fs/nfs/unlink.c

   1 /*
   2  *  linux/fs/nfs/unlink.c
   3  *
   4  * nfs sillydelete handling
   5  *
   6  */
   7
   8 #include <linux/slab.h>
   9 #include <linux/string.h>
  10 #include <linux/dcache.h>
  11 #include <linux/sunrpc/sched.h>
  12 #include <linux/sunrpc/clnt.h>
  13 #include <linux/nfs_fs.h>
  14 #include <linux/sched.h>
  15 #include <linux/wait.h>
  16 #include <linux/namei.h>
  17
  18 #include "internal.h"
  19 #include "nfs4_fs.h"
  20 #include "iostat.h"
  21 #include "delegation.h"
  22
  23 struct nfs_unlinkdata {
  24         struct hlist_node list;
  25         struct nfs_removeargs args;
  26         struct nfs_removeres res;
  27         struct inode *dir;
  28         struct rpc_cred *cred;
  29         struct nfs_fattr dir_attr;
  30 };
  31
  32 /**
  33  * nfs_free_unlinkdata - release data from a sillydelete operation.
  34  * @data: pointer to unlink structure.
  35  */
  36 static void
  37 nfs_free_unlinkdata(struct nfs_unlinkdata *data)
  38 {
  39         iput(data->dir);
  40         put_rpccred(data->cred);
  41         kfree(data->args.name.name);
  42         kfree(data);
  43 }
  44
  45 #define NAME_ALLOC_LEN(len)     ((len+16) & ~15)
  46 /**
  47  * nfs_copy_dname - copy dentry name to data structure
  48  * @dentry: pointer to dentry
  49  * @data: nfs_unlinkdata
  50  */
  51 static int nfs_copy_dname(struct dentry *dentry, struct nfs_unlinkdata *data)
  52 {
  53         char            *str;
  54         int             len = dentry->d_name.len;
  55
  56         str = kmemdup(dentry->d_name.name, NAME_ALLOC_LEN(len), GFP_KERNEL);
  57         if (!str)
  58                 return -ENOMEM;
  59         data->args.name.len = len;
  60         data->args.name.name = str;
  61         return 0;
  62 }
  63
  64 static void nfs_free_dname(struct nfs_unlinkdata *data)
  65 {
  66         kfree(data->args.name.name);
  67         data->args.name.name = NULL;
  68         data->args.name.len = 0;
  69 }
  70
  71 static void nfs_dec_sillycount(struct inode *dir)
  72 {
  73         struct nfs_inode *nfsi = NFS_I(dir);
  74         if (atomic_dec_return(&nfsi->silly_count) == 1)
  75                 wake_up(&nfsi->waitqueue);
  76 }
  77
  78 /**
  79  * nfs_async_unlink_done - Sillydelete post-processing
  80  * @task: rpc_task of the sillydelete
  81  *
  82  * Do the directory attribute update.
  83  */
  84 static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
  85 {
  86         struct nfs_unlinkdata *data = calldata;
  87         struct inode *dir = data->dir;
  88
  89         if (!NFS_PROTO(dir)->unlink_done(task, dir))
  90                 nfs_restart_rpc(task, NFS_SERVER(dir)->nfs_client);
  91 }
  92
  93 /**
  94  * nfs_async_unlink_release - Release the sillydelete data.
  95  * @task: rpc_task of the sillydelete
  96  *
  97  * We need to call nfs_put_unlinkdata as a 'tk_release' task since the
  98  * rpc_task would be freed too.
