588         struct inode *inode;
 589         int retval = -EOPNOTSUPP;
 590         struct p9_fid *v9fid, *dfid;
 591         struct v9fs_session_info *v9ses;
 592 
 593         p9_debug(P9_DEBUG_VFS, "inode: %p dentry: %p rmdir: %x\n",
 594                  dir, dentry, flags);
 595 
 596         v9ses = v9fs_inode2v9ses(dir);
 597         inode = d_inode(dentry);
 598         dfid = v9fs_parent_fid(dentry);
 599         if (IS_ERR(dfid)) {
 600                 retval = PTR_ERR(dfid);
 601                 p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", retval);
 602                 return retval;
 603         }
 604         if (v9fs_proto_dotl(v9ses))
 605                 retval = p9_client_unlinkat(dfid, dentry->d_name.name,
 606                                             v9fs_at_to_dotl_flags(flags));
 607         if (retval == -EOPNOTSUPP) {
 608                 /* Try the one based on path */
 609                 v9fid = v9fs_fid_clone(dentry);
 610                 if (IS_ERR(v9fid))
 611                         return PTR_ERR(v9fid);
 612                 retval = p9_client_remove(v9fid);
 613         }
 614         if (!retval) {
 615                 /*
 616                  * directories on unlink should have zero
 617                  * link count
 618                  */
 619                 if (flags & AT_REMOVEDIR) {
 620                         clear_nlink(inode);
 621                         v9fs_dec_count(dir);
 622                 } else
 623                         v9fs_dec_count(inode);
 624 
 625                 v9fs_invalidate_inode_attr(inode);
 626                 v9fs_invalidate_inode_attr(dir);
 627         }
 628         return retval;
 629 }
 630 
 631 /**
 632  * v9fs_create - Create a file
 633  * @v9ses: session information
 634  * @dir: directory that dentry is being created in
 635  * @dentry:  dentry that is being created
 636  * @extension: 9p2000.u extension string to support devices, etc.
 637  * @perm: create permissions
 638  * @mode: open mode
 639  *
 640  */
 641 static struct p9_fid *
 642 v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
 643                 struct dentry *dentry, char *extension, u32 perm, u8 mode)
 644 {
 645         int err;
 646         const unsigned char *name;
 647         struct p9_fid *dfid, *ofid, *fid;
 648         struct inode *inode;
 649 
 650         p9_debug(P9_DEBUG_VFS, "name %pd\n", dentry);
 651 
 652         err = 0;
 653         ofid = NULL;
 654         fid = NULL;
 655         name = dentry->d_name.name;
 656         dfid = v9fs_parent_fid(dentry);
 657         if (IS_ERR(dfid)) {
 658                 err = PTR_ERR(dfid);
 659                 p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", err);
 660                 return ERR_PTR(err);
 661         }
 662 
 663         /* clone a fid to use for creation */
 664         ofid = clone_fid(dfid);
 665         if (IS_ERR(ofid)) {
 666                 err = PTR_ERR(ofid);
 667                 p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n", err);
 668                 return ERR_PTR(err);
 669         }
 670 
 671         err = p9_client_fcreate(ofid, name, perm, mode, extension);
 672         if (err < 0) {
 673                 p9_debug(P9_DEBUG_VFS, "p9_client_fcreate failed %d\n", err);
 674                 goto error;
 675         }
 676 
 677         if (!(perm & P9_DMLINK)) {
 678                 /* now walk from the parent so we can get unopened fid */
 679                 fid = p9_client_walk(dfid, 1, &name, 1);
 680                 if (IS_ERR(fid)) {
 681                         err = PTR_ERR(fid);
 682                         p9_debug(P9_DEBUG_VFS,
 683                                    "p9_client_walk failed %d\n", err);
 684                         fid = NULL;
 685                         goto error;
 686                 }
 687                 /*
 688                  * instantiate inode and assign the unopened fid to the dentry
 689                  */
 690                 inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
 691                 if (IS_ERR(inode)) {
 692                         err = PTR_ERR(inode);
 693                         p9_debug(P9_DEBUG_VFS,
 694                                    "inode creation failed %d\n", err);
 695                         goto error;
 696                 }
 697                 v9fs_fid_add(dentry, fid);
 698                 d_instantiate(dentry, inode);
 699         }
 700         return ofid;
 701 error:
 702         if (ofid)
 703                 p9_client_clunk(ofid);
 704 
 705         if (fid)
 706                 p9_client_clunk(fid);
 707 
 708         return ERR_PTR(err);
 709 }
 710 
 711 /**
 712  * v9fs_vfs_create - VFS hook to create a regular file
 713  *
 714  * open(.., O_CREAT) is handled in v9fs_vfs_atomic_open().  This is only called
 715  * for mknod(2).
