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.seq_res.sr_slotid = NFS4_MAX_SLOT_TABLE;
 266         data->res.dir_attr = &data->dir_attr;
 267
 268         status = -EBUSY;
 269         spin_lock(&dentry->d_lock);
 270         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 271                 goto out_unlock;
 272         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
 273         dentry->d_fsdata = data;
 274         spin_unlock(&dentry->d_lock);
 275         return 0;
 276 out_unlock:
 277         spin_unlock(&dentry->d_lock);
 278         put_rpccred(data->cred);
 279 out_free:
 280         kfree(data);
 281 out:
 282         return status;
 283 }
 284
 285 /**
 286  * nfs_complete_unlink - Initialize completion of the sillydelete
 287  * @dentry: dentry to delete
 288  * @inode: inode
 289  *
 290  * Since we're most likely to be called by dentry_iput(), we
 291  * only use the dentry to find the sillydelete. We then copy the name
 292  * into the qstr.
 293  */
 294 void
 295 nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
 296 {
 297         struct nfs_unlinkdata   *data = NULL;
 298
 299         spin_lock(&dentry->d_lock);
 300         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
 301                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 302                 data = dentry->d_fsdata;
 303         }
 304         spin_unlock(&dentry->d_lock);
 305
 306         if (data != NULL && (NFS_STALE(inode) || !nfs_call_unlink(dentry, data)))
 307                 nfs_free_unlinkdata(data);
 308 }
 309
 310 /* Cancel a queued async unlink. Called when a sillyrename run fails. */
 311 static void
 312 nfs_cancel_async_unlink(struct dentry *dentry)
 313 {
 314         spin_lock(&dentry->d_lock);
 315         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
 316                 struct nfs_unlinkdata *data = dentry->d_fsdata;
 317
 318                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 319                 spin_unlock(&dentry->d_lock);
 320                 nfs_free_unlinkdata(data);
 321                 return;
 322         }
 323         spin_unlock(&dentry->d_lock);
 324 }
 325
 326 struct nfs_renamedata {
 327         struct nfs_renameargs   args;
 328         struct nfs_renameres    res;
 329         struct rpc_cred         *cred;
 330         struct inode            *old_dir;
 331         struct dentry           *old_dentry;
 332         struct nfs_fattr        old_fattr;
 333         struct inode            *new_dir;
 334         struct dentry           *new_dentry;
 335         struct nfs_fattr        new_fattr;
 336 };
 337
 338 /**
 339  * nfs_async_rename_done - Sillyrename post-processing
 340  * @task: rpc_task of the sillyrename
 341  * @calldata: nfs_renamedata for the sillyrename
 342  *
 343  * Do the directory attribute updates and the d_move
 344  */
 345 static void nfs_async_rename_done(struct rpc_task *task, void *calldata)
 346 {
 347         struct nfs_renamedata *data = calldata;
 348         struct inode *old_dir = data->old_dir;
 349         struct inode *new_dir = data->new_dir;
 350
 351         if (!NFS_PROTO(old_dir)->rename_done(task, old_dir, new_dir)) {
 352                 nfs_restart_rpc(task, NFS_SERVER(old_dir)->nfs_client);
 353                 return;
 354         }
 355
 356         if (task->tk_status != 0) {
 357                 nfs_cancel_async_unlink(data->old_dentry);
 358                 return;
 359         }
 360
 361         nfs_set_verifier(data->old_dentry, nfs_save_change_attribute(old_dir));
 362         d_move(data->old_dentry, data->new_dentry);
 363 }
 364
 365 /**
 366  * nfs_async_rename_release - Release the sillyrename data.
 367  * @calldata: the struct nfs_renamedata to be released
 368  */
 369 static void nfs_async_rename_release(void *calldata)
 370 {
 371         struct nfs_renamedata   *data = calldata;
 372         struct super_block *sb = data->old_dir->i_sb;
 373
 374         if (data->old_dentry->d_inode)
 375                 nfs_mark_for_revalidate(data->old_dentry->d_inode);
 376
 377         dput(data->old_dentry);
 378         dput(data->new_dentry);
 379         iput(data->old_dir);
 380         iput(data->new_dir);
 381         nfs_sb_deactive(sb);
 382         put_rpccred(data->cred);
 383         kfree(data);
 384 }
 385
 386 #if defined(CONFIG_NFS_V4_1)
 387 static void nfs_rename_prepare(struct rpc_task *task, void *calldata)
 388 {
 389         struct nfs_renamedata *data = calldata;
 390         struct nfs_server *server = NFS_SERVER(data->old_dir);
 391
 392         if (nfs4_setup_sequence(server, &data->args.seq_args,
 393                                 &data->res.seq_res, 1, task))
 394                 return;
 395         rpc_call_start(task);
 396 }
 397 #endif /* CONFIG_NFS_V4_1 */
 398
 399 static const struct rpc_call_ops nfs_rename_ops = {
 400         .rpc_call_done = nfs_async_rename_done,
 401         .rpc_release = nfs_async_rename_release,
 402 #if defined(CONFIG_NFS_V4_1)
 403         .rpc_call_prepare = nfs_rename_prepare,
 404 #endif /* CONFIG_NFS_V4_1 */
 405 };
 406
 407 /**
 408  * nfs_async_rename - perform an asynchronous rename operation
 409  * @old_dir: directory that currently holds the dentry to be renamed
 410  * @new_dir: target directory for the rename
 411  * @old_dentry: original dentry to be renamed
 412  * @new_dentry: dentry to which the old_dentry should be renamed
 413  *
 414  * It's expected that valid references to the dentries and inodes are held
 415  */
 416 static struct rpc_task *
 417 nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
 418                  struct dentry *old_dentry, struct dentry *new_dentry)