  99  */
 100 static void nfs_async_unlink_release(void *calldata)
 101 {
 102         struct nfs_unlinkdata   *data = calldata;
 103         struct super_block *sb = data->dir->i_sb;
 104
 105         nfs_dec_sillycount(data->dir);
 106         nfs_free_unlinkdata(data);
 107         nfs_sb_deactive(sb);
 108 }
 109
 110 #if defined(CONFIG_NFS_V4_1)
 111 void nfs_unlink_prepare(struct rpc_task *task, void *calldata)
 112 {
 113         struct nfs_unlinkdata *data = calldata;
 114         struct nfs_server *server = NFS_SERVER(data->dir);
 115
 116         if (nfs4_setup_sequence(server, &data->args.seq_args,
 117                                 &data->res.seq_res, 1, task))
 118                 return;
 119         rpc_call_start(task);
 120 }
 121 #endif /* CONFIG_NFS_V4_1 */
 122
 123 static const struct rpc_call_ops nfs_unlink_ops = {
 124         .rpc_call_done = nfs_async_unlink_done,
 125         .rpc_release = nfs_async_unlink_release,
 126 #if defined(CONFIG_NFS_V4_1)
 127         .rpc_call_prepare = nfs_unlink_prepare,
 128 #endif /* CONFIG_NFS_V4_1 */
 129 };
 130
 131 static int nfs_do_call_unlink(struct dentry *parent, struct inode *dir, struct nfs_unlinkdata *data)
 132 {
 133         struct rpc_message msg = {
 134                 .rpc_argp = &data->args,
 135                 .rpc_resp = &data->res,
 136                 .rpc_cred = data->cred,
 137         };
 138         struct rpc_task_setup task_setup_data = {
 139                 .rpc_message = &msg,
 140                 .callback_ops = &nfs_unlink_ops,
 141                 .callback_data = data,
 142                 .workqueue = nfsiod_workqueue,
 143                 .flags = RPC_TASK_ASYNC,
 144         };
 145         struct rpc_task *task;
 146         struct dentry *alias;
 147
 148         alias = d_lookup(parent, &data->args.name);
 149         if (alias != NULL) {
 150                 int ret = 0;
 151                 void *devname_garbage = NULL;
 152
 153                 /*
 154                  * Hey, we raced with lookup... See if we need to transfer
 155                  * the sillyrename information to the aliased dentry.
 156                  */
 157                 nfs_free_dname(data);
 158                 spin_lock(&alias->d_lock);
 159                 if (alias->d_inode != NULL &&
 160                     !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
 161                         devname_garbage = alias->d_fsdata;
 162                         alias->d_fsdata = data;
 163                         alias->d_flags |= DCACHE_NFSFS_RENAMED;
 164                         ret = 1;
 165                 }
 166                 spin_unlock(&alias->d_lock);
 167                 nfs_dec_sillycount(dir);
 168                 dput(alias);
 169                 /*
 170                  * If we'd displaced old cached devname, free it.  At that
 171                  * point dentry is definitely not a root, so we won't need
 172                  * that anymore.
 173                  */
 174                 if (devname_garbage)
 175                         kfree(devname_garbage);
 176                 return ret;
 177         }
 178         data->dir = igrab(dir);
 179         if (!data->dir) {
 180                 nfs_dec_sillycount(dir);
 181                 return 0;
 182         }
 183         nfs_sb_active(dir->i_sb);
 184         data->args.fh = NFS_FH(dir);
 185         nfs_fattr_init(data->res.dir_attr);
 186
 187         NFS_PROTO(dir)->unlink_setup(&msg, dir);
 188
 189         task_setup_data.rpc_client = NFS_CLIENT(dir);
 190         task = rpc_run_task(&task_setup_data);
 191         if (!IS_ERR(task))
 192                 rpc_put_task_async(task);
 193         return 1;
 194 }
 195
 196 static int nfs_call_unlink(struct dentry *dentry, struct nfs_unlinkdata *data)
 197 {
 198         struct dentry *parent;
 199         struct inode *dir;
 200         int ret = 0;
 201
 202
 203         parent = dget_parent(dentry);
 204         if (parent == NULL)
 205                 goto out_free;
 206         dir = parent->d_inode;
 207         if (nfs_copy_dname(dentry, data) != 0)
 208                 goto out_dput;
 209         /* Non-exclusive lock protects against concurrent lookup() calls */
 210         spin_lock(&dir->i_lock);
 211         if (atomic_inc_not_zero(&NFS_I(dir)->silly_count) == 0) {
 212                 /* Deferred delete */
 213                 hlist_add_head(&data->list, &NFS_I(dir)->silly_list);
 214                 spin_unlock(&dir->i_lock);
 215                 ret = 1;
 216                 goto out_dput;
 217         }
 218         spin_unlock(&dir->i_lock);
 219         ret = nfs_do_call_unlink(parent, dir, data);
 220 out_dput:
 221         dput(parent);
 222 out_free:
 223         return ret;
 224 }
 225
 226 void nfs_block_sillyrename(struct dentry *dentry)
 227 {
 228         struct nfs_inode *nfsi = NFS_I(dentry->d_inode);
 229
 230         wait_event(nfsi->waitqueue, atomic_cmpxchg(&nfsi->silly_count, 1, 0) == 1);
 231 }
 232
 233 void nfs_unblock_sillyrename(struct dentry *dentry)
 234 {
 235         struct inode *dir = dentry->d_inode;
 236         struct nfs_inode *nfsi = NFS_I(dir);
 237         struct nfs_unlinkdata *data;
 238
 239         atomic_inc(&nfsi->silly_count);
 240         spin_lock(&dir->i_lock);