 716  *
 717  * @dir: directory inode that is being created
 718  * @dentry:  dentry that is being deleted
 719  * @mode: create permissions
 720  *
 721  */
 722 
 723 static int
 724 v9fs_vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 725                 bool excl)
 726 {
 727         struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
 728         u32 perm = unixmode2p9mode(v9ses, mode);
 729         struct p9_fid *fid;
 730 
 731         /* P9_OEXCL? */
 732         fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_ORDWR);
 733         if (IS_ERR(fid))
 734                 return PTR_ERR(fid);
 735 
 736         v9fs_invalidate_inode_attr(dir);
 737         p9_client_clunk(fid);
 738 
 739         return 0;
 740 }
 741 
 742 /**
 743  * v9fs_vfs_mkdir - VFS mkdir hook to create a directory
 744  * @dir:  inode that is being unlinked
 745  * @dentry: dentry that is being unlinked
 746  * @mode: mode for new directory
 747  *
 748  */
 749 
 750 static int v9fs_vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 751 {
 752         int err;
 753         u32 perm;
 754         struct p9_fid *fid;
 755         struct v9fs_session_info *v9ses;
 756 
 757         p9_debug(P9_DEBUG_VFS, "name %pd\n", dentry);
 758         err = 0;
 759         v9ses = v9fs_inode2v9ses(dir);
 760         perm = unixmode2p9mode(v9ses, mode | S_IFDIR);
 761         fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_OREAD);
 762         if (IS_ERR(fid)) {
 763                 err = PTR_ERR(fid);
 764                 fid = NULL;
 765         } else {
 766                 inc_nlink(dir);
 767                 v9fs_invalidate_inode_attr(dir);
 768         }
 769 
 770         if (fid)
 771                 p9_client_clunk(fid);
 772 
 773         return err;
 774 }
 775 
 776 /**
 777  * v9fs_vfs_lookup - VFS lookup hook to "walk" to a new inode
 778  * @dir:  inode that is being walked from
 779  * @dentry: dentry that is being walked to?
 780  * @flags: lookup flags (unused)
 781  *
 782  */
 783 
 784 struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
 785                                       unsigned int flags)
 786 {
 787         struct dentry *res;
 788         struct v9fs_session_info *v9ses;
 789         struct p9_fid *dfid, *fid;
 790         struct inode *inode;
 791         const unsigned char *name;
 792 
 793         p9_debug(P9_DEBUG_VFS, "dir: %p dentry: (%pd) %p flags: %x\n",
 794                  dir, dentry, dentry, flags);
 795 
 796         if (dentry->d_name.len > NAME_MAX)
 797                 return ERR_PTR(-ENAMETOOLONG);
 798 
 799         v9ses = v9fs_inode2v9ses(dir);
 800         /* We can walk d_parent because we hold the dir->i_mutex */
 801         dfid = v9fs_parent_fid(dentry);
 802         if (IS_ERR(dfid))
 803                 return ERR_CAST(dfid);
 804 
 805         /*
 806          * Make sure we don't use a wrong inode due to parallel
 807          * unlink. For cached mode create calls request for new
 808          * inode. But with cache disabled, lookup should do this.
 809          */
 810         name = dentry->d_name.name;
 811         fid = p9_client_walk(dfid, 1, &name, 1);
 812         if (fid == ERR_PTR(-ENOENT))
 813                 inode = NULL;
 814         else if (IS_ERR(fid))
 815                 inode = ERR_CAST(fid);
 816         else if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
 817                 inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
 818         else
 819                 inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
 820         /*
 821          * If we had a rename on the server and a parallel lookup
 822          * for the new name, then make sure we instantiate with
 823          * the new name. ie look up for a/b, while on server somebody
 824          * moved b under k and client parallely did a lookup for
 825          * k/b.
