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 /**
  24  * nfs_free_unlinkdata - release data from a sillydelete operation.
  25  * @data: pointer to unlink structure.
  26  */
  27 static void
  28 nfs_free_unlinkdata(struct nfs_unlinkdata *data)
  29 {
  30         iput(data->dir);
  31         put_rpccred(data->cred);
  32         kfree(data->args.name.name);
  33         kfree(data);
  34 }
  35
  36 #define NAME_ALLOC_LEN(len)     ((len+16) & ~15)
  37 /**
  38  * nfs_copy_dname - copy dentry name to data structure
  39  * @dentry: pointer to dentry
  40  * @data: nfs_unlinkdata
  41  */
  42 static int nfs_copy_dname(struct dentry *dentry, struct nfs_unlinkdata *data)
  43 {
  44         char            *str;
  45         int             len = dentry->d_name.len;
  46
  47         str = kmemdup(dentry->d_name.name, NAME_ALLOC_LEN(len), GFP_KERNEL);
  48         if (!str)
  49                 return -ENOMEM;
  50         data->args.name.len = len;
  51         data->args.name.name = str;
  52         return 0;
  53 }
  54
  55 static void nfs_free_dname(struct nfs_unlinkdata *data)
  56 {
  57         kfree(data->args.name.name);
  58         data->args.name.name = NULL;
  59         data->args.name.len = 0;
  60 }
  61
  62 static void nfs_dec_sillycount(struct inode *dir)
  63 {
  64         struct nfs_inode *nfsi = NFS_I(dir);
  65         if (atomic_dec_return(&nfsi->silly_count) == 1)
  66                 wake_up(&nfsi->waitqueue);
  67 }
  68
  69 /**
  70  * nfs_async_unlink_done - Sillydelete post-processing
  71  * @task: rpc_task of the sillydelete
  72  *
  73  * Do the directory attribute update.
  74  */
  75 static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
  76 {
  77         struct nfs_unlinkdata *data = calldata;
  78         struct inode *dir = data->dir;
  79
  80         if (!NFS_PROTO(dir)->unlink_done(task, dir))
  81                 rpc_restart_call_prepare(task);
  82 }
  83
  84 /**
  85  * nfs_async_unlink_release - Release the sillydelete data.
  86  * @task: rpc_task of the sillydelete
  87  *
  88  * We need to call nfs_put_unlinkdata as a 'tk_release' task since the
  89  * rpc_task would be freed too.
  90  */
  91 static void nfs_async_unlink_release(void *calldata)
  92 {
  93         struct nfs_unlinkdata   *data = calldata;
  94         struct super_block *sb = data->dir->i_sb;
  95
  96         nfs_dec_sillycount(data->dir);
  97         nfs_free_unlinkdata(data);
  98         nfs_sb_deactive(sb);
  99 }
 100
 101 static void nfs_unlink_prepare(struct rpc_task *task, void *calldata)
 102 {
 103         struct nfs_unlinkdata *data = calldata;
 104         NFS_PROTO(data->dir)->unlink_rpc_prepare(task, data);
 105 }
 106
 107 static const struct rpc_call_ops nfs_unlink_ops = {
 108         .rpc_call_done = nfs_async_unlink_done,
 109         .rpc_release = nfs_async_unlink_release,
 110         .rpc_call_prepare = nfs_unlink_prepare,
 111 };
 112
 113 static int nfs_do_call_unlink(struct dentry *parent, struct inode *dir, struct nfs_unlinkdata *data)
 114 {
 115         struct rpc_message msg = {
 116                 .rpc_argp = &data->args,
 117                 .rpc_resp = &data->res,
 118                 .rpc_cred = data->cred,
 119         };
 120         struct rpc_task_setup task_setup_data = {
 121                 .rpc_message = &msg,
 122                 .callback_ops = &nfs_unlink_ops,
 123                 .callback_data = data,
 124                 .workqueue = nfsiod_workqueue,
 125                 .flags = RPC_TASK_ASYNC,
 126         };
 127         struct rpc_task *task;
 128         struct dentry *alias;
 129
 130         alias = d_lookup(parent, &data->args.name);
 131         if (alias != NULL) {
 132                 int ret;
 133                 void *devname_garbage = NULL;
 134
 135                 /*
 136                  * Hey, we raced with lookup... See if we need to transfer
 137                  * the sillyrename information to the aliased dentry.