 241         while (!hlist_empty(&nfsi->silly_list)) {
 242                 if (!atomic_inc_not_zero(&nfsi->silly_count))
 243                         break;
 244                 data = hlist_entry(nfsi->silly_list.first, struct nfs_unlinkdata, list);
 245                 hlist_del(&data->list);
 246                 spin_unlock(&dir->i_lock);
 247                 if (nfs_do_call_unlink(dentry, dir, data) == 0)
 248                         nfs_free_unlinkdata(data);
 249                 spin_lock(&dir->i_lock);
 250         }
 251         spin_unlock(&dir->i_lock);
 252 }
 253
 254 /**
 255  * nfs_async_unlink - asynchronous unlinking of a file
 256  * @dir: parent directory of dentry
 257  * @dentry: dentry to unlink
 258  */
 259 static int
 260 nfs_async_unlink(struct inode *dir, struct dentry *dentry)
 261 {
 262         struct nfs_unlinkdata *data;
 263         int status = -ENOMEM;
 264         void *devname_garbage = NULL;
 265
 266         data = kzalloc(sizeof(*data), GFP_KERNEL);
 267         if (data == NULL)
 268                 goto out;
 269
 270         data->cred = rpc_lookup_cred();
 271         if (IS_ERR(data->cred)) {
 272                 status = PTR_ERR(data->cred);
 273                 goto out_free;
 274         }
 275         data->res.dir_attr = &data->dir_attr;
 276
 277         status = -EBUSY;
 278         spin_lock(&dentry->d_lock);
 279         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 280                 goto out_unlock;
 281         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
 282         devname_garbage = dentry->d_fsdata;
 283         dentry->d_fsdata = data;
 284         spin_unlock(&dentry->d_lock);
 285         /*
 286          * If we'd displaced old cached devname, free it.  At that
 287          * point dentry is definitely not a root, so we won't need
 288          * that anymore.
 289          */
 290         if (devname_garbage)
 291                 kfree(devname_garbage);
 292         return 0;
 293 out_unlock:
 294         spin_unlock(&dentry->d_lock);
 295         put_rpccred(data->cred);
 296 out_free:
 297         kfree(data);
 298 out:
 299         return status;
 300 }
 301
 302 /**
 303  * nfs_complete_unlink - Initialize completion of the sillydelete
 304  * @dentry: dentry to delete
 305  * @inode: inode
 306  *
 307  * Since we're most likely to be called by dentry_iput(), we
 308  * only use the dentry to find the sillydelete. We then copy the name
 309  * into the qstr.
 310  */
 311 void
 312 nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
 313 {
 314         struct nfs_unlinkdata   *data = NULL;
 315
 316         spin_lock(&dentry->d_lock);
 317         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
 318                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 319                 data = dentry->d_fsdata;
 320                 dentry->d_fsdata = NULL;
 321         }
 322         spin_unlock(&dentry->d_lock);
 323
 324         if (data != NULL && (NFS_STALE(inode) || !nfs_call_unlink(dentry, data)))
 325                 nfs_free_unlinkdata(data);
 326 }
 327
 328 /* Cancel a queued async unlink. Called when a sillyrename run fails. */
 329 static void
 330 nfs_cancel_async_unlink(struct dentry *dentry)
 331 {
 332         spin_lock(&dentry->d_lock);
 333         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
 334                 struct nfs_unlinkdata *data = dentry->d_fsdata;
 335
 336                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 337                 dentry->d_fsdata = NULL;
 338                 spin_unlock(&dentry->d_lock);
 339                 nfs_free_unlinkdata(data);
 340                 return;
 341         }
 342         spin_unlock(&dentry->d_lock);
 343 }
 344
 345 struct nfs_renamedata {
 346         struct nfs_renameargs   args;
 347         struct nfs_renameres    res;
 348         struct rpc_cred         *cred;
 349         struct inode            *old_dir;
 350         struct dentry           *old_dentry;
 351         struct nfs_fattr        old_fattr;
 352         struct inode            *new_dir;
 353         struct dentry           *new_dentry;
 354         struct nfs_fattr        new_fattr;
 355 };
 356
 357 /**
 358  * nfs_async_rename_done - Sillyrename post-processing
 359  * @task: rpc_task of the sillyrename
 360  * @calldata: nfs_renamedata for the sillyrename
 361  *
 362  * Do the directory attribute updates and the d_move
 363  */
 364 static void nfs_async_rename_done(struct rpc_task *task, void *calldata)
 365 {
 366         struct nfs_renamedata *data = calldata;
 367         struct inode *old_dir = data->old_dir;
 368         struct inode *new_dir = data->new_dir;
 369
 370         if (!NFS_PROTO(old_dir)->rename_done(task, old_dir, new_dir)) {
 371                 nfs_restart_rpc(task, NFS_SERVER(old_dir)->nfs_client);
 372                 return;
 373         }
 374
 375         if (task->tk_status != 0) {
 376                 nfs_cancel_async_unlink(data->old_dentry);
 377                 return;
 378         }
 379
 380         nfs_set_verifier(data->old_dentry, nfs_save_change_attribute(old_dir));
 381         d_move(data->old_dentry, data->new_dentry);
 382 }
 383
 384 /**
 385  * nfs_async_rename_release - Release the sillyrename data.
