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         nfs_sb_active(dir->i_sb);
 106         data->args.fh = NFS_FH(dir);
 107         nfs_fattr_init(data->res.dir_attr);
 108
 109         NFS_PROTO(dir)->unlink_setup(&msg, data->dentry, inode);
 110
 111         task_setup_data.rpc_client = NFS_CLIENT(dir);
 112         task = rpc_run_task(&task_setup_data);
 113         if (!IS_ERR(task))
 114                 rpc_put_task_async(task);
 115 }
 116
 117 static int nfs_call_unlink(struct dentry *dentry, struct inode *inode, struct nfs_unlinkdata *data)
 118 {
 119         struct inode *dir = d_inode(dentry->d_parent);
 120         struct dentry *alias;
 121
 122         down_read_non_owner(&NFS_I(dir)->rmdir_sem);
 123         alias = d_alloc_parallel(dentry->d_parent, &data->args.name, &data->wq);
 124         if (IS_ERR(alias)) {
 125                 up_read_non_owner(&NFS_I(dir)->rmdir_sem);
 126                 return 0;
 127         }
 128         if (!d_in_lookup(alias)) {
 129                 int ret;
 130                 void *devname_garbage = NULL;
 131
 132                 /*
 133                  * Hey, we raced with lookup... See if we need to transfer
 134                  * the sillyrename information to the aliased dentry.
 135                  */
 136                 spin_lock(&alias->d_lock);
 137                 if (d_really_is_positive(alias) &&
 138                     !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
 139                         devname_garbage = alias->d_fsdata;
 140                         alias->d_fsdata = data;
 141                         alias->d_flags |= DCACHE_NFSFS_RENAMED;
 142                         ret = 1;
 143                 } else
 144                         ret = 0;
 145                 spin_unlock(&alias->d_lock);
 146                 dput(alias);
 147                 up_read_non_owner(&NFS_I(dir)->rmdir_sem);
 148                 /*
 149                  * If we'd displaced old cached devname, free it.  At that
 150                  * point dentry is definitely not a root, so we won't need
 151                  * that anymore.
 152                  */
 153                 kfree(devname_garbage);
 154                 return ret;
 155         }
 156         data->dentry = alias;
 157         nfs_do_call_unlink(inode, data);
 158         return 1;
 159 }
 160
 161 /**
 162  * nfs_async_unlink - asynchronous unlinking of a file
 163  * @dentry: parent directory of dentry
 164  * @name: name of dentry to unlink
 165  */
 166 static int
 167 nfs_async_unlink(struct dentry *dentry, const struct qstr *name)
 168 {
 169         struct nfs_unlinkdata *data;
 170         int status = -ENOMEM;
 171         void *devname_garbage = NULL;
 172
 173         data = kzalloc(sizeof(*data), GFP_KERNEL);
 174         if (data == NULL)
 175                 goto out;
 176         data->args.name.name = kstrdup(name->name, GFP_KERNEL);
 177         if (!data->args.name.name)
 178                 goto out_free;
 179         data->args.name.len = name->len;
 180
 181         data->cred = get_current_cred();
 182         data->res.dir_attr = &data->dir_attr;
 183         init_waitqueue_head(&data->wq);
 184
 185         status = -EBUSY;
 186         spin_lock(&dentry->d_lock);
 187         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 188                 goto out_unlock;
 189         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
 190         devname_garbage = dentry->d_fsdata;
 191         dentry->d_fsdata = data;
 192         spin_unlock(&dentry->d_lock);
 193         /*
 194          * If we'd displaced old cached devname, free it.  At that
 195          * point dentry is definitely not a root, so we won't need
 196          * that anymore.
 197          */
 198         kfree(devname_garbage);
 199         return 0;
 200 out_unlock:
 201         spin_unlock(&dentry->d_lock);
 202         put_cred(data->cred);
 203         kfree(data->args.name.name);
 204 out_free:
 205         kfree(data);
 206 out:
 207         return status;
 208 }
 209
 210 /**
 211  * nfs_complete_unlink - Initialize completion of the sillydelete
 212  * @dentry: dentry to delete
 213  * @inode: inode
 214  *
 215  * Since we're most likely to be called by dentry_iput(), we
 216  * only use the dentry to find the sillydelete. We then copy the name
 217  * into the qstr.