 826          */
 827         res = d_splice_alias(inode, dentry);
 828         if (!IS_ERR(fid)) {
 829                 if (!res)
 830                         v9fs_fid_add(dentry, fid);
 831                 else if (!IS_ERR(res))
 832                         v9fs_fid_add(res, fid);
 833                 else
 834                         p9_client_clunk(fid);
 835         }
 836         return res;
 837 }
 838 
 839 static int
 840 v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
 841                      struct file *file, unsigned flags, umode_t mode)
 842 {
 843         int err;
 844         u32 perm;
 845         struct v9fs_inode *v9inode;
 846         struct v9fs_session_info *v9ses;
 847         struct p9_fid *fid, *inode_fid;
 848         struct dentry *res = NULL;
 849 
 850         if (d_in_lookup(dentry)) {
 851                 res = v9fs_vfs_lookup(dir, dentry, 0);
 852                 if (IS_ERR(res))
 853                         return PTR_ERR(res);
 854 
 855                 if (res)
 856                         dentry = res;
 857         }
 858 
 859         /* Only creates */
 860         if (!(flags & O_CREAT) || d_really_is_positive(dentry))
 861                 return finish_no_open(file, res);
 862 
 863         err = 0;
 864 
 865         v9ses = v9fs_inode2v9ses(dir);
 866         perm = unixmode2p9mode(v9ses, mode);
 867         fid = v9fs_create(v9ses, dir, dentry, NULL, perm,
 868                                 v9fs_uflags2omode(flags,
 869                                                 v9fs_proto_dotu(v9ses)));
 870         if (IS_ERR(fid)) {
 871                 err = PTR_ERR(fid);
 872                 fid = NULL;
 873                 goto error;
 874         }
 875 
 876         v9fs_invalidate_inode_attr(dir);
 877         v9inode = V9FS_I(d_inode(dentry));
 878         mutex_lock(&v9inode->v_mutex);
 879         if ((v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) &&
 880             !v9inode->writeback_fid &&
 881             ((flags & O_ACCMODE) != O_RDONLY)) {
 882                 /*
 883                  * clone a fid and add it to writeback_fid
 884                  * we do it during open time instead of
 885                  * page dirty time via write_begin/page_mkwrite
 886                  * because we want write after unlink usecase
 887                  * to work.
 888                  */
 889                 inode_fid = v9fs_writeback_fid(dentry);
 890                 if (IS_ERR(inode_fid)) {
 891                         err = PTR_ERR(inode_fid);
 892                         mutex_unlock(&v9inode->v_mutex);
 893                         goto error;
 894                 }
 895                 v9inode->writeback_fid = (void *) inode_fid;
 896         }
 897         mutex_unlock(&v9inode->v_mutex);
 898         err = finish_open(file, dentry, generic_file_open);
 899         if (err)
 900                 goto error;
 901 
 902         file->private_data = fid;
 903         if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
 904                 v9fs_cache_inode_set_cookie(d_inode(dentry), file);
 905 
 906         file->f_mode |= FMODE_CREATED;
 907 out:
 908         dput(res);
 909         return err;
 910 
 911 error:
 912         if (fid)
 913                 p9_client_clunk(fid);
 914         goto out;
 915 }
 916 
 917 /**
 918  * v9fs_vfs_unlink - VFS unlink hook to delete an inode
 919  * @i:  inode that is being unlinked
 920  * @d: dentry that is being unlinked
 921  *
 922  */
 923 
 924 int v9fs_vfs_unlink(struct inode *i, struct dentry *d)
 925 {
 926         return v9fs_remove(i, d, 0);
 927 }
 928 
 929 /**
 930  * v9fs_vfs_rmdir - VFS unlink hook to delete a directory
