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                     !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
 143                         devname_garbage = alias->d_fsdata;
 144                         alias->d_fsdata = data;
 145                         alias->d_flags |= DCACHE_NFSFS_RENAMED;
 146                         ret = 1;
 147                 } else
 148                         ret = 0;
 149                 spin_unlock(&alias->d_lock);
 150                 dput(alias);
 151                 up_read_non_owner(&NFS_I(dir)->rmdir_sem);
 152                 /*
 153                  * If we'd displaced old cached devname, free it.  At that
 154                  * point dentry is definitely not a root, so we won't need
 155                  * that anymore.
 156                  */
 157                 kfree(devname_garbage);
 158                 return ret;
 159         }
 160         data->dentry = alias;
 161         nfs_do_call_unlink(inode, data);
 162         return 1;
 163 }
 164
 165 /**
 166  * nfs_async_unlink - asynchronous unlinking of a file
 167  * @dentry: parent directory of dentry
 168  * @name: name of dentry to unlink
 169  */
 170 static int
 171 nfs_async_unlink(struct dentry *dentry, const struct qstr *name)
 172 {
 173         struct nfs_unlinkdata *data;
 174         int status = -ENOMEM;
 175         void *devname_garbage = NULL;
 176
 177         data = kzalloc(sizeof(*data), GFP_KERNEL);
 178         if (data == NULL)
 179                 goto out;
 180         data->args.name.name = kstrdup(name->name, GFP_KERNEL);
 181         if (!data->args.name.name)
 182                 goto out_free;
 183         data->args.name.len = name->len;
 184
 185         data->cred = get_current_cred();
 186         data->res.dir_attr = &data->dir_attr;
 187         init_waitqueue_head(&data->wq);
 188
 189         status = -EBUSY;
 190         spin_lock(&dentry->d_lock);
 191         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 192                 goto out_unlock;
 193         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
 194         devname_garbage = dentry->d_fsdata;
 195         dentry->d_fsdata = data;
 196         spin_unlock(&dentry->d_lock);
 197         /*
 198          * If we'd displaced old cached devname, free it.  At that
 199          * point dentry is definitely not a root, so we won't need
 200          * that anymore.
 201          */
 202         kfree(devname_garbage);
 203         return 0;
 204 out_unlock:
 205         spin_unlock(&dentry->d_lock);
 206         put_cred(data->cred);
 207         kfree(data->args.name.name);
 208 out_free:
 209         kfree(data);
 210 out:
 211         return status;
 212 }
 213
 214 /**
 215  * nfs_complete_unlink - Initialize completion of the sillydelete
 216  * @dentry: dentry to delete
 217  * @inode: inode
 218  *
 219  * Since we're most likely to be called by dentry_iput(), we
 220  * only use the dentry to find the sillydelete. We then copy the name
 221  * into the qstr.
 222  */
 223 void
 224 nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
 225 {
 226         struct nfs_unlinkdata   *data;
 227
 228         spin_lock(&dentry->d_lock);
 229         dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 230         data = dentry->d_fsdata;
 231         dentry->d_fsdata = NULL;
 232         spin_unlock(&dentry->d_lock);
 233
 234         if (NFS_STALE(inode) || !nfs_call_unlink(dentry, inode, data))
 235                 nfs_free_unlinkdata(data);
 236 }
 237
 238 /* Cancel a queued async unlink. Called when a sillyrename run fails. */
 239 static void
 240 nfs_cancel_async_unlink(struct dentry *dentry)
 241 {
 242         spin_lock(&dentry->d_lock);
 243         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
 244                 struct nfs_unlinkdata *data = dentry->d_fsdata;
 245
 246                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 247                 dentry->d_fsdata = NULL;
 248                 spin_unlock(&dentry->d_lock);
 249                 nfs_free_unlinkdata(data);
 250                 return;
 251         }
 252         spin_unlock(&dentry->d_lock);
 253 }
 254
 255 /**
 256  * nfs_async_rename_done - Sillyrename post-processing
 257  * @task: rpc_task of the sillyrename
 258  * @calldata: nfs_renamedata for the sillyrename
 259  *
 260  * Do the directory attribute updates and the d_move
 261  */
 262 static void nfs_async_rename_done(struct rpc_task *task, void *calldata)
 263 {
 264         struct nfs_renamedata *data = calldata;
 265         struct inode *old_dir = data->old_dir;
 266         struct inode *new_dir = data->new_dir;
 267         struct dentry *old_dentry = data->old_dentry;
 268
 269         trace_nfs_sillyrename_rename(old_dir, old_dentry,
 270                         new_dir, data->new_dentry, task->tk_status);
 271         if (!NFS_PROTO(old_dir)->rename_done(task, old_dir, new_dir)) {
 272                 rpc_restart_call_prepare(task);
 273                 return;
 274         }
 275
 276         if (data->complete)
 277                 data->complete(task, data);
 278 }
 279
 280 /**
 281  * nfs_async_rename_release - Release the sillyrename data.