 218  */
 219 void
 220 nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
 221 {
 222         struct nfs_unlinkdata   *data;
 223
 224         spin_lock(&dentry->d_lock);
 225         dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 226         data = dentry->d_fsdata;
 227         dentry->d_fsdata = NULL;
 228         spin_unlock(&dentry->d_lock);
 229
 230         if (NFS_STALE(inode) || !nfs_call_unlink(dentry, inode, data))
 231                 nfs_free_unlinkdata(data);
 232 }
 233
 234 /* Cancel a queued async unlink. Called when a sillyrename run fails. */
 235 static void
 236 nfs_cancel_async_unlink(struct dentry *dentry)
 237 {
 238         spin_lock(&dentry->d_lock);
 239         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
 240                 struct nfs_unlinkdata *data = dentry->d_fsdata;
 241
 242                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 243                 dentry->d_fsdata = NULL;
 244                 spin_unlock(&dentry->d_lock);
 245                 nfs_free_unlinkdata(data);
 246                 return;
 247         }
 248         spin_unlock(&dentry->d_lock);
 249 }
 250
 251 /**
 252  * nfs_async_rename_done - Sillyrename post-processing
 253  * @task: rpc_task of the sillyrename
 254  * @calldata: nfs_renamedata for the sillyrename
 255  *
 256  * Do the directory attribute updates and the d_move
 257  */
 258 static void nfs_async_rename_done(struct rpc_task *task, void *calldata)
 259 {
 260         struct nfs_renamedata *data = calldata;
 261         struct inode *old_dir = data->old_dir;
 262         struct inode *new_dir = data->new_dir;
 263         struct dentry *old_dentry = data->old_dentry;
 264
 265         trace_nfs_sillyrename_rename(old_dir, old_dentry,
 266                         new_dir, data->new_dentry, task->tk_status);
 267         if (!NFS_PROTO(old_dir)->rename_done(task, old_dir, new_dir)) {
 268                 rpc_restart_call_prepare(task);
 269                 return;
 270         }
 271
 272         if (data->complete)
 273                 data->complete(task, data);
 274 }
 275
 276 /**
 277  * nfs_async_rename_release - Release the sillyrename data.
 278  * @calldata: the struct nfs_renamedata to be released
 279  */
 280 static void nfs_async_rename_release(void *calldata)
 281 {
 282         struct nfs_renamedata   *data = calldata;
 283         struct super_block *sb = data->old_dir->i_sb;
 284
 285         if (d_really_is_positive(data->old_dentry))
 286                 nfs_mark_for_revalidate(d_inode(data->old_dentry));
 287
 288         /* The result of the rename is unknown. Play it safe by
 289          * forcing a new lookup */
 290         if (data->cancelled) {
 291                 spin_lock(&data->old_dir->i_lock);
 292                 nfs_force_lookup_revalidate(data->old_dir);
 293                 spin_unlock(&data->old_dir->i_lock);
 294                 if (data->new_dir != data->old_dir) {
 295                         spin_lock(&data->new_dir->i_lock);
 296                         nfs_force_lookup_revalidate(data->new_dir);
 297                         spin_unlock(&data->new_dir->i_lock);
 298                 }
 299         }
 300
 301         dput(data->old_dentry);
 302         dput(data->new_dentry);
 303         iput(data->old_dir);
 304         iput(data->new_dir);
 305         nfs_sb_deactive(sb);
 306         put_cred(data->cred);
 307         kfree(data);
 308 }
 309
 310 static void nfs_rename_prepare(struct rpc_task *task, void *calldata)
 311 {
 312         struct nfs_renamedata *data = calldata;
 313         NFS_PROTO(data->old_dir)->rename_rpc_prepare(task, data);
 314 }
 315
 316 static const struct rpc_call_ops nfs_rename_ops = {
 317         .rpc_call_done = nfs_async_rename_done,
 318         .rpc_release = nfs_async_rename_release,
 319         .rpc_call_prepare = nfs_rename_prepare,
 320 };
 321
 322 /**
 323  * nfs_async_rename - perform an asynchronous rename operation
