fs/nfs/unlink.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/nfs/unlink.c
   4  *
   5  * nfs sillydelete handling
   6  *
   7  */
   8
   9 #include <linux/slab.h>
  10 #include <linux/string.h>
  11 #include <linux/dcache.h>
  12 #include <linux/sunrpc/sched.h>
  13 #include <linux/sunrpc/clnt.h>
  14 #include <linux/nfs_fs.h>
  15 #include <linux/sched.h>
  16 #include <linux/wait.h>
  17 #include <linux/namei.h>
  18 #include <linux/fsnotify.h>
  19
  20 #include "internal.h"
  21 #include "nfs4_fs.h"
  22 #include "iostat.h"
  23 #include "delegation.h"
  24
  25 #include "nfstrace.h"
  26
  27 /**
  28  * nfs_free_unlinkdata - release data from a sillydelete operation.
  29  * @data: pointer to unlink structure.
  30  */
  31 static void
  32 nfs_free_unlinkdata(struct nfs_unlinkdata *data)
  33 {
  34         put_cred(data->cred);
  35         kfree(data->args.name.name);
  36         kfree(data);
  37 }
  38
  39 /**
  40  * nfs_async_unlink_done - Sillydelete post-processing
  41  * @task: rpc_task of the sillydelete
  42  * @calldata: pointer to nfs_unlinkdata
  43  *
  44  * Do the directory attribute update.
  45  */
  46 static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
  47 {
  48         struct nfs_unlinkdata *data = calldata;
  49         struct inode *dir = d_inode(data->dentry->d_parent);
  50
  51         trace_nfs_sillyrename_unlink(data, task->tk_status);
  52         if (!NFS_PROTO(dir)->unlink_done(task, dir))
  53                 rpc_restart_call_prepare(task);
  54 }
  55
  56 /**
  57  * nfs_async_unlink_release - Release the sillydelete data.
  58  * @calldata: struct nfs_unlinkdata to release
  59  *
  60  * We need to call nfs_put_unlinkdata as a 'tk_release' task since the
  61  * rpc_task would be freed too.
  62  */
  63 static void nfs_async_unlink_release(void *calldata)
  64 {
  65         struct nfs_unlinkdata   *data = calldata;
  66         struct dentry *dentry = data->dentry;
  67         struct super_block *sb = dentry->d_sb;
  68
  69         up_read_non_owner(&NFS_I(d_inode(dentry->d_parent))->rmdir_sem);
  70         d_lookup_done(dentry);
  71         nfs_free_unlinkdata(data);
  72         dput(dentry);
  73         nfs_sb_deactive(sb);
  74 }
  75
  76 static void nfs_unlink_prepare(struct rpc_task *task, void *calldata)
  77 {
  78         struct nfs_unlinkdata *data = calldata;
  79         struct inode *dir = d_inode(data->dentry->d_parent);
  80         NFS_PROTO(dir)->unlink_rpc_prepare(task, data);
  81 }
  82
  83 static const struct rpc_call_ops nfs_unlink_ops = {
  84         .rpc_call_done = nfs_async_unlink_done,
  85         .rpc_release = nfs_async_unlink_release,
  86         .rpc_call_prepare = nfs_unlink_prepare,
  87 };
  88
  89 static void nfs_do_call_unlink(struct inode *inode, struct nfs_unlinkdata *data)
  90 {
  91         struct rpc_message msg = {
  92                 .rpc_argp = &data->args,
  93                 .rpc_resp = &data->res,
  94                 .rpc_cred = data->cred,
  95         };
  96         struct rpc_task_setup task_setup_data = {
  97                 .rpc_message = &msg,
  98                 .callback_ops = &nfs_unlink_ops,
  99                 .callback_data = data,
 100                 .workqueue = nfsiod_workqueue,
 101                 .flags = RPC_TASK_ASYNC | RPC_TASK_CRED_NOREF,
 102         };
 103         struct rpc_task *task;
 104         struct inode *dir = d_inode(data->dentry->d_parent);
 105
 106         if (nfs_server_capable(inode, NFS_CAP_MOVEABLE))
 107                 task_setup_data.flags |= RPC_TASK_MOVEABLE;
 108
 109         nfs_sb_active(dir->i_sb);
 110         data->args.fh = NFS_FH(dir);