 282  * @calldata: the struct nfs_renamedata to be released
 283  */
 284 static void nfs_async_rename_release(void *calldata)
 285 {
 286         struct nfs_renamedata   *data = calldata;
 287         struct super_block *sb = data->old_dir->i_sb;
 288
 289         if (d_really_is_positive(data->old_dentry))
 290                 nfs_mark_for_revalidate(d_inode(data->old_dentry));
 291
 292         /* The result of the rename is unknown. Play it safe by
 293          * forcing a new lookup */
 294         if (data->cancelled) {
 295                 spin_lock(&data->old_dir->i_lock);
 296                 nfs_force_lookup_revalidate(data->old_dir);
 297                 spin_unlock(&data->old_dir->i_lock);
 298                 if (data->new_dir != data->old_dir) {
 299                         spin_lock(&data->new_dir->i_lock);
 300                         nfs_force_lookup_revalidate(data->new_dir);
 301                         spin_unlock(&data->new_dir->i_lock);
 302                 }
 303         }
 304
 305         dput(data->old_dentry);
 306         dput(data->new_dentry);
 307         iput(data->old_dir);
 308         iput(data->new_dir);
 309         nfs_sb_deactive(sb);
 310         put_cred(data->cred);
 311         kfree(data);
 312 }
 313
 314 static void nfs_rename_prepare(struct rpc_task *task, void *calldata)
 315 {
 316         struct nfs_renamedata *data = calldata;
 317         NFS_PROTO(data->old_dir)->rename_rpc_prepare(task, data);
 318 }
 319
 320 static const struct rpc_call_ops nfs_rename_ops = {
 321         .rpc_call_done = nfs_async_rename_done,
 322         .rpc_release = nfs_async_rename_release,
 323         .rpc_call_prepare = nfs_rename_prepare,
 324 };
 325
 326 /**
 327  * nfs_async_rename - perform an asynchronous rename operation
 328  * @old_dir: directory that currently holds the dentry to be renamed
 329  * @new_dir: target directory for the rename
 330  * @old_dentry: original dentry to be renamed
 331  * @new_dentry: dentry to which the old_dentry should be renamed
 332  * @complete: Function to run on successful completion
 333  *
 334  * It's expected that valid references to the dentries and inodes are held
 335  */
 336 struct rpc_task *
 337 nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
 338                  struct dentry *old_dentry, struct dentry *new_dentry,
 339                  void (*complete)(struct rpc_task *, struct nfs_renamedata *))
 340 {
 341         struct nfs_renamedata *data;
 342         struct rpc_message msg = { };
 343         struct rpc_task_setup task_setup_data = {
 344                 .rpc_message = &msg,
 345                 .callback_ops = &nfs_rename_ops,
 346                 .workqueue = nfsiod_workqueue,
 347                 .rpc_client = NFS_CLIENT(old_dir),
 348                 .flags = RPC_TASK_ASYNC | RPC_TASK_CRED_NOREF,
 349         };
 350
 351         if (nfs_server_capable(old_dir, NFS_CAP_MOVEABLE) &&
 352             nfs_server_capable(new_dir, NFS_CAP_MOVEABLE))