 324  * @old_dir: directory that currently holds the dentry to be renamed
 325  * @new_dir: target directory for the rename
 326  * @old_dentry: original dentry to be renamed
 327  * @new_dentry: dentry to which the old_dentry should be renamed
 328  * @complete: Function to run on successful completion
 329  *
 330  * It's expected that valid references to the dentries and inodes are held
 331  */
 332 struct rpc_task *
 333 nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
 334                  struct dentry *old_dentry, struct dentry *new_dentry,
 335                  void (*complete)(struct rpc_task *, struct nfs_renamedata *))
 336 {
 337         struct nfs_renamedata *data;
 338         struct rpc_message msg = { };
 339         struct rpc_task_setup task_setup_data = {
 340                 .rpc_message = &msg,
 341                 .callback_ops = &nfs_rename_ops,
 342                 .workqueue = nfsiod_workqueue,
 343                 .rpc_client = NFS_CLIENT(old_dir),
 344                 .flags = RPC_TASK_ASYNC | RPC_TASK_CRED_NOREF,
 345         };
 346
 347         data = kzalloc(sizeof(*data), GFP_KERNEL);
 348         if (data == NULL)
 349                 return ERR_PTR(-ENOMEM);
 350         task_setup_data.task = &data->task;
 351         task_setup_data.callback_data = data;
 352
 353         data->cred = get_current_cred();
 354
 355         msg.rpc_argp = &data->args;
 356         msg.rpc_resp = &data->res;
 357         msg.rpc_cred = data->cred;
 358
 359         /* set up nfs_renamedata */
 360         data->old_dir = old_dir;
 361         ihold(old_dir);
 362         data->new_dir = new_dir;
 363         ihold(new_dir);
 364         data->old_dentry = dget(old_dentry);
 365         data->new_dentry = dget(new_dentry);
 366         nfs_fattr_init(&data->old_fattr);
 367         nfs_fattr_init(&data->new_fattr);
 368         data->complete = complete;
 369
 370         /* set up nfs_renameargs */
 371         data->args.old_dir = NFS_FH(old_dir);
 372         data->args.old_name = &old_dentry->d_name;
 373         data->args.new_dir = NFS_FH(new_dir);
 374         data->args.new_name = &new_dentry->d_name;
 375
 376         /* set up nfs_renameres */
 377         data->res.old_fattr = &data->old_fattr;
 378         data->res.new_fattr = &data->new_fattr;
 379
 380         nfs_sb_active(old_dir->i_sb);
 381
 382         NFS_PROTO(data->old_dir)->rename_setup(&msg, old_dentry, new_dentry);
 383
 384         return rpc_run_task(&task_setup_data);
 385 }
 386
 387 /*
 388  * Perform tasks needed when a sillyrename is done such as cancelling the
 389  * queued async unlink if it failed.
 390  */
 391 static void
 392 nfs_complete_sillyrename(struct rpc_task *task, struct nfs_renamedata *data)
 393 {
 394         struct dentry *dentry = data->old_dentry;
 395
 396         if (task->tk_status != 0) {
 397                 nfs_cancel_async_unlink(dentry);
 398                 return;
 399         }
 400 }
 401
 402 #define SILLYNAME_PREFIX ".nfs"
 403 #define SILLYNAME_PREFIX_LEN ((unsigned)sizeof(SILLYNAME_PREFIX) - 1)
 404 #define SILLYNAME_FILEID_LEN ((unsigned)sizeof(u64) << 1)
 405 #define SILLYNAME_COUNTER_LEN ((unsigned)sizeof(unsigned int) << 1)
 406 #define SILLYNAME_LEN (SILLYNAME_PREFIX_LEN + \
 407                 SILLYNAME_FILEID_LEN + \
 408                 SILLYNAME_COUNTER_LEN)
 409
 410 /**
 411  * nfs_sillyrename - Perform a silly-rename of a dentry
 412  * @dir: inode of directory that contains dentry
 413  * @dentry: dentry to be sillyrenamed
 414  *
 415  * NFSv2/3 is stateless and the server doesn't know when the client is
 416  * holding a file open. To prevent application problems when a file is
 417  * unlinked while it's still open, the client performs a "silly-rename".
 418  * That is, it renames the file to a hidden file in the same directory,
 419  * and only performs the unlink once the last reference to it is put.