 111         nfs_fattr_init(data->res.dir_attr);
 112
 113         NFS_PROTO(dir)->unlink_setup(&msg, data->dentry, inode);
 114
 115         task_setup_data.rpc_client = NFS_CLIENT(dir);
 116         task = rpc_run_task(&task_setup_data);
 117         if (!IS_ERR(task))
 118                 rpc_put_task_async(task);
 119 }
 120
 121 static int nfs_call_unlink(struct dentry *dentry, struct inode *inode, struct nfs_unlinkdata *data)
 122 {
 123         struct inode *dir = d_inode(dentry->d_parent);
 124         struct dentry *alias;
 125
 126         down_read_non_owner(&NFS_I(dir)->rmdir_sem);
 127         alias = d_alloc_parallel(dentry->d_parent, &data->args.name, &data->wq);
 128         if (IS_ERR(alias)) {
 129                 up_read_non_owner(&NFS_I(dir)->rmdir_sem);
 130                 return 0;
 131         }
 132         if (!d_in_lookup(alias)) {
 133                 int ret;
 134                 void *devname_garbage = NULL;
 135
 136                 /*
 137                  * Hey, we raced with lookup... See if we need to transfer
 138                  * the sillyrename information to the aliased dentry.
 139                  */
 140                 spin_lock(&alias->d_lock);
 141                 if (d_really_is_positive(alias) &&
 142                     !nfs_compare_fh(NFS_FH(inode), NFS_FH(d_inode(alias))) &&
 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                 dput(alias);
 152                 up_read_non_owner(&NFS_I(dir)->rmdir_sem);
 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->dentry = alias;
 162         nfs_do_call_unlink(inode, data);
 163         return 1;
 164 }
 165
 166 /**
 167  * nfs_async_unlink - asynchronous unlinking of a file
 168  * @dentry: parent directory of dentry
 169  * @name: name of dentry to unlink
 170  */
 171 static int
 172 nfs_async_unlink(struct dentry *dentry, const struct qstr *name)
 173 {
 174         struct nfs_unlinkdata *data;
 175         int status = -ENOMEM;
 176         void *devname_garbage = NULL;
 177
 178         data = kzalloc(sizeof(*data), GFP_KERNEL);
 179         if (data == NULL)
 180                 goto out;
 181         data->args.name.name = kstrdup(name->name, GFP_KERNEL);
 182         if (!data->args.name.name)
 183                 goto out_free;
 184         data->args.name.len = name->len;
 185
 186         data->cred = get_current_cred();
 187         data->res.dir_attr = &data->dir_attr;
 188         init_waitqueue_head(&data->wq);
 189
 190         status = -EBUSY;
 191         spin_lock(&dentry->d_lock);
 192         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 193                 goto out_unlock;
 194         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
 195         devname_garbage = dentry->d_fsdata;
 196         dentry->d_fsdata = data;
 197         spin_unlock(&dentry->d_lock);
 198         /*
 199          * If we'd displaced old cached devname, free it.  At that
 200          * point dentry is definitely not a root, so we won't need
 201          * that anymore.
 202          */
 203         kfree(devname_garbage);
 204         return 0;
 205 out_unlock:
 206         spin_unlock(&dentry->d_lock);
 207         put_cred(data->cred);
 208         kfree(data->args.name.name);
 209 out_free:
 210         kfree(data);
 211 out:
 212         return status;
 213 }
 214
 215 /**
 216  * nfs_complete_unlink - Initialize completion of the sillydelete
 217  * @dentry: dentry to delete
 218  * @inode: inode
 219  *
 220  * Since we're most likely to be called by dentry_iput(), we
 221  * only use the dentry to find the sillydelete. We then copy the name
 222  * into the qstr.