 138                  */
 139                 nfs_free_dname(data);
 140                 ret = nfs_copy_dname(alias, data);
 141                 spin_lock(&alias->d_lock);
 142                 if (ret == 0 && alias->d_inode != NULL &&
 143                     !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
 144                         devname_garbage = alias->d_fsdata;
 145                         alias->d_fsdata = data;
 146                         alias->d_flags |= DCACHE_NFSFS_RENAMED;
 147                         ret = 1;
 148                 } else
 149                         ret = 0;
 150                 spin_unlock(&alias->d_lock);
 151                 nfs_dec_sillycount(dir);
 152                 dput(alias);
 153                 /*
 154                  * If we'd displaced old cached devname, free it.  At that
 155                  * point dentry is definitely not a root, so we won't need
 156                  * that anymore.
 157                  */
 158                 kfree(devname_garbage);
 159                 return ret;
 160         }
 161         data->dir = igrab(dir);
 162         if (!data->dir) {
 163                 nfs_dec_sillycount(dir);
 164                 return 0;
 165         }
 166         nfs_sb_active(dir->i_sb);
 167         data->args.fh = NFS_FH(dir);
 168         nfs_fattr_init(data->res.dir_attr);
 169
 170         NFS_PROTO(dir)->unlink_setup(&msg, dir);
 171
 172         task_setup_data.rpc_client = NFS_CLIENT(dir);
 173         task = rpc_run_task(&task_setup_data);
 174         if (!IS_ERR(task))
 175                 rpc_put_task_async(task);
 176         return 1;
 177 }
 178
 179 static int nfs_call_unlink(struct dentry *dentry, struct nfs_unlinkdata *data)
 180 {
 181         struct dentry *parent;
 182         struct inode *dir;
 183         int ret = 0;
 184
 185
 186         parent = dget_parent(dentry);
 187         if (parent == NULL)
 188                 goto out_free;
 189         dir = parent->d_inode;
 190         /* Non-exclusive lock protects against concurrent lookup() calls */
 191         spin_lock(&dir->i_lock);
 192         if (atomic_inc_not_zero(&NFS_I(dir)->silly_count) == 0) {
 193                 /* Deferred delete */
 194                 hlist_add_head(&data->list, &NFS_I(dir)->silly_list);
 195                 spin_unlock(&dir->i_lock);
 196                 ret = 1;
 197                 goto out_dput;
 198         }
 199         spin_unlock(&dir->i_lock);
 200         ret = nfs_do_call_unlink(parent, dir, data);
 201 out_dput:
 202         dput(parent);
 203 out_free:
 204         return ret;
 205 }
 206
 207 void nfs_block_sillyrename(struct dentry *dentry)
 208 {
 209         struct nfs_inode *nfsi = NFS_I(dentry->d_inode);
 210
 211         wait_event(nfsi->waitqueue, atomic_cmpxchg(&nfsi->silly_count, 1, 0) == 1);
 212 }
 213
 214 void nfs_unblock_sillyrename(struct dentry *dentry)
 215 {
 216         struct inode *dir = dentry->d_inode;
 217         struct nfs_inode *nfsi = NFS_I(dir);
 218         struct nfs_unlinkdata *data;
 219
 220         atomic_inc(&nfsi->silly_count);
 221         spin_lock(&dir->i_lock);
 222         while (!hlist_empty(&nfsi->silly_list)) {
 223                 if (!atomic_inc_not_zero(&nfsi->silly_count))
 224                         break;
 225                 data = hlist_entry(nfsi->silly_list.first, struct nfs_unlinkdata, list);
 226                 hlist_del(&data->list);
 227                 spin_unlock(&dir->i_lock);
 228                 if (nfs_do_call_unlink(dentry, dir, data) == 0)
 229                         nfs_free_unlinkdata(data);
 230                 spin_lock(&dir->i_lock);
 231         }
 232         spin_unlock(&dir->i_lock);
 233 }
 234
 235 /**
 236  * nfs_async_unlink - asynchronous unlinking of a file
 237  * @dir: parent directory of dentry
 238  * @dentry: dentry to unlink
 239  */
 240 static int
 241 nfs_async_unlink(struct inode *dir, struct dentry *dentry)
 242 {
 243         struct nfs_unlinkdata *data;
 244         int status = -ENOMEM;
 245         void *devname_garbage = NULL;
 246
 247         data = kzalloc(sizeof(*data), GFP_KERNEL);
 248         if (data == NULL)
 249                 goto out;
 250
 251         data->cred = rpc_lookup_cred();
 252         if (IS_ERR(data->cred)) {
 253                 status = PTR_ERR(data->cred);
 254                 goto out_free;
 255         }
 256         data->res.dir_attr = &data->dir_attr;
 257
 258         status = -EBUSY;
 259         spin_lock(&dentry->d_lock);
 260         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 261                 goto out_unlock;
 262         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
 263         devname_garbage = dentry->d_fsdata;
 264         dentry->d_fsdata = data;
 265         spin_unlock(&dentry->d_lock);
 266         /*
 267          * If we'd displaced old cached devname, free it.  At that
 268          * point dentry is definitely not a root, so we won't need
 269          * that anymore.