 931  * @i:  inode that is being unlinked
 932  * @d: dentry that is being unlinked
 933  *
 934  */
 935 
 936 int v9fs_vfs_rmdir(struct inode *i, struct dentry *d)
 937 {
 938         return v9fs_remove(i, d, AT_REMOVEDIR);
 939 }
 940 
 941 /**
 942  * v9fs_vfs_rename - VFS hook to rename an inode
 943  * @old_dir:  old dir inode
 944  * @old_dentry: old dentry
 945  * @new_dir: new dir inode
 946  * @new_dentry: new dentry
 947  *
 948  */
 949 
 950 int
 951 v9fs_vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 952                 struct inode *new_dir, struct dentry *new_dentry,
 953                 unsigned int flags)
 954 {
 955         int retval;
 956         struct inode *old_inode;
 957         struct inode *new_inode;
 958         struct v9fs_session_info *v9ses;
 959         struct p9_fid *oldfid;
 960         struct p9_fid *olddirfid;
 961         struct p9_fid *newdirfid;
 962         struct p9_wstat wstat;
 963 
 964         if (flags)
 965                 return -EINVAL;
 966 
 967         p9_debug(P9_DEBUG_VFS, "\n");
 968         retval = 0;
 969         old_inode = d_inode(old_dentry);
 970         new_inode = d_inode(new_dentry);
 971         v9ses = v9fs_inode2v9ses(old_inode);
 972         oldfid = v9fs_fid_lookup(old_dentry);
 973         if (IS_ERR(oldfid))
 974                 return PTR_ERR(oldfid);
 975 
 976         olddirfid = clone_fid(v9fs_parent_fid(old_dentry));
 977         if (IS_ERR(olddirfid)) {
 978                 retval = PTR_ERR(olddirfid);
 979                 goto done;
 980         }
 981 
 982         newdirfid = clone_fid(v9fs_parent_fid(new_dentry));
 983         if (IS_ERR(newdirfid)) {
 984                 retval = PTR_ERR(newdirfid);
 985                 goto clunk_olddir;
 986         }
 987 
 988         down_write(&v9ses->rename_sem);
 989         if (v9fs_proto_dotl(v9ses)) {
 990                 retval = p9_client_renameat(olddirfid, old_dentry->d_name.name,
 991                                             newdirfid, new_dentry->d_name.name);
 992                 if (retval == -EOPNOTSUPP)
 993                         retval = p9_client_rename(oldfid, newdirfid,
 994                                                   new_dentry->d_name.name);
 995                 if (retval != -EOPNOTSUPP)
 996                         goto clunk_newdir;
 997         }
 998         if (old_dentry->d_parent != new_dentry->d_parent) {
 999                 /*
1000                  * 9P .u can only handle file rename in the same directory
1001                  */
1002 
1003                 p9_debug(P9_DEBUG_ERROR, "old dir and new dir are different\n");
1004                 retval = -EXDEV;
1005                 goto clunk_newdir;
1006         }
1007         v9fs_blank_wstat(&wstat);
1008         wstat.muid = v9ses->uname;
1009         wstat.name = new_dentry->d_name.name;
1010         retval = p9_client_wstat(oldfid, &wstat);
1011 
1012 clunk_newdir:
1013         if (!retval) {
1014                 if (new_inode) {
1015                         if (S_ISDIR(new_inode->i_mode))
1016                                 clear_nlink(new_inode);
1017                         else
1018                                 v9fs_dec_count(new_inode);
1019                 }
1020                 if (S_ISDIR(old_inode->i_mode)) {
1021                         if (!new_inode)
1022                                 inc_nlink(new_dir);
1023                         v9fs_dec_count(old_dir);
1024                 }
1025                 v9fs_invalidate_inode_attr(old_inode);
1026                 v9fs_invalidate_inode_attr(old_dir);
1027                 v9fs_invalidate_inode_attr(new_dir);
1028 
1029                 /* successful rename */
