fs/afs/file.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* AFS filesystem file handling
   3  *
   4  * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/init.h>
  11 #include <linux/fs.h>
  12 #include <linux/pagemap.h>
  13 #include <linux/writeback.h>
  14 #include <linux/gfp.h>
  15 #include <linux/task_io_accounting_ops.h>
  16 #include <linux/mm.h>
  17 #include <linux/swap.h>
  18 #include <linux/netfs.h>
  19 #include "internal.h"
  20
  21 static int afs_file_mmap(struct file *file, struct vm_area_struct *vma);
  22 static int afs_symlink_read_folio(struct file *file, struct folio *folio);
  23 static void afs_invalidate_folio(struct folio *folio, size_t offset,
  24                                size_t length);
  25 static bool afs_release_folio(struct folio *folio, gfp_t gfp_flags);
  26
  27 static ssize_t afs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);
  28 static ssize_t afs_file_splice_read(struct file *in, loff_t *ppos,
  29                                     struct pipe_inode_info *pipe,
  30                                     size_t len, unsigned int flags);
  31 static void afs_vm_open(struct vm_area_struct *area);
  32 static void afs_vm_close(struct vm_area_struct *area);
  33 static vm_fault_t afs_vm_map_pages(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff);
  34
  35 const struct file_operations afs_file_operations = {
  36         .open           = afs_open,
  37         .release        = afs_release,
  38         .llseek         = generic_file_llseek,
  39         .read_iter      = afs_file_read_iter,
  40         .write_iter     = afs_file_write,
  41         .mmap           = afs_file_mmap,
  42         .splice_read    = afs_file_splice_read,
  43         .splice_write   = iter_file_splice_write,
  44         .fsync          = afs_fsync,
  45         .lock           = afs_lock,
  46         .flock          = afs_flock,
  47 };
  48
  49 const struct inode_operations afs_file_inode_operations = {
  50         .getattr        = afs_getattr,
  51         .setattr        = afs_setattr,
  52         .permission     = afs_permission,
  53 };
  54
  55 const struct address_space_operations afs_file_aops = {
  56         .read_folio     = netfs_read_folio,
  57         .readahead      = netfs_readahead,
  58         .dirty_folio    = afs_dirty_folio,
  59         .launder_folio  = afs_launder_folio,
  60         .release_folio  = afs_release_folio,
  61         .invalidate_folio = afs_invalidate_folio,
  62         .write_begin    = afs_write_begin,
  63         .write_end      = afs_write_end,
  64         .writepages     = afs_writepages,
  65         .migrate_folio  = filemap_migrate_folio,
  66 };
  67
  68 const struct address_space_operations afs_symlink_aops = {
  69         .read_folio     = afs_symlink_read_folio,
  70         .release_folio  = afs_release_folio,
  71         .invalidate_folio = afs_invalidate_folio,
  72         .migrate_folio  = filemap_migrate_folio,
  73 };
  74
  75 static const struct vm_operations_struct afs_vm_ops = {
  76         .open           = afs_vm_open,
  77         .close          = afs_vm_close,
  78         .fault          = filemap_fault,
  79         .map_pages      = afs_vm_map_pages,
  80         .page_mkwrite   = afs_page_mkwrite,
  81 };
  82
  83 /*
  84  * Discard a pin on a writeback key.
  85  */
  86 void afs_put_wb_key(struct afs_wb_key *wbk)
  87 {
  88         if (wbk && refcount_dec_and_test(&wbk->usage)) {
  89                 key_put(wbk->key);
  90                 kfree(wbk);
  91         }
  92 }
  93
  94 /*
  95  * Cache key for writeback.