 270          */
 271         kfree(devname_garbage);
 272         return 0;
 273 out_unlock:
 274         spin_unlock(&dentry->d_lock);
 275         put_rpccred(data->cred);
 276 out_free:
 277         kfree(data);
 278 out:
 279         return status;
 280 }
 281
 282 /**
 283  * nfs_complete_unlink - Initialize completion of the sillydelete
 284  * @dentry: dentry to delete
 285  * @inode: inode
 286  *
 287  * Since we're most likely to be called by dentry_iput(), we
 288  * only use the dentry to find the sillydelete. We then copy the name
 289  * into the qstr.
 290  */
 291 void
 292 nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
 293 {
 294         struct nfs_unlinkdata   *data = NULL;
 295
 296         spin_lock(&dentry->d_lock);
 297         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
 298                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 299                 data = dentry->d_fsdata;
 300                 dentry->d_fsdata = NULL;
 301         }
 302         spin_unlock(&dentry->d_lock);
 303
 304         if (data != NULL && (NFS_STALE(inode) || !nfs_call_unlink(dentry, data)))
 305                 nfs_free_unlinkdata(data);
 306 }
 307
 308 /* Cancel a queued async unlink. Called when a sillyrename run fails. */
 309 static void
 310 nfs_cancel_async_unlink(struct dentry *dentry)
 311 {
 312         spin_lock(&dentry->d_lock);
 313         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
 314                 struct nfs_unlinkdata *data = dentry->d_fsdata;
 315
 316                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 317                 dentry->d_fsdata = NULL;
 318                 spin_unlock(&dentry->d_lock);
 319                 nfs_free_unlinkdata(data);
 320                 return;
 321         }
 322         spin_unlock(&dentry->d_lock);
 323 }
 324
 325 /**
 326  * nfs_async_rename_done - Sillyrename post-processing
 327  * @task: rpc_task of the sillyrename
 328  * @calldata: nfs_renamedata for the sillyrename
 329  *
 330  * Do the directory attribute updates and the d_move
 331  */
 332 static void nfs_async_rename_done(struct rpc_task *task, void *calldata)
 333 {
 334         struct nfs_renamedata *data = calldata;
 335         struct inode *old_dir = data->old_dir;
 336         struct inode *new_dir = data->new_dir;
 337         struct dentry *old_dentry = data->old_dentry;
 338         struct dentry *new_dentry = data->new_dentry;
 339
 340         if (!NFS_PROTO(old_dir)->rename_done(task, old_dir, new_dir)) {
 341                 rpc_restart_call_prepare(task);
 342                 return;
 343         }
 344
 345         if (task->tk_status != 0) {
 346                 nfs_cancel_async_unlink(old_dentry);
 347                 return;
 348         }
 349
 350         d_drop(old_dentry);
 351         d_drop(new_dentry);
 352 }
 353
 354 /**
 355  * nfs_async_rename_release - Release the sillyrename data.