 419 {
 420         struct nfs_renamedata *data;
 421         struct rpc_message msg = { };
 422         struct rpc_task_setup task_setup_data = {
 423                 .rpc_message = &msg,
 424                 .callback_ops = &nfs_rename_ops,
 425                 .workqueue = nfsiod_workqueue,
 426                 .rpc_client = NFS_CLIENT(old_dir),
 427                 .flags = RPC_TASK_ASYNC,
 428         };
 429
 430         data = kmalloc(sizeof(*data), GFP_KERNEL);
 431         if (data == NULL)
 432                 return ERR_PTR(-ENOMEM);
 433         task_setup_data.callback_data = data,
 434
 435         data->cred = rpc_lookup_cred();
 436         if (IS_ERR(data->cred)) {
 437                 struct rpc_task *task = ERR_CAST(data->cred);
 438                 kfree(data);
 439                 return task;
 440         }
 441
 442         msg.rpc_argp = &data->args;
 443         msg.rpc_resp = &data->res;
 444         msg.rpc_cred = data->cred;
 445
 446         /* set up nfs_renamedata */
 447         data->old_dir = old_dir;
 448         atomic_inc(&old_dir->i_count);
 449         data->new_dir = new_dir;
 450         atomic_inc(&new_dir->i_count);
 451         data->old_dentry = dget(old_dentry);
 452         data->new_dentry = dget(new_dentry);
 453         nfs_fattr_init(&data->old_fattr);
 454         nfs_fattr_init(&data->new_fattr);
 455
 456         /* set up nfs_renameargs */
 457         data->args.old_dir = NFS_FH(old_dir);
 458         data->args.old_name = &old_dentry->d_name;
 459         data->args.new_dir = NFS_FH(new_dir);
 460         data->args.new_name = &new_dentry->d_name;
 461
 462         /* set up nfs_renameres */
 463         data->res.old_fattr = &data->old_fattr;
 464         data->res.new_fattr = &data->new_fattr;
 465
 466         nfs_sb_active(old_dir->i_sb);
 467
 468         NFS_PROTO(data->old_dir)->rename_setup(&msg, old_dir);
 469
 470         return rpc_run_task(&task_setup_data);
 471 }
 472
 473 /**
 474  * nfs_sillyrename - Perform a silly-rename of a dentry
 475  * @dir: inode of directory that contains dentry
 476  * @dentry: dentry to be sillyrenamed
 477  *
 478  * NFSv2/3 is stateless and the server doesn't know when the client is
 479  * holding a file open. To prevent application problems when a file is
 480  * unlinked while it's still open, the client performs a "silly-rename".
 481  * That is, it renames the file to a hidden file in the same directory,
 482  * and only performs the unlink once the last reference to it is put.
 483  *
 484  * The final cleanup is done during dentry_iput.
 485  */
 486 int
 487 nfs_sillyrename(struct inode *dir, struct dentry *dentry)
 488 {
 489         static unsigned int sillycounter;
 490         const int      fileidsize  = sizeof(NFS_FILEID(dentry->d_inode))*2;
 491         const int      countersize = sizeof(sillycounter)*2;
 492         const int      slen        = sizeof(".nfs")+fileidsize+countersize-1;
 493         char           silly[slen+1];
 494         struct dentry *sdentry;
 495         struct rpc_task *task;
 496         int            error = -EIO;
 497
 498         dfprintk(VFS, "NFS: silly-rename(%s/%s, ct=%d)\n",
 499                 dentry->d_parent->d_name.name, dentry->d_name.name,
 500                 atomic_read(&dentry->d_count));
 501         nfs_inc_stats(dir, NFSIOS_SILLYRENAME);
 502
 503         /*
 504          * We don't allow a dentry to be silly-renamed twice.
 505          */
 506         error = -EBUSY;
 507         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 508                 goto out;
 509
 510         sprintf(silly, ".nfs%*.*Lx",
 511                 fileidsize, fileidsize,
 512                 (unsigned long long)NFS_FILEID(dentry->d_inode));
 513
 514         /* Return delegation in anticipation of the rename */
 515         nfs_inode_return_delegation(dentry->d_inode);
 516
 517         sdentry = NULL;
 518         do {
 519                 char *suffix = silly + slen - countersize;
 520
 521                 dput(sdentry);
 522                 sillycounter++;
 523                 sprintf(suffix, "%*.*x", countersize, countersize, sillycounter);
 524
 525                 dfprintk(VFS, "NFS: trying to rename %s to %s\n",
 526                                 dentry->d_name.name, silly);
 527
 528                 sdentry = lookup_one_len(silly, dentry->d_parent, slen);
 529                 /*
 530                  * N.B. Better to return EBUSY here ... it could be
 531                  * dangerous to delete the file while it's in use.
 532                  */
 533                 if (IS_ERR(sdentry))
 534                         goto out;
 535         } while (sdentry->d_inode != NULL); /* need negative lookup */
 536
 537         /* queue unlink first. Can't do this from rpc_release as it
 538          * has to allocate memory
 539          */
 540         error = nfs_async_unlink(dir, dentry);
 541         if (error)
 542                 goto out_dput;
 543
 544         /* run the rename task, undo unlink if it fails */
 545         task = nfs_async_rename(dir, dir, dentry, sdentry);
 546         if (IS_ERR(task)) {
 547                 error = -EBUSY;
 548                 nfs_cancel_async_unlink(dentry);
 549                 goto out_dput;
 550         }
 551
 552         /* wait for the RPC task to complete, unless a SIGKILL intervenes */
 553         error = rpc_wait_for_completion_task(task);
 554         if (error == 0)
 555                 error = task->tk_status;
 556         rpc_put_task(task);
 557 out_dput:
 558         dput(sdentry);
 559 out:
 560         return error;
 561 }