 386  * @calldata: the struct nfs_renamedata to be released
 387  */
 388 static void nfs_async_rename_release(void *calldata)
 389 {
 390         struct nfs_renamedata   *data = calldata;
 391         struct super_block *sb = data->old_dir->i_sb;
 392
 393         if (data->old_dentry->d_inode)
 394                 nfs_mark_for_revalidate(data->old_dentry->d_inode);
 395
 396         dput(data->old_dentry);
 397         dput(data->new_dentry);
 398         iput(data->old_dir);
 399         iput(data->new_dir);
 400         nfs_sb_deactive(sb);
 401         put_rpccred(data->cred);
 402         kfree(data);
 403 }
 404
 405 #if defined(CONFIG_NFS_V4_1)
 406 static void nfs_rename_prepare(struct rpc_task *task, void *calldata)
 407 {
 408         struct nfs_renamedata *data = calldata;
 409         struct nfs_server *server = NFS_SERVER(data->old_dir);
 410
 411         if (nfs4_setup_sequence(server, &data->args.seq_args,
 412                                 &data->res.seq_res, 1, task))
 413                 return;
 414         rpc_call_start(task);
 415 }
 416 #endif /* CONFIG_NFS_V4_1 */
 417
 418 static const struct rpc_call_ops nfs_rename_ops = {
 419         .rpc_call_done = nfs_async_rename_done,
 420         .rpc_release = nfs_async_rename_release,
 421 #if defined(CONFIG_NFS_V4_1)
 422         .rpc_call_prepare = nfs_rename_prepare,
 423 #endif /* CONFIG_NFS_V4_1 */
 424 };
 425
 426 /**
 427  * nfs_async_rename - perform an asynchronous rename operation
 428  * @old_dir: directory that currently holds the dentry to be renamed
 429  * @new_dir: target directory for the rename
 430  * @old_dentry: original dentry to be renamed
 431  * @new_dentry: dentry to which the old_dentry should be renamed
 432  *
 433  * It's expected that valid references to the dentries and inodes are held
 434  */
 435 static struct rpc_task *
 436 nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
 437                  struct dentry *old_dentry, struct dentry *new_dentry)
 438 {
 439         struct nfs_renamedata *data;
 440         struct rpc_message msg = { };
 441         struct rpc_task_setup task_setup_data = {
 442                 .rpc_message = &msg,
 443                 .callback_ops = &nfs_rename_ops,
 444                 .workqueue = nfsiod_workqueue,
 445                 .rpc_client = NFS_CLIENT(old_dir),
 446                 .flags = RPC_TASK_ASYNC,
 447         };
 448
 449         data = kzalloc(sizeof(*data), GFP_KERNEL);
 450         if (data == NULL)
 451                 return ERR_PTR(-ENOMEM);
 452         task_setup_data.callback_data = data;
 453
 454         data->cred = rpc_lookup_cred();
 455         if (IS_ERR(data->cred)) {
 456                 struct rpc_task *task = ERR_CAST(data->cred);
 457                 kfree(data);
 458                 return task;
 459         }
 460
 461         msg.rpc_argp = &data->args;
 462         msg.rpc_resp = &data->res;
 463         msg.rpc_cred = data->cred;
 464
 465         /* set up nfs_renamedata */
 466         data->old_dir = old_dir;
 467         ihold(old_dir);
 468         data->new_dir = new_dir;
 469         ihold(new_dir);
 470         data->old_dentry = dget(old_dentry);
 471         data->new_dentry = dget(new_dentry);
 472         nfs_fattr_init(&data->old_fattr);
 473         nfs_fattr_init(&data->new_fattr);
 474
 475         /* set up nfs_renameargs */
 476         data->args.old_dir = NFS_FH(old_dir);
 477         data->args.old_name = &old_dentry->d_name;
 478         data->args.new_dir = NFS_FH(new_dir);
 479         data->args.new_name = &new_dentry->d_name;
 480
 481         /* set up nfs_renameres */
 482         data->res.old_fattr = &data->old_fattr;
 483         data->res.new_fattr = &data->new_fattr;
 484
 485         nfs_sb_active(old_dir->i_sb);
 486
 487         NFS_PROTO(data->old_dir)->rename_setup(&msg, old_dir);
 488
 489         return rpc_run_task(&task_setup_data);
 490 }
 491
 492 /**
 493  * nfs_sillyrename - Perform a silly-rename of a dentry
 494  * @dir: inode of directory that contains dentry
 495  * @dentry: dentry to be sillyrenamed
 496  *
 497  * NFSv2/3 is stateless and the server doesn't know when the client is
 498  * holding a file open. To prevent application problems when a file is
 499  * unlinked while it's still open, the client performs a "silly-rename".