  96  */
  97 int afs_cache_wb_key(struct afs_vnode *vnode, struct afs_file *af)
  98 {
  99         struct afs_wb_key *wbk, *p;
 100
 101         wbk = kzalloc(sizeof(struct afs_wb_key), GFP_KERNEL);
 102         if (!wbk)
 103                 return -ENOMEM;
 104         refcount_set(&wbk->usage, 2);
 105         wbk->key = af->key;
 106
 107         spin_lock(&vnode->wb_lock);
 108         list_for_each_entry(p, &vnode->wb_keys, vnode_link) {
 109                 if (p->key == wbk->key)
 110                         goto found;
 111         }
 112
 113         key_get(wbk->key);
 114         list_add_tail(&wbk->vnode_link, &vnode->wb_keys);
 115         spin_unlock(&vnode->wb_lock);
 116         af->wb = wbk;
 117         return 0;
 118
 119 found:
 120         refcount_inc(&p->usage);
 121         spin_unlock(&vnode->wb_lock);
 122         af->wb = p;
 123         kfree(wbk);
 124         return 0;
 125 }
 126
 127 /*
 128  * open an AFS file or directory and attach a key to it
 129  */
 130 int afs_open(struct inode *inode, struct file *file)
 131 {
 132         struct afs_vnode *vnode = AFS_FS_I(inode);
 133         struct afs_file *af;
 134         struct key *key;
 135         int ret;
 136
 137         _enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);
 138
 139         key = afs_request_key(vnode->volume->cell);
 140         if (IS_ERR(key)) {
 141                 ret = PTR_ERR(key);
 142                 goto error;
 143         }
 144
 145         af = kzalloc(sizeof(*af), GFP_KERNEL);
 146         if (!af) {
 147                 ret = -ENOMEM;
 148                 goto error_key;
 149         }
 150         af->key = key;
 151
 152         ret = afs_validate(vnode, key);
 153         if (ret < 0)
 154                 goto error_af;
 155
 156         if (file->f_mode & FMODE_WRITE) {
 157                 ret = afs_cache_wb_key(vnode, af);
 158                 if (ret < 0)
 159                         goto error_af;
 160         }
 161
 162         if (file->f_flags & O_TRUNC)
 163                 set_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
 164
 165         fscache_use_cookie(afs_vnode_cache(vnode), file->f_mode & FMODE_WRITE);
 166
 167         file->private_data = af;
 168         _leave(" = 0");
 169         return 0;
 170
 171 error_af:
 172         kfree(af);
 173 error_key:
 174         key_put(key);
 175 error:
 176         _leave(" = %d", ret);
 177         return ret;
 178 }
 179
 180 /*
 181  * release an AFS file or directory and discard its key
 182  */
 183 int afs_release(struct inode *inode, struct file *file)
 184 {
 185         struct afs_vnode_cache_aux aux;
 186         struct afs_vnode *vnode = AFS_FS_I(inode);
 187         struct afs_file *af = file->private_data;
 188         loff_t i_size;
 189         int ret = 0;
 190
 191         _enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);
 192
 193         if ((file->f_mode & FMODE_WRITE))
 194                 ret = vfs_fsync(file, 0);
 195
 196         file->private_data = NULL;
 197         if (af->wb)
 198                 afs_put_wb_key(af->wb);
 199
 200         if ((file->f_mode & FMODE_WRITE)) {
 201                 i_size = i_size_read(&vnode->netfs.inode);
 202                 afs_set_cache_aux(vnode, &aux);
 203                 fscache_unuse_cookie(afs_vnode_cache(vnode), &aux, &i_size);
 204         } else {
 205                 fscache_unuse_cookie(afs_vnode_cache(vnode), NULL, NULL);
 206         }
 207
 208         key_put(af->key);
 209         kfree(af);
 210         afs_prune_wb_keys(vnode);
 211         _leave(" = %d", ret);
 212         return ret;
 213 }
 214
 215 /*
 216  * Allocate a new read record.
 217  */
 218 struct afs_read *afs_alloc_read(gfp_t gfp)
 219 {
 220         struct afs_read *req;
 221
 222         req = kzalloc(sizeof(struct afs_read), gfp);
 223         if (req)
 224                 refcount_set(&req->usage, 1);
 225
 226         return req;
 227 }
 228
 229 /*
 230  * Dispose of a ref to a read record.