 420  *
 421  * The final cleanup is done during dentry_iput.
 422  *
 423  * (Note: NFSv4 is stateful, and has opens, so in theory an NFSv4 server
 424  * could take responsibility for keeping open files referenced.  The server
 425  * would also need to ensure that opened-but-deleted files were kept over
 426  * reboots.  However, we may not assume a server does so.  (RFC 5661
 427  * does provide an OPEN4_RESULT_PRESERVE_UNLINKED flag that a server can
 428  * use to advertise that it does this; some day we may take advantage of
 429  * it.))
 430  */
 431 int
 432 nfs_sillyrename(struct inode *dir, struct dentry *dentry)
 433 {
 434         static unsigned int sillycounter;
 435         unsigned char silly[SILLYNAME_LEN + 1];
 436         unsigned long long fileid;
 437         struct dentry *sdentry;
 438         struct inode *inode = d_inode(dentry);
 439         struct rpc_task *task;
 440         int            error = -EBUSY;
 441
 442         dfprintk(VFS, "NFS: silly-rename(%pd2, ct=%d)\n",
 443                 dentry, d_count(dentry));
 444         nfs_inc_stats(dir, NFSIOS_SILLYRENAME);
 445
 446         /*
 447          * We don't allow a dentry to be silly-renamed twice.
 448          */
 449         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 450                 goto out;
 451
 452         fileid = NFS_FILEID(d_inode(dentry));
 453
 454         sdentry = NULL;
 455         do {
 456                 int slen;
 457                 dput(sdentry);
 458                 sillycounter++;
 459                 slen = scnprintf(silly, sizeof(silly),
 460                                 SILLYNAME_PREFIX "%0*llx%0*x",
 461                                 SILLYNAME_FILEID_LEN, fileid,
 462                                 SILLYNAME_COUNTER_LEN, sillycounter);
 463
 464                 dfprintk(VFS, "NFS: trying to rename %pd to %s\n",
 465                                 dentry, silly);
 466
 467                 sdentry = lookup_one_len(silly, dentry->d_parent, slen);
 468                 /*
 469                  * N.B. Better to return EBUSY here ... it could be
 470                  * dangerous to delete the file while it's in use.
 471                  */
 472                 if (IS_ERR(sdentry))
 473                         goto out;
 474         } while (d_inode(sdentry) != NULL); /* need negative lookup */
 475
 476         ihold(inode);
 477
 478         /* queue unlink first. Can't do this from rpc_release as it
 479          * has to allocate memory
 480          */
 481         error = nfs_async_unlink(dentry, &sdentry->d_name);
 482         if (error)
 483                 goto out_dput;
 484
 485         /* run the rename task, undo unlink if it fails */
 486         task = nfs_async_rename(dir, dir, dentry, sdentry,
 487                                         nfs_complete_sillyrename);
 488         if (IS_ERR(task)) {
 489                 error = -EBUSY;
 490                 nfs_cancel_async_unlink(dentry);
 491                 goto out_dput;
 492         }
 493
 494         /* wait for the RPC task to complete, unless a SIGKILL intervenes */
 495         error = rpc_wait_for_completion_task(task);
 496         if (error == 0)
 497                 error = task->tk_status;
 498         switch (error) {
 499         case 0:
 500                 /* The rename succeeded */
 501                 nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
 502                 spin_lock(&inode->i_lock);
 503                 NFS_I(inode)->attr_gencount = nfs_inc_attr_generation_counter();
 504                 nfs_set_cache_invalid(inode, NFS_INO_INVALID_CHANGE |
 505                                                      NFS_INO_INVALID_CTIME |
 506                                                      NFS_INO_REVAL_FORCED);
 507                 spin_unlock(&inode->i_lock);
 508                 d_move(dentry, sdentry);
 509                 break;
 510         case -ERESTARTSYS:
 511                 /* The result of the rename is unknown. Play it safe by
 512                  * forcing a new lookup */
 513                 d_drop(dentry);
 514                 d_drop(sdentry);
 515         }
 516         rpc_put_task(task);
 517 out_dput:
 518         iput(inode);
 519         dput(sdentry);
 520 out:
 521         return error;
 522 }