1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * This file is part of UBIFS.
   4 *
   5 * Copyright (C) 2006-2008 Nokia Corporation.
   6 *
   7 * Authors: Artem Bityutskiy (Битюцкий Артём)
   8 *          Adrian Hunter
   9 */
  10
  11/*
  12 * This file implements VFS file and inode operations for regular files, device
  13 * nodes and symlinks as well as address space operations.
  14 *
  15 * UBIFS uses 2 page flags: @PG_private and @PG_checked. @PG_private is set if
  16 * the page is dirty and is used for optimization purposes - dirty pages are
  17 * not budgeted so the flag shows that 'ubifs_write_end()' should not release
  18 * the budget for this page. The @PG_checked flag is set if full budgeting is
  19 * required for the page e.g., when it corresponds to a file hole or it is
  20 * beyond the file size. The budgeting is done in 'ubifs_write_begin()', because
  21 * it is OK to fail in this function, and the budget is released in
  22 * 'ubifs_write_end()'. So the @PG_private and @PG_checked flags carry
  23 * information about how the page was budgeted, to make it possible to release
  24 * the budget properly.
  25 *
  26 * A thing to keep in mind: inode @i_mutex is locked in most VFS operations we
  27 * implement. However, this is not true for 'ubifs_writepage()', which may be
  28 * called with @i_mutex unlocked. For example, when flusher thread is doing
  29 * background write-back, it calls 'ubifs_writepage()' with unlocked @i_mutex.
  30 * At "normal" work-paths the @i_mutex is locked in 'ubifs_writepage()', e.g.
  31 * in the "sys_write -> alloc_pages -> direct reclaim path". So, in
  32 * 'ubifs_writepage()' we are only guaranteed that the page is locked.
  33 *
  34 * Similarly, @i_mutex is not always locked in 'ubifs_read_folio()', e.g., the
  35 * read-ahead path does not lock it ("sys_read -> generic_file_aio_read ->
  36 * ondemand_readahead -> read_folio"). In case of readahead, @I_SYNC flag is not
  37 * set as well. However, UBIFS disables readahead.
  38 */
  39
  40#include "ubifs.h"
  41#include <linux/mount.h>
  42#include <linux/slab.h>
  43#include <linux/migrate.h>
  44
  45static int read_block(struct inode *inode, void *addr, unsigned int block,
  46		      struct ubifs_data_node *dn)
  47{
  48	struct ubifs_info *c = inode->i_sb->s_fs_info;
  49	int err, len, out_len;
  50	union ubifs_key key;
  51	unsigned int dlen;
  52
  53	data_key_init(c, &key, inode->i_ino, block);
  54	err = ubifs_tnc_lookup(c, &key, dn);
  55	if (err) {
  56		if (err == -ENOENT)
  57			/* Not found, so it must be a hole */
  58			memset(addr, 0, UBIFS_BLOCK_SIZE);
  59		return err;
  60	}
  61
  62	ubifs_assert(c, le64_to_cpu(dn->ch.sqnum) >
  63		     ubifs_inode(inode)->creat_sqnum);
  64	len = le32_to_cpu(dn->size);
  65	if (len <= 0 || len > UBIFS_BLOCK_SIZE)
  66		goto dump;
  67
  68	dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ;
  69
  70	if (IS_ENCRYPTED(inode)) {
  71		err = ubifs_decrypt(inode, dn, &dlen, block);
  72		if (err)
  73			goto dump;
  74	}
  75
  76	out_len = UBIFS_BLOCK_SIZE;
  77	err = ubifs_decompress(c, &dn->data, dlen, addr, &out_len,
  78			       le16_to_cpu(dn->compr_type));
  79	if (err || len != out_len)
  80		goto dump;
  81
  82	/*
  83	 * Data length can be less than a full block, even for blocks that are
  84	 * not the last in the file (e.g., as a result of making a hole and
  85	 * appending data). Ensure that the remainder is zeroed out.
  86	 */
  87	if (len < UBIFS_BLOCK_SIZE)
  88		memset(addr + len, 0, UBIFS_BLOCK_SIZE - len);
  89
  90	return 0;
  91
  92dump:
  93	ubifs_err(c, "bad data node (block %u, inode %lu)",
  94		  block, inode->i_ino);
  95	ubifs_dump_node(c, dn, UBIFS_MAX_DATA_NODE_SZ);
  96	return -EINVAL;
  97}
  98
  99static int do_readpage(struct page *page)
 100{
 101	void *addr;
 102	int err = 0, i;
 103	unsigned int block, beyond;
 104	struct ubifs_data_node *dn;
 105	struct inode *inode = page->mapping->host;
 106	struct ubifs_info *c = inode->i_sb->s_fs_info;
 107	loff_t i_size = i_size_read(inode);
 108
 109	dbg_gen("ino %lu, pg %lu, i_size %lld, flags %#lx",
 110		inode->i_ino, page->index, i_size, page->flags);
 111	ubifs_assert(c, !PageChecked(page));
 112	ubifs_assert(c, !PagePrivate(page));
 113
 114	addr = kmap(page);
 115
 116	block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT;
 117	beyond = (i_size + UBIFS_BLOCK_SIZE - 1) >> UBIFS_BLOCK_SHIFT;
 118	if (block >= beyond) {
 119		/* Reading beyond inode */
 120		SetPageChecked(page);
 121		memset(addr, 0, PAGE_SIZE);
 122		goto out;
 123	}
 124
 125	dn = kmalloc(UBIFS_MAX_DATA_NODE_SZ, GFP_NOFS);
 126	if (!dn) {
 127		err = -ENOMEM;
 128		goto error;
 129	}
 130
 131	i = 0;
 132	while (1) {
 133		int ret;
 134
 135		if (block >= beyond) {
 136			/* Reading beyond inode */
 137			err = -ENOENT;
 138			memset(addr, 0, UBIFS_BLOCK_SIZE);
 139		} else {
 140			ret = read_block(inode, addr, block, dn);
 141			if (ret) {
 142				err = ret;
 143				if (err != -ENOENT)
 144					break;
 145			} else if (block + 1 == beyond) {
 146				int dlen = le32_to_cpu(dn->size);
 147				int ilen = i_size & (UBIFS_BLOCK_SIZE - 1);
 148
 149				if (ilen && ilen < dlen)
 150					memset(addr + ilen, 0, dlen - ilen);
 151			}
 152		}
 153		if (++i >= UBIFS_BLOCKS_PER_PAGE)
 154			break;
 155		block += 1;
 156		addr += UBIFS_BLOCK_SIZE;
 
 
 
 
 157	}
 
 158	if (err) {
 159		struct ubifs_info *c = inode->i_sb->s_fs_info;
 160		if (err == -ENOENT) {
 161			/* Not found, so it must be a hole */
 162			SetPageChecked(page);
 163			dbg_gen("hole");
 164			goto out_free;
 
 
 
