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 #include <linux/fsnotify.h>
  18
  19 #include "internal.h"
  20 #include "nfs4_fs.h"
  21 #include "iostat.h"
  22 #include "delegation.h"
  23
  24 #include "nfstrace.h"
  25
  26 /**
  27  * nfs_free_unlinkdata - release data from a sillydelete operation.
  28  * @data: pointer to unlink structure.
  29  */
  30 static void
  31 nfs_free_unlinkdata(struct nfs_unlinkdata *data)
  32 {
  33         put_rpccred(data->cred);
  34         kfree(data->args.name.name);
  35         kfree(data);
  36 }
  37
  38 /**
  39  * nfs_async_unlink_done - Sillydelete post-processing
  40  * @task: rpc_task of the sillydelete
  41  *
  42  * Do the directory attribute update.
  43  */
  44 static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
  45 {
  46         struct nfs_unlinkdata *data = calldata;
  47         struct inode *dir = d_inode(data->dentry->d_parent);
  48
  49         trace_nfs_sillyrename_unlink(data, task->tk_status);
  50         if (!NFS_PROTO(dir)->unlink_done(task, dir))
  51                 rpc_restart_call_prepare(task);
  52 }
  53
  54 /**
  55  * nfs_async_unlink_release - Release the sillydelete data.
  56  * @task: rpc_task of the sillydelete
  57  *
  58  * We need to call nfs_put_unlinkdata as a 'tk_release' task since the
  59  * rpc_task would be freed too.
  60  */
  61 static void nfs_async_unlink_release(void *calldata)
  62 {
  63         struct nfs_unlinkdata   *data = calldata;
  64         struct dentry *dentry = data->dentry;
  65         struct super_block *sb = dentry->d_sb;
  66
  67         up_read_non_owner(&NFS_I(d_inode(dentry->d_parent))->rmdir_sem);
  68         d_lookup_done(dentry);
  69         nfs_free_unlinkdata(data);
  70         dput(dentry);
  71         nfs_sb_deactive(sb);
  72 }
  73
  74 static void nfs_unlink_prepare(struct rpc_task *task, void *calldata)
  75 {
  76         struct nfs_unlinkdata *data = calldata;
  77         struct inode *dir = d_inode(data->dentry->d_parent);
  78         NFS_PROTO(dir)->unlink_rpc_prepare(task, data);
  79 }
  80
  81 static const struct rpc_call_ops nfs_unlink_ops = {
  82         .rpc_call_done = nfs_async_unlink_done,
  83         .rpc_release = nfs_async_unlink_release,
  84         .rpc_call_prepare = nfs_unlink_prepare,
  85 };
  86
  87 static void nfs_do_call_unlink(struct nfs_unlinkdata *data)
  88 {
  89         struct rpc_message msg = {
  90                 .rpc_argp = &data->args,
  91                 .rpc_resp = &data->res,
  92                 .rpc_cred = data->cred,
  93         };
  94         struct rpc_task_setup task_setup_data = {
  95                 .rpc_message = &msg,
  96                 .callback_ops = &nfs_unlink_ops,
  97                 .callback_data = data,
  98                 .workqueue = nfsiod_workqueue,
  99                 .flags = RPC_TASK_ASYNC,
 100         };
 101         struct rpc_task *task;
 102         struct inode *dir = d_inode(data->dentry->d_parent);
 103         nfs_sb_active(dir->i_sb);
 104         data->args.fh = NFS_FH(dir);
 105         nfs_fattr_init(data->res.dir_attr);
 106
 107         NFS_PROTO(dir)->unlink_setup(&msg, dir);
 108
 109         task_setup_data.rpc_client = NFS_CLIENT(dir);
 110         task = rpc_run_task(&task_setup_data);
 111         if (!IS_ERR(task))
 112                 rpc_put_task_async(task);
 113 }
 114
 115 static int nfs_call_unlink(struct dentry *dentry, struct nfs_unlinkdata *data)
 116 {
 117         struct inode *dir = d_inode(dentry->d_parent);
 118         struct dentry *alias;
 119
 120         down_read_non_owner(&NFS_I(dir)->rmdir_sem);
 121         alias = d_alloc_parallel(dentry->d_parent, &data->args.name, &data->wq);
 122         if (IS_ERR(alias)) {
 123                 up_read_non_owner(&NFS_I(dir)->rmdir_sem);
 124                 return 0;
 125         }
 126         if (!d_in_lookup(alias)) {
 127                 int ret;
 128                 void *devname_garbage = NULL;
 129
 130                 /*
 131                  * Hey, we raced with lookup... See if we need to transfer
 132                  * the sillyrename information to the aliased dentry.