 356  * @calldata: the struct nfs_renamedata to be released
 357  */
 358 static void nfs_async_rename_release(void *calldata)
 359 {
 360         struct nfs_renamedata   *data = calldata;
 361         struct super_block *sb = data->old_dir->i_sb;
 362
 363         if (data->old_dentry->d_inode)
 364                 nfs_mark_for_revalidate(data->old_dentry->d_inode);
 365
 366         dput(data->old_dentry);
 367         dput(data->new_dentry);
 368         iput(data->old_dir);
 369         iput(data->new_dir);
 370         nfs_sb_deactive(sb);
 371         put_rpccred(data->cred);
 372         kfree(data);
 373 }
 374
 375 static void nfs_rename_prepare(struct rpc_task *task, void *calldata)
 376 {
 377         struct nfs_renamedata *data = calldata;
 378         NFS_PROTO(data->old_dir)->rename_rpc_prepare(task, data);
 379 }
 380
 381 static const struct rpc_call_ops nfs_rename_ops = {
 382         .rpc_call_done = nfs_async_rename_done,
 383         .rpc_release = nfs_async_rename_release,
 384         .rpc_call_prepare = nfs_rename_prepare,
 385 };
 386
 387 /**
 388  * nfs_async_rename - perform an asynchronous rename operation
 389  * @old_dir: directory that currently holds the dentry to be renamed
 390  * @new_dir: target directory for the rename
 391  * @old_dentry: original dentry to be renamed
 392  * @new_dentry: dentry to which the old_dentry should be renamed
 393  *
 394  * It's expected that valid references to the dentries and inodes are held
 395  */
 396 static struct rpc_task *
 397 nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
 398                  struct dentry *old_dentry, struct dentry *new_dentry)
 399 {
 400         struct nfs_renamedata *data;
 401         struct rpc_message msg = { };
 402         struct rpc_task_setup task_setup_data = {
 403                 .rpc_message = &msg,
 404                 .callback_ops = &nfs_rename_ops,
 405                 .workqueue = nfsiod_workqueue,
 406                 .rpc_client = NFS_CLIENT(old_dir),
 407                 .flags = RPC_TASK_ASYNC,
 408         };
 409
 410         data = kzalloc(sizeof(*data), GFP_KERNEL);
 411         if (data == NULL)
 412                 return ERR_PTR(-ENOMEM);
 413         task_setup_data.callback_data = data;
 414
 415         data->cred = rpc_lookup_cred();
 416         if (IS_ERR(data->cred)) {
 417                 struct rpc_task *task = ERR_CAST(data->cred);
 418                 kfree(data);
 419                 return task;
 420         }
 421
 422         msg.rpc_argp = &data->args;
 423         msg.rpc_resp = &data->res;
 424         msg.rpc_cred = data->cred;
 425
 426         /* set up nfs_renamedata */
 427         data->old_dir = old_dir;
 428         ihold(old_dir);
 429         data->new_dir = new_dir;
 430         ihold(new_dir);
 431         data->old_dentry = dget(old_dentry);
 432         data->new_dentry = dget(new_dentry);
 433         nfs_fattr_init(&data->old_fattr);
 434         nfs_fattr_init(&data->new_fattr);
 435
 436         /* set up nfs_renameargs */
 437         data->args.old_dir = NFS_FH(old_dir);
 438         data->args.old_name = &old_dentry->d_name;
 439         data->args.new_dir = NFS_FH(new_dir);
 440         data->args.new_name = &new_dentry->d_name;
 441
 442         /* set up nfs_renameres */
 443         data->res.old_fattr = &data->old_fattr;
 444         data->res.new_fattr = &data->new_fattr;
 445
 446         nfs_sb_active(old_dir->i_sb);
 447
 448         NFS_PROTO(data->old_dir)->rename_setup(&msg, old_dir);
 449
 450         return rpc_run_task(&task_setup_data);
 451 }
 452
 453 /**
 454  * nfs_sillyrename - Perform a silly-rename of a dentry
 455  * @dir: inode of directory that contains dentry
 456  * @dentry: dentry to be sillyrenamed
 457  *
 458  * NFSv2/3 is stateless and the server doesn't know when the client is
 459  * holding a file open. To prevent application problems when a file is
 460  * unlinked while it's still open, the client performs a "silly-rename".
