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  *
  43  * Do the directory attribute update.
  44  */
  45 static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
  46 {
  47         struct nfs_unlinkdata *data = calldata;
  48         struct inode *dir = d_inode(data->dentry->d_parent);
  49
  50         trace_nfs_sillyrename_unlink(data, task->tk_status);
  51         if (!NFS_PROTO(dir)->unlink_done(task, dir))
  52                 rpc_restart_call_prepare(task);
  53 }
  54
  55 /**
  56  * nfs_async_unlink_release - Release the sillydelete data.
  57  * @task: rpc_task of the sillydelete
  58  *
  59  * We need to call nfs_put_unlinkdata as a 'tk_release' task since the
  60  * rpc_task would be freed too.
  61  */
  62 static void nfs_async_unlink_release(void *calldata)
  63 {
  64         struct nfs_unlinkdata   *data = calldata;
  65         struct dentry *dentry = data->dentry;
  66         struct super_block *sb = dentry->d_sb;
  67
  68         up_read_non_owner(&NFS_I(d_inode(dentry->d_parent))->rmdir_sem);
  69         d_lookup_done(dentry);
  70         nfs_free_unlinkdata(data);
  71         dput(dentry);
  72         nfs_sb_deactive(sb);
  73 }
  74
  75 static void nfs_unlink_prepare(struct rpc_task *task, void *calldata)
  76 {
  77         struct nfs_unlinkdata *data = calldata;
  78         struct inode *dir = d_inode(data->dentry->d_parent);
  79         NFS_PROTO(dir)->unlink_rpc_prepare(task, data);
  80 }
  81
  82 static const struct rpc_call_ops nfs_unlink_ops = {
  83         .rpc_call_done = nfs_async_unlink_done,
  84         .rpc_release = nfs_async_unlink_release,
  85         .rpc_call_prepare = nfs_unlink_prepare,
  86 };
  87
  88 static void nfs_do_call_unlink(struct inode *inode, struct nfs_unlinkdata *data)
  89 {
  90         struct rpc_message msg = {
  91                 .rpc_argp = &data->args,
  92                 .rpc_resp = &data->res,
  93                 .rpc_cred = data->cred,
  94         };
  95         struct rpc_task_setup task_setup_data = {
  96                 .rpc_message = &msg,
  97                 .callback_ops = &nfs_unlink_ops,
  98                 .callback_data = data,
  99                 .workqueue = nfsiod_workqueue,
 100                 .flags = RPC_TASK_ASYNC,
 101         };
 102         struct rpc_task *task;
 103         struct inode *dir = d_inode(data->dentry->d_parent);
 104         nfs_sb_active(dir->i_sb);
 105         data->args.fh = NFS_FH(dir);
 106         nfs_fattr_init(data->res.dir_attr);
 107
 108         NFS_PROTO(dir)->unlink_setup(&msg, data->dentry, inode);
 109
 110         task_setup_data.rpc_client = NFS_CLIENT(dir);
 111         task = rpc_run_task(&task_setup_data);
 112         if (!IS_ERR(task))
 113                 rpc_put_task_async(task);
 114 }
 115
 116 static int nfs_call_unlink(struct dentry *dentry, struct inode *inode, struct nfs_unlinkdata *data)
 117 {
 118         struct inode *dir = d_inode(dentry->d_parent);
 119         struct dentry *alias;
 120
 121         down_read_non_owner(&NFS_I(dir)->rmdir_sem);
 122         alias = d_alloc_parallel(dentry->d_parent, &data->args.name, &data->wq);
 123         if (IS_ERR(alias)) {
 124                 up_read_non_owner(&NFS_I(dir)->rmdir_sem);
 125                 return 0;
 126         }
 127         if (!d_in_lookup(alias)) {
 128                 int ret;
 129                 void *devname_garbage = NULL;
 130
 131                 /*
 132                  * Hey, we raced with lookup... See if we need to transfer
 133                  * the sillyrename information to the aliased dentry.