 133                  */
 134                 spin_lock(&alias->d_lock);
 135                 if (d_really_is_positive(alias) &&
 136                     !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
 137                         devname_garbage = alias->d_fsdata;
 138                         alias->d_fsdata = data;
 139                         alias->d_flags |= DCACHE_NFSFS_RENAMED;
 140                         ret = 1;
 141                 } else
 142                         ret = 0;
 143                 spin_unlock(&alias->d_lock);
 144                 dput(alias);
 145                 up_read_non_owner(&NFS_I(dir)->rmdir_sem);
 146                 /*
 147                  * If we'd displaced old cached devname, free it.  At that
 148                  * point dentry is definitely not a root, so we won't need
 149                  * that anymore.
 150                  */
 151                 kfree(devname_garbage);
 152                 return ret;
 153         }
 154         data->dentry = alias;
 155         nfs_do_call_unlink(data);
 156         return 1;
 157 }
 158
 159 /**
 160  * nfs_async_unlink - asynchronous unlinking of a file
 161  * @dir: parent directory of dentry
 162  * @dentry: dentry to unlink
 163  */
 164 static int
 165 nfs_async_unlink(struct dentry *dentry, const struct qstr *name)
 166 {
 167         struct nfs_unlinkdata *data;
 168         int status = -ENOMEM;
 169         void *devname_garbage = NULL;
 170
 171         data = kzalloc(sizeof(*data), GFP_KERNEL);
 172         if (data == NULL)
 173                 goto out;
 174         data->args.name.name = kstrdup(name->name, GFP_KERNEL);
 175         if (!data->args.name.name)
 176                 goto out_free;
 177         data->args.name.len = name->len;
 178
 179         data->cred = rpc_lookup_cred();
 180         if (IS_ERR(data->cred)) {
 181                 status = PTR_ERR(data->cred);
 182                 goto out_free_name;
 183         }
 184         data->res.dir_attr = &data->dir_attr;
 185         init_waitqueue_head(&data->wq);
 186
 187         status = -EBUSY;
 188         spin_lock(&dentry->d_lock);
 189         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 190                 goto out_unlock;
 191         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
 192         devname_garbage = dentry->d_fsdata;
 193         dentry->d_fsdata = data;
 194         spin_unlock(&dentry->d_lock);
 195         /*
 196          * If we'd displaced old cached devname, free it.  At that
 197          * point dentry is definitely not a root, so we won't need
 198          * that anymore.
 199          */
 200         kfree(devname_garbage);
 201         return 0;
 202 out_unlock:
 203         spin_unlock(&dentry->d_lock);
 204         put_rpccred(data->cred);
 205 out_free_name:
 206         kfree(data->args.name.name);
 207 out_free:
 208         kfree(data);
 209 out:
 210         return status;
 211 }
 212
 213 /**
 214  * nfs_complete_unlink - Initialize completion of the sillydelete
 215  * @dentry: dentry to delete
 216  * @inode: inode
 217  *
 218  * Since we're most likely to be called by dentry_iput(), we
 219  * only use the dentry to find the sillydelete. We then copy the name
 220  * into the qstr.