 231  */
 232 void afs_put_read(struct afs_read *req)
 233 {
 234         if (refcount_dec_and_test(&req->usage)) {
 235                 if (req->cleanup)
 236                         req->cleanup(req);
 237                 key_put(req->key);
 238                 kfree(req);
 239         }
 240 }
 241
 242 static void afs_fetch_data_notify(struct afs_operation *op)
 243 {
 244         struct afs_read *req = op->fetch.req;
 245         struct netfs_io_subrequest *subreq = req->subreq;
 246         int error = afs_op_error(op);
 247
 248         req->error = error;
 249         if (subreq) {
 250                 __set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
 251                 netfs_subreq_terminated(subreq, error ?: req->actual_len, false);
 252                 req->subreq = NULL;
 253         } else if (req->done) {
 254                 req->done(req);
 255         }
 256 }
 257
 258 static void afs_fetch_data_success(struct afs_operation *op)
 259 {
 260         struct afs_vnode *vnode = op->file[0].vnode;
 261
 262         _enter("op=%08x", op->debug_id);
 263         afs_vnode_commit_status(op, &op->file[0]);
 264         afs_stat_v(vnode, n_fetches);
 265         atomic_long_add(op->fetch.req->actual_len, &op->net->n_fetch_bytes);
 266         afs_fetch_data_notify(op);
 267 }
 268
 269 static void afs_fetch_data_put(struct afs_operation *op)
 270 {
 271         op->fetch.req->error = afs_op_error(op);
 272         afs_put_read(op->fetch.req);
 273 }
 274
 275 static const struct afs_operation_ops afs_fetch_data_operation = {
 276         .issue_afs_rpc  = afs_fs_fetch_data,
 277         .issue_yfs_rpc  = yfs_fs_fetch_data,
 278         .success        = afs_fetch_data_success,
 279         .aborted        = afs_check_for_remote_deletion,
 280         .failed         = afs_fetch_data_notify,
 281         .put            = afs_fetch_data_put,
 282 };
 283
 284 /*
 285  * Fetch file data from the volume.
 286  */
 287 int afs_fetch_data(struct afs_vnode *vnode, struct afs_read *req)
 288 {
 289         struct afs_operation *op;
 290
 291         _enter("%s{%llx:%llu.%u},%x,,,",
 292                vnode->volume->name,
 293                vnode->fid.vid,
 294                vnode->fid.vnode,
 295                vnode->fid.unique,
 296                key_serial(req->key));
 297
 298         op = afs_alloc_operation(req->key, vnode->volume);
 299         if (IS_ERR(op)) {
 300                 if (req->subreq)
 301                         netfs_subreq_terminated(req->subreq, PTR_ERR(op), false);
 302                 return PTR_ERR(op);
 303         }
 304
 305         afs_op_set_vnode(op, 0, vnode);
 306
 307         op->fetch.req   = afs_get_read(req);
 308         op->ops         = &afs_fetch_data_operation;
 309         return afs_do_sync_operation(op);
 310 }
 311
 312 static void afs_issue_read(struct netfs_io_subrequest *subreq)
 313 {
 314         struct afs_vnode *vnode = AFS_FS_I(subreq->rreq->inode);
 315         struct afs_read *fsreq;
 316
 317         fsreq = afs_alloc_read(GFP_NOFS);
 318         if (!fsreq)
 319                 return netfs_subreq_terminated(subreq, -ENOMEM, false);
 320
 321         fsreq->subreq   = subreq;
 322         fsreq->pos      = subreq->start + subreq->transferred;
 323         fsreq->len      = subreq->len   - subreq->transferred;
 324         fsreq->key      = key_get(subreq->rreq->netfs_priv);
 325         fsreq->vnode    = vnode;
 326         fsreq->iter     = &fsreq->def_iter;
 327
 328         iov_iter_xarray(&fsreq->def_iter, ITER_DEST,
 329                         &fsreq->vnode->netfs.inode.i_mapping->i_pages,
 330                         fsreq->pos, fsreq->len);
 331
 332         afs_fetch_data(fsreq->vnode, fsreq);
 333         afs_put_read(fsreq);
 334 }
 335
 336 static int afs_symlink_read_folio(struct file *file, struct folio *folio)
 337 {
 338         struct afs_vnode *vnode = AFS_FS_I(folio->mapping->host);
 339         struct afs_read *fsreq;
 340         int ret;
 341
 342         fsreq = afs_alloc_read(GFP_NOFS);
 343         if (!fsreq)
 344                 return -ENOMEM;
 345
 346         fsreq->pos      = folio_pos(folio);
 347         fsreq->len      = folio_size(folio);
 348         fsreq->vnode    = vnode;
 349         fsreq->iter     = &fsreq->def_iter;
 350         iov_iter_xarray(&fsreq->def_iter, ITER_DEST, &folio->mapping->i_pages,
 351                         fsreq->pos, fsreq->len);