 353                 task_setup_data.flags |= RPC_TASK_MOVEABLE;
 354
 355         data = kzalloc(sizeof(*data), GFP_KERNEL);
 356         if (data == NULL)
 357                 return ERR_PTR(-ENOMEM);
 358         task_setup_data.task = &data->task;
 359         task_setup_data.callback_data = data;
 360
 361         data->cred = get_current_cred();
 362
 363         msg.rpc_argp = &data->args;
 364         msg.rpc_resp = &data->res;
 365         msg.rpc_cred = data->cred;
 366
 367         /* set up nfs_renamedata */
 368         data->old_dir = old_dir;
 369         ihold(old_dir);
 370         data->new_dir = new_dir;
 371         ihold(new_dir);
 372         data->old_dentry = dget(old_dentry);
 373         data->new_dentry = dget(new_dentry);
 374         nfs_fattr_init(&data->old_fattr);
 375         nfs_fattr_init(&data->new_fattr);
 376         data->complete = complete;
 377
 378         /* set up nfs_renameargs */
 379         data->args.old_dir = NFS_FH(old_dir);
 380         data->args.old_name = &old_dentry->d_name;
 381         data->args.new_dir = NFS_FH(new_dir);
 382         data->args.new_name = &new_dentry->d_name;
 383
 384         /* set up nfs_renameres */
 385         data->res.old_fattr = &data->old_fattr;
 386         data->res.new_fattr = &data->new_fattr;
 387
 388         nfs_sb_active(old_dir->i_sb);
 389
 390         NFS_PROTO(data->old_dir)->rename_setup(&msg, old_dentry, new_dentry);
 391
 392         return rpc_run_task(&task_setup_data);
 393 }
 394
 395 /*
 396  * Perform tasks needed when a sillyrename is done such as cancelling the
 397  * queued async unlink if it failed.
 398  */
 399 static void
 400 nfs_complete_sillyrename(struct rpc_task *task, struct nfs_renamedata *data)
 401 {
 402         struct dentry *dentry = data->old_dentry;
 403
 404         if (task->tk_status != 0) {
 405                 nfs_cancel_async_unlink(dentry);
 406                 return;
 407         }
 408 }
 409
 410 #define SILLYNAME_PREFIX ".nfs"
 411 #define SILLYNAME_PREFIX_LEN ((unsigned)sizeof(SILLYNAME_PREFIX) - 1)
 412 #define SILLYNAME_FILEID_LEN ((unsigned)sizeof(u64) << 1)
 413 #define SILLYNAME_COUNTER_LEN ((unsigned)sizeof(unsigned int) << 1)
 414 #define SILLYNAME_LEN (SILLYNAME_PREFIX_LEN + \
 415                 SILLYNAME_FILEID_LEN + \
 416                 SILLYNAME_COUNTER_LEN)
 417
 418 /**
 419  * nfs_sillyrename - Perform a silly-rename of a dentry
 420  * @dir: inode of directory that contains dentry
 421  * @dentry: dentry to be sillyrenamed
 422  *
 423  * NFSv2/3 is stateless and the server doesn't know when the client is
 424  * holding a file open. To prevent application problems when a file is
 425  * unlinked while it's still open, the client performs a "silly-rename".
 426  * That is, it renames the file to a hidden file in the same directory,
 427  * and only performs the unlink once the last reference to it is put.
 428  *
 429  * The final cleanup is done during dentry_iput.