 134                  */
 135                 spin_lock(&alias->d_lock);
 136                 if (d_really_is_positive(alias) &&
 137                     !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
 138                         devname_garbage = alias->d_fsdata;
 139                         alias->d_fsdata = data;
 140                         alias->d_flags |= DCACHE_NFSFS_RENAMED;
 141                         ret = 1;
 142                 } else
 143                         ret = 0;
 144                 spin_unlock(&alias->d_lock);
 145                 dput(alias);
 146                 up_read_non_owner(&NFS_I(dir)->rmdir_sem);
 147                 /*
 148                  * If we'd displaced old cached devname, free it.  At that
 149                  * point dentry is definitely not a root, so we won't need
 150                  * that anymore.
 151                  */
 152                 kfree(devname_garbage);
 153                 return ret;
 154         }
 155         data->dentry = alias;
 156         nfs_do_call_unlink(inode, data);
 157         return 1;
 158 }
 159
 160 /**
 161  * nfs_async_unlink - asynchronous unlinking of a file
 162  * @dir: parent directory of dentry
 163  * @dentry: dentry to unlink
 164  */
 165 static int
 166 nfs_async_unlink(struct dentry *dentry, const struct qstr *name)
 167 {
 168         struct nfs_unlinkdata *data;
 169         int status = -ENOMEM;
 170         void *devname_garbage = NULL;
 171
 172         data = kzalloc(sizeof(*data), GFP_KERNEL);
 173         if (data == NULL)
 174                 goto out;
 175         data->args.name.name = kstrdup(name->name, GFP_KERNEL);
 176         if (!data->args.name.name)
 177                 goto out_free;
 178         data->args.name.len = name->len;
 179
 180         data->cred = get_current_cred();
 181         data->res.dir_attr = &data->dir_attr;
 182         init_waitqueue_head(&data->wq);
 183
 184         status = -EBUSY;
 185         spin_lock(&dentry->d_lock);
 186         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 187                 goto out_unlock;
 188         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
 189         devname_garbage = dentry->d_fsdata;
 190         dentry->d_fsdata = data;
 191         spin_unlock(&dentry->d_lock);
 192         /*
 193          * If we'd displaced old cached devname, free it.  At that
 194          * point dentry is definitely not a root, so we won't need
 195          * that anymore.
 196          */
 197         kfree(devname_garbage);
 198         return 0;
 199 out_unlock:
 200         spin_unlock(&dentry->d_lock);
 201         put_cred(data->cred);
 202         kfree(data->args.name.name);
 203 out_free:
 204         kfree(data);
 205 out:
 206         return status;
 207 }
 208
 209 /**
 210  * nfs_complete_unlink - Initialize completion of the sillydelete
 211  * @dentry: dentry to delete
 212  * @inode: inode
 213  *
 214  * Since we're most likely to be called by dentry_iput(), we
 215  * only use the dentry to find the sillydelete. We then copy the name
 216  * into the qstr.