 352
 353         ret = afs_fetch_data(fsreq->vnode, fsreq);
 354         if (ret == 0)
 355                 folio_mark_uptodate(folio);
 356         folio_unlock(folio);
 357         return ret;
 358 }
 359
 360 static int afs_init_request(struct netfs_io_request *rreq, struct file *file)
 361 {
 362         rreq->netfs_priv = key_get(afs_file_key(file));
 363         return 0;
 364 }
 365
 366 static int afs_begin_cache_operation(struct netfs_io_request *rreq)
 367 {
 368 #ifdef CONFIG_AFS_FSCACHE
 369         struct afs_vnode *vnode = AFS_FS_I(rreq->inode);
 370
 371         return fscache_begin_read_operation(&rreq->cache_resources,
 372                                             afs_vnode_cache(vnode));
 373 #else
 374         return -ENOBUFS;
 375 #endif
 376 }
 377
 378 static int afs_check_write_begin(struct file *file, loff_t pos, unsigned len,
 379                                  struct folio **foliop, void **_fsdata)
 380 {
 381         struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
 382
 383         return test_bit(AFS_VNODE_DELETED, &vnode->flags) ? -ESTALE : 0;
 384 }
 385
 386 static void afs_free_request(struct netfs_io_request *rreq)
 387 {
 388         key_put(rreq->netfs_priv);
 389 }
 390
 391 const struct netfs_request_ops afs_req_ops = {
 392         .init_request           = afs_init_request,
 393         .free_request           = afs_free_request,
 394         .begin_cache_operation  = afs_begin_cache_operation,
 395         .check_write_begin      = afs_check_write_begin,
 396         .issue_read             = afs_issue_read,
 397 };
 398
 399 int afs_write_inode(struct inode *inode, struct writeback_control *wbc)
 400 {
 401         fscache_unpin_writeback(wbc, afs_vnode_cache(AFS_FS_I(inode)));
 402         return 0;
 403 }
 404
 405 /*
 406  * Adjust the dirty region of the page on truncation or full invalidation,
 407  * getting rid of the markers altogether if the region is entirely invalidated.
 408  */
 409 static void afs_invalidate_dirty(struct folio *folio, size_t offset,
 410                                  size_t length)
 411 {
 412         struct afs_vnode *vnode = AFS_FS_I(folio_inode(folio));
 413         unsigned long priv;
 414         unsigned int f, t, end = offset + length;
 415
 416         priv = (unsigned long)folio_get_private(folio);
 417
 418         /* we clean up only if the entire page is being invalidated */
 419         if (offset == 0 && length == folio_size(folio))
 420                 goto full_invalidate;
 421
 422          /* If the page was dirtied by page_mkwrite(), the PTE stays writable
 423           * and we don't get another notification to tell us to expand it
 424           * again.
 425           */
 426         if (afs_is_folio_dirty_mmapped(priv))
 427                 return;
 428
 429         /* We may need to shorten the dirty region */
 430         f = afs_folio_dirty_from(folio, priv);
 431         t = afs_folio_dirty_to(folio, priv);
 432
 433         if (t <= offset || f >= end)
 434                 return; /* Doesn't overlap */
 435
 436         if (f < offset && t > end)
 437                 return; /* Splits the dirty region - just absorb it */
 438
 439         if (f >= offset && t <= end)
 440                 goto undirty;
 441
 442         if (f < offset)
 443                 t = offset;
 444         else
 445                 f = end;
 446         if (f == t)
 447                 goto undirty;
 448
 449         priv = afs_folio_dirty(folio, f, t);
 450         folio_change_private(folio, (void *)priv);
 451         trace_afs_folio_dirty(vnode, tracepoint_string("trunc"), folio);
 452         return;
 453
 454 undirty:
 455         trace_afs_folio_dirty(vnode, tracepoint_string("undirty"), folio);
 456         folio_clear_dirty_for_io(folio);
 457 full_invalidate:
 458         trace_afs_folio_dirty(vnode, tracepoint_string("inval"), folio);
 459         folio_detach_private(folio);
 460 }
 461
 462 /*
 463  * invalidate part or all of a page
 464  * - release a page and clean up its private data if offset is 0 (indicating
 465  *   the entire page)
 466  */
 467 static void afs_invalidate_folio(struct folio *folio, size_t offset,
 468                                size_t length)
 469 {
 470         _enter("{%lu},%zu,%zu", folio->index, offset, length);
 471
 472         BUG_ON(!folio_test_locked(folio));
 473
 474         if (folio_get_private(folio))
