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
 152                 /*
 153                  * Hey, we raced with lookup... See if we need to transfer
 154                  * the sillyrename information to the aliased dentry.
 155                  */
 156                 nfs_free_dname(data);
 157                 spin_lock(&alias->d_lock);
 158                 if (alias->d_inode != NULL &&
 159                     !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
 160                         alias->d_fsdata = data;
 161                         alias->d_flags |= DCACHE_NFSFS_RENAMED;
 162                         ret = 1;
 163                 }
 164                 spin_unlock(&alias->d_lock);
 165                 nfs_dec_sillycount(dir);
 166                 dput(alias);
 167                 return ret;
 168         }
 169         data->dir = igrab(dir);
 170         if (!data->dir) {
 171                 nfs_dec_sillycount(dir);
 172                 return 0;
 173         }
 174         nfs_sb_active(dir->i_sb);
 175         data->args.fh = NFS_FH(dir);
 176         nfs_fattr_init(data->res.dir_attr);
 177
 178         NFS_PROTO(dir)->unlink_setup(&msg, dir);
 179
 180         task_setup_data.rpc_client = NFS_CLIENT(dir);
 181         task = rpc_run_task(&task_setup_data);
 182         if (!IS_ERR(task))
 183                 rpc_put_task(task);
 184         return 1;
 185 }
 186
 187 static int nfs_call_unlink(struct dentry *dentry, struct nfs_unlinkdata *data)
 188 {
 189         struct dentry *parent;
 190         struct inode *dir;
 191         int ret = 0;
 192
 193
 194         parent = dget_parent(dentry);
 195         if (parent == NULL)
 196                 goto out_free;
 197         dir = parent->d_inode;
 198         if (nfs_copy_dname(dentry, data) != 0)
 199                 goto out_dput;
 200         /* Non-exclusive lock protects against concurrent lookup() calls */
 201         spin_lock(&dir->i_lock);
 202         if (atomic_inc_not_zero(&NFS_I(dir)->silly_count) == 0) {
 203                 /* Deferred delete */
 204                 hlist_add_head(&data->list, &NFS_I(dir)->silly_list);
 205                 spin_unlock(&dir->i_lock);
 206                 ret = 1;
 207                 goto out_dput;
 208         }
 209         spin_unlock(&dir->i_lock);
 210         ret = nfs_do_call_unlink(parent, dir, data);
 211 out_dput:
 212         dput(parent);
 213 out_free:
 214         return ret;
 215 }
 216
 217 void nfs_block_sillyrename(struct dentry *dentry)
 218 {
 219         struct nfs_inode *nfsi = NFS_I(dentry->d_inode);
 220
 221         wait_event(nfsi->waitqueue, atomic_cmpxchg(&nfsi->silly_count, 1, 0) == 1);
 222 }
 223
 224 void nfs_unblock_sillyrename(struct dentry *dentry)
 225 {
 226         struct inode *dir = dentry->d_inode;
 227         struct nfs_inode *nfsi = NFS_I(dir);
 228         struct nfs_unlinkdata *data;
 229
 230         atomic_inc(&nfsi->silly_count);
 231         spin_lock(&dir->i_lock);
 232         while (!hlist_empty(&nfsi->silly_list)) {
 233                 if (!atomic_inc_not_zero(&nfsi->silly_count))
 234                         break;
 235                 data = hlist_entry(nfsi->silly_list.first, struct nfs_unlinkdata, list);
 236                 hlist_del(&data->list);
 237                 spin_unlock(&dir->i_lock);
 238                 if (nfs_do_call_unlink(dentry, dir, data) == 0)
 239                         nfs_free_unlinkdata(data);
 240                 spin_lock(&dir->i_lock);
 241         }
 242         spin_unlock(&dir->i_lock);
 243 }
 244
 245 /**
 246  * nfs_async_unlink - asynchronous unlinking of a file
 247  * @dir: parent directory of dentry
 248  * @dentry: dentry to unlink
 249  */
 250 static int
 251 nfs_async_unlink(struct inode *dir, struct dentry *dentry)
 252 {
 253         struct nfs_unlinkdata *data;
 254         int status = -ENOMEM;
 255