 217  */
 218 void
 219 nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
 220 {
 221         struct nfs_unlinkdata   *data;
 222
 223         spin_lock(&dentry->d_lock);
 224         dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 225         data = dentry->d_fsdata;
 226         dentry->d_fsdata = NULL;
 227         spin_unlock(&dentry->d_lock);
 228
 229         if (NFS_STALE(inode) || !nfs_call_unlink(dentry, inode, data))
 230                 nfs_free_unlinkdata(data);
 231 }
 232
 233 /* Cancel a queued async unlink. Called when a sillyrename run fails. */
 234 static void
 235 nfs_cancel_async_unlink(struct dentry *dentry)
 236 {
 237         spin_lock(&dentry->d_lock);
 238         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
 239                 struct nfs_unlinkdata *data = dentry->d_fsdata;
 240
 241                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 242                 dentry->d_fsdata = NULL;
 243                 spin_unlock(&dentry->d_lock);
 244                 nfs_free_unlinkdata(data);
 245                 return;
 246         }
 247         spin_unlock(&dentry->d_lock);
 248 }
 249
 250 /**
 251  * nfs_async_rename_done - Sillyrename post-processing
 252  * @task: rpc_task of the sillyrename
 253  * @calldata: nfs_renamedata for the sillyrename
 254  *
 255  * Do the directory attribute updates and the d_move
 256  */
 257 static void nfs_async_rename_done(struct rpc_task *task, void *calldata)
 258 {
 259         struct nfs_renamedata *data = calldata;
 260         struct inode *old_dir = data->old_dir;
 261         struct inode *new_dir = data->new_dir;
 262         struct dentry *old_dentry = data->old_dentry;
 263
 264         trace_nfs_sillyrename_rename(old_dir, old_dentry,
 265                         new_dir, data->new_dentry, task->tk_status);
 266         if (!NFS_PROTO(old_dir)->rename_done(task, old_dir, new_dir)) {
 267                 rpc_restart_call_prepare(task);
 268                 return;
 269         }
 270
 271         if (data->complete)
 272                 data->complete(task, data);
 273 }
 274
 275 /**
 276  * nfs_async_rename_release - Release the sillyrename data.
 277  * @calldata: the struct nfs_renamedata to be released
 278  */
 279 static void nfs_async_rename_release(void *calldata)
 280 {
 281         struct nfs_renamedata   *data = calldata;
 282         struct super_block *sb = data->old_dir->i_sb;
 283
 284         if (d_really_is_positive(data->old_dentry))
 285                 nfs_mark_for_revalidate(d_inode(data->old_dentry));
 286
 287         /* The result of the rename is unknown. Play it safe by
 288          * forcing a new lookup */
 289         if (data->cancelled) {
 290                 spin_lock(&data->old_dir->i_lock);
 291                 nfs_force_lookup_revalidate(data->old_dir);
 292                 spin_unlock(&data->old_dir->i_lock);
 293                 if (data->new_dir != data->old_dir) {
 294                         spin_lock(&data->new_dir->i_lock);
 295                         nfs_force_lookup_revalidate(data->new_dir);
 296                         spin_unlock(&data->new_dir->i_lock);
 297                 }
 298         }
 299
 300         dput(data->old_dentry);
 301         dput(data->new_dentry);
 302         iput(data->old_dir);
 303         iput(data->new_dir);
 304         nfs_sb_deactive(sb);
 305         put_cred(data->cred);
 306         kfree(data);
 307 }
 308
 309 static void nfs_rename_prepare(struct rpc_task *task, void *calldata)
 310 {
 311         struct nfs_renamedata *data = calldata;
 312         NFS_PROTO(data->old_dir)->rename_rpc_prepare(task, data);
 313 }
 314
 315 static const struct rpc_call_ops nfs_rename_ops = {
 316         .rpc_call_done = nfs_async_rename_done,
 317         .rpc_release = nfs_async_rename_release,
 318         .rpc_call_prepare = nfs_rename_prepare,
 319 };
 320
 321 /**
 322  * nfs_async_rename - perform an asynchronous rename operation
 323  * @old_dir: directory that currently holds the dentry to be renamed