 475                 afs_invalidate_dirty(folio, offset, length);
 476
 477         folio_wait_fscache(folio);
 478         _leave("");
 479 }
 480
 481 /*
 482  * release a page and clean up its private state if it's not busy
 483  * - return true if the page can now be released, false if not
 484  */
 485 static bool afs_release_folio(struct folio *folio, gfp_t gfp)
 486 {
 487         struct afs_vnode *vnode = AFS_FS_I(folio_inode(folio));
 488
 489         _enter("{{%llx:%llu}[%lu],%lx},%x",
 490                vnode->fid.vid, vnode->fid.vnode, folio_index(folio), folio->flags,
 491                gfp);
 492
 493         /* deny if folio is being written to the cache and the caller hasn't
 494          * elected to wait */
 495 #ifdef CONFIG_AFS_FSCACHE
 496         if (folio_test_fscache(folio)) {
 497                 if (current_is_kswapd() || !(gfp & __GFP_FS))
 498                         return false;
 499                 folio_wait_fscache(folio);
 500         }
 501         fscache_note_page_release(afs_vnode_cache(vnode));
 502 #endif
 503
 504         if (folio_test_private(folio)) {
 505                 trace_afs_folio_dirty(vnode, tracepoint_string("rel"), folio);
 506                 folio_detach_private(folio);
 507         }
 508
 509         /* Indicate that the folio can be released */
 510         _leave(" = T");
 511         return true;
 512 }
 513
 514 static void afs_add_open_mmap(struct afs_vnode *vnode)
 515 {
 516         if (atomic_inc_return(&vnode->cb_nr_mmap) == 1) {
 517                 down_write(&vnode->volume->open_mmaps_lock);
 518
 519                 if (list_empty(&vnode->cb_mmap_link))
 520                         list_add_tail(&vnode->cb_mmap_link, &vnode->volume->open_mmaps);
 521
 522                 up_write(&vnode->volume->open_mmaps_lock);
 523         }
 524 }
 525
 526 static void afs_drop_open_mmap(struct afs_vnode *vnode)
 527 {
 528         if (!atomic_dec_and_test(&vnode->cb_nr_mmap))
 529                 return;
 530
 531         down_write(&vnode->volume->open_mmaps_lock);
 532
 533         if (atomic_read(&vnode->cb_nr_mmap) == 0)
 534                 list_del_init(&vnode->cb_mmap_link);
 535
 536         up_write(&vnode->volume->open_mmaps_lock);
 537         flush_work(&vnode->cb_work);
 538 }
 539
 540 /*
 541  * Handle setting up a memory mapping on an AFS file.
 542  */
 543 static int afs_file_mmap(struct file *file, struct vm_area_struct *vma)
 544 {
 545         struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
 546         int ret;
 547
 548         afs_add_open_mmap(vnode);
 549
 550         ret = generic_file_mmap(file, vma);
 551         if (ret == 0)
 552                 vma->vm_ops = &afs_vm_ops;
 553         else
 554                 afs_drop_open_mmap(vnode);
 555         return ret;
 556 }
 557
 558 static void afs_vm_open(struct vm_area_struct *vma)
 559 {
 560         afs_add_open_mmap(AFS_FS_I(file_inode(vma->vm_file)));
 561 }
 562
 563 static void afs_vm_close(struct vm_area_struct *vma)
 564 {
 565         afs_drop_open_mmap(AFS_FS_I(file_inode(vma->vm_file)));
 566 }
 567
 568 static vm_fault_t afs_vm_map_pages(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff)
 569 {
 570         struct afs_vnode *vnode = AFS_FS_I(file_inode(vmf->vma->vm_file));
 571
 572         if (afs_check_validity(vnode))
 573                 return filemap_map_pages(vmf, start_pgoff, end_pgoff);
 574         return 0;
 575 }
 576
 577 static ssize_t afs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 578 {
 579         struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
 580         struct afs_file *af = iocb->ki_filp->private_data;
 581         int ret;
 582
 583         ret = afs_validate(vnode, af->key);
 584         if (ret < 0)
 585                 return ret;
 586
 587         return generic_file_read_iter(iocb, iter);
 588 }
 589
 590 static ssize_t afs_file_splice_read(struct file *in, loff_t *ppos,
 591                                     struct pipe_inode_info *pipe,
 592                                     size_t len, unsigned int flags)
 593 {
 594         struct afs_vnode *vnode = AFS_FS_I(file_inode(in));
 595         struct afs_file *af = in->private_data;
 596         int ret;
 597
 598         ret = afs_validate(vnode, af->key);
 599         if (ret < 0)
 600                 return ret;
 601
 602         return filemap_splice_read(in, ppos, pipe, len, flags);
 603 }