 256         data = kzalloc(sizeof(*data), GFP_KERNEL);
 257         if (data == NULL)
 258                 goto out;
 259
 260         data->cred = rpc_lookup_cred();
 261         if (IS_ERR(data->cred)) {
 262                 status = PTR_ERR(data->cred);
 263                 goto out_free;
 264         }
 265         data->res.dir_attr = &data->dir_attr;
 266
 267         status = -EBUSY;
 268         spin_lock(&dentry->d_lock);
 269         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 270                 goto out_unlock;
 271         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
 272         dentry->d_fsdata = data;
 273         spin_unlock(&dentry->d_lock);
 274         return 0;
 275 out_unlock:
 276         spin_unlock(&dentry->d_lock);
 277         put_rpccred(data->cred);
 278 out_free:
 279         kfree(data);
 280 out:
 281         return status;
 282 }
 283
 284 /**
 285  * nfs_complete_unlink - Initialize completion of the sillydelete
 286  * @dentry: dentry to delete
 287  * @inode: inode
 288  *
 289  * Since we're most likely to be called by dentry_iput(), we
 290  * only use the dentry to find the sillydelete. We then copy the name
 291  * into the qstr.
 292  */
 293 void
 294 nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
 295 {
 296         struct nfs_unlinkdata   *data = NULL;
 297
 298         spin_lock(&dentry->d_lock);
 299         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
 300                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 301                 data = dentry->d_fsdata;
 302         }
 303         spin_unlock(&dentry->d_lock);
 304
 305         if (data != NULL && (NFS_STALE(inode) || !nfs_call_unlink(dentry, data)))
 306                 nfs_free_unlinkdata(data);
 307 }
 308
 309 /* Cancel a queued async unlink. Called when a sillyrename run fails. */
 310 static void
 311 nfs_cancel_async_unlink(struct dentry *dentry)
 312 {
 313         spin_lock(&dentry->d_lock);
 314         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
 315                 struct nfs_unlinkdata *data = dentry->d_fsdata;
 316
 317                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 318                 spin_unlock(&dentry->d_lock);
 319                 nfs_free_unlinkdata(data);
 320                 return;
 321         }
 322         spin_unlock(&dentry->d_lock);
 323 }
 324
 325 struct nfs_renamedata {
 326         struct nfs_renameargs   args;
 327         struct nfs_renameres    res;
 328         struct rpc_cred         *cred;
 329         struct inode            *old_dir;
 330         struct dentry           *old_dentry;
 331         struct nfs_fattr        old_fattr;
 332         struct inode            *new_dir;
 333         struct dentry           *new_dentry;
 334         struct nfs_fattr        new_fattr;
 335 };
 336
 337 /**
 338  * nfs_async_rename_done - Sillyrename post-processing
 339  * @task: rpc_task of the sillyrename
 340  * @calldata: nfs_renamedata for the sillyrename
 341  *
 342  * Do the directory attribute updates and the d_move
 343  */
 344 static void nfs_async_rename_done(struct rpc_task *task, void *calldata)
 345 {
 346         struct nfs_renamedata *data = calldata;
 347         struct inode *old_dir = data->old_dir;
 348         struct inode *new_dir = data->new_dir;
 349
 350         if (!NFS_PROTO(old_dir)->rename_done(task, old_dir, new_dir)) {
 351                 nfs_restart_rpc(task, NFS_SERVER(old_dir)->nfs_client);
 352                 return;
 353         }
 354
 355         if (task->tk_status != 0) {
 356                 nfs_cancel_async_unlink(data->old_dentry);
 357                 return;
 358         }
 359
 360         nfs_set_verifier(data->old_dentry, nfs_save_change_attribute(old_dir));
 361         d_move(data->old_dentry, data->new_dentry);
 362 }
 363
 364 /**
 365  * nfs_async_rename_release - Release the sillyrename data.