 165		}
 166		ubifs_err(c, "cannot read page %lu of inode %lu, error %d",
 167			  page->index, inode->i_ino, err);
 168		goto error;
 169	}
 170
 171out_free:
 172	kfree(dn);
 173out:
 174	SetPageUptodate(page);
 175	ClearPageError(page);
 176	flush_dcache_page(page);
 177	kunmap(page);
 178	return 0;
 179
 180error:
 181	kfree(dn);
 182	ClearPageUptodate(page);
 183	SetPageError(page);
 184	flush_dcache_page(page);
 185	kunmap(page);
 186	return err;
 187}
 188
 189/**
 190 * release_new_page_budget - release budget of a new page.
 191 * @c: UBIFS file-system description object
 192 *
 193 * This is a helper function which releases budget corresponding to the budget
 194 * of one new page of data.
 195 */
 196static void release_new_page_budget(struct ubifs_info *c)
 197{
 198	struct ubifs_budget_req req = { .recalculate = 1, .new_page = 1 };
 199
 200	ubifs_release_budget(c, &req);
 201}
 202
 203/**
 204 * release_existing_page_budget - release budget of an existing page.
 205 * @c: UBIFS file-system description object
 206 *
 207 * This is a helper function which releases budget corresponding to the budget
 208 * of changing one page of data which already exists on the flash media.
 209 */
 210static void release_existing_page_budget(struct ubifs_info *c)
 211{
 212	struct ubifs_budget_req req = { .dd_growth = c->bi.page_budget};
 213
 214	ubifs_release_budget(c, &req);
 215}
 216
 217static int write_begin_slow(struct address_space *mapping,
 218			    loff_t pos, unsigned len, struct page **pagep)
 219{
 220	struct inode *inode = mapping->host;
 221	struct ubifs_info *c = inode->i_sb->s_fs_info;
 222	pgoff_t index = pos >> PAGE_SHIFT;
 223	struct ubifs_budget_req req = { .new_page = 1 };
 224	int err, appending = !!(pos + len > inode->i_size);
 225	struct page *page;
 226
 227	dbg_gen("ino %lu, pos %llu, len %u, i_size %lld",
 228		inode->i_ino, pos, len, inode->i_size);
 229
 230	/*
 231	 * At the slow path we have to budget before locking the page, because
 232	 * budgeting may force write-back, which would wait on locked pages and
 233	 * deadlock if we had the page locked. At this point we do not know
 234	 * anything about the page, so assume that this is a new page which is
 235	 * written to a hole. This corresponds to largest budget. Later the
 236	 * budget will be amended if this is not true.
 237	 */
 238	if (appending)
 239		/* We are appending data, budget for inode change */
 240		req.dirtied_ino = 1;
 241
 242	err = ubifs_budget_space(c, &req);
 243	if (unlikely(err))
 244		return err;
 245
 246	page = grab_cache_page_write_begin(mapping, index);
 247	if (unlikely(!page)) {
 
 248		ubifs_release_budget(c, &req);
 249		return -ENOMEM;
 250	}
 251
 252	if (!PageUptodate(page)) {
 253		if (!(pos & ~PAGE_MASK) && len == PAGE_SIZE)
 254			SetPageChecked(page);
 255		else {
 256			err = do_readpage(page);
 257			if (err) {
 258				unlock_page(page);
 259				put_page(page);
 260				ubifs_release_budget(c, &req);
 261				return err;
 262			}
 263		}
 264
 265		SetPageUptodate(page);
 266		ClearPageError(page);
 267	}
 268
 269	if (PagePrivate(page))
 270		/*
 271		 * The page is dirty, which means it was budgeted twice:
 272		 *   o first time the budget was allocated by the task which
 273		 *     made the page dirty and set the PG_private flag;
 274		 *   o and then we budgeted for it for the second time at the
 275		 *     very beginning of this function.
 276		 *
 277		 * So what we have to do is to release the page budget we
 278		 * allocated.
 279		 */
 280		release_new_page_budget(c);
 281	else if (!PageChecked(page))
 282		/*
 283		 * We are changing a page which already exists on the media.
 284		 * This means that changing the page does not make the amount
 285		 * of indexing information larger, and this part of the budget
 286		 * which we have already acquired may be released.
 287		 */
 288		ubifs_convert_page_budget(c);
 289
 290	if (appending) {
 291		struct ubifs_inode *ui = ubifs_inode(inode);
 292
 293		/*
 294		 * 'ubifs_write_end()' is optimized from the fast-path part of
 295		 * 'ubifs_write_begin()' and expects the @ui_mutex to be locked
 296		 * if data is appended.
 297		 */
 298		mutex_lock(&ui->ui_mutex);
 299		if (ui->dirty)
 300			/*
 301			 * The inode is dirty already, so we may free the
 302			 * budget we allocated.
 303			 */
 304			ubifs_release_dirty_inode_budget(c, ui);
 305	}
 306
 307	*pagep = page;
 308	return 0;
 309}
 310
 311/**
 312 * allocate_budget - allocate budget for 'ubifs_write_begin()'.
 313 * @c: UBIFS file-system description object
 314 * @page: page to allocate budget for
 315 * @ui: UBIFS inode object the page belongs to
 316 * @appending: non-zero if the page is appended
 317 *
 318 * This is a helper function for 'ubifs_write_begin()' which allocates budget
 319 * for the operation. The budget is allocated differently depending on whether
 320 * this is appending, whether the page is dirty or not, and so on. This
 321 * function leaves the @ui->ui_mutex locked in case of appending. Returns zero
 322 * in case of success and %-ENOSPC in case of failure.
 
 323 */
 324static int allocate_budget(struct ubifs_info *c, struct page *page,
 325			   struct ubifs_inode *ui, int appending)
 326{
 327	struct ubifs_budget_req req = { .fast = 1 };
 328
 329	if (PagePrivate(page)) {
 330		if (!appending)
 331			/*
 332			 * The page is dirty and we are not appending, which
 333			 * means no budget is needed at all.
 334			 */
 335			return 0;
 336
 337		mutex_lock(&ui->ui_mutex);
 338		if (ui->dirty)
 339			/*
 340			 * The page is dirty and we are appending, so the inode
 341			 * has to be marked as dirty. However, it is already
 342			 * dirty, so we do not need any budget. We may return,
 343			 * but @ui->ui_mutex hast to be left locked because we
 344			 * should prevent write-back from flushing the inode
 345			 * and freeing the budget. The lock will be released in
 346			 * 'ubifs_write_end()'.
 347			 */
 348			return 0;
 349
 350		/*
 351		 * The page is dirty, we are appending, the inode is clean, so
 352		 * we need to budget the inode change.
 353		 */
 354		req.dirtied_ino = 1;
 355	} else {
 356		if (PageChecked(page))
 357			/*
 358			 * The page corresponds to a hole and does not
 359			 * exist on the media. So changing it makes
 360			 * make the amount of indexing information
 361			 * larger, and we have to budget for a new
 362			 * page.
 363			 */
 364			req.new_page = 1;
 365		else
 366			/*
 367			 * Not a hole, the change will not add any new
 368			 * indexing information, budget for page
 369			 * change.
 370			 */
 371			req.dirtied_page = 1;
 372
 373		if (appending) {
 374			mutex_lock(&ui->ui_mutex);
 375			if (!ui->dirty)
 376				/*
 377				 * The inode is clean but we will have to mark
 378				 * it as dirty because we are appending. This
 379				 * needs a budget.
 380				 */
 381				req.dirtied_ino = 1;
 382		}
 383	}
 384
 385	return ubifs_budget_space(c, &req);
 386}
 387
 388/*
 389 * This function is called when a page of data is going to be written. Since
 390 * the page of data will not necessarily go to the flash straight away, UBIFS
 391 * has to reserve space on the media for it, which is done by means of
 392 * budgeting.
 393 *
 394 * This is the hot-path of the file-system and we are trying to optimize it as
 395 * much as possible. For this reasons it is split on 2 parts - slow and fast.
 396 *
 397 * There many budgeting cases:
 398 *     o a new page is appended - we have to budget for a new page and for
 399 *       changing the inode; however, if the inode is already dirty, there is
 400 *       no need to budget for it;
 401 *     o an existing clean page is changed - we have budget for it; if the page
 402 *       does not exist on the media (a hole), we have to budget for a new
 403 *       page; otherwise, we may budget for changing an existing page; the
 404 *       difference between these cases is that changing an existing page does
 405 *       not introduce anything new to the FS indexing information, so it does
 406 *       not grow, and smaller budget is acquired in this case;
 407 *     o an existing dirty page is changed - no need to budget at all, because
 408 *       the page budget has been acquired by earlier, when the page has been
 409 *       marked dirty.
 410 *
 411 * UBIFS budgeting sub-system may force write-back if it thinks there is no
 412 * space to reserve. This imposes some locking restrictions and makes it
 413 * impossible to take into account the above cases, and makes it impossible to
 414 * optimize budgeting.
 415 *
 416 * The solution for this is that the fast path of 'ubifs_write_begin()' assumes
 417 * there is a plenty of flash space and the budget will be acquired quickly,
 418 * without forcing write-back. The slow path does not make this assumption.
 419 */
 420static int ubifs_write_begin(struct file *file, struct address_space *mapping,
 421			     loff_t pos, unsigned len,
 422			     struct page **pagep, void **fsdata)
 423{
 424	struct inode *inode = mapping->host;
 425	struct ubifs_info *c = inode->i_sb->s_fs_info;
 426	struct ubifs_inode *ui = ubifs_inode(inode);
 427	pgoff_t index = pos >> PAGE_SHIFT;
 428	int err, appending = !!(pos + len > inode->i_size);
 429	int skipped_read = 0;
 430	struct page *page;
 431
 432	ubifs_assert(c, ubifs_inode(inode)->ui_size == inode->i_size);
 433	ubifs_assert(c, !c->ro_media && !c->ro_mount);
 434
 435	if (unlikely(c->ro_error))
 436		return -EROFS;
 437
 438	/* Try out the fast-path part first */
 439	page = grab_cache_page_write_begin(mapping, index);
 440	if (unlikely(!page))
 441		return -ENOMEM;
 