 461  * That is, it renames the file to a hidden file in the same directory,
 462  * and only performs the unlink once the last reference to it is put.
 463  *
 464  * The final cleanup is done during dentry_iput.
 465  *
 466  * (Note: NFSv4 is stateful, and has opens, so in theory an NFSv4 server
 467  * could take responsibility for keeping open files referenced.  The server
 468  * would also need to ensure that opened-but-deleted files were kept over
 469  * reboots.  However, we may not assume a server does so.  (RFC 5661
 470  * does provide an OPEN4_RESULT_PRESERVE_UNLINKED flag that a server can
 471  * use to advertise that it does this; some day we may take advantage of
 472  * it.))
 473  */
 474 int
 475 nfs_sillyrename(struct inode *dir, struct dentry *dentry)
 476 {
 477         static unsigned int sillycounter;
 478         const int      fileidsize  = sizeof(NFS_FILEID(dentry->d_inode))*2;
 479         const int      countersize = sizeof(sillycounter)*2;
 480         const int      slen        = sizeof(".nfs")+fileidsize+countersize-1;
 481         char           silly[slen+1];
 482         struct dentry *sdentry;
 483         struct rpc_task *task;
 484         int            error = -EIO;
 485
 486         dfprintk(VFS, "NFS: silly-rename(%s/%s, ct=%d)\n",
 487                 dentry->d_parent->d_name.name, dentry->d_name.name,
 488                 dentry->d_count);
 489         nfs_inc_stats(dir, NFSIOS_SILLYRENAME);
 490
 491         /*
 492          * We don't allow a dentry to be silly-renamed twice.
 493          */
 494         error = -EBUSY;
 495         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 496                 goto out;
 497
 498         sprintf(silly, ".nfs%*.*Lx",
 499                 fileidsize, fileidsize,
 500                 (unsigned long long)NFS_FILEID(dentry->d_inode));
 501
 502         /* Return delegation in anticipation of the rename */
 503         NFS_PROTO(dentry->d_inode)->return_delegation(dentry->d_inode);
 504
 505         sdentry = NULL;
 506         do {
 507                 char *suffix = silly + slen - countersize;
 508
 509                 dput(sdentry);
 510                 sillycounter++;
 511                 sprintf(suffix, "%*.*x", countersize, countersize, sillycounter);
 512
 513                 dfprintk(VFS, "NFS: trying to rename %s to %s\n",
 514                                 dentry->d_name.name, silly);
 515
 516                 sdentry = lookup_one_len(silly, dentry->d_parent, slen);
 517                 /*
 518                  * N.B. Better to return EBUSY here ... it could be
 519                  * dangerous to delete the file while it's in use.
 520                  */
 521                 if (IS_ERR(sdentry))
 522                         goto out;
 523         } while (sdentry->d_inode != NULL); /* need negative lookup */
 524
 525         /* queue unlink first. Can't do this from rpc_release as it
 526          * has to allocate memory
 527          */
 528         error = nfs_async_unlink(dir, dentry);
 529         if (error)
 530                 goto out_dput;
 531
 532         /* populate unlinkdata with the right dname */
 533         error = nfs_copy_dname(sdentry,
 534                                 (struct nfs_unlinkdata *)dentry->d_fsdata);
 535         if (error) {
 536                 nfs_cancel_async_unlink(dentry);
 537                 goto out_dput;
 538         }
 539
 540         /* run the rename task, undo unlink if it fails */
 541         task = nfs_async_rename(dir, dir, dentry, sdentry);
 542         if (IS_ERR(task)) {
 543                 error = -EBUSY;
 544                 nfs_cancel_async_unlink(dentry);
 545                 goto out_dput;
 546         }
 547
 548         /* wait for the RPC task to complete, unless a SIGKILL intervenes */
 549         error = rpc_wait_for_completion_task(task);
 550         if (error == 0)
 551                 error = task->tk_status;
 552         rpc_put_task(task);
 553 out_dput:
 554         dput(sdentry);
 555 out:
 556         return error;
 557 }