 366  * @calldata: the struct nfs_renamedata to be released
 367  */
 368 static void nfs_async_rename_release(void *calldata)
 369 {
 370         struct nfs_renamedata   *data = calldata;
 371         struct super_block *sb = data->old_dir->i_sb;
 372
 373         if (data->old_dentry->d_inode)
 374                 nfs_mark_for_revalidate(data->old_dentry->d_inode);
 375
 376         dput(data->old_dentry);
 377         dput(data->new_dentry);
 378         iput(data->old_dir);
 379         iput(data->new_dir);
 380         nfs_sb_deactive(sb);
 381         put_rpccred(data->cred);
 382         kfree(data);
 383 }
 384
 385 #if defined(CONFIG_NFS_V4_1)
 386 static void nfs_rename_prepare(struct rpc_task *task, void *calldata)
 387 {
 388         struct nfs_renamedata *data = calldata;
 389         struct nfs_server *server = NFS_SERVER(data->old_dir);
 390
 391         if (nfs4_setup_sequence(server, &data->args.seq_args,
 392                                 &data->res.seq_res, 1, task))
 393                 return;
 394         rpc_call_start(task);
 395 }
 396 #endif /* CONFIG_NFS_V4_1 */
 397
 398 static const struct rpc_call_ops nfs_rename_ops = {
 399         .rpc_call_done = nfs_async_rename_done,
 400         .rpc_release = nfs_async_rename_release,
 401 #if defined(CONFIG_NFS_V4_1)
 402         .rpc_call_prepare = nfs_rename_prepare,
 403 #endif /* CONFIG_NFS_V4_1 */
 404 };
 405
 406 /**
 407  * nfs_async_rename - perform an asynchronous rename operation
 408  * @old_dir: directory that currently holds the dentry to be renamed
 409  * @new_dir: target directory for the rename
 410  * @old_dentry: original dentry to be renamed
 411  * @new_dentry: dentry to which the old_dentry should be renamed
 412  *
 413  * It's expected that valid references to the dentries and inodes are held
 414  */
 415 static struct rpc_task *
 416 nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
 417                  struct dentry *old_dentry, struct dentry *new_dentry)
 418 {
 419         struct nfs_renamedata *data;
 420         struct rpc_message msg = { };
 421         struct rpc_task_setup task_setup_data = {
 422                 .rpc_message = &msg,
 423                 .callback_ops = &nfs_rename_ops,
 424                 .workqueue = nfsiod_workqueue,
 425                 .rpc_client = NFS_CLIENT(old_dir),
 426                 .flags = RPC_TASK_ASYNC,
 427         };
 428
 429         data = kzalloc(sizeof(*data), GFP_KERNEL);
 430         if (data == NULL)
 431                 return ERR_PTR(-ENOMEM);
 432         task_setup_data.callback_data = data;
 433
 434         data->cred = rpc_lookup_cred();
 435         if (IS_ERR(data->cred)) {
 436                 struct rpc_task *task = ERR_CAST(data->cred);
 437                 kfree(data);
 438                 return task;
 439         }
 440
 441         msg.rpc_argp = &data->args;
 442         msg.rpc_resp = &data->res;
 443         msg.rpc_cred = data->cred;
 444
 445         /* set up nfs_renamedata */
 446         data->old_dir = old_dir;
 447         ihold(old_dir);
 448         data->new_dir = new_dir;
 449         ihold(new_dir);
 450         data->old_dentry = dget(old_dentry);
 451         data->new_dentry = dget(new_dentry);
 452         nfs_fattr_init(&data->old_fattr);
 453         nfs_fattr_init(&data->new_fattr);
 454
 455         /* set up nfs_renameargs */
 456         data->args.old_dir = NFS_FH(old_dir);
 457         data->args.old_name = &old_dentry->d_name;
 458         data->args.new_dir = NFS_FH(new_dir);
 459         data->args.new_name = &new_dentry->d_name;
 460
 461         /* set up nfs_renameres */
 462         data->res.old_fattr = &data->old_fattr;
 463         data->res.new_fattr = &data->new_fattr;
 464
 465         nfs_sb_active(old_dir->i_sb);
 466
 467         NFS_PROTO(data->old_dir)->rename_setup(&msg, old_dir);
 468
 469         return rpc_run_task(&task_setup_data);
 470 }
 471
 472 /**
 473  * nfs_sillyrename - Perform a silly-rename of a dentry
 474  * @dir: inode of directory that contains dentry
 475  * @dentry: dentry to be sillyrenamed
 476  *
 477  * NFSv2/3 is stateless and the server doesn't know when the client is
 478  * holding a file open. To prevent application problems when a file is
 479  * unlinked while it's still open, the client performs a "silly-rename".