 324  * @new_dir: target directory for the rename
 325  * @old_dentry: original dentry to be renamed
 326  * @new_dentry: dentry to which the old_dentry should be renamed
 327  *
 328  * It's expected that valid references to the dentries and inodes are held
 329  */
 330 struct rpc_task *
 331 nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
 332                  struct dentry *old_dentry, struct dentry *new_dentry,
 333                  void (*complete)(struct rpc_task *, struct nfs_renamedata *))
 334 {
 335         struct nfs_renamedata *data;
 336         struct rpc_message msg = { };
 337         struct rpc_task_setup task_setup_data = {
 338                 .rpc_message = &msg,
 339                 .callback_ops = &nfs_rename_ops,
 340                 .workqueue = nfsiod_workqueue,
 341                 .rpc_client = NFS_CLIENT(old_dir),
 342                 .flags = RPC_TASK_ASYNC,
 343         };
 344
 345         data = kzalloc(sizeof(*data), GFP_KERNEL);
 346         if (data == NULL)
 347                 return ERR_PTR(-ENOMEM);
 348         task_setup_data.callback_data = data;
 349
 350         data->cred = get_current_cred();
 351
 352         msg.rpc_argp = &data->args;
 353         msg.rpc_resp = &data->res;
 354         msg.rpc_cred = data->cred;
 355
 356         /* set up nfs_renamedata */
 357         data->old_dir = old_dir;
 358         ihold(old_dir);
 359         data->new_dir = new_dir;
 360         ihold(new_dir);
 361         data->old_dentry = dget(old_dentry);
 362         data->new_dentry = dget(new_dentry);
 363         nfs_fattr_init(&data->old_fattr);
 364         nfs_fattr_init(&data->new_fattr);
 365         data->complete = complete;
 366
 367         /* set up nfs_renameargs */
 368         data->args.old_dir = NFS_FH(old_dir);
 369         data->args.old_name = &old_dentry->d_name;
 370         data->args.new_dir = NFS_FH(new_dir);
 371         data->args.new_name = &new_dentry->d_name;
 372
 373         /* set up nfs_renameres */
 374         data->res.old_fattr = &data->old_fattr;
 375         data->res.new_fattr = &data->new_fattr;
 376
 377         nfs_sb_active(old_dir->i_sb);
 378
 379         NFS_PROTO(data->old_dir)->rename_setup(&msg, old_dentry, new_dentry);
 380
 381         return rpc_run_task(&task_setup_data);
 382 }
 383
 384 /*
 385  * Perform tasks needed when a sillyrename is done such as cancelling the
 386  * queued async unlink if it failed.
 387  */
 388 static void
 389 nfs_complete_sillyrename(struct rpc_task *task, struct nfs_renamedata *data)
 390 {
 391         struct dentry *dentry = data->old_dentry;
 392
 393         if (task->tk_status != 0) {
 394                 nfs_cancel_async_unlink(dentry);
 395                 return;
 396         }
 397
 398         /*
 399          * vfs_unlink and the like do not issue this when a file is
 400          * sillyrenamed, so do it here.
 401          */
 402         fsnotify_nameremove(dentry, 0);
 403 }
 404
 405 #define SILLYNAME_PREFIX ".nfs"
 406 #define SILLYNAME_PREFIX_LEN ((unsigned)sizeof(SILLYNAME_PREFIX) - 1)
 407 #define SILLYNAME_FILEID_LEN ((unsigned)sizeof(u64) << 1)
 408 #define SILLYNAME_COUNTER_LEN ((unsigned)sizeof(unsigned int) << 1)
 409 #define SILLYNAME_LEN (SILLYNAME_PREFIX_LEN + \
 410                 SILLYNAME_FILEID_LEN + \
 411                 SILLYNAME_COUNTER_LEN)
 412
 413 /**
 414  * nfs_sillyrename - Perform a silly-rename of a dentry
 415  * @dir: inode of directory that contains dentry
 416  * @dentry: dentry to be sillyrenamed
 417  *
 418  * NFSv2/3 is stateless and the server doesn't know when the client is
 419  * holding a file open. To prevent application problems when a file is
 420  * unlinked while it's still open, the client performs a "silly-rename".
 421  * That is, it renames the file to a hidden file in the same directory,
 422  * and only performs the unlink once the last reference to it is put.
 423  *
 424  * The final cleanup is done during dentry_iput.
 425  *
 426  * (Note: NFSv4 is stateful, and has opens, so in theory an NFSv4 server
 427  * could take responsibility for keeping open files referenced.  The server
 428  * would also need to ensure that opened-but-deleted files were kept over
 429  * reboots.  However, we may not assume a server does so.  (RFC 5661
 430  * does provide an OPEN4_RESULT_PRESERVE_UNLINKED flag that a server can
 431  * use to advertise that it does this; some day we may take advantage of
 432  * it.))
 433  */
 434 int
 435 nfs_sillyrename(struct inode *dir, struct dentry *dentry)
 436 {
 437         static unsigned int sillycounter;
 438         unsigned char silly[SILLYNAME_LEN + 1];
 439         unsigned long long fileid;
 440         struct dentry *sdentry;
 441         struct inode *inode = d_inode(dentry);
 442         struct rpc_task *task;
 443         int            error = -EBUSY;
 444
 445         dfprintk(VFS, "NFS: silly-rename(%pd2, ct=%d)\n",
 446                 dentry, d_count(dentry));
 447         nfs_inc_stats(dir, NFSIOS_SILLYRENAME);
 448
 449         /*
 450          * We don't allow a dentry to be silly-renamed twice.
 451          */
 452         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 453                 goto out;
 454
 455         fileid = NFS_FILEID(d_inode(dentry));
 456
 457         sdentry = NULL;
 458         do {
 459                 int slen;
 460                 dput(sdentry);
 461                 sillycounter++;
 462                 slen = scnprintf(silly, sizeof(silly),
 463                                 SILLYNAME_PREFIX "%0*llx%0*x",
 464                                 SILLYNAME_FILEID_LEN, fileid,
 465                                 SILLYNAME_COUNTER_LEN, sillycounter);
 466
 467                 dfprintk(VFS, "NFS: trying to rename %pd to %s\n",
 468                                 dentry, silly);
 469
 470                 sdentry = lookup_one_len(silly, dentry->d_parent, slen);
 471                 /*
 472                  * N.B. Better to return EBUSY here ... it could be
 473                  * dangerous to delete the file while it's in use.
 474                  */
 475                 if (IS_ERR(sdentry))
 476                         goto out;
 477         } while (d_inode(sdentry) != NULL); /* need negative lookup */
 478
 479         ihold(inode);
 480
 481         /* queue unlink first. Can't do this from rpc_release as it
 482          * has to allocate memory
 483          */
 484         error = nfs_async_unlink(dentry, &sdentry->d_name);
 485         if (error)
 486                 goto out_dput;
 487
 488         /* run the rename task, undo unlink if it fails */
 489         task = nfs_async_rename(dir, dir, dentry, sdentry,
 490                                         nfs_complete_sillyrename);
 491         if (IS_ERR(task)) {
 492                 error = -EBUSY;
 493                 nfs_cancel_async_unlink(dentry);
 494                 goto out_dput;
 495         }
 496
 497         /* wait for the RPC task to complete, unless a SIGKILL intervenes */
 498         error = rpc_wait_for_completion_task(task);
 499         if (error == 0)
 500                 error = task->tk_status;
 501         switch (error) {
 502         case 0:
 503                 /* The rename succeeded */
 504                 nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
 505                 spin_lock(&inode->i_lock);
 506                 NFS_I(inode)->attr_gencount = nfs_inc_attr_generation_counter();
 507                 NFS_I(inode)->cache_validity |= NFS_INO_INVALID_CHANGE
 508                         | NFS_INO_INVALID_CTIME
 509                         | NFS_INO_REVAL_FORCED;
 510                 spin_unlock(&inode->i_lock);
 511                 d_move(dentry, sdentry);
 512                 break;
 513         case -ERESTARTSYS:
 514                 /* The result of the rename is unknown. Play it safe by
 515                  * forcing a new lookup */
 516                 d_drop(dentry);
 517                 d_drop(sdentry);
 518         }
 519         rpc_put_task(task);
 520 out_dput:
 521         iput(inode);
 522         dput(sdentry);
 523 out:
 524         return error;
 525 }