 442
 443	if (!PageUptodate(page)) {
 444		/* The page is not loaded from the flash */
 445		if (!(pos & ~PAGE_MASK) && len == PAGE_SIZE) {
 446			/*
 447			 * We change whole page so no need to load it. But we
 448			 * do not know whether this page exists on the media or
 449			 * not, so we assume the latter because it requires
 450			 * larger budget. The assumption is that it is better
 451			 * to budget a bit more than to read the page from the
 452			 * media. Thus, we are setting the @PG_checked flag
 453			 * here.
 454			 */
 455			SetPageChecked(page);
 456			skipped_read = 1;
 457		} else {
 458			err = do_readpage(page);
 459			if (err) {
 460				unlock_page(page);
 461				put_page(page);
 462				return err;
 463			}
 464		}
 465
 466		SetPageUptodate(page);
 467		ClearPageError(page);
 468	}
 469
 470	err = allocate_budget(c, page, ui, appending);
 471	if (unlikely(err)) {
 472		ubifs_assert(c, err == -ENOSPC);
 473		/*
 474		 * If we skipped reading the page because we were going to
 475		 * write all of it, then it is not up to date.
 476		 */
 477		if (skipped_read) {
 478			ClearPageChecked(page);
 479			ClearPageUptodate(page);
 480		}
 481		/*
 482		 * Budgeting failed which means it would have to force
 483		 * write-back but didn't, because we set the @fast flag in the
 484		 * request. Write-back cannot be done now, while we have the
 485		 * page locked, because it would deadlock. Unlock and free
 486		 * everything and fall-back to slow-path.
 487		 */
 488		if (appending) {
 489			ubifs_assert(c, mutex_is_locked(&ui->ui_mutex));
 490			mutex_unlock(&ui->ui_mutex);
 491		}
 492		unlock_page(page);
 493		put_page(page);
 494
 495		return write_begin_slow(mapping, pos, len, pagep);
 496	}
 497
 498	/*
 499	 * Whee, we acquired budgeting quickly - without involving
 500	 * garbage-collection, committing or forcing write-back. We return
 501	 * with @ui->ui_mutex locked if we are appending pages, and unlocked
 502	 * otherwise. This is an optimization (slightly hacky though).
 503	 */
 504	*pagep = page;
 505	return 0;
 506
 507}
 508
 509/**
 510 * cancel_budget - cancel budget.
 511 * @c: UBIFS file-system description object
 512 * @page: page to cancel budget for
 513 * @ui: UBIFS inode object the page belongs to
 514 * @appending: non-zero if the page is appended
 515 *
 516 * This is a helper function for a page write operation. It unlocks the
 517 * @ui->ui_mutex in case of appending.
 518 */
 519static void cancel_budget(struct ubifs_info *c, struct page *page,
 520			  struct ubifs_inode *ui, int appending)
 521{
 522	if (appending) {
 523		if (!ui->dirty)
 524			ubifs_release_dirty_inode_budget(c, ui);
 525		mutex_unlock(&ui->ui_mutex);
 526	}
 527	if (!PagePrivate(page)) {
 528		if (PageChecked(page))
 529			release_new_page_budget(c);
 530		else
 531			release_existing_page_budget(c);
 532	}
 533}
 534
 535static int ubifs_write_end(struct file *file, struct address_space *mapping,
 536			   loff_t pos, unsigned len, unsigned copied,
 537			   struct page *page, void *fsdata)
 538{
 539	struct inode *inode = mapping->host;
 540	struct ubifs_inode *ui = ubifs_inode(inode);
 541	struct ubifs_info *c = inode->i_sb->s_fs_info;
 542	loff_t end_pos = pos + len;
 543	int appending = !!(end_pos > inode->i_size);
 544
 545	dbg_gen("ino %lu, pos %llu, pg %lu, len %u, copied %d, i_size %lld",
 546		inode->i_ino, pos, page->index, len, copied, inode->i_size);
 547
 548	if (unlikely(copied < len && len == PAGE_SIZE)) {
 549		/*
 550		 * VFS copied less data to the page that it intended and
 551		 * declared in its '->write_begin()' call via the @len
 552		 * argument. If the page was not up-to-date, and @len was
 553		 * @PAGE_SIZE, the 'ubifs_write_begin()' function did
 554		 * not load it from the media (for optimization reasons). This
 555		 * means that part of the page contains garbage. So read the
 556		 * page now.
 557		 */
 558		dbg_gen("copied %d instead of %d, read page and repeat",
 559			copied, len);
 560		cancel_budget(c, page, ui, appending);
 561		ClearPageChecked(page);
 562
 563		/*
 564		 * Return 0 to force VFS to repeat the whole operation, or the
 565		 * error code if 'do_readpage()' fails.
 566		 */
 567		copied = do_readpage(page);
 568		goto out;
 569	}
 570
 571	if (!PagePrivate(page)) {
 572		attach_page_private(page, (void *)1);
 
 
 