1030                 d_move(old_dentry, new_dentry);
1031         }
1032         up_write(&v9ses->rename_sem);
1033         p9_client_clunk(newdirfid);
1034 
1035 clunk_olddir:
1036         p9_client_clunk(olddirfid);
1037 
1038 done:
1039         return retval;
1040 }
1041 
1042 /**
1043  * v9fs_vfs_getattr - retrieve file metadata
1044  * @path: Object to query
1045  * @stat: metadata structure to populate
1046  * @request_mask: Mask of STATX_xxx flags indicating the caller's interests
1047  * @flags: AT_STATX_xxx setting
1048  *
1049  */
1050 
1051 static int
1052 v9fs_vfs_getattr(const struct path *path, struct kstat *stat,
1053                  u32 request_mask, unsigned int flags)
1054 {
1055         struct dentry *dentry = path->dentry;
1056         struct v9fs_session_info *v9ses;
1057         struct p9_fid *fid;
1058         struct p9_wstat *st;
1059 
1060         p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
1061         v9ses = v9fs_dentry2v9ses(dentry);
1062         if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
1063                 generic_fillattr(d_inode(dentry), stat);
1064                 return 0;
1065         }
1066         fid = v9fs_fid_lookup(dentry);
1067         if (IS_ERR(fid))
1068                 return PTR_ERR(fid);
1069 
1070         st = p9_client_stat(fid);
1071         if (IS_ERR(st))
1072                 return PTR_ERR(st);
1073 
1074         v9fs_stat2inode(st, d_inode(dentry), dentry->d_sb, 0);
1075         generic_fillattr(d_inode(dentry), stat);
1076 
1077         p9stat_free(st);
1078         kfree(st);
1079         return 0;
1080 }
1081 
1082 /**
1083  * v9fs_vfs_setattr - set file metadata
1084  * @dentry: file whose metadata to set
1085  * @iattr: metadata assignment structure
1086  *
1087  */
1088 
1089 static int v9fs_vfs_setattr(struct dentry *dentry, struct iattr *iattr)
1090 {
1091         int retval;
1092         struct v9fs_session_info *v9ses;
1093         struct p9_fid *fid;
1094         struct p9_wstat wstat;
1095 
1096         p9_debug(P9_DEBUG_VFS, "\n");
1097         retval = setattr_prepare(dentry, iattr);
1098         if (retval)
1099                 return retval;
1100 
1101         retval = -EPERM;
1102         v9ses = v9fs_dentry2v9ses(dentry);
1103         fid = v9fs_fid_lookup(dentry);
1104         if(IS_ERR(fid))
1105                 return PTR_ERR(fid);
1106 
1107         v9fs_blank_wstat(&wstat);
1108         if (iattr->ia_valid & ATTR_MODE)
1109                 wstat.mode = unixmode2p9mode(v9ses, iattr->ia_mode);
1110 
1111         if (iattr->ia_valid & ATTR_MTIME)
1112                 wstat.mtime = iattr->ia_mtime.tv_sec;
1113 
1114         if (iattr->ia_valid & ATTR_ATIME)
1115                 wstat.atime = iattr->ia_atime.tv_sec;
1116 
1117         if (iattr->ia_valid & ATTR_SIZE)
1118                 wstat.length = iattr->ia_size;
1119 
1120         if (v9fs_proto_dotu(v9ses)) {
1121                 if (iattr->ia_valid & ATTR_UID)
1122                         wstat.n_uid = iattr->ia_uid;
1123 
1124                 if (iattr->ia_valid & ATTR_GID)
1125                         wstat.n_gid = iattr->ia_gid;
1126         }
1127 
1128         /* Write all dirty data */
1129         if (d_is_reg(dentry))
1130                 filemap_write_and_wait(d_inode(dentry)->i_mapping);
1131 
1132         retval = p9_client_wstat(fid, &wstat);
1133         if (retval < 0)
1134                 return retval;
1135 
1136         if ((iattr->ia_valid & ATTR_SIZE) &&
1137             iattr->ia_size != i_size_read(d_inode(dentry)))
1138                 truncate_setsize(d_inode(dentry), iattr->ia_size);
1139 
1140         v9fs_invalidate_inode_attr(d_inode(dentry));
1141 
1142         setattr_copy(d_inode(dentry), iattr);