 480  * That is, it renames the file to a hidden file in the same directory,
 481  * and only performs the unlink once the last reference to it is put.
 482  *
 483  * The final cleanup is done during dentry_iput.
 484  */
 485 int
 486 nfs_sillyrename(struct inode *dir, struct dentry *dentry)
 487 {
 488         static unsigned int sillycounter;
 489         const int      fileidsize  = sizeof(NFS_FILEID(dentry->d_inode))*2;
 490         const int      countersize = sizeof(sillycounter)*2;
 491         const int      slen        = sizeof(".nfs")+fileidsize+countersize-1;
 492         char           silly[slen+1];
 493         struct dentry *sdentry;
 494         struct rpc_task *task;
 495         int            error = -EIO;
 496
 497         dfprintk(VFS, "NFS: silly-rename(%s/%s, ct=%d)\n",
 498                 dentry->d_parent->d_name.name, dentry->d_name.name,
 499                 dentry->d_count);
 500         nfs_inc_stats(dir, NFSIOS_SILLYRENAME);
 501
 502         /*
 503          * We don't allow a dentry to be silly-renamed twice.
 504          */
 505         error = -EBUSY;
 506         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 507                 goto out;
 508
 509         sprintf(silly, ".nfs%*.*Lx",
 510                 fileidsize, fileidsize,
 511                 (unsigned long long)NFS_FILEID(dentry->d_inode));
 512
 513         /* Return delegation in anticipation of the rename */
 514         nfs_inode_return_delegation(dentry->d_inode);
 515
 516         sdentry = NULL;
 517         do {
 518                 char *suffix = silly + slen - countersize;
 519
 520                 dput(sdentry);
 521                 sillycounter++;
 522                 sprintf(suffix, "%*.*x", countersize, countersize, sillycounter);
 523
 524                 dfprintk(VFS, "NFS: trying to rename %s to %s\n",
 525                                 dentry->d_name.name, silly);
 526
 527                 sdentry = lookup_one_len(silly, dentry->d_parent, slen);
 528                 /*
 529                  * N.B. Better to return EBUSY here ... it could be
 530                  * dangerous to delete the file while it's in use.
 531                  */
 532                 if (IS_ERR(sdentry))
 533                         goto out;
 534         } while (sdentry->d_inode != NULL); /* need negative lookup */
 535
 536         /* queue unlink first. Can't do this from rpc_release as it
 537          * has to allocate memory
 538          */
 539         error = nfs_async_unlink(dir, dentry);
 540         if (error)
 541                 goto out_dput;
 542
 543         /* run the rename task, undo unlink if it fails */
 544         task = nfs_async_rename(dir, dir, dentry, sdentry);
 545         if (IS_ERR(task)) {
 546                 error = -EBUSY;
 547                 nfs_cancel_async_unlink(dentry);
 548                 goto out_dput;
 549         }
 550
 551         /* wait for the RPC task to complete, unless a SIGKILL intervenes */
 552         error = rpc_wait_for_completion_task(task);
 553         if (error == 0)
 554                 error = task->tk_status;
 555         rpc_put_task(task);
 556 out_dput:
 557         dput(sdentry);
 558 out:
 559         return error;
 560 }