 573		atomic_long_inc(&c->dirty_pg_cnt);
 574		__set_page_dirty_nobuffers(page);
 575	}
 576
 577	if (appending) {
 578		i_size_write(inode, end_pos);
 579		ui->ui_size = end_pos;
 580		/*
 581		 * Note, we do not set @I_DIRTY_PAGES (which means that the
 582		 * inode has dirty pages), this has been done in
 583		 * '__set_page_dirty_nobuffers()'.
 584		 */
 585		__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
 586		ubifs_assert(c, mutex_is_locked(&ui->ui_mutex));
 587		mutex_unlock(&ui->ui_mutex);
 588	}
 589
 590out:
 591	unlock_page(page);
 592	put_page(page);
 593	return copied;
 594}
 595
 596/**
 597 * populate_page - copy data nodes into a page for bulk-read.
 598 * @c: UBIFS file-system description object
 599 * @page: page
 600 * @bu: bulk-read information
 601 * @n: next zbranch slot
 602 *
 603 * This function returns %0 on success and a negative error code on failure.
 604 */
 605static int populate_page(struct ubifs_info *c, struct page *page,
 606			 struct bu_info *bu, int *n)
 607{
 608	int i = 0, nn = *n, offs = bu->zbranch[0].offs, hole = 0, read = 0;
 609	struct inode *inode = page->mapping->host;
 610	loff_t i_size = i_size_read(inode);
 611	unsigned int page_block;
 612	void *addr, *zaddr;
 613	pgoff_t end_index;
 614
 615	dbg_gen("ino %lu, pg %lu, i_size %lld, flags %#lx",
 616		inode->i_ino, page->index, i_size, page->flags);
 617
 618	addr = zaddr = kmap(page);
 619
 620	end_index = (i_size - 1) >> PAGE_SHIFT;
 621	if (!i_size || page->index > end_index) {
 622		hole = 1;
 623		memset(addr, 0, PAGE_SIZE);
 624		goto out_hole;
 625	}
 626
 627	page_block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT;
 628	while (1) {
 629		int err, len, out_len, dlen;
 630
 631		if (nn >= bu->cnt) {
 632			hole = 1;
 633			memset(addr, 0, UBIFS_BLOCK_SIZE);
 634		} else if (key_block(c, &bu->zbranch[nn].key) == page_block) {
 635			struct ubifs_data_node *dn;
 636
 637			dn = bu->buf + (bu->zbranch[nn].offs - offs);
 638
 639			ubifs_assert(c, le64_to_cpu(dn->ch.sqnum) >
 640				     ubifs_inode(inode)->creat_sqnum);
 641
 642			len = le32_to_cpu(dn->size);
 643			if (len <= 0 || len > UBIFS_BLOCK_SIZE)
 644				goto out_err;
 645
 646			dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ;
 647			out_len = UBIFS_BLOCK_SIZE;
 648
 649			if (IS_ENCRYPTED(inode)) {
 650				err = ubifs_decrypt(inode, dn, &dlen, page_block);
 651				if (err)
 652					goto out_err;
 653			}
 654
 655			err = ubifs_decompress(c, &dn->data, dlen, addr, &out_len,
 656					       le16_to_cpu(dn->compr_type));
 657			if (err || len != out_len)
 658				goto out_err;
 659
 660			if (len < UBIFS_BLOCK_SIZE)
 661				memset(addr + len, 0, UBIFS_BLOCK_SIZE - len);
 662
 663			nn += 1;
 664			read = (i << UBIFS_BLOCK_SHIFT) + len;
 665		} else if (key_block(c, &bu->zbranch[nn].key) < page_block) {
 666			nn += 1;
 667			continue;
 668		} else {
 669			hole = 1;
 670			memset(addr, 0, UBIFS_BLOCK_SIZE);
 671		}
 672		if (++i >= UBIFS_BLOCKS_PER_PAGE)
 673			break;
 674		addr += UBIFS_BLOCK_SIZE;
 675		page_block += 1;
 
 
 
 
 676	}
 677
 678	if (end_index == page->index) {
 679		int len = i_size & (PAGE_SIZE - 1);
 680
 681		if (len && len < read)
 682			memset(zaddr + len, 0, read - len);
 683	}
 684
 685out_hole:
 686	if (hole) {
 687		SetPageChecked(page);
 688		dbg_gen("hole");
 689	}
 690
 691	SetPageUptodate(page);
 692	ClearPageError(page);
 693	flush_dcache_page(page);
 694	kunmap(page);
 695	*n = nn;
 696	return 0;
 697
 698out_err:
 699	ClearPageUptodate(page);
 700	SetPageError(page);
 701	flush_dcache_page(page);
 702	kunmap(page);
 703	ubifs_err(c, "bad data node (block %u, inode %lu)",
 704		  page_block, inode->i_ino);
 705	return -EINVAL;
 706}
 707
 708/**
 709 * ubifs_do_bulk_read - do bulk-read.
 710 * @c: UBIFS file-system description object
 711 * @bu: bulk-read information
 712 * @page1: first page to read
 713 *
 714 * This function returns %1 if the bulk-read is done, otherwise %0 is returned.
 715 */
 716static int ubifs_do_bulk_read(struct ubifs_info *c, struct bu_info *bu,
 717			      struct page *page1)
 718{
 719	pgoff_t offset = page1->index, end_index;
 720	struct address_space *mapping = page1->mapping;
 721	struct inode *inode = mapping->host;
 722	struct ubifs_inode *ui = ubifs_inode(inode);
 723	int err, page_idx, page_cnt, ret = 0, n = 0;
 724	int allocate = bu->buf ? 0 : 1;
 725	loff_t isize;
 726	gfp_t ra_gfp_mask = readahead_gfp_mask(mapping) & ~__GFP_FS;
 727
 728	err = ubifs_tnc_get_bu_keys(c, bu);
 729	if (err)
 730		goto out_warn;
 731
 732	if (bu->eof) {
 733		/* Turn off bulk-read at the end of the file */
 734		ui->read_in_a_row = 1;
 735		ui->bulk_read = 0;
 736	}
 737
 738	page_cnt = bu->blk_cnt >> UBIFS_BLOCKS_PER_PAGE_SHIFT;
 739	if (!page_cnt) {
 740		/*
 741		 * This happens when there are multiple blocks per page and the
 742		 * blocks for the first page we are looking for, are not
 743		 * together. If all the pages were like this, bulk-read would
 744		 * reduce performance, so we turn it off for a while.
 745		 */
 746		goto out_bu_off;
 747	}
 748
 749	if (bu->cnt) {
 750		if (allocate) {
 751			/*
 752			 * Allocate bulk-read buffer depending on how many data
 753			 * nodes we are going to read.
 754			 */
 755			bu->buf_len = bu->zbranch[bu->cnt - 1].offs +
 756				      bu->zbranch[bu->cnt - 1].len -
 757				      bu->zbranch[0].offs;
 758			ubifs_assert(c, bu->buf_len > 0);
 759			ubifs_assert(c, bu->buf_len <= c->leb_size);
 760			bu->buf = kmalloc(bu->buf_len, GFP_NOFS | __GFP_NOWARN);
 761			if (!bu->buf)
 762				goto out_bu_off;
 763		}
 764
 765		err = ubifs_tnc_bulk_read(c, bu);
 766		if (err)
 767			goto out_warn;
 768	}
 769
 770	err = populate_page(c, page1, bu, &n);
 771	if (err)
 772		goto out_warn;
 773
 774	unlock_page(page1);
 775	ret = 1;
 776
 777	isize = i_size_read(inode);
 778	if (isize == 0)
 779		goto out_free;
 780	end_index = ((isize - 1) >> PAGE_SHIFT);
 781
 782	for (page_idx = 1; page_idx < page_cnt; page_idx++) {
 783		pgoff_t page_offset = offset + page_idx;
 784		struct page *page;
 785
 786		if (page_offset > end_index)
 787			break;
 788		page = pagecache_get_page(mapping, page_offset,
 789				 FGP_LOCK|FGP_ACCESSED|FGP_CREAT|FGP_NOWAIT,
 790				 ra_gfp_mask);
 791		if (!page)
 792			break;
 793		if (!PageUptodate(page))
 794			err = populate_page(c, page, bu, &n);
 795		unlock_page(page);
 796		put_page(page);
 797		if (err)
 798			break;
 799	}
 800
 801	ui->last_page_read = offset + page_idx - 1;
 802
 803out_free:
 804	if (allocate)
 805		kfree(bu->buf);
 806	return ret;
 807
 808out_warn:
 809	ubifs_warn(c, "ignoring error %d and skipping bulk-read", err);
 810	goto out_free;
 811
 812out_bu_off:
 813	ui->read_in_a_row = ui->bulk_read = 0;
 814	goto out_free;
 815}
 816
 817/**
 818 * ubifs_bulk_read - determine whether to bulk-read and, if so, do it.
 819 * @page: page from which to start bulk-read.
 820 *
 821 * Some flash media are capable of reading sequentially at faster rates. UBIFS
 822 * bulk-read facility is designed to take advantage of that, by reading in one
 823 * go consecutive data nodes that are also located consecutively in the same
 824 * LEB. This function returns %1 if a bulk-read is done and %0 otherwise.
 
 
 825 */
 826static int ubifs_bulk_read(struct page *page)
 827{
 828	struct inode *inode = page->mapping->host;
 829	struct ubifs_info *c = inode->i_sb->s_fs_info;
 830	struct ubifs_inode *ui = ubifs_inode(inode);
 831	pgoff_t index = page->index, last_page_read = ui->last_page_read;
 832	struct bu_info *bu;
 833	int err = 0, allocated = 0;
 834
 835	ui->last_page_read = index;
 836	if (!c->bulk_read)
 837		return 0;
 838
 839	/*
 840	 * Bulk-read is protected by @ui->ui_mutex, but it is an optimization,
 841	 * so don't bother if we cannot lock the mutex.
 842	 */
 843	if (!mutex_trylock(&ui->ui_mutex))
 844		return 0;
 845
 846	if (index != last_page_read + 1) {
 847		/* Turn off bulk-read if we stop reading sequentially */
 848		ui->read_in_a_row = 1;
 849		if (ui->bulk_read)
 850			ui->bulk_read = 0;
 851		goto out_unlock;
 852	}
 853
 854	if (!ui->bulk_read) {
 855		ui->read_in_a_row += 1;
 856		if (ui->read_in_a_row < 3)
 857			goto out_unlock;
 858		/* Three reads in a row, so switch on bulk-read */
 859		ui->bulk_read = 1;
 860	}
 861
 862	/*
 863	 * If possible, try to use pre-allocated bulk-read information, which
 864	 * is protected by @c->bu_mutex.
 865	 */
 866	if (mutex_trylock(&c->bu_mutex))
 867		bu = &c->bu;
 868	else {
 869		bu = kmalloc(sizeof(struct bu_info), GFP_NOFS | __GFP_NOWARN);
 870		if (!bu)
 871			goto out_unlock;
 872
 873		bu->buf = NULL;
 874		allocated = 1;
 875	}
 876
 877	bu->buf_len = c->max_bu_buf_len;
 878	data_key_init(c, &bu->key, inode->i_ino,
 879		      page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT);
 880	err = ubifs_do_bulk_read(c, bu, page);
 881
 882	if (!allocated)
 883		mutex_unlock(&c->bu_mutex);
 884	else
 885		kfree(bu);
 886
 887out_unlock:
 888	mutex_unlock(&ui->ui_mutex);
 889	return err;
 890}
 891
 892static int ubifs_read_folio(struct file *file, struct folio *folio)
 893{
 894	struct page *page = &folio->page;
 895
 896	if (ubifs_bulk_read(page))
 897		return 0;
 898	do_readpage(page);
 899	folio_unlock(folio);
 900	return 0;
 901}
 902
 903static int do_writepage(struct page *page, int len)
 904{
 905	int err = 0, i, blen;
 906	unsigned int block;
 907	void *addr;
 
 908	union ubifs_key key;
 909	struct inode *inode = page->mapping->host;
 910	struct ubifs_info *c = inode->i_sb->s_fs_info;
 911
 912#ifdef UBIFS_DEBUG
 913	struct ubifs_inode *ui = ubifs_inode(inode);
 914	spin_lock(&ui->ui_lock);
 915	ubifs_assert(c, page->index <= ui->synced_i_size >> PAGE_SHIFT);
 916	spin_unlock(&ui->ui_lock);
 917#endif
 918
 919	/* Update radix tree tags */
 920	set_page_writeback(page);
 921
 922	addr = kmap(page);
 923	block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT;
 924	i = 0;
 925	while (len) {
 926		blen = min_t(int, len, UBIFS_BLOCK_SIZE);
 927		data_key_init(c, &key, inode->i_ino, block);
 928		err = ubifs_jnl_write_data(c, inode, &key, addr, blen);
 929		if (err)
 930			break;
 931		if (++i >= UBIFS_BLOCKS_PER_PAGE)
 
 932			break;
 933		block += 1;
 934		addr += blen;
 935		len -= blen;
 
 
 
 
 936	}
 
 937	if (err) {
 938		SetPageError(page);
 939		ubifs_err(c, "cannot write page %lu of inode %lu, error %d",
 940			  page->index, inode->i_ino, err);
 941		ubifs_ro_mode(c, err);
 942	}
 943
 944	ubifs_assert(c, PagePrivate(page));
 945	if (PageChecked(page))
 946		release_new_page_budget(c);
 947	else
 948		release_existing_page_budget(c);
 949
 950	atomic_long_dec(&c->dirty_pg_cnt);
 951	detach_page_private(page);
 952	ClearPageChecked(page);
 953
 954	kunmap(page);
 955	unlock_page(page);
 956	end_page_writeback(page);
 957	return err;
 958}
 959
 960/*
 961 * When writing-back dirty inodes, VFS first writes-back pages belonging to the
 962 * inode, then the inode itself. For UBIFS this may cause a problem. Consider a
 963 * situation when a we have an inode with size 0, then a megabyte of data is
 964 * appended to the inode, then write-back starts and flushes some amount of the
 965 * dirty pages, the journal becomes full, commit happens and finishes, and then
 966 * an unclean reboot happens. When the file system is mounted next time, the
 967 * inode size would still be 0, but there would be many pages which are beyond
 968 * the inode size, they would be indexed and consume flash space. Because the
 969 * journal has been committed, the replay would not be able to detect this
 970 * situation and correct the inode size. This means UBIFS would have to scan
 971 * whole index and correct all inode sizes, which is long an unacceptable.
 972 *
 973 * To prevent situations like this, UBIFS writes pages back only if they are
 974 * within the last synchronized inode size, i.e. the size which has been
 975 * written to the flash media last time. Otherwise, UBIFS forces inode
 976 * write-back, thus making sure the on-flash inode contains current inode size,
 977 * and then keeps writing pages back.
 978 *
 979 * Some locking issues explanation. 'ubifs_writepage()' first is called with
 980 * the page locked, and it locks @ui_mutex. However, write-back does take inode
 981 * @i_mutex, which means other VFS operations may be run on this inode at the
 982 * same time. And the problematic one is truncation to smaller size, from where
 983 * we have to call 'truncate_setsize()', which first changes @inode->i_size,
 984 * then drops the truncated pages. And while dropping the pages, it takes the
 985 * page lock. This means that 'do_truncation()' cannot call 'truncate_setsize()'
 986 * with @ui_mutex locked, because it would deadlock with 'ubifs_writepage()'.
 987 * This means that @inode->i_size is changed while @ui_mutex is unlocked.
 988 *
 989 * XXX(truncate): with the new truncate sequence this is not true anymore,
 990 * and the calls to truncate_setsize can be move around freely.  They should
 991 * be moved to the very end of the truncate sequence.
 992 *
 993 * But in 'ubifs_writepage()' we have to guarantee that we do not write beyond
 994 * inode size. How do we do this if @inode->i_size may became smaller while we
 995 * are in the middle of 'ubifs_writepage()'? The UBIFS solution is the
 996 * @ui->ui_isize "shadow" field which UBIFS uses instead of @inode->i_size
 997 * internally and updates it under @ui_mutex.
 998 *
 999 * Q: why we do not worry that if we race with truncation, we may end up with a
1000 * situation when the inode is truncated while we are in the middle of
1001 * 'do_writepage()', so we do write beyond inode size?
1002 * A: If we are in the middle of 'do_writepage()', truncation would be locked
1003 * on the page lock and it would not write the truncated inode node to the
1004 * journal before we have finished.
1005 */
1006static int ubifs_writepage(struct page *page, struct writeback_control *wbc)
 
1007{
1008	struct inode *inode = page->mapping->host;
1009	struct ubifs_info *c = inode->i_sb->s_fs_info;
1010	struct ubifs_inode *ui = ubifs_inode(inode);
1011	loff_t i_size =  i_size_read(inode), synced_i_size;
1012	pgoff_t end_index = i_size >> PAGE_SHIFT;
1013	int err, len = i_size & (PAGE_SIZE - 1);
1014	void *kaddr;
1015
1016	dbg_gen("ino %lu, pg %lu, pg flags %#lx",
1017		inode->i_ino, page->index, page->flags);
1018	ubifs_assert(c, PagePrivate(page));
1019
1020	/* Is the page fully outside @i_size? (truncate in progress) */
1021	if (page->index > end_index || (page->index == end_index && !len)) {
1022		err = 0;
1023		goto out_unlock;
1024	}
1025
1026	spin_lock(&ui->ui_lock);
1027	synced_i_size = ui->synced_i_size;
1028	spin_unlock(&ui->ui_lock);
1029
1030	/* Is the page fully inside @i_size? */
1031	if (page->index < end_index) {
1032		if (page->index >= synced_i_size >> PAGE_SHIFT) {
1033			err = inode->i_sb->s_op->write_inode(inode, NULL);
1034			if (err)
1035				goto out_unlock;
1036			/*
1037			 * The inode has been written, but the write-buffer has
1038			 * not been synchronized, so in case of an unclean
1039			 * reboot we may end up with some pages beyond inode
1040			 * size, but they would be in the journal (because
1041			 * commit flushes write buffers) and recovery would deal
1042			 * with this.
1043			 */
1044		}
1045		return do_writepage(page, PAGE_SIZE);
1046	}
1047
1048	/*
1049	 * The page straddles @i_size. It must be zeroed out on each and every
1050	 * writepage invocation because it may be mmapped. "A file is mapped
1051	 * in multiples of the page size. For a file that is not a multiple of
1052	 * the page size, the remaining memory is zeroed when mapped, and
1053	 * writes to that region are not written out to the file."
1054	 */
1055	kaddr = kmap_atomic(page);
1056	memset(kaddr + len, 0, PAGE_SIZE - len);
1057	flush_dcache_page(page);
1058	kunmap_atomic(kaddr);
1059
1060	if (i_size > synced_i_size) {
1061		err = inode->i_sb->s_op->write_inode(inode, NULL);
1062		if (err)
1063			goto out_unlock;
1064	}
1065
1066	return do_writepage(page, len);
1067
 
 
 
 
 
 
1068out_unlock:
1069	unlock_page(page);
1070	return err;
1071}
1072
 
 
 
 
 
 
1073/**
1074 * do_attr_changes - change inode attributes.
1075 * @inode: inode to change attributes for
1076 * @attr: describes attributes to change
1077 */
1078static void do_attr_changes(struct inode *inode, const struct iattr *attr)
1079{
1080	if (attr->ia_valid & ATTR_UID)
1081		inode->i_uid = attr->ia_uid;
1082	if (attr->ia_valid & ATTR_GID)
1083		inode->i_gid = attr->ia_gid;
1084	if (attr->ia_valid & ATTR_ATIME)
1085		inode->i_atime = attr->ia_atime;
1086	if (attr->ia_valid & ATTR_MTIME)
1087		inode->i_mtime = attr->ia_mtime;
1088	if (attr->ia_valid & ATTR_CTIME)
1089		inode->i_ctime = attr->ia_ctime;
1090	if (attr->ia_valid & ATTR_MODE) {
1091		umode_t mode = attr->ia_mode;
1092
1093		if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
1094			mode &= ~S_ISGID;
1095		inode->i_mode = mode;
1096	}
1097}
1098
1099/**
1100 * do_truncation - truncate an inode.
1101 * @c: UBIFS file-system description object
1102 * @inode: inode to truncate
1103 * @attr: inode attribute changes description
1104 *
1105 * This function implements VFS '->setattr()' call when the inode is truncated
1106 * to a smaller size. Returns zero in case of success and a negative error code
 
 
1107 * in case of failure.
1108 */
1109static int do_truncation(struct ubifs_info *c, struct inode *inode,
1110			 const struct iattr *attr)
1111{
1112	int err;
1113	struct ubifs_budget_req req;
1114	loff_t old_size = inode->i_size, new_size = attr->ia_size;
1115	int offset = new_size & (UBIFS_BLOCK_SIZE - 1), budgeted = 1;
1116	struct ubifs_inode *ui = ubifs_inode(inode);
1117
1118	dbg_gen("ino %lu, size %lld -> %lld", inode->i_ino, old_size, new_size);
1119	memset(&req, 0, sizeof(struct ubifs_budget_req));
1120
1121	/*
1122	 * If this is truncation to a smaller size, and we do not truncate on a
1123	 * block boundary, budget for changing one data block, because the last
1124	 * block will be re-written.
1125	 */
1126	if (new_size & (UBIFS_BLOCK_SIZE - 1))
1127		req.dirtied_page = 1;
1128
1129	req.dirtied_ino = 1;
1130	/* A funny way to budget for truncation node */
1131	req.dirtied_ino_d = UBIFS_TRUN_NODE_SZ;
1132	err = ubifs_budget_space(c, &req);
1133	if (err) {
1134		/*
1135		 * Treat truncations to zero as deletion and always allow them,
1136		 * just like we do for '->unlink()'.
1137		 */
1138		if (new_size || err != -ENOSPC)
1139			return err;
1140		budgeted = 0;
1141	}
1142
1143	truncate_setsize(inode, new_size);
1144
1145	if (offset) {
1146		pgoff_t index = new_size >> PAGE_SHIFT;
1147		struct page *page;
1148
1149		page = find_lock_page(inode->i_mapping, index);
1150		if (page) {
1151			if (PageDirty(page)) {
1152				/*
1153				 * 'ubifs_jnl_truncate()' will try to truncate
1154				 * the last data node, but it contains
1155				 * out-of-date data because the page is dirty.
1156				 * Write the page now, so that
1157				 * 'ubifs_jnl_truncate()' will see an already
1158				 * truncated (and up to date) data node.
1159				 */
1160				ubifs_assert(c, PagePrivate(page));
1161
1162				clear_page_dirty_for_io(page);
1163				if (UBIFS_BLOCKS_PER_PAGE_SHIFT)
1164					offset = new_size &
1165						 (PAGE_SIZE - 1);
1166				err = do_writepage(page, offset);
1167				put_page(page);
1168				if (err)
1169					goto out_budg;
1170				/*
1171				 * We could now tell 'ubifs_jnl_truncate()' not
1172				 * to read the last block.
1173				 */
1174			} else {
1175				/*
1176				 * We could 'kmap()' the page and pass the data
1177				 * to 'ubifs_jnl_truncate()' to save it from
1178				 * having to read it.
1179				 */
1180				unlock_page(page);
1181				put_page(page);
1182			}
1183		}
1184	}
1185
1186	mutex_lock(&ui->ui_mutex);
1187	ui->ui_size = inode->i_size;
1188	/* Truncation changes inode [mc]time */
1189	inode->i_mtime = inode->i_ctime = current_time(inode);
1190	/* Other attributes may be changed at the same time as well */
1191	do_attr_changes(inode, attr);
1192	err = ubifs_jnl_truncate(c, inode, old_size, new_size);
1193	mutex_unlock(&ui->ui_mutex);
1194
1195out_budg:
1196	if (budgeted)
1197		ubifs_release_budget(c, &req);
1198	else {
1199		c->bi.nospace = c->bi.nospace_rp = 0;
1200		smp_wmb();
1201	}
1202	return err;
1203}
1204
1205/**
1206 * do_setattr - change inode attributes.
1207 * @c: UBIFS file-system description object
1208 * @inode: inode to change attributes for
1209 * @attr: inode attribute changes description
1210 *
1211 * This function implements VFS '->setattr()' call for all cases except
1212 * truncations to smaller size. Returns zero in case of success and a negative
 