 223  */
 224 void
 225 nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
 226 {
 227         struct nfs_unlinkdata   *data;
 228
 229         spin_lock(&dentry->d_lock);
 230         dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 231         data = dentry->d_fsdata;
 232         dentry->d_fsdata = NULL;
 233         spin_unlock(&dentry->d_lock);
 234
 235         if (NFS_STALE(inode) || !nfs_call_unlink(dentry, inode, data))
 236                 nfs_free_unlinkdata(data);
 237 }
 238
 239 /* Cancel a queued async unlink. Called when a sillyrename run fails. */
 240 static void
 241 nfs_cancel_async_unlink(struct dentry *dentry)
 242 {
 243         spin_lock(&dentry->d_lock);
 244         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
 245                 struct nfs_unlinkdata *data = dentry->d_fsdata;
 246
 247                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 248                 dentry->d_fsdata = NULL;
 249                 spin_unlock(&dentry->d_lock);
 250                 nfs_free_unlinkdata(data);
 251                 return;
 252         }
 253         spin_unlock(&dentry->d_lock);
 254 }
 255
 256 /**
 257  * nfs_async_rename_done - Sillyrename post-processing
 258  * @task: rpc_task of the sillyrename
 259  * @calldata: nfs_renamedata for the sillyrename
 260  *
 261  * Do the directory attribute updates and the d_move
 262  */
 263 static void nfs_async_rename_done(struct rpc_task *task, void *calldata)
 264 {
 265         struct nfs_renamedata *data = calldata;
 266         struct inode *old_dir = data->old_dir;
 267         struct inode *new_dir = data->new_dir;
 268         struct dentry *old_dentry = data->old_dentry;
 269
 270         trace_nfs_async_rename_done(old_dir, old_dentry,
 271                         new_dir, data->new_dentry, task->tk_status);
 272         if (!NFS_PROTO(old_dir)->rename_done(task, old_dir, new_dir)) {
 273                 rpc_restart_call_prepare(task);
 274                 return;
 275         }
 276
 277         if (data->complete)
 278                 data->complete(task, data);
 279 }
 280
 281 /**
 282  * nfs_async_rename_release - Release the sillyrename data.
 283  * @calldata: the struct nfs_renamedata to be released
 284  */
 285 static void nfs_async_rename_release(void *calldata)
 286 {
 287         struct nfs_renamedata   *data = calldata;
 288         struct super_block *sb = data->old_dir->i_sb;
 289
 290         if (d_really_is_positive(data->old_dentry))
 291                 nfs_mark_for_revalidate(d_inode(data->old_dentry));
 292
 293         /* The result of the rename is unknown. Play it safe by
 294          * forcing a new lookup */
 295         if (data->cancelled) {
 296                 spin_lock(&data->old_dir->i_lock);
 297                 nfs_force_lookup_revalidate(data->old_dir);
 298                 spin_unlock(&data->old_dir->i_lock);
 299                 if (data->new_dir != data->old_dir) {
 300                         spin_lock(&data->new_dir->i_lock);
 301                         nfs_force_lookup_revalidate(data->new_dir);
 302                         spin_unlock(&data->new_dir->i_lock);
 303                 }
 304         }
 305
 306         dput(data->old_dentry);
 307         dput(data->new_dentry);
 308         iput(data->old_dir);
 309         iput(data->new_dir);
 310         nfs_sb_deactive(sb);
 311         put_cred(data->cred);
 312         kfree(data);
 313 }
 314
 315 static void nfs_rename_prepare(struct rpc_task *task, void *calldata)
 316 {
 317         struct nfs_renamedata *data = calldata;
 318         NFS_PROTO(data->old_dir)->rename_rpc_prepare(task, data);
 319 }
 320
 321 static const struct rpc_call_ops nfs_rename_ops = {
 322         .rpc_call_done = nfs_async_rename_done,
 323         .rpc_release = nfs_async_rename_release,
 324         .rpc_call_prepare = nfs_rename_prepare,
 325 };
 326
 327 /**
 328  * nfs_async_rename - perform an asynchronous rename operation
 329  * @old_dir: directory that currently holds the dentry to be renamed