 500  * That is, it renames the file to a hidden file in the same directory,
 501  * and only performs the unlink once the last reference to it is put.
 502  *
 503  * The final cleanup is done during dentry_iput.
 504  */
 505 int
 506 nfs_sillyrename(struct inode *dir, struct dentry *dentry)
 507 {
 508         static unsigned int sillycounter;
 509         const int      fileidsize  = sizeof(NFS_FILEID(dentry->d_inode))*2;
 510         const int      countersize = sizeof(sillycounter)*2;
 511         const int      slen        = sizeof(".nfs")+fileidsize+countersize-1;
 512         char           silly[slen+1];
 513         struct dentry *sdentry;
 514         struct rpc_task *task;
 515         int            error = -EIO;
 516
 517         dfprintk(VFS, "NFS: silly-rename(%s/%s, ct=%d)\n",
 518                 dentry->d_parent->d_name.name, dentry->d_name.name,
 519                 dentry->d_count);
 520         nfs_inc_stats(dir, NFSIOS_SILLYRENAME);
 521
 522         /*
 523          * We don't allow a dentry to be silly-renamed twice.
 524          */
 525         error = -EBUSY;
 526         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 527                 goto out;
 528
 529         sprintf(silly, ".nfs%*.*Lx",
 530                 fileidsize, fileidsize,
 531                 (unsigned long long)NFS_FILEID(dentry->d_inode));
 532
 533         /* Return delegation in anticipation of the rename */
 534         nfs_inode_return_delegation(dentry->d_inode);
 535
 536         sdentry = NULL;
 537         do {
 538                 char *suffix = silly + slen - countersize;
 539
 540                 dput(sdentry);
 541                 sillycounter++;
 542                 sprintf(suffix, "%*.*x", countersize, countersize, sillycounter);
 543
 544                 dfprintk(VFS, "NFS: trying to rename %s to %s\n",
 545                                 dentry->d_name.name, silly);
 546
 547                 sdentry = lookup_one_len(silly, dentry->d_parent, slen);
 548                 /*
 549                  * N.B. Better to return EBUSY here ... it could be
 550                  * dangerous to delete the file while it's in use.
 551                  */
 552                 if (IS_ERR(sdentry))
 553                         goto out;
 554         } while (sdentry->d_inode != NULL); /* need negative lookup */
 555
 556         /* queue unlink first. Can't do this from rpc_release as it
 557          * has to allocate memory
 558          */
 559         error = nfs_async_unlink(dir, dentry);
 560         if (error)
 561                 goto out_dput;
 562
 563         /* run the rename task, undo unlink if it fails */
 564         task = nfs_async_rename(dir, dir, dentry, sdentry);
 565         if (IS_ERR(task)) {
 566                 error = -EBUSY;
 567                 nfs_cancel_async_unlink(dentry);
 568                 goto out_dput;
 569         }
 570
 571         /* wait for the RPC task to complete, unless a SIGKILL intervenes */
 572         error = rpc_wait_for_completion_task(task);
 573         if (error == 0)
 574                 error = task->tk_status;
 575         rpc_put_task(task);
 576 out_dput:
 577         dput(sdentry);
 578 out:
 579         return error;
 580 }