1143         mark_inode_dirty(d_inode(dentry));
1144         return 0;
1145 }
1146 
1147 /**
1148  * v9fs_stat2inode - populate an inode structure with mistat info
1149  * @stat: Plan 9 metadata (mistat) structure
1150  * @inode: inode to populate
1151  * @sb: superblock of filesystem
1152  * @flags: control flags (e.g. V9FS_STAT2INODE_KEEP_ISIZE)
1153  *
1154  */
1155 
1156 void
1157 v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
1158                  struct super_block *sb, unsigned int flags)
1159 {
1160         umode_t mode;
1161         char ext[32];
1162         char tag_name[14];
1163         unsigned int i_nlink;
1164         struct v9fs_session_info *v9ses = sb->s_fs_info;
1165         struct v9fs_inode *v9inode = V9FS_I(inode);
1166 
1167         set_nlink(inode, 1);
1168 
1169         inode->i_atime.tv_sec = stat->atime;
1170         inode->i_mtime.tv_sec = stat->mtime;
1171         inode->i_ctime.tv_sec = stat->mtime;
1172 
1173         inode->i_uid = v9ses->dfltuid;
1174         inode->i_gid = v9ses->dfltgid;
1175 
1176         if (v9fs_proto_dotu(v9ses)) {
1177                 inode->i_uid = stat->n_uid;
1178                 inode->i_gid = stat->n_gid;
1179         }
1180         if ((S_ISREG(inode->i_mode)) || (S_ISDIR(inode->i_mode))) {
1181                 if (v9fs_proto_dotu(v9ses) && (stat->extension[0] != '\0')) {
1182                         /*
1183                          * Hadlink support got added later to
1184                          * to the .u extension. So there can be
1185                          * server out there that doesn't support
1186                          * this even with .u extension. So check
1187                          * for non NULL stat->extension
1188                          */
1189                         strlcpy(ext, stat->extension, sizeof(ext));
1190                         /* HARDLINKCOUNT %u */
1191                         sscanf(ext, "%13s %u", tag_name, &i_nlink);
1192                         if (!strncmp(tag_name, "HARDLINKCOUNT", 13))
1193                                 set_nlink(inode, i_nlink);
1194                 }
1195         }
1196         mode = p9mode2perm(v9ses, stat);
1197         mode |= inode->i_mode & ~S_IALLUGO;
1198         inode->i_mode = mode;
1199 
1200         if (!(flags & V9FS_STAT2INODE_KEEP_ISIZE))
1201                 v9fs_i_size_write(inode, stat->length);
1202         /* not real number of blocks, but 512 byte ones ... */
1203         inode->i_blocks = (stat->length + 512 - 1) >> 9;
1204         v9inode->cache_validity &= ~V9FS_INO_INVALID_ATTR;
1205 }
1206 
1207 /**
1208  * v9fs_qid2ino - convert qid into inode number
1209  * @qid: qid to hash
1210  *
1211  * BUG: potential for inode number collisions?
1212  */
1213 
1214 ino_t v9fs_qid2ino(struct p9_qid *qid)
1215 {
1216         u64 path = qid->path + 2;
1217         ino_t i = 0;
1218 
1219         if (sizeof(ino_t) == sizeof(path))
1220                 memcpy(&i, &path, sizeof(ino_t));
1221         else
1222                 i = (ino_t) (path ^ (path >> 32));
1223 
1224         return i;
1225 }
1226 
1227 /**
1228  * v9fs_vfs_get_link - follow a symlink path
1229  * @dentry: dentry for symlink
1230  * @inode: inode for symlink
1231  * @done: delayed call for when we are done with the return value
1232  */
1233 
1234 static const char *v9fs_vfs_get_link(struct dentry *dentry,
1235                                      struct inode *inode,
1236                                      struct delayed_call *done)
1237 {
1238         struct v9fs_session_info *v9ses;
1239         struct p9_fid *fid;
1240         struct p9_wstat *st;
1241         char *res;
1242 
1243         if (!dentry)