 221  */
 222 void
 223 nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
 224 {
 225         struct nfs_unlinkdata   *data;
 226
 227         spin_lock(&dentry->d_lock);
 228         dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 229         data = dentry->d_fsdata;
 230         dentry->d_fsdata = NULL;
 231         spin_unlock(&dentry->d_lock);
 232
 233         if (NFS_STALE(inode) || !nfs_call_unlink(dentry, data))
 234                 nfs_free_unlinkdata(data);
 235 }
 236
 237 /* Cancel a queued async unlink. Called when a sillyrename run fails. */
 238 static void
 239 nfs_cancel_async_unlink(struct dentry *dentry)
 240 {
 241         spin_lock(&dentry->d_lock);
 242         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
 243                 struct nfs_unlinkdata *data = dentry->d_fsdata;
 244
 245                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 246                 dentry->d_fsdata = NULL;
 247                 spin_unlock(&dentry->d_lock);
 248                 nfs_free_unlinkdata(data);
 249                 return;
 250         }
 251         spin_unlock(&dentry->d_lock);
 252 }
 253
 254 /**
 255  * nfs_async_rename_done - Sillyrename post-processing
 256  * @task: rpc_task of the sillyrename
 257  * @calldata: nfs_renamedata for the sillyrename
 258  *
 259  * Do the directory attribute updates and the d_move
 260  */
 261 static void nfs_async_rename_done(struct rpc_task *task, void *calldata)
 262 {
 263         struct nfs_renamedata *data = calldata;
 264         struct inode *old_dir = data->old_dir;
 265         struct inode *new_dir = data->new_dir;
 266         struct dentry *old_dentry = data->old_dentry;
 267
 268         trace_nfs_sillyrename_rename(old_dir, old_dentry,
 269                         new_dir, data->new_dentry, task->tk_status);
 270         if (!NFS_PROTO(old_dir)->rename_done(task, old_dir, new_dir)) {
 271                 rpc_restart_call_prepare(task);
 272                 return;
 273         }
 274
 275         if (data->complete)
 276                 data->complete(task, data);
 277 }
 278
 279 /**
 280  * nfs_async_rename_release - Release the sillyrename data.
 281  * @calldata: the struct nfs_renamedata to be released
 282  */
 283 static void nfs_async_rename_release(void *calldata)
 284 {
 285         struct nfs_renamedata   *data = calldata;
 286         struct super_block *sb = data->old_dir->i_sb;
 287
 288         if (d_really_is_positive(data->old_dentry))
 289                 nfs_mark_for_revalidate(d_inode(data->old_dentry));
 290
 291         /* The result of the rename is unknown. Play it safe by
 292          * forcing a new lookup */
 293         if (data->cancelled) {
 294                 spin_lock(&data->old_dir->i_lock);
 295                 nfs_force_lookup_revalidate(data->old_dir);
 296                 spin_unlock(&data->old_dir->i_lock);
 297                 if (data->new_dir != data->old_dir) {
 298                         spin_lock(&data->new_dir->i_lock);
 299                         nfs_force_lookup_revalidate(data->new_dir);
 300                         spin_unlock(&data->new_dir->i_lock);
 301                 }
 302         }
 303
 304         dput(data->old_dentry);
 305         dput(data->new_dentry);
 306         iput(data->old_dir);
 307         iput(data->new_dir);
 308         nfs_sb_deactive(sb);
 309         put_rpccred(data->cred);
 310         kfree(data);
 311 }
 312
 313 static void nfs_rename_prepare(struct rpc_task *task, void *calldata)
 314 {
 315         struct nfs_renamedata *data = calldata;
 316         NFS_PROTO(data->old_dir)->rename_rpc_prepare(task, data);
 317 }
 318
 319 static const struct rpc_call_ops nfs_rename_ops = {
 320         .rpc_call_done = nfs_async_rename_done,
 321         .rpc_release = nfs_async_rename_release,
 322         .rpc_call_prepare = nfs_rename_prepare,
 323 };
 324
 325 /**
 326  * nfs_async_rename - perform an asynchronous rename operation
 327  * @old_dir: directory that currently holds the dentry to be renamed
 328  * @new_dir: target directory for the rename
 329  * @old_dentry: original dentry to be renamed
 330  * @new_dentry: dentry to which the old_dentry should be renamed
 331  *
 332  * It's expected that valid references to the dentries and inodes are held
 333  */
 334 struct rpc_task *
 335 nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
 336                  struct dentry *old_dentry, struct dentry *new_dentry,
 337                  void (*complete)(struct rpc_task *, struct nfs_renamedata *))
 338 {
 339         struct nfs_renamedata *data;
 340         struct rpc_message msg = { };
 341         struct rpc_task_setup task_setup_data = {
 342                 .rpc_message = &msg,
 343                 .callback_ops = &nfs_rename_ops,
 344                 .workqueue = nfsiod_workqueue,
 345                 .rpc_client = NFS_CLIENT(old_dir),
 346                 .flags = RPC_TASK_ASYNC,
 347         };
 348
 349         data = kzalloc(sizeof(*data), GFP_KERNEL);
 350         if (data == NULL)
 351                 return ERR_PTR(-ENOMEM);
 352         task_setup_data.callback_data = data;
 353
 354         data->cred = rpc_lookup_cred();
 355         if (IS_ERR(data->cred)) {
 356                 struct rpc_task *task = ERR_CAST(data->cred);
 357                 kfree(data);
 358                 return task;
 359         }
 360
 361         msg.rpc_argp = &data->args;
 362         msg.rpc_resp = &data->res;
 363         msg.rpc_cred = data->cred;
 364
 365         /* set up nfs_renamedata */
 366         data->old_dir = old_dir;
 367         ihold(old_dir);
 368         data->new_dir = new_dir;
 369         ihold(new_dir);
 370         data->old_dentry = dget(old_dentry);
 371         data->new_dentry = dget(new_dentry);
 372         nfs_fattr_init(&data->old_fattr);
 373         nfs_fattr_init(&data->new_fattr);
 374         data->complete = complete;
 375
 376         /* set up nfs_renameargs */
 377         data->args.old_dir = NFS_FH(old_dir);
 378         data->args.old_name = &old_dentry->d_name;
 379         data->args.new_dir = NFS_FH(new_dir);
 380         data->args.new_name = &new_dentry->d_name;
 381
 382         /* set up nfs_renameres */
 383         data->res.old_fattr = &data->old_fattr;
 384         data->res.new_fattr = &data->new_fattr;
 385
 386         nfs_sb_active(old_dir->i_sb);
 387
 388         NFS_PROTO(data->old_dir)->rename_setup(&msg, old_dir);
 389
 390         return rpc_run_task(&task_setup_data);
 391 }
 392
 393 /*
 394  * Perform tasks needed when a sillyrename is done such as cancelling the
 395  * queued async unlink if it failed.
 396  */
 397 static void
 398 nfs_complete_sillyrename(struct rpc_task *task, struct nfs_renamedata *data)
 399 {
 400         struct dentry *dentry = data->old_dentry;
 401
 402         if (task->tk_status != 0) {
 403                 nfs_cancel_async_unlink(dentry);
 404                 return;
 405         }
 406
 407         /*
 408          * vfs_unlink and the like do not issue this when a file is
 409          * sillyrenamed, so do it here.
 410          */
 411         fsnotify_nameremove(dentry, 0);
 412 }
 413
 414 #define SILLYNAME_PREFIX ".nfs"
 415 #define SILLYNAME_PREFIX_LEN ((unsigned)sizeof(SILLYNAME_PREFIX) - 1)
 416 #define SILLYNAME_FILEID_LEN ((unsigned)sizeof(u64) << 1)
 417 #define SILLYNAME_COUNTER_LEN ((unsigned)sizeof(unsigned int) << 1)
 418 #define SILLYNAME_LEN (SILLYNAME_PREFIX_LEN + \
 419                 SILLYNAME_FILEID_LEN + \
 420                 SILLYNAME_COUNTER_LEN)
 421
 422 /**
 423  * nfs_sillyrename - Perform a silly-rename of a dentry
 424  * @dir: inode of directory that contains dentry
 425  * @dentry: dentry to be sillyrenamed
 426  *
 427  * NFSv2/3 is stateless and the server doesn't know when the client is
 428  * holding a file open. To prevent application problems when a file is
 429  * unlinked while it's still open, the client performs a "silly-rename".
 430  * That is, it renames the file to a hidden file in the same directory,
 431  * and only performs the unlink once the last reference to it is put.
 432  *
 433  * The final cleanup is done during dentry_iput.
 434  *
 435  * (Note: NFSv4 is stateful, and has opens, so in theory an NFSv4 server
 436  * could take responsibility for keeping open files referenced.  The server
 437  * would also need to ensure that opened-but-deleted files were kept over
 438  * reboots.  However, we may not assume a server does so.  (RFC 5661
 439  * does provide an OPEN4_RESULT_PRESERVE_UNLINKED flag that a server can
 440  * use to advertise that it does this; some day we may take advantage of
 441  * it.))
 442  */
 443 int
 444 nfs_sillyrename(struct inode *dir, struct dentry *dentry)
 445 {
 446         static unsigned int sillycounter;
 447         unsigned char silly[SILLYNAME_LEN + 1];
 448         unsigned long long fileid;
 449         struct dentry *sdentry;
 450         struct rpc_task *task;
 451         int            error = -EBUSY;
 452
 453         dfprintk(VFS, "NFS: silly-rename(%pd2, ct=%d)\n",
 454                 dentry, d_count(dentry));
 455         nfs_inc_stats(dir, NFSIOS_SILLYRENAME);
 456
 457         /*
 458          * We don't allow a dentry to be silly-renamed twice.
 459          */
 460         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 461                 goto out;
 462
 463         fileid = NFS_FILEID(d_inode(dentry));
 464
 465         /* Return delegation in anticipation of the rename */
 466         NFS_PROTO(d_inode(dentry))->return_delegation(d_inode(dentry));
 467
 468         sdentry = NULL;
 469         do {
 470                 int slen;
 471                 dput(sdentry);
 472                 sillycounter++;
 473                 slen = scnprintf(silly, sizeof(silly),
 474                                 SILLYNAME_PREFIX "%0*llx%0*x",
 475                                 SILLYNAME_FILEID_LEN, fileid,
 476                                 SILLYNAME_COUNTER_LEN, sillycounter);
 477
 478                 dfprintk(VFS, "NFS: trying to rename %pd to %s\n",
 479                                 dentry, silly);
 480
 481                 sdentry = lookup_one_len(silly, dentry->d_parent, slen);
 482                 /*
 483                  * N.B. Better to return EBUSY here ... it could be
 484                  * dangerous to delete the file while it's in use.
 485                  */
 486                 if (IS_ERR(sdentry))
 487                         goto out;
 488         } while (d_inode(sdentry) != NULL); /* need negative lookup */
 489
 490         /* queue unlink first. Can't do this from rpc_release as it
 491          * has to allocate memory
 492          */
 493         error = nfs_async_unlink(dentry, &sdentry->d_name);
 494         if (error)
 495                 goto out_dput;
 496
 497         /* run the rename task, undo unlink if it fails */
 498         task = nfs_async_rename(dir, dir, dentry, sdentry,
 499                                         nfs_complete_sillyrename);
 500         if (IS_ERR(task)) {
 501                 error = -EBUSY;
 502                 nfs_cancel_async_unlink(dentry);
 503                 goto out_dput;
 504         }
 505
 506         /* wait for the RPC task to complete, unless a SIGKILL intervenes */
 507         error = rpc_wait_for_completion_task(task);
 508         if (error == 0)
 509                 error = task->tk_status;
 510         switch (error) {
 511         case 0:
 512                 /* The rename succeeded */
 513                 nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
 514                 d_move(dentry, sdentry);
 515                 break;
 516         case -ERESTARTSYS:
 517                 /* The result of the rename is unknown. Play it safe by
 518                  * forcing a new lookup */
 519                 d_drop(dentry);
 520                 d_drop(sdentry);
 521         }
 522         rpc_put_task(task);
 523 out_dput:
 524         dput(sdentry);
 525 out:
 526         return error;
 527 }