 330  * @new_dir: target directory for the rename
 331  * @old_dentry: original dentry to be renamed
 332  * @new_dentry: dentry to which the old_dentry should be renamed
 333  * @complete: Function to run on successful completion
 334  *
 335  * It's expected that valid references to the dentries and inodes are held
 336  */
 337 struct rpc_task *
 338 nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
 339                  struct dentry *old_dentry, struct dentry *new_dentry,
 340                  void (*complete)(struct rpc_task *, struct nfs_renamedata *))
 341 {
 342         struct nfs_renamedata *data;
 343         struct rpc_message msg = { };
 344         struct rpc_task_setup task_setup_data = {
 345                 .rpc_message = &msg,
 346                 .callback_ops = &nfs_rename_ops,
 347                 .workqueue = nfsiod_workqueue,
 348                 .rpc_client = NFS_CLIENT(old_dir),
 349                 .flags = RPC_TASK_ASYNC | RPC_TASK_CRED_NOREF,
 350         };
 351
 352         if (nfs_server_capable(old_dir, NFS_CAP_MOVEABLE) &&
 353             nfs_server_capable(new_dir, NFS_CAP_MOVEABLE))
 354                 task_setup_data.flags |= RPC_TASK_MOVEABLE;
 355
 356         data = kzalloc(sizeof(*data), GFP_KERNEL);
 357         if (data == NULL)
 358                 return ERR_PTR(-ENOMEM);
 359         task_setup_data.task = &data->task;
 360         task_setup_data.callback_data = data;
 361
 362         data->cred = get_current_cred();
 363
 364         msg.rpc_argp = &data->args;
 365         msg.rpc_resp = &data->res;
 366         msg.rpc_cred = data->cred;
 367
 368         /* set up nfs_renamedata */
 369         data->old_dir = old_dir;
 370         ihold(old_dir);
 371         data->new_dir = new_dir;
 372         ihold(new_dir);
 373         data->old_dentry = dget(old_dentry);
 374         data->new_dentry = dget(new_dentry);
 375         nfs_fattr_init(&data->old_fattr);
 376         nfs_fattr_init(&data->new_fattr);
 377         data->complete = complete;
 378
 379         /* set up nfs_renameargs */
 380         data->args.old_dir = NFS_FH(old_dir);
 381         data->args.old_name = &old_dentry->d_name;
 382         data->args.new_dir = NFS_FH(new_dir);
 383         data->args.new_name = &new_dentry->d_name;
 384
 385         /* set up nfs_renameres */
 386         data->res.old_fattr = &data->old_fattr;
 387         data->res.new_fattr = &data->new_fattr;
 388
 389         nfs_sb_active(old_dir->i_sb);
 390
 391         NFS_PROTO(data->old_dir)->rename_setup(&msg, old_dentry, new_dentry);
 392
 393         return rpc_run_task(&task_setup_data);
 394 }
 395
 396 /*
 397  * Perform tasks needed when a sillyrename is done such as cancelling the
 398  * queued async unlink if it failed.
 399  */
 400 static void
 401 nfs_complete_sillyrename(struct rpc_task *task, struct nfs_renamedata *data)
 402 {
 403         struct dentry *dentry = data->old_dentry;
 404
 405         if (task->tk_status != 0) {
 406                 nfs_cancel_async_unlink(dentry);
 407                 return;
 408         }
 409 }
 410
 411 #define SILLYNAME_PREFIX ".nfs"
 412 #define SILLYNAME_PREFIX_LEN ((unsigned)sizeof(SILLYNAME_PREFIX) - 1)
 413 #define SILLYNAME_FILEID_LEN ((unsigned)sizeof(u64) << 1)
 414 #define SILLYNAME_COUNTER_LEN ((unsigned)sizeof(unsigned int) << 1)
 415 #define SILLYNAME_LEN (SILLYNAME_PREFIX_LEN + \
 416                 SILLYNAME_FILEID_LEN + \
 417                 SILLYNAME_COUNTER_LEN)
 418
 419 /**
 420  * nfs_sillyrename - Perform a silly-rename of a dentry
 421  * @dir: inode of directory that contains dentry
 422  * @dentry: dentry to be sillyrenamed
 423  *
 424  * NFSv2/3 is stateless and the server doesn't know when the client is
 425  * holding a file open. To prevent application problems when a file is
 426  * unlinked while it's still open, the client performs a "silly-rename".
 427  * That is, it renames the file to a hidden file in the same directory,
 428  * and only performs the unlink once the last reference to it is put.
 429  *
 430  * The final cleanup is done during dentry_iput.
 431  *
 432  * (Note: NFSv4 is stateful, and has opens, so in theory an NFSv4 server
 433  * could take responsibility for keeping open files referenced.  The server
 434  * would also need to ensure that opened-but-deleted files were kept over
 435  * reboots.  However, we may not assume a server does so.  (RFC 5661
 436  * does provide an OPEN4_RESULT_PRESERVE_UNLINKED flag that a server can
 437  * use to advertise that it does this; some day we may take advantage of
 438  * it.))
 439  */
 440 int
 441 nfs_sillyrename(struct inode *dir, struct dentry *dentry)
 442 {
 443         static unsigned int sillycounter;
 444         unsigned char silly[SILLYNAME_LEN + 1];
 445         unsigned long long fileid;
 446         struct dentry *sdentry;
 447         struct inode *inode = d_inode(dentry);
 448         struct rpc_task *task;
 449         int            error = -EBUSY;
 450
 451         dfprintk(VFS, "NFS: silly-rename(%pd2, ct=%d)\n",
 452                 dentry, d_count(dentry));
 453         nfs_inc_stats(dir, NFSIOS_SILLYRENAME);
 454
 455         /*
 456          * We don't allow a dentry to be silly-renamed twice.
 457          */
 458         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 459                 goto out;
 460
 461         fileid = NFS_FILEID(d_inode(dentry));
 462
 463         sdentry = NULL;
 464         do {
 465                 int slen;
 466                 dput(sdentry);
 467                 sillycounter++;
 468                 slen = scnprintf(silly, sizeof(silly),
 469                                 SILLYNAME_PREFIX "%0*llx%0*x",
 470                                 SILLYNAME_FILEID_LEN, fileid,
 471                                 SILLYNAME_COUNTER_LEN, sillycounter);
 472
 473                 dfprintk(VFS, "NFS: trying to rename %pd to %s\n",
 474                                 dentry, silly);
 475
 476                 sdentry = lookup_one_len(silly, dentry->d_parent, slen);
 477                 /*
 478                  * N.B. Better to return EBUSY here ... it could be
 479                  * dangerous to delete the file while it's in use.
 480                  */
 481                 if (IS_ERR(sdentry))
 482                         goto out;
 483         } while (d_inode(sdentry) != NULL); /* need negative lookup */
 484
 485         ihold(inode);
 486
 487         /* queue unlink first. Can't do this from rpc_release as it
 488          * has to allocate memory
 489          */
 490         error = nfs_async_unlink(dentry, &sdentry->d_name);
 491         if (error)
 492                 goto out_dput;
 493
 494         /* run the rename task, undo unlink if it fails */
 495         task = nfs_async_rename(dir, dir, dentry, sdentry,
 496                                         nfs_complete_sillyrename);
 497         if (IS_ERR(task)) {
 498                 error = -EBUSY;
 499                 nfs_cancel_async_unlink(dentry);
 500                 goto out_dput;
 501         }
 502
 503         /* wait for the RPC task to complete, unless a SIGKILL intervenes */
 504         error = rpc_wait_for_completion_task(task);
 505         if (error == 0)
 506                 error = task->tk_status;
 507         switch (error) {
 508         case 0:
 509                 /* The rename succeeded */
 510                 nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
 511                 spin_lock(&inode->i_lock);
 512                 NFS_I(inode)->attr_gencount = nfs_inc_attr_generation_counter();
 513                 nfs_set_cache_invalid(inode, NFS_INO_INVALID_CHANGE |
 514                                                      NFS_INO_INVALID_CTIME |
 515                                                      NFS_INO_REVAL_FORCED);
 516                 spin_unlock(&inode->i_lock);
 517                 d_move(dentry, sdentry);
 518                 break;
 519         case -ERESTARTSYS:
 520                 /* The result of the rename is unknown. Play it safe by
 521                  * forcing a new lookup */
 522                 d_drop(dentry);
 523                 d_drop(sdentry);
 524         }
 525         rpc_put_task(task);
 526 out_dput:
 527         iput(inode);
 528         dput(sdentry);
 529 out:
 530         return error;
 531 }