1244                 return ERR_PTR(-ECHILD);
1245 
1246         v9ses = v9fs_dentry2v9ses(dentry);
1247         fid = v9fs_fid_lookup(dentry);
1248         p9_debug(P9_DEBUG_VFS, "%pd\n", dentry);
1249 
1250         if (IS_ERR(fid))
1251                 return ERR_CAST(fid);
1252 
1253         if (!v9fs_proto_dotu(v9ses))
1254                 return ERR_PTR(-EBADF);
1255 
1256         st = p9_client_stat(fid);
1257         if (IS_ERR(st))
1258                 return ERR_CAST(st);
1259 
1260         if (!(st->mode & P9_DMSYMLINK)) {
1261                 p9stat_free(st);
1262                 kfree(st);
1263                 return ERR_PTR(-EINVAL);
1264         }
1265         res = st->extension;
1266         st->extension = NULL;
1267         if (strlen(res) >= PATH_MAX)
1268                 res[PATH_MAX - 1] = '\0';
1269 
1270         p9stat_free(st);
1271         kfree(st);
1272         set_delayed_call(done, kfree_link, res);
1273         return res;
1274 }
1275 
1276 /**
1277  * v9fs_vfs_mkspecial - create a special file
1278  * @dir: inode to create special file in
1279  * @dentry: dentry to create
1280  * @perm: mode to create special file
1281  * @extension: 9p2000.u format extension string representing special file
1282  *
1283  */
1284 
1285 static int v9fs_vfs_mkspecial(struct inode *dir, struct dentry *dentry,
1286         u32 perm, const char *extension)
1287 {
1288         struct p9_fid *fid;
1289         struct v9fs_session_info *v9ses;
1290 
1291         v9ses = v9fs_inode2v9ses(dir);
1292         if (!v9fs_proto_dotu(v9ses)) {
1293                 p9_debug(P9_DEBUG_ERROR, "not extended\n");
1294                 return -EPERM;
1295         }
1296 
1297         fid = v9fs_create(v9ses, dir, dentry, (char *) extension, perm,
1298                                                                 P9_OREAD);
1299         if (IS_ERR(fid))
1300                 return PTR_ERR(fid);
1301 
1302         v9fs_invalidate_inode_attr(dir);
1303         p9_client_clunk(fid);
1304         return 0;
1305 }
1306 
1307 /**
1308  * v9fs_vfs_symlink - helper function to create symlinks
1309  * @dir: directory inode containing symlink
1310  * @dentry: dentry for symlink
1311  * @symname: symlink data
1312  *
1313  * See Also: 9P2000.u RFC for more information
1314  *
1315  */
1316 
1317 static int
1318 v9fs_vfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1319 {
1320         p9_debug(P9_DEBUG_VFS, " %lu,%pd,%s\n",
1321                  dir->i_ino, dentry, symname);
1322 
1323         return v9fs_vfs_mkspecial(dir, dentry, P9_DMSYMLINK, symname);
1324 }
1325 
1326 #define U32_MAX_DIGITS 10
1327 
1328 /**
1329  * v9fs_vfs_link - create a hardlink
1330  * @old_dentry: dentry for file to link to
1331  * @dir: inode destination for new link
1332  * @dentry: dentry for link
1333  *
1334  */
1335 
1336 static int
1337 v9fs_vfs_link(struct dentry *old_dentry, struct inode *dir,
1338               struct dentry *dentry)
1339 {
1340         int retval;
1341         char name[1 + U32_MAX_DIGITS + 2]; /* sign + number + \n + \0 */
1342         struct p9_fid *oldfid;
1343 
1344         p9_debug(P9_DEBUG_VFS, " %lu,%pd,%pd\n",
1345                  dir->i_ino, dentry, old_dentry);
1346 
1347         oldfid = v9fs_fid_clone(old_dentry);
1348         if (IS_ERR(oldfid))
1349                 return PTR_ERR(oldfid);
1350 
1351         sprintf(name, "%d\n", oldfid->fid);
1352         retval = v9fs_vfs_mkspecial(dir, dentry, P9_DMLINK, name);
1353         if (!retval) {
1354                 v9fs_refresh_inode(oldfid, d_inode(old_dentry));
1355                 v9fs_invalidate_inode_attr(dir);
1356         }
1357         p9_client_clunk(oldfid);
1358         return retval;
1359 }
1360 
1361 /**
1362  * v9fs_vfs_mknod - create a special file
1363  * @dir: inode destination for new link
1364  * @dentry: dentry for file
1365  * @mode: mode for creation
1366  * @rdev: device associated with special file
1367  *
1368  */
1369 
1370 static int
1371 v9fs_vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t rdev)
1372 {
1373         struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
1374         int retval;
1375         char name[2 + U32_MAX_DIGITS + 1 + U32_MAX_DIGITS + 1];
1376         u32 perm;
1377 
1378         p9_debug(P9_DEBUG_VFS, " %lu,%pd mode: %hx MAJOR: %u MINOR: %u\n",
1379                  dir->i_ino, dentry, mode,
1380                  MAJOR(rdev), MINOR(rdev));
1381 
1382         /* build extension */
1383         if (S_ISBLK(mode))
1384                 sprintf(name, "b %u %u", MAJOR(rdev), MINOR(rdev));
1385         else if (S_ISCHR(mode))
1386                 sprintf(name, "c %u %u", MAJOR(rdev), MINOR(rdev));
1387         else
1388                 *name = 0;
1389 
1390         perm = unixmode2p9mode(v9ses, mode);
1391         retval = v9fs_vfs_mkspecial(dir, dentry, perm, name);
1392 
1393         return retval;
1394 }
1395 
1396 int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode)
1397 {
1398         int umode;
1399         dev_t rdev;
1400         struct p9_wstat *st;
1401         struct v9fs_session_info *v9ses;
1402         unsigned int flags;
1403 
1404         v9ses = v9fs_inode2v9ses(inode);
1405         st = p9_client_stat(fid);
1406         if (IS_ERR(st))
1407                 return PTR_ERR(st);
1408         /*
1409          * Don't update inode if the file type is different
1410          */
1411         umode = p9mode2unixmode(v9ses, st, &rdev);
1412         if ((inode->i_mode & S_IFMT) != (umode & S_IFMT))
1413                 goto out;
1414 
1415         /*
1416          * We don't want to refresh inode->i_size,
1417          * because we may have cached data
1418          */
1419         flags = (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) ?
1420                 V9FS_STAT2INODE_KEEP_ISIZE : 0;
1421         v9fs_stat2inode(st, inode, inode->i_sb, flags);
1422 out:
1423         p9stat_free(st);
1424         kfree(st);
1425         return 0;
1426 }
1427 
1428 static const struct inode_operations v9fs_dir_inode_operations_dotu = {
1429         .create = v9fs_vfs_create,
1430         .lookup = v9fs_vfs_lookup,
1431         .atomic_open = v9fs_vfs_atomic_open,
1432         .symlink = v9fs_vfs_symlink,
1433         .link = v9fs_vfs_link,
1434         .unlink = v9fs_vfs_unlink,
1435         .mkdir = v9fs_vfs_mkdir,
1436         .rmdir = v9fs_vfs_rmdir,
1437         .mknod = v9fs_vfs_mknod,
1438         .rename = v9fs_vfs_rename,
1439         .getattr = v9fs_vfs_getattr,
1440         .setattr = v9fs_vfs_setattr,
1441 };
1442 
1443 static const struct inode_operations v9fs_dir_inode_operations = {
1444         .create = v9fs_vfs_create,
1445         .lookup = v9fs_vfs_lookup,
1446         .atomic_open = v9fs_vfs_atomic_open,
1447         .unlink = v9fs_vfs_unlink,
1448         .mkdir = v9fs_vfs_mkdir,
1449         .rmdir = v9fs_vfs_rmdir,
1450         .mknod = v9fs_vfs_mknod,
1451         .rename = v9fs_vfs_rename,
1452         .getattr = v9fs_vfs_getattr,
1453         .setattr = v9fs_vfs_setattr,
1454 };
1455 
1456 static const struct inode_operations v9fs_file_inode_operations = {
1457         .getattr = v9fs_vfs_getattr,
1458         .setattr = v9fs_vfs_setattr,
1459 };
1460 
1461 static const struct inode_operations v9fs_symlink_inode_operations = {
1462         .get_link = v9fs_vfs_get_link,
1463         .getattr = v9fs_vfs_getattr,
1464         .setattr = v9fs_vfs_setattr,
1465 };
1466