 430  *
 431  * (Note: NFSv4 is stateful, and has opens, so in theory an NFSv4 server
 432  * could take responsibility for keeping open files referenced.  The server
 433  * would also need to ensure that opened-but-deleted files were kept over
 434  * reboots.  However, we may not assume a server does so.  (RFC 5661
 435  * does provide an OPEN4_RESULT_PRESERVE_UNLINKED flag that a server can
 436  * use to advertise that it does this; some day we may take advantage of
 437  * it.))
 438  */
 439 int
 440 nfs_sillyrename(struct inode *dir, struct dentry *dentry)
 441 {
 442         static unsigned int sillycounter;
 443         unsigned char silly[SILLYNAME_LEN + 1];
 444         unsigned long long fileid;
 445         struct dentry *sdentry;
 446         struct inode *inode = d_inode(dentry);
 447         struct rpc_task *task;
 448         int            error = -EBUSY;
 449
 450         dfprintk(VFS, "NFS: silly-rename(%pd2, ct=%d)\n",
 451                 dentry, d_count(dentry));
 452         nfs_inc_stats(dir, NFSIOS_SILLYRENAME);
 453
 454         /*
 455          * We don't allow a dentry to be silly-renamed twice.
 456          */
 457         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 458                 goto out;
 459
 460         fileid = NFS_FILEID(d_inode(dentry));
 461
 462         sdentry = NULL;
 463         do {
 464                 int slen;
 465                 dput(sdentry);
 466                 sillycounter++;
 467                 slen = scnprintf(silly, sizeof(silly),
 468                                 SILLYNAME_PREFIX "%0*llx%0*x",
 469                                 SILLYNAME_FILEID_LEN, fileid,
 470                                 SILLYNAME_COUNTER_LEN, sillycounter);
 471
 472                 dfprintk(VFS, "NFS: trying to rename %pd to %s\n",
 473                                 dentry, silly);
 474
 475                 sdentry = lookup_one_len(silly, dentry->d_parent, slen);
 476                 /*
 477                  * N.B. Better to return EBUSY here ... it could be
 478                  * dangerous to delete the file while it's in use.
 479                  */
 480                 if (IS_ERR(sdentry))
 481                         goto out;
 482         } while (d_inode(sdentry) != NULL); /* need negative lookup */
 483
 484         ihold(inode);
 485
 486         /* queue unlink first. Can't do this from rpc_release as it
 487          * has to allocate memory
 488          */
 489         error = nfs_async_unlink(dentry, &sdentry->d_name);
 490         if (error)
 491                 goto out_dput;
 492
 493         /* run the rename task, undo unlink if it fails */
 494         task = nfs_async_rename(dir, dir, dentry, sdentry,
 495                                         nfs_complete_sillyrename);
 496         if (IS_ERR(task)) {
 497                 error = -EBUSY;
 498                 nfs_cancel_async_unlink(dentry);
 499                 goto out_dput;
 500         }
 501
 502         /* wait for the RPC task to complete, unless a SIGKILL intervenes */
 503         error = rpc_wait_for_completion_task(task);
 504         if (error == 0)
 505                 error = task->tk_status;
 506         switch (error) {
 507         case 0:
 508                 /* The rename succeeded */
 509                 nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
 510                 spin_lock(&inode->i_lock);
 511                 NFS_I(inode)->attr_gencount = nfs_inc_attr_generation_counter();
 512                 nfs_set_cache_invalid(inode, NFS_INO_INVALID_CHANGE |
 513                                                      NFS_INO_INVALID_CTIME |
 514                                                      NFS_INO_REVAL_FORCED);
 515                 spin_unlock(&inode->i_lock);
 516                 d_move(dentry, sdentry);
 517                 break;
 518         case -ERESTARTSYS:
 519                 /* The result of the rename is unknown. Play it safe by
 520                  * forcing a new lookup */
 521                 d_drop(dentry);
 522                 d_drop(sdentry);
 523         }
 524         rpc_put_task(task);
 525 out_dput:
 526         iput(inode);
 527         dput(sdentry);
 528 out:
 529         return error;
 530 }