 
1213 * error code in case of failure.
1214 */
1215static int do_setattr(struct ubifs_info *c, struct inode *inode,
1216		      const struct iattr *attr)
1217{
1218	int err, release;
1219	loff_t new_size = attr->ia_size;
1220	struct ubifs_inode *ui = ubifs_inode(inode);
1221	struct ubifs_budget_req req = { .dirtied_ino = 1,
1222				.dirtied_ino_d = ALIGN(ui->data_len, 8) };
1223
1224	err = ubifs_budget_space(c, &req);
1225	if (err)
1226		return err;
1227
1228	if (attr->ia_valid & ATTR_SIZE) {
1229		dbg_gen("size %lld -> %lld", inode->i_size, new_size);
1230		truncate_setsize(inode, new_size);
1231	}
1232
1233	mutex_lock(&ui->ui_mutex);
1234	if (attr->ia_valid & ATTR_SIZE) {
1235		/* Truncation changes inode [mc]time */
1236		inode->i_mtime = inode->i_ctime = current_time(inode);
1237		/* 'truncate_setsize()' changed @i_size, update @ui_size */
1238		ui->ui_size = inode->i_size;
1239	}
1240
1241	do_attr_changes(inode, attr);
1242
1243	release = ui->dirty;
1244	if (attr->ia_valid & ATTR_SIZE)
1245		/*
1246		 * Inode length changed, so we have to make sure
1247		 * @I_DIRTY_DATASYNC is set.
1248		 */
1249		 __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1250	else
1251		mark_inode_dirty_sync(inode);
1252	mutex_unlock(&ui->ui_mutex);
1253
1254	if (release)
1255		ubifs_release_budget(c, &req);
1256	if (IS_SYNC(inode))
1257		err = inode->i_sb->s_op->write_inode(inode, NULL);
1258	return err;
1259}
1260
1261int ubifs_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
1262		  struct iattr *attr)
1263{
1264	int err;
1265	struct inode *inode = d_inode(dentry);
1266	struct ubifs_info *c = inode->i_sb->s_fs_info;
1267
1268	dbg_gen("ino %lu, mode %#x, ia_valid %#x",
1269		inode->i_ino, inode->i_mode, attr->ia_valid);
1270	err = setattr_prepare(&init_user_ns, dentry, attr);
1271	if (err)
1272		return err;
1273
1274	err = dbg_check_synced_i_size(c, inode);
1275	if (err)
1276		return err;
1277
1278	err = fscrypt_prepare_setattr(dentry, attr);
1279	if (err)
1280		return err;
1281
1282	if ((attr->ia_valid & ATTR_SIZE) && attr->ia_size < inode->i_size)
1283		/* Truncation to a smaller size */
1284		err = do_truncation(c, inode, attr);
1285	else
1286		err = do_setattr(c, inode, attr);
1287
1288	return err;
1289}
1290
1291static void ubifs_invalidate_folio(struct folio *folio, size_t offset,
1292				 size_t length)
1293{
1294	struct inode *inode = folio->mapping->host;
1295	struct ubifs_info *c = inode->i_sb->s_fs_info;
1296
1297	ubifs_assert(c, folio_test_private(folio));
1298	if (offset || length < folio_size(folio))
1299		/* Partial folio remains dirty */
1300		return;
1301
1302	if (folio_test_checked(folio))
1303		release_new_page_budget(c);
1304	else
1305		release_existing_page_budget(c);
1306
1307	atomic_long_dec(&c->dirty_pg_cnt);
1308	folio_detach_private(folio);
1309	folio_clear_checked(folio);
1310}
1311
1312int ubifs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
1313{
1314	struct inode *inode = file->f_mapping->host;
1315	struct ubifs_info *c = inode->i_sb->s_fs_info;
1316	int err;
1317
1318	dbg_gen("syncing inode %lu", inode->i_ino);
1319
1320	if (c->ro_mount)
1321		/*
1322		 * For some really strange reasons VFS does not filter out
1323		 * 'fsync()' for R/O mounted file-systems as per 2.6.39.
1324		 */
1325		return 0;
1326
1327	err = file_write_and_wait_range(file, start, end);
1328	if (err)
1329		return err;
1330	inode_lock(inode);
1331
1332	/* Synchronize the inode unless this is a 'datasync()' call. */
1333	if (!datasync || (inode->i_state & I_DIRTY_DATASYNC)) {
1334		err = inode->i_sb->s_op->write_inode(inode, NULL);
1335		if (err)
1336			goto out;
1337	}
1338
1339	/*
1340	 * Nodes related to this inode may still sit in a write-buffer. Flush
1341	 * them.
1342	 */
1343	err = ubifs_sync_wbufs_by_inode(c, inode);
1344out:
1345	inode_unlock(inode);
1346	return err;
1347}
1348
1349/**
1350 * mctime_update_needed - check if mtime or ctime update is needed.
1351 * @inode: the inode to do the check for
1352 * @now: current time
1353 *
1354 * This helper function checks if the inode mtime/ctime should be updated or
1355 * not. If current values of the time-stamps are within the UBIFS inode time
1356 * granularity, they are not updated. This is an optimization.
 
 
1357 */
1358static inline int mctime_update_needed(const struct inode *inode,
1359				       const struct timespec64 *now)
1360{
1361	if (!timespec64_equal(&inode->i_mtime, now) ||
1362	    !timespec64_equal(&inode->i_ctime, now))
 
 
1363		return 1;
1364	return 0;
1365}
1366
1367/**
1368 * ubifs_update_time - update time of inode.
1369 * @inode: inode to update
 
 
1370 *
1371 * This function updates time of the inode.
 
 
1372 */
1373int ubifs_update_time(struct inode *inode, struct timespec64 *time,
1374			     int flags)
1375{
1376	struct ubifs_inode *ui = ubifs_inode(inode);
1377	struct ubifs_info *c = inode->i_sb->s_fs_info;
1378	struct ubifs_budget_req req = { .dirtied_ino = 1,
1379			.dirtied_ino_d = ALIGN(ui->data_len, 8) };
1380	int err, release;
1381
1382	if (!IS_ENABLED(CONFIG_UBIFS_ATIME_SUPPORT))
1383		return generic_update_time(inode, time, flags);
 
 
1384
1385	err = ubifs_budget_space(c, &req);
1386	if (err)
1387		return err;
1388
1389	mutex_lock(&ui->ui_mutex);
1390	if (flags & S_ATIME)
1391		inode->i_atime = *time;
1392	if (flags & S_CTIME)
1393		inode->i_ctime = *time;
1394	if (flags & S_MTIME)
1395		inode->i_mtime = *time;
1396
1397	release = ui->dirty;
1398	__mark_inode_dirty(inode, I_DIRTY_SYNC);
1399	mutex_unlock(&ui->ui_mutex);
1400	if (release)
1401		ubifs_release_budget(c, &req);
1402	return 0;
1403}
1404
1405/**
1406 * update_mctime - update mtime and ctime of an inode.
1407 * @inode: inode to update
1408 *
1409 * This function updates mtime and ctime of the inode if it is not equivalent to
1410 * current time. Returns zero in case of success and a negative error code in
 
 
1411 * case of failure.
1412 */
1413static int update_mctime(struct inode *inode)
1414{
1415	struct timespec64 now = current_time(inode);
1416	struct ubifs_inode *ui = ubifs_inode(inode);
1417	struct ubifs_info *c = inode->i_sb->s_fs_info;
1418
1419	if (mctime_update_needed(inode, &now)) {
1420		int err, release;
1421		struct ubifs_budget_req req = { .dirtied_ino = 1,
1422				.dirtied_ino_d = ALIGN(ui->data_len, 8) };
1423
1424		err = ubifs_budget_space(c, &req);
1425		if (err)
1426			return err;
1427
1428		mutex_lock(&ui->ui_mutex);
1429		inode->i_mtime = inode->i_ctime = current_time(inode);
1430		release = ui->dirty;
1431		mark_inode_dirty_sync(inode);
1432		mutex_unlock(&ui->ui_mutex);
1433		if (release)
1434			ubifs_release_budget(c, &req);
1435	}
1436
1437	return 0;
1438}
1439
1440static ssize_t ubifs_write_iter(struct kiocb *iocb, struct iov_iter *from)
1441{
1442	int err = update_mctime(file_inode(iocb->ki_filp));
1443	if (err)
1444		return err;
1445
1446	return generic_file_write_iter(iocb, from);
1447}
1448
1449static bool ubifs_dirty_folio(struct address_space *mapping,
1450		struct folio *folio)
1451{
1452	bool ret;
1453	struct ubifs_info *c = mapping->host->i_sb->s_fs_info;
1454
1455	ret = filemap_dirty_folio(mapping, folio);
1456	/*
1457	 * An attempt to dirty a page without budgeting for it - should not
1458	 * happen.
1459	 */
1460	ubifs_assert(c, ret == false);
1461	return ret;
1462}
1463
1464static bool ubifs_release_folio(struct folio *folio, gfp_t unused_gfp_flags)
1465{
1466	struct inode *inode = folio->mapping->host;
1467	struct ubifs_info *c = inode->i_sb->s_fs_info;
1468
1469	/*
1470	 * An attempt to release a dirty page without budgeting for it - should
1471	 * not happen.
1472	 */
1473	if (folio_test_writeback(folio))
1474		return false;
 
 
 
 
 
 
 
 
1475	ubifs_assert(c, folio_test_private(folio));
1476	ubifs_assert(c, 0);
 
 
 
 
 
1477	folio_detach_private(folio);
1478	folio_clear_checked(folio);
1479	return true;
1480}
1481
1482/*
1483 * mmap()d file has taken write protection fault and is being made writable.
1484 * UBIFS must ensure page is budgeted for.
1485 */
1486static vm_fault_t ubifs_vm_page_mkwrite(struct vm_fault *vmf)
1487{
1488	struct page *page = vmf->page;
1489	struct inode *inode = file_inode(vmf->vma->vm_file);
1490	struct ubifs_info *c = inode->i_sb->s_fs_info;
1491	struct timespec64 now = current_time(inode);
1492	struct ubifs_budget_req req = { .new_page = 1 };
1493	int err, update_time;
1494
1495	dbg_gen("ino %lu, pg %lu, i_size %lld",	inode->i_ino, page->index,
1496		i_size_read(inode));
1497	ubifs_assert(c, !c->ro_media && !c->ro_mount);
1498
1499	if (unlikely(c->ro_error))
1500		return VM_FAULT_SIGBUS; /* -EROFS */
1501
1502	/*
1503	 * We have not locked @page so far so we may budget for changing the
1504	 * page. Note, we cannot do this after we locked the page, because
1505	 * budgeting may cause write-back which would cause deadlock.
1506	 *
1507	 * At the moment we do not know whether the page is dirty or not, so we
1508	 * assume that it is not and budget for a new page. We could look at
1509	 * the @PG_private flag and figure this out, but we may race with write
1510	 * back and the page state may change by the time we lock it, so this
1511	 * would need additional care. We do not bother with this at the
1512	 * moment, although it might be good idea to do. Instead, we allocate
1513	 * budget for a new page and amend it later on if the page was in fact
1514	 * dirty.
1515	 *
1516	 * The budgeting-related logic of this function is similar to what we
1517	 * do in 'ubifs_write_begin()' and 'ubifs_write_end()'. Glance there
1518	 * for more comments.
1519	 */
1520	update_time = mctime_update_needed(inode, &now);
1521	if (update_time)
1522		/*
1523		 * We have to change inode time stamp which requires extra
1524		 * budgeting.
1525		 */
1526		req.dirtied_ino = 1;
1527
1528	err = ubifs_budget_space(c, &req);
1529	if (unlikely(err)) {
1530		if (err == -ENOSPC)
1531			ubifs_warn(c, "out of space for mmapped file (inode number %lu)",
1532				   inode->i_ino);
1533		return VM_FAULT_SIGBUS;
1534	}
1535
1536	lock_page(page);
1537	if (unlikely(page->mapping != inode->i_mapping ||
1538		     page_offset(page) > i_size_read(inode))) {
1539		/* Page got truncated out from underneath us */
1540		goto sigbus;
1541	}
1542
1543	if (PagePrivate(page))
1544		release_new_page_budget(c);
1545	else {
1546		if (!PageChecked(page))
1547			ubifs_convert_page_budget(c);
1548		attach_page_private(page, (void *)1);
1549		atomic_long_inc(&c->dirty_pg_cnt);
1550		__set_page_dirty_nobuffers(page);
1551	}
1552
1553	if (update_time) {
1554		int release;
1555		struct ubifs_inode *ui = ubifs_inode(inode);
1556
1557		mutex_lock(&ui->ui_mutex);
1558		inode->i_mtime = inode->i_ctime = current_time(inode);
1559		release = ui->dirty;
1560		mark_inode_dirty_sync(inode);
1561		mutex_unlock(&ui->ui_mutex);
1562		if (release)
1563			ubifs_release_dirty_inode_budget(c, ui);
1564	}
1565
1566	wait_for_stable_page(page);
1567	return VM_FAULT_LOCKED;
1568
1569sigbus:
1570	unlock_page(page);
1571	ubifs_release_budget(c, &req);
1572	return VM_FAULT_SIGBUS;
1573}
1574
1575static const struct vm_operations_struct ubifs_file_vm_ops = {
1576	.fault        = filemap_fault,
1577	.map_pages = filemap_map_pages,
1578	.page_mkwrite = ubifs_vm_page_mkwrite,
1579};
1580
1581static int ubifs_file_mmap(struct file *file, struct vm_area_struct *vma)
1582{
1583	int err;
1584
1585	err = generic_file_mmap(file, vma);
1586	if (err)
1587		return err;
1588	vma->vm_ops = &ubifs_file_vm_ops;
1589
1590	if (IS_ENABLED(CONFIG_UBIFS_ATIME_SUPPORT))
1591		file_accessed(file);
1592
1593	return 0;
1594}
1595
1596static const char *ubifs_get_link(struct dentry *dentry,
1597					    struct inode *inode,
1598					    struct delayed_call *done)
1599{
1600	struct ubifs_inode *ui = ubifs_inode(inode);
1601
1602	if (!IS_ENCRYPTED(inode))
1603		return ui->data;
1604
1605	if (!dentry)
1606		return ERR_PTR(-ECHILD);
1607
1608	return fscrypt_get_symlink(inode, ui->data, ui->data_len, done);
1609}
1610
1611static int ubifs_symlink_getattr(struct user_namespace *mnt_userns,
1612				 const struct path *path, struct kstat *stat,
1613				 u32 request_mask, unsigned int query_flags)
1614{
1615	ubifs_getattr(mnt_userns, path, stat, request_mask, query_flags);
1616
1617	if (IS_ENCRYPTED(d_inode(path->dentry)))
1618		return fscrypt_symlink_getattr(path, stat);
1619	return 0;
1620}
1621
1622const struct address_space_operations ubifs_file_address_operations = {
1623	.read_folio     = ubifs_read_folio,
1624	.writepage      = ubifs_writepage,
1625	.write_begin    = ubifs_write_begin,
1626	.write_end      = ubifs_write_end,
1627	.invalidate_folio = ubifs_invalidate_folio,
1628	.dirty_folio	= ubifs_dirty_folio,
1629	.migrate_folio	= filemap_migrate_folio,
1630	.release_folio	= ubifs_release_folio,
1631};
1632
1633const struct inode_operations ubifs_file_inode_operations = {
1634	.setattr     = ubifs_setattr,
1635	.getattr     = ubifs_getattr,
1636	.listxattr   = ubifs_listxattr,
1637	.update_time = ubifs_update_time,
1638	.fileattr_get = ubifs_fileattr_get,
1639	.fileattr_set = ubifs_fileattr_set,
1640};
1641
1642const struct inode_operations ubifs_symlink_inode_operations = {
1643	.get_link    = ubifs_get_link,
1644	.setattr     = ubifs_setattr,
1645	.getattr     = ubifs_symlink_getattr,
1646	.listxattr   = ubifs_listxattr,
1647	.update_time = ubifs_update_time,
1648};
1649
1650const struct file_operations ubifs_file_operations = {
1651	.llseek         = generic_file_llseek,
1652	.read_iter      = generic_file_read_iter,
1653	.write_iter     = ubifs_write_iter,
1654	.mmap           = ubifs_file_mmap,
1655	.fsync          = ubifs_fsync,
1656	.unlocked_ioctl = ubifs_ioctl,
1657	.splice_read	= generic_file_splice_read,
1658	.splice_write	= iter_file_splice_write,
1659	.open		= fscrypt_file_open,
1660#ifdef CONFIG_COMPAT
1661	.compat_ioctl   = ubifs_compat_ioctl,
1662#endif
1663};