1/*
   2 * This file is part of UBIFS.
   3 *
   4 * Copyright (C) 2006-2008 Nokia Corporation.
   5 *
   6 * This program is free software; you can redistribute it and/or modify it
   7 * under the terms of the GNU General Public License version 2 as published by
   8 * the Free Software Foundation.
   9 *
  10 * This program is distributed in the hope that it will be useful, but WITHOUT
  11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13 * more details.
  14 *
  15 * You should have received a copy of the GNU General Public License along with
  16 * this program; if not, write to the Free Software Foundation, Inc., 51
  17 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  18 *
  19 * Authors: Artem Bityutskiy (Битюцкий Артём)
  20 *          Adrian Hunter
  21 */
  22
  23/*
  24 * This file implements VFS file and inode operations for regular files, device
  25 * nodes and symlinks as well as address space operations.
  26 *
  27 * UBIFS uses 2 page flags: @PG_private and @PG_checked. @PG_private is set if
  28 * the page is dirty and is used for optimization purposes - dirty pages are
  29 * not budgeted so the flag shows that 'ubifs_write_end()' should not release
  30 * the budget for this page. The @PG_checked flag is set if full budgeting is
  31 * required for the page e.g., when it corresponds to a file hole or it is
  32 * beyond the file size. The budgeting is done in 'ubifs_write_begin()', because
  33 * it is OK to fail in this function, and the budget is released in
  34 * 'ubifs_write_end()'. So the @PG_private and @PG_checked flags carry
  35 * information about how the page was budgeted, to make it possible to release
  36 * the budget properly.
  37 *
  38 * A thing to keep in mind: inode @i_mutex is locked in most VFS operations we
  39 * implement. However, this is not true for 'ubifs_writepage()', which may be
  40 * called with @i_mutex unlocked. For example, when pdflush is doing background
  41 * write-back, it calls 'ubifs_writepage()' with unlocked @i_mutex. At "normal"
  42 * work-paths the @i_mutex is locked in 'ubifs_writepage()', e.g. in the
  43 * "sys_write -> alloc_pages -> direct reclaim path". So, in 'ubifs_writepage()'
  44 * we are only guaranteed that the page is locked.
  45 *
  46 * Similarly, @i_mutex is not always locked in 'ubifs_readpage()', e.g., the
  47 * read-ahead path does not lock it ("sys_read -> generic_file_aio_read ->
  48 * ondemand_readahead -> readpage"). In case of readahead, @I_SYNC flag is not
  49 * set as well. However, UBIFS disables readahead.
  50 */
  51
  52#include "ubifs.h"
  53#include <linux/mount.h>
  54#include <linux/namei.h>
  55#include <linux/slab.h>
 
  56
  57static int read_block(struct inode *inode, void *addr, unsigned int block,
  58		      struct ubifs_data_node *dn)
  59{
  60	struct ubifs_info *c = inode->i_sb->s_fs_info;
  61	int err, len, out_len;
  62	union ubifs_key key;
  63	unsigned int dlen;
  64
  65	data_key_init(c, &key, inode->i_ino, block);
  66	err = ubifs_tnc_lookup(c, &key, dn);
  67	if (err) {
  68		if (err == -ENOENT)
  69			/* Not found, so it must be a hole */
  70			memset(addr, 0, UBIFS_BLOCK_SIZE);
  71		return err;
  72	}
  73
  74	ubifs_assert(le64_to_cpu(dn->ch.sqnum) >
  75		     ubifs_inode(inode)->creat_sqnum);
  76	len = le32_to_cpu(dn->size);
  77	if (len <= 0 || len > UBIFS_BLOCK_SIZE)
  78		goto dump;
  79
  80	dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ;
 
 
 
 
 
 
 
  81	out_len = UBIFS_BLOCK_SIZE;
  82	err = ubifs_decompress(&dn->data, dlen, addr, &out_len,
  83			       le16_to_cpu(dn->compr_type));
  84	if (err || len != out_len)
  85		goto dump;
  86
  87	/*
  88	 * Data length can be less than a full block, even for blocks that are
  89	 * not the last in the file (e.g., as a result of making a hole and
  90	 * appending data). Ensure that the remainder is zeroed out.
  91	 */
  92	if (len < UBIFS_BLOCK_SIZE)
  93		memset(addr + len, 0, UBIFS_BLOCK_SIZE - len);
  94
  95	return 0;
  96
  97dump:
  98	ubifs_err("bad data node (block %u, inode %lu)",
  99		  block, inode->i_ino);
 100	dbg_dump_node(c, dn);
 101	return -EINVAL;
 102}
 103
 104static int do_readpage(struct page *page)
 105{
 106	void *addr;
 107	int err = 0, i;
 108	unsigned int block, beyond;
 109	struct ubifs_data_node *dn;
 110	struct inode *inode = page->mapping->host;
 
 111	loff_t i_size = i_size_read(inode);
 112
 113	dbg_gen("ino %lu, pg %lu, i_size %lld, flags %#lx",
 114		inode->i_ino, page->index, i_size, page->flags);
 115	ubifs_assert(!PageChecked(page));
 116	ubifs_assert(!PagePrivate(page));
 117
 118	addr = kmap(page);
 119
 120	block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT;
 121	beyond = (i_size + UBIFS_BLOCK_SIZE - 1) >> UBIFS_BLOCK_SHIFT;
 122	if (block >= beyond) {
 123		/* Reading beyond inode */
 124		SetPageChecked(page);
 125		memset(addr, 0, PAGE_CACHE_SIZE);
 126		goto out;
 127	}
 128
 129	dn = kmalloc(UBIFS_MAX_DATA_NODE_SZ, GFP_NOFS);
 130	if (!dn) {
 131		err = -ENOMEM;
 132		goto error;
 133	}
 134
 135	i = 0;
 136	while (1) {
 137		int ret;
 138
 139		if (block >= beyond) {
 140			/* Reading beyond inode */
 141			err = -ENOENT;
 142			memset(addr, 0, UBIFS_BLOCK_SIZE);
 143		} else {
 144			ret = read_block(inode, addr, block, dn);
 145			if (ret) {
 146				err = ret;
 147				if (err != -ENOENT)
 148					break;
 149			} else if (block + 1 == beyond) {
 150				int dlen = le32_to_cpu(dn->size);
 151				int ilen = i_size & (UBIFS_BLOCK_SIZE - 1);
 152
 153				if (ilen && ilen < dlen)
 154					memset(addr + ilen, 0, dlen - ilen);
 155			}
 156		}
 157		if (++i >= UBIFS_BLOCKS_PER_PAGE)
 158			break;
 159		block += 1;
 160		addr += UBIFS_BLOCK_SIZE;
 
 
 
 
 161	}
 
 162	if (err) {
 
 163		if (err == -ENOENT) {
 164			/* Not found, so it must be a hole */
 165			SetPageChecked(page);
 166			dbg_gen("hole");
 167			goto out_free;
 
 
 
 168		}
 169		ubifs_err("cannot read page %lu of inode %lu, error %d",
 170			  page->index, inode->i_ino, err);
 171		goto error;
 172	}
 173
 174out_free:
 175	kfree(dn);
 176out:
 177	SetPageUptodate(page);
 178	ClearPageError(page);
 179	flush_dcache_page(page);
 180	kunmap(page);
 181	return 0;
 182
 183error:
 184	kfree(dn);
 185	ClearPageUptodate(page);
 186	SetPageError(page);
 187	flush_dcache_page(page);
 188	kunmap(page);
 189	return err;
 190}
 191
 192/**
 193 * release_new_page_budget - release budget of a new page.
 194 * @c: UBIFS file-system description object
 195 *
 196 * This is a helper function which releases budget corresponding to the budget
 197 * of one new page of data.
 198 */
 199static void release_new_page_budget(struct ubifs_info *c)
 200{
 201	struct ubifs_budget_req req = { .recalculate = 1, .new_page = 1 };
 202
 203	ubifs_release_budget(c, &req);
 204}
 205
 206/**
 207 * release_existing_page_budget - release budget of an existing page.
 208 * @c: UBIFS file-system description object
 209 *
 210 * This is a helper function which releases budget corresponding to the budget
 211 * of changing one one page of data which already exists on the flash media.
 212 */
 213static void release_existing_page_budget(struct ubifs_info *c)
 214{
 215	struct ubifs_budget_req req = { .dd_growth = c->bi.page_budget};
 216
 217	ubifs_release_budget(c, &req);
 218}
 219
 220static int write_begin_slow(struct address_space *mapping,
 221			    loff_t pos, unsigned len, struct page **pagep,
 222			    unsigned flags)
 223{
 224	struct inode *inode = mapping->host;
 225	struct ubifs_info *c = inode->i_sb->s_fs_info;
 226	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
 227	struct ubifs_budget_req req = { .new_page = 1 };
 228	int uninitialized_var(err), appending = !!(pos + len > inode->i_size);
 229	struct page *page;
 230
 231	dbg_gen("ino %lu, pos %llu, len %u, i_size %lld",
 232		inode->i_ino, pos, len, inode->i_size);
 233
 234	/*
 235	 * At the slow path we have to budget before locking the page, because
 236	 * budgeting may force write-back, which would wait on locked pages and
 237	 * deadlock if we had the page locked. At this point we do not know
 238	 * anything about the page, so assume that this is a new page which is
 239	 * written to a hole. This corresponds to largest budget. Later the
 240	 * budget will be amended if this is not true.
 241	 */
 242	if (appending)
 243		/* We are appending data, budget for inode change */
 244		req.dirtied_ino = 1;
 245
 246	err = ubifs_budget_space(c, &req);
 247	if (unlikely(err))
 248		return err;
 249
 250	page = grab_cache_page_write_begin(mapping, index, flags);
 251	if (unlikely(!page)) {
 
 252		ubifs_release_budget(c, &req);
 253		return -ENOMEM;
 254	}
 255
 256	if (!PageUptodate(page)) {
 257		if (!(pos & ~PAGE_CACHE_MASK) && len == PAGE_CACHE_SIZE)
 258			SetPageChecked(page);
 259		else {
 260			err = do_readpage(page);
 261			if (err) {
 262				unlock_page(page);
 263				page_cache_release(page);
 
 264				return err;
 265			}
 266		}
 267
 268		SetPageUptodate(page);
 269		ClearPageError(page);
 270	}
 271
 272	if (PagePrivate(page))
 273		/*
 274		 * The page is dirty, which means it was budgeted twice:
 275		 *   o first time the budget was allocated by the task which
 276		 *     made the page dirty and set the PG_private flag;
 277		 *   o and then we budgeted for it for the second time at the
 278		 *     very beginning of this function.
 279		 *
 280		 * So what we have to do is to release the page budget we
 281		 * allocated.
 282		 */
 283		release_new_page_budget(c);
 284	else if (!PageChecked(page))
 285		/*
 286		 * We are changing a page which already exists on the media.
 287		 * This means that changing the page does not make the amount
 288		 * of indexing information larger, and this part of the budget
 289		 * which we have already acquired may be released.
 290		 */
 291		ubifs_convert_page_budget(c);
 292
 293	if (appending) {
 294		struct ubifs_inode *ui = ubifs_inode(inode);
 295
 296		/*
 297		 * 'ubifs_write_end()' is optimized from the fast-path part of
 298		 * 'ubifs_write_begin()' and expects the @ui_mutex to be locked
 299		 * if data is appended.
 300		 */
 301		mutex_lock(&ui->ui_mutex);
 302		if (ui->dirty)
 303			/*
 304			 * The inode is dirty already, so we may free the
 305			 * budget we allocated.
 306			 */
 307			ubifs_release_dirty_inode_budget(c, ui);
 308	}
 309
 310	*pagep = page;
 311	return 0;
 312}
 313
 314/**
 315 * allocate_budget - allocate budget for 'ubifs_write_begin()'.
 316 * @c: UBIFS file-system description object
 317 * @page: page to allocate budget for
 318 * @ui: UBIFS inode object the page belongs to
 319 * @appending: non-zero if the page is appended
 320 *
 321 * This is a helper function for 'ubifs_write_begin()' which allocates budget
 322 * for the operation. The budget is allocated differently depending on whether
 323 * this is appending, whether the page is dirty or not, and so on. This
 324 * function leaves the @ui->ui_mutex locked in case of appending. Returns zero
 325 * in case of success and %-ENOSPC in case of failure.
 
 326 */
 327static int allocate_budget(struct ubifs_info *c, struct page *page,
 328			   struct ubifs_inode *ui, int appending)
 329{
 330	struct ubifs_budget_req req = { .fast = 1 };
 331
 332	if (PagePrivate(page)) {
 333		if (!appending)
 334			/*
 335			 * The page is dirty and we are not appending, which
 336			 * means no budget is needed at all.
 337			 */
 338			return 0;
 339
 340		mutex_lock(&ui->ui_mutex);
 341		if (ui->dirty)
 342			/*
 343			 * The page is dirty and we are appending, so the inode
 344			 * has to be marked as dirty. However, it is already
 345			 * dirty, so we do not need any budget. We may return,
 346			 * but @ui->ui_mutex hast to be left locked because we
 347			 * should prevent write-back from flushing the inode
 348			 * and freeing the budget. The lock will be released in
 349			 * 'ubifs_write_end()'.
 350			 */
 351			return 0;
 352
 353		/*
 354		 * The page is dirty, we are appending, the inode is clean, so
 355		 * we need to budget the inode change.
 356		 */
 357		req.dirtied_ino = 1;
 358	} else {
 359		if (PageChecked(page))
 360			/*
 361			 * The page corresponds to a hole and does not
 362			 * exist on the media. So changing it makes
 363			 * make the amount of indexing information
 364			 * larger, and we have to budget for a new
 365			 * page.
 366			 */
 367			req.new_page = 1;
 368		else
 369			/*
 370			 * Not a hole, the change will not add any new
 371			 * indexing information, budget for page
 372			 * change.
 373			 */
 374			req.dirtied_page = 1;
 375
 376		if (appending) {
 377			mutex_lock(&ui->ui_mutex);
 378			if (!ui->dirty)
 379				/*
 380				 * The inode is clean but we will have to mark
 381				 * it as dirty because we are appending. This
 382				 * needs a budget.
 383				 */
 384				req.dirtied_ino = 1;
 385		}
 386	}
 387
 388	return ubifs_budget_space(c, &req);
 389}
 390
 391/*
 392 * This function is called when a page of data is going to be written. Since
 393 * the page of data will not necessarily go to the flash straight away, UBIFS
 394 * has to reserve space on the media for it, which is done by means of
 395 * budgeting.
 396 *
 397 * This is the hot-path of the file-system and we are trying to optimize it as
 398 * much as possible. For this reasons it is split on 2 parts - slow and fast.
 399 *
 400 * There many budgeting cases:
 401 *     o a new page is appended - we have to budget for a new page and for
 402 *       changing the inode; however, if the inode is already dirty, there is
 403 *       no need to budget for it;
 404 *     o an existing clean page is changed - we have budget for it; if the page
 405 *       does not exist on the media (a hole), we have to budget for a new
 406 *       page; otherwise, we may budget for changing an existing page; the
 407 *       difference between these cases is that changing an existing page does
 408 *       not introduce anything new to the FS indexing information, so it does
 409 *       not grow, and smaller budget is acquired in this case;
 410 *     o an existing dirty page is changed - no need to budget at all, because
 411 *       the page budget has been acquired by earlier, when the page has been
 412 *       marked dirty.
 413 *
 414 * UBIFS budgeting sub-system may force write-back if it thinks there is no
 415 * space to reserve. This imposes some locking restrictions and makes it
 416 * impossible to take into account the above cases, and makes it impossible to
 417 * optimize budgeting.
 418 *
 419 * The solution for this is that the fast path of 'ubifs_write_begin()' assumes
 420 * there is a plenty of flash space and the budget will be acquired quickly,
 421 * without forcing write-back. The slow path does not make this assumption.
 422 */
 423static int ubifs_write_begin(struct file *file, struct address_space *mapping,
 424			     loff_t pos, unsigned len, unsigned flags,
 425			     struct page **pagep, void **fsdata)
 426{
 427	struct inode *inode = mapping->host;
 428	struct ubifs_info *c = inode->i_sb->s_fs_info;
 429	struct ubifs_inode *ui = ubifs_inode(inode);
 430	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
 431	int uninitialized_var(err), appending = !!(pos + len > inode->i_size);
 432	int skipped_read = 0;
 433	struct page *page;
 434
 435	ubifs_assert(ubifs_inode(inode)->ui_size == inode->i_size);
 436	ubifs_assert(!c->ro_media && !c->ro_mount);
 437
 438	if (unlikely(c->ro_error))
 439		return -EROFS;
 440
 441	/* Try out the fast-path part first */
 442	page = grab_cache_page_write_begin(mapping, index, flags);
 443	if (unlikely(!page))
 444		return -ENOMEM;
 
 445
 446	if (!PageUptodate(page)) {
 447		/* The page is not loaded from the flash */
 448		if (!(pos & ~PAGE_CACHE_MASK) && len == PAGE_CACHE_SIZE) {
 449			/*
 450			 * We change whole page so no need to load it. But we
 451			 * do not know whether this page exists on the media or
 452			 * not, so we assume the latter because it requires
 453			 * larger budget. The assumption is that it is better
 454			 * to budget a bit more than to read the page from the
 455			 * media. Thus, we are setting the @PG_checked flag
 456			 * here.
 457			 */
 458			SetPageChecked(page);
 459			skipped_read = 1;
 460		} else {
 461			err = do_readpage(page);
 462			if (err) {
 463				unlock_page(page);
 464				page_cache_release(page);
 465				return err;
 466			}
 467		}
 468
 469		SetPageUptodate(page);
 470		ClearPageError(page);
 471	}
 472
 473	err = allocate_budget(c, page, ui, appending);
 474	if (unlikely(err)) {
 475		ubifs_assert(err == -ENOSPC);
 476		/*
 477		 * If we skipped reading the page because we were going to
 478		 * write all of it, then it is not up to date.
 479		 */
 480		if (skipped_read) {
 481			ClearPageChecked(page);
 482			ClearPageUptodate(page);
 483		}
 484		/*
 485		 * Budgeting failed which means it would have to force
 486		 * write-back but didn't, because we set the @fast flag in the
 487		 * request. Write-back cannot be done now, while we have the
 488		 * page locked, because it would deadlock. Unlock and free
 489		 * everything and fall-back to slow-path.
 490		 */
 491		if (appending) {
 492			ubifs_assert(mutex_is_locked(&ui->ui_mutex));
 493			mutex_unlock(&ui->ui_mutex);
 494		}
 495		unlock_page(page);
 496		page_cache_release(page);
 497
 498		return write_begin_slow(mapping, pos, len, pagep, flags);
 499	}
 500
 501	/*
 502	 * Whee, we acquired budgeting quickly - without involving
 503	 * garbage-collection, committing or forcing write-back. We return
 504	 * with @ui->ui_mutex locked if we are appending pages, and unlocked
 505	 * otherwise. This is an optimization (slightly hacky though).
 506	 */
 507	*pagep = page;
 508	return 0;
 509
 510}
 511
 512/**
 513 * cancel_budget - cancel budget.
 514 * @c: UBIFS file-system description object
 515 * @page: page to cancel budget for
 516 * @ui: UBIFS inode object the page belongs to
 517 * @appending: non-zero if the page is appended
 518 *
 519 * This is a helper function for a page write operation. It unlocks the
 520 * @ui->ui_mutex in case of appending.
 521 */
 522static void cancel_budget(struct ubifs_info *c, struct page *page,
 523			  struct ubifs_inode *ui, int appending)
 524{
 525	if (appending) {
 526		if (!ui->dirty)
 527			ubifs_release_dirty_inode_budget(c, ui);
 528		mutex_unlock(&ui->ui_mutex);
 529	}
 530	if (!PagePrivate(page)) {
 531		if (PageChecked(page))
 532			release_new_page_budget(c);
 533		else
 534			release_existing_page_budget(c);
 535	}
 536}
 537
 538static int ubifs_write_end(struct file *file, struct address_space *mapping,
 539			   loff_t pos, unsigned len, unsigned copied,
 540			   struct page *page, void *fsdata)
 541{
 
 542	struct inode *inode = mapping->host;
 543	struct ubifs_inode *ui = ubifs_inode(inode);
 544	struct ubifs_info *c = inode->i_sb->s_fs_info;
 545	loff_t end_pos = pos + len;
 546	int appending = !!(end_pos > inode->i_size);
 547
 548	dbg_gen("ino %lu, pos %llu, pg %lu, len %u, copied %d, i_size %lld",
 549		inode->i_ino, pos, page->index, len, copied, inode->i_size);
 550
 551	if (unlikely(copied < len && len == PAGE_CACHE_SIZE)) {
 552		/*
 553		 * VFS copied less data to the page that it intended and
 554		 * declared in its '->write_begin()' call via the @len
 555		 * argument. If the page was not up-to-date, and @len was
 556		 * @PAGE_CACHE_SIZE, the 'ubifs_write_begin()' function did
 557		 * not load it from the media (for optimization reasons). This
 558		 * means that part of the page contains garbage. So read the
 559		 * page now.
 560		 */
 561		dbg_gen("copied %d instead of %d, read page and repeat",
 562			copied, len);
 563		cancel_budget(c, page, ui, appending);
 564		ClearPageChecked(page);
 565
 566		/*
 567		 * Return 0 to force VFS to repeat the whole operation, or the
 568		 * error code if 'do_readpage()' fails.
 569		 */
 570		copied = do_readpage(page);
 571		goto out;
 572	}
 573
 574	if (!PagePrivate(page)) {
 575		SetPagePrivate(page);
 
 
 
 576		atomic_long_inc(&c->dirty_pg_cnt);
 577		__set_page_dirty_nobuffers(page);
 578	}
 579
 580	if (appending) {
 581		i_size_write(inode, end_pos);
 582		ui->ui_size = end_pos;
 583		/*
 584		 * Note, we do not set @I_DIRTY_PAGES (which means that the
 585		 * inode has dirty pages), this has been done in
 586		 * '__set_page_dirty_nobuffers()'.
 587		 */
 588		__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
 589		ubifs_assert(mutex_is_locked(&ui->ui_mutex));
 590		mutex_unlock(&ui->ui_mutex);
 591	}
 592
 593out:
 594	unlock_page(page);
 595	page_cache_release(page);
 596	return copied;
 597}
 598
 599/**
 600 * populate_page - copy data nodes into a page for bulk-read.
 601 * @c: UBIFS file-system description object
 602 * @page: page
 603 * @bu: bulk-read information
 604 * @n: next zbranch slot
 605 *
 606 * This function returns %0 on success and a negative error code on failure.
 607 */
 608static int populate_page(struct ubifs_info *c, struct page *page,
 609			 struct bu_info *bu, int *n)
 610{
 611	int i = 0, nn = *n, offs = bu->zbranch[0].offs, hole = 0, read = 0;
 612	struct inode *inode = page->mapping->host;
 613	loff_t i_size = i_size_read(inode);
 614	unsigned int page_block;
 615	void *addr, *zaddr;
 616	pgoff_t end_index;
 617
 618	dbg_gen("ino %lu, pg %lu, i_size %lld, flags %#lx",
 619		inode->i_ino, page->index, i_size, page->flags);
 620
 621	addr = zaddr = kmap(page);
 622
 623	end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
 624	if (!i_size || page->index > end_index) {
 625		hole = 1;
 626		memset(addr, 0, PAGE_CACHE_SIZE);
 627		goto out_hole;
 628	}
 629
 630	page_block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT;
 631	while (1) {
 632		int err, len, out_len, dlen;
 633
 634		if (nn >= bu->cnt) {
 635			hole = 1;
 636			memset(addr, 0, UBIFS_BLOCK_SIZE);
 637		} else if (key_block(c, &bu->zbranch[nn].key) == page_block) {
 638			struct ubifs_data_node *dn;
 639
 640			dn = bu->buf + (bu->zbranch[nn].offs - offs);
 641
 642			ubifs_assert(le64_to_cpu(dn->ch.sqnum) >
 643				     ubifs_inode(inode)->creat_sqnum);
 644
 645			len = le32_to_cpu(dn->size);
 646			if (len <= 0 || len > UBIFS_BLOCK_SIZE)
 647				goto out_err;
 648
 649			dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ;
 650			out_len = UBIFS_BLOCK_SIZE;
 651			err = ubifs_decompress(&dn->data, dlen, addr, &out_len,
 
 
 
 
 
 
 
 652					       le16_to_cpu(dn->compr_type));
 653			if (err || len != out_len)
 654				goto out_err;
 655
 656			if (len < UBIFS_BLOCK_SIZE)
 657				memset(addr + len, 0, UBIFS_BLOCK_SIZE - len);
 658
 659			nn += 1;
 660			read = (i << UBIFS_BLOCK_SHIFT) + len;
 661		} else if (key_block(c, &bu->zbranch[nn].key) < page_block) {
 662			nn += 1;
 663			continue;
 664		} else {
 665			hole = 1;
 666			memset(addr, 0, UBIFS_BLOCK_SIZE);
 667		}
 668		if (++i >= UBIFS_BLOCKS_PER_PAGE)
 669			break;
 670		addr += UBIFS_BLOCK_SIZE;
 671		page_block += 1;
 
 
 
 
 672	}
 673
 674	if (end_index == page->index) {
 675		int len = i_size & (PAGE_CACHE_SIZE - 1);
 676
 677		if (len && len < read)
 678			memset(zaddr + len, 0, read - len);
 679	}
 680
 681out_hole:
 682	if (hole) {
 683		SetPageChecked(page);
 684		dbg_gen("hole");
 685	}
 686
 687	SetPageUptodate(page);
 688	ClearPageError(page);
 689	flush_dcache_page(page);
 690	kunmap(page);
 691	*n = nn;
 692	return 0;
 693
 694out_err:
 695	ClearPageUptodate(page);
 696	SetPageError(page);
 697	flush_dcache_page(page);
 698	kunmap(page);
 699	ubifs_err("bad data node (block %u, inode %lu)",
 700		  page_block, inode->i_ino);
 701	return -EINVAL;
 702}
 703
 704/**
 705 * ubifs_do_bulk_read - do bulk-read.
 706 * @c: UBIFS file-system description object
 707 * @bu: bulk-read information
 708 * @page1: first page to read
 709 *
 710 * This function returns %1 if the bulk-read is done, otherwise %0 is returned.
 711 */
 712static int ubifs_do_bulk_read(struct ubifs_info *c, struct bu_info *bu,
 713			      struct page *page1)
 714{
 715	pgoff_t offset = page1->index, end_index;
 716	struct address_space *mapping = page1->mapping;
 717	struct inode *inode = mapping->host;
 718	struct ubifs_inode *ui = ubifs_inode(inode);
 719	int err, page_idx, page_cnt, ret = 0, n = 0;
 720	int allocate = bu->buf ? 0 : 1;
 721	loff_t isize;
 
 722
 723	err = ubifs_tnc_get_bu_keys(c, bu);
 724	if (err)
 725		goto out_warn;
 726
 727	if (bu->eof) {
 728		/* Turn off bulk-read at the end of the file */
 729		ui->read_in_a_row = 1;
 730		ui->bulk_read = 0;
 731	}
 732
 733	page_cnt = bu->blk_cnt >> UBIFS_BLOCKS_PER_PAGE_SHIFT;
 734	if (!page_cnt) {
 735		/*
 736		 * This happens when there are multiple blocks per page and the
 737		 * blocks for the first page we are looking for, are not
 738		 * together. If all the pages were like this, bulk-read would
 739		 * reduce performance, so we turn it off for a while.
 740		 */
 741		goto out_bu_off;
 742	}
 743
 744	if (bu->cnt) {
 745		if (allocate) {
 746			/*
 747			 * Allocate bulk-read buffer depending on how many data
 748			 * nodes we are going to read.
 749			 */
 750			bu->buf_len = bu->zbranch[bu->cnt - 1].offs +
 751				      bu->zbranch[bu->cnt - 1].len -
 752				      bu->zbranch[0].offs;
 753			ubifs_assert(bu->buf_len > 0);
 754			ubifs_assert(bu->buf_len <= c->leb_size);
 755			bu->buf = kmalloc(bu->buf_len, GFP_NOFS | __GFP_NOWARN);
 756			if (!bu->buf)
 757				goto out_bu_off;
 758		}
 759
 760		err = ubifs_tnc_bulk_read(c, bu);
 761		if (err)
 762			goto out_warn;
 763	}
 764
 765	err = populate_page(c, page1, bu, &n);
 766	if (err)
 767		goto out_warn;
 768
 769	unlock_page(page1);
 770	ret = 1;
 771
 772	isize = i_size_read(inode);
 773	if (isize == 0)
 774		goto out_free;
 775	end_index = ((isize - 1) >> PAGE_CACHE_SHIFT);
 776
 777	for (page_idx = 1; page_idx < page_cnt; page_idx++) {
 778		pgoff_t page_offset = offset + page_idx;
 779		struct page *page;
 780
 781		if (page_offset > end_index)
 782			break;
 783		page = find_or_create_page(mapping, page_offset,
 784					   GFP_NOFS | __GFP_COLD);
 785		if (!page)
 
 786			break;
 787		if (!PageUptodate(page))
 788			err = populate_page(c, page, bu, &n);
 789		unlock_page(page);
 790		page_cache_release(page);
 791		if (err)
 792			break;
 793	}
 794
 795	ui->last_page_read = offset + page_idx - 1;
 796
 797out_free:
 798	if (allocate)
 799		kfree(bu->buf);
 800	return ret;
 801
 802out_warn:
 803	ubifs_warn("ignoring error %d and skipping bulk-read", err);
 804	goto out_free;
 805
 806out_bu_off:
 807	ui->read_in_a_row = ui->bulk_read = 0;
 808	goto out_free;
 809}
 810
 811/**
 812 * ubifs_bulk_read - determine whether to bulk-read and, if so, do it.
 813 * @page: page from which to start bulk-read.
 814 *
 815 * Some flash media are capable of reading sequentially at faster rates. UBIFS
 816 * bulk-read facility is designed to take advantage of that, by reading in one
 817 * go consecutive data nodes that are also located consecutively in the same
 818 * LEB. This function returns %1 if a bulk-read is done and %0 otherwise.
 
 
 819 */
 820static int ubifs_bulk_read(struct page *page)
 821{
 822	struct inode *inode = page->mapping->host;
 823	struct ubifs_info *c = inode->i_sb->s_fs_info;
 824	struct ubifs_inode *ui = ubifs_inode(inode);
 825	pgoff_t index = page->index, last_page_read = ui->last_page_read;
 826	struct bu_info *bu;
 827	int err = 0, allocated = 0;
 828
 829	ui->last_page_read = index;
 830	if (!c->bulk_read)
 831		return 0;
 832
 833	/*
 834	 * Bulk-read is protected by @ui->ui_mutex, but it is an optimization,
 835	 * so don't bother if we cannot lock the mutex.
 836	 */
 837	if (!mutex_trylock(&ui->ui_mutex))
 838		return 0;
 839
 840	if (index != last_page_read + 1) {
 841		/* Turn off bulk-read if we stop reading sequentially */
 842		ui->read_in_a_row = 1;
 843		if (ui->bulk_read)
 844			ui->bulk_read = 0;
 845		goto out_unlock;
 846	}
 847
 848	if (!ui->bulk_read) {
 849		ui->read_in_a_row += 1;
 850		if (ui->read_in_a_row < 3)
 851			goto out_unlock;
 852		/* Three reads in a row, so switch on bulk-read */
 853		ui->bulk_read = 1;
 854	}
 855
 856	/*
 857	 * If possible, try to use pre-allocated bulk-read information, which
 858	 * is protected by @c->bu_mutex.
 859	 */
 860	if (mutex_trylock(&c->bu_mutex))
 861		bu = &c->bu;
 862	else {
 863		bu = kmalloc(sizeof(struct bu_info), GFP_NOFS | __GFP_NOWARN);
 864		if (!bu)
 865			goto out_unlock;
 866
 867		bu->buf = NULL;
 868		allocated = 1;
 869	}
 870
 871	bu->buf_len = c->max_bu_buf_len;
 872	data_key_init(c, &bu->key, inode->i_ino,
 873		      page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT);
 874	err = ubifs_do_bulk_read(c, bu, page);
 875
 876	if (!allocated)
 877		mutex_unlock(&c->bu_mutex);
 878	else
 879		kfree(bu);
 880
 881out_unlock:
 882	mutex_unlock(&ui->ui_mutex);
 883	return err;
 884}
 885
 886static int ubifs_readpage(struct file *file, struct page *page)
 887{
 888	if (ubifs_bulk_read(page))
 889		return 0;
 890	do_readpage(page);
 891	unlock_page(page);
 892	return 0;
 893}
 894
 895static int do_writepage(struct page *page, int len)
 896{
 897	int err = 0, i, blen;
 898	unsigned int block;
 899	void *addr;
 
 900	union ubifs_key key;
 901	struct inode *inode = page->mapping->host;
 902	struct ubifs_info *c = inode->i_sb->s_fs_info;
 903
 904#ifdef UBIFS_DEBUG
 
 905	spin_lock(&ui->ui_lock);
 906	ubifs_assert(page->index <= ui->synced_i_size << PAGE_CACHE_SIZE);
 907	spin_unlock(&ui->ui_lock);
 908#endif
 909
 910	/* Update radix tree tags */
 911	set_page_writeback(page);
 912
 913	addr = kmap(page);
 914	block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT;
 915	i = 0;
 916	while (len) {
 917		blen = min_t(int, len, UBIFS_BLOCK_SIZE);
 918		data_key_init(c, &key, inode->i_ino, block);
 919		err = ubifs_jnl_write_data(c, inode, &key, addr, blen);
 920		if (err)
 921			break;
 922		if (++i >= UBIFS_BLOCKS_PER_PAGE)
 
 923			break;
 924		block += 1;
 925		addr += blen;
 926		len -= blen;
 
 
 
 
 927	}
 
 928	if (err) {
 929		SetPageError(page);
 930		ubifs_err("cannot write page %lu of inode %lu, error %d",
 931			  page->index, inode->i_ino, err);
 932		ubifs_ro_mode(c, err);
 933	}
 934
 935	ubifs_assert(PagePrivate(page));
 936	if (PageChecked(page))
 937		release_new_page_budget(c);
 938	else
 939		release_existing_page_budget(c);
 940
 941	atomic_long_dec(&c->dirty_pg_cnt);
 942	ClearPagePrivate(page);
 943	ClearPageChecked(page);
 944
 945	kunmap(page);
 946	unlock_page(page);
 947	end_page_writeback(page);
 948	return err;
 949}
 950
 951/*
 952 * When writing-back dirty inodes, VFS first writes-back pages belonging to the
 953 * inode, then the inode itself. For UBIFS this may cause a problem. Consider a
 954 * situation when a we have an inode with size 0, then a megabyte of data is
 955 * appended to the inode, then write-back starts and flushes some amount of the
 956 * dirty pages, the journal becomes full, commit happens and finishes, and then
 957 * an unclean reboot happens. When the file system is mounted next time, the
 958 * inode size would still be 0, but there would be many pages which are beyond
 959 * the inode size, they would be indexed and consume flash space. Because the
 960 * journal has been committed, the replay would not be able to detect this
 961 * situation and correct the inode size. This means UBIFS would have to scan
 962 * whole index and correct all inode sizes, which is long an unacceptable.
 963 *
 964 * To prevent situations like this, UBIFS writes pages back only if they are
 965 * within the last synchronized inode size, i.e. the size which has been
 966 * written to the flash media last time. Otherwise, UBIFS forces inode
 967 * write-back, thus making sure the on-flash inode contains current inode size,
 968 * and then keeps writing pages back.
 969 *
 970 * Some locking issues explanation. 'ubifs_writepage()' first is called with
 971 * the page locked, and it locks @ui_mutex. However, write-back does take inode
 972 * @i_mutex, which means other VFS operations may be run on this inode at the
 973 * same time. And the problematic one is truncation to smaller size, from where
 974 * we have to call 'truncate_setsize()', which first changes @inode->i_size,
 975 * then drops the truncated pages. And while dropping the pages, it takes the
 976 * page lock. This means that 'do_truncation()' cannot call 'truncate_setsize()'
 977 * with @ui_mutex locked, because it would deadlock with 'ubifs_writepage()'.
 978 * This means that @inode->i_size is changed while @ui_mutex is unlocked.
 979 *
 980 * XXX(truncate): with the new truncate sequence this is not true anymore,
 981 * and the calls to truncate_setsize can be move around freely.  They should
 982 * be moved to the very end of the truncate sequence.
 983 *
 984 * But in 'ubifs_writepage()' we have to guarantee that we do not write beyond
 985 * inode size. How do we do this if @inode->i_size may became smaller while we
 986 * are in the middle of 'ubifs_writepage()'? The UBIFS solution is the
 987 * @ui->ui_isize "shadow" field which UBIFS uses instead of @inode->i_size
 988 * internally and updates it under @ui_mutex.
 989 *
 990 * Q: why we do not worry that if we race with truncation, we may end up with a
 991 * situation when the inode is truncated while we are in the middle of
 992 * 'do_writepage()', so we do write beyond inode size?
 993 * A: If we are in the middle of 'do_writepage()', truncation would be locked
 994 * on the page lock and it would not write the truncated inode node to the
 995 * journal before we have finished.
 996 */
 997static int ubifs_writepage(struct page *page, struct writeback_control *wbc)
 
 998{
 999	struct inode *inode = page->mapping->host;
 
1000	struct ubifs_inode *ui = ubifs_inode(inode);
1001	loff_t i_size =  i_size_read(inode), synced_i_size;
1002	pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
1003	int err, len = i_size & (PAGE_CACHE_SIZE - 1);
1004	void *kaddr;
1005
1006	dbg_gen("ino %lu, pg %lu, pg flags %#lx",
1007		inode->i_ino, page->index, page->flags);
1008	ubifs_assert(PagePrivate(page));
1009
1010	/* Is the page fully outside @i_size? (truncate in progress) */
1011	if (page->index > end_index || (page->index == end_index && !len)) {
1012		err = 0;
1013		goto out_unlock;
1014	}
1015
1016	spin_lock(&ui->ui_lock);
1017	synced_i_size = ui->synced_i_size;
1018	spin_unlock(&ui->ui_lock);
1019
1020	/* Is the page fully inside @i_size? */
1021	if (page->index < end_index) {
1022		if (page->index >= synced_i_size >> PAGE_CACHE_SHIFT) {
1023			err = inode->i_sb->s_op->write_inode(inode, NULL);
1024			if (err)
1025				goto out_unlock;
1026			/*
1027			 * The inode has been written, but the write-buffer has
1028			 * not been synchronized, so in case of an unclean
1029			 * reboot we may end up with some pages beyond inode
1030			 * size, but they would be in the journal (because
1031			 * commit flushes write buffers) and recovery would deal
1032			 * with this.
1033			 */
1034		}
1035		return do_writepage(page, PAGE_CACHE_SIZE);
1036	}
1037
1038	/*
1039	 * The page straddles @i_size. It must be zeroed out on each and every
1040	 * writepage invocation because it may be mmapped. "A file is mapped
1041	 * in multiples of the page size. For a file that is not a multiple of
1042	 * the page size, the remaining memory is zeroed when mapped, and
1043	 * writes to that region are not written out to the file."
1044	 */
1045	kaddr = kmap_atomic(page, KM_USER0);
1046	memset(kaddr + len, 0, PAGE_CACHE_SIZE - len);
1047	flush_dcache_page(page);
1048	kunmap_atomic(kaddr, KM_USER0);
1049
1050	if (i_size > synced_i_size) {
1051		err = inode->i_sb->s_op->write_inode(inode, NULL);
1052		if (err)
1053			goto out_unlock;
1054	}
1055
1056	return do_writepage(page, len);
1057
 
 
 
 
 
 
1058out_unlock:
1059	unlock_page(page);
1060	return err;
1061}
1062
 
 
 
 
 
 
1063/**
1064 * do_attr_changes - change inode attributes.
1065 * @inode: inode to change attributes for
1066 * @attr: describes attributes to change
1067 */
1068static void do_attr_changes(struct inode *inode, const struct iattr *attr)
1069{
1070	if (attr->ia_valid & ATTR_UID)
1071		inode->i_uid = attr->ia_uid;
1072	if (attr->ia_valid & ATTR_GID)
1073		inode->i_gid = attr->ia_gid;
1074	if (attr->ia_valid & ATTR_ATIME)
1075		inode->i_atime = timespec_trunc(attr->ia_atime,
1076						inode->i_sb->s_time_gran);
1077	if (attr->ia_valid & ATTR_MTIME)
1078		inode->i_mtime = timespec_trunc(attr->ia_mtime,
1079						inode->i_sb->s_time_gran);
1080	if (attr->ia_valid & ATTR_CTIME)
1081		inode->i_ctime = timespec_trunc(attr->ia_ctime,
1082						inode->i_sb->s_time_gran);
1083	if (attr->ia_valid & ATTR_MODE) {
1084		umode_t mode = attr->ia_mode;
1085
1086		if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
1087			mode &= ~S_ISGID;
1088		inode->i_mode = mode;
1089	}
1090}
1091
1092/**
1093 * do_truncation - truncate an inode.
1094 * @c: UBIFS file-system description object
1095 * @inode: inode to truncate
1096 * @attr: inode attribute changes description
1097 *
1098 * This function implements VFS '->setattr()' call when the inode is truncated
1099 * to a smaller size. Returns zero in case of success and a negative error code
 
 
1100 * in case of failure.
1101 */
1102static int do_truncation(struct ubifs_info *c, struct inode *inode,
1103			 const struct iattr *attr)
1104{
1105	int err;
1106	struct ubifs_budget_req req;
1107	loff_t old_size = inode->i_size, new_size = attr->ia_size;
1108	int offset = new_size & (UBIFS_BLOCK_SIZE - 1), budgeted = 1;
1109	struct ubifs_inode *ui = ubifs_inode(inode);
1110
1111	dbg_gen("ino %lu, size %lld -> %lld", inode->i_ino, old_size, new_size);
1112	memset(&req, 0, sizeof(struct ubifs_budget_req));
1113
1114	/*
1115	 * If this is truncation to a smaller size, and we do not truncate on a
1116	 * block boundary, budget for changing one data block, because the last
1117	 * block will be re-written.
1118	 */
1119	if (new_size & (UBIFS_BLOCK_SIZE - 1))
1120		req.dirtied_page = 1;
1121
1122	req.dirtied_ino = 1;
1123	/* A funny way to budget for truncation node */
1124	req.dirtied_ino_d = UBIFS_TRUN_NODE_SZ;
1125	err = ubifs_budget_space(c, &req);
1126	if (err) {
1127		/*
1128		 * Treat truncations to zero as deletion and always allow them,
1129		 * just like we do for '->unlink()'.
1130		 */
1131		if (new_size || err != -ENOSPC)
1132			return err;
1133		budgeted = 0;
1134	}
1135
1136	truncate_setsize(inode, new_size);
1137
1138	if (offset) {
1139		pgoff_t index = new_size >> PAGE_CACHE_SHIFT;
1140		struct page *page;
1141
1142		page = find_lock_page(inode->i_mapping, index);
1143		if (page) {
1144			if (PageDirty(page)) {
1145				/*
1146				 * 'ubifs_jnl_truncate()' will try to truncate
1147				 * the last data node, but it contains
1148				 * out-of-date data because the page is dirty.
1149				 * Write the page now, so that
1150				 * 'ubifs_jnl_truncate()' will see an already
1151				 * truncated (and up to date) data node.
1152				 */
1153				ubifs_assert(PagePrivate(page));
1154
1155				clear_page_dirty_for_io(page);
1156				if (UBIFS_BLOCKS_PER_PAGE_SHIFT)
1157					offset = new_size &
1158						 (PAGE_CACHE_SIZE - 1);
1159				err = do_writepage(page, offset);
1160				page_cache_release(page);
1161				if (err)
1162					goto out_budg;
1163				/*
1164				 * We could now tell 'ubifs_jnl_truncate()' not
1165				 * to read the last block.
1166				 */
1167			} else {
1168				/*
1169				 * We could 'kmap()' the page and pass the data
1170				 * to 'ubifs_jnl_truncate()' to save it from
1171				 * having to read it.
1172				 */
1173				unlock_page(page);
1174				page_cache_release(page);
1175			}
1176		}
1177	}
1178
1179	mutex_lock(&ui->ui_mutex);
1180	ui->ui_size = inode->i_size;
1181	/* Truncation changes inode [mc]time */
1182	inode->i_mtime = inode->i_ctime = ubifs_current_time(inode);
1183	/* Other attributes may be changed at the same time as well */
1184	do_attr_changes(inode, attr);
1185	err = ubifs_jnl_truncate(c, inode, old_size, new_size);
1186	mutex_unlock(&ui->ui_mutex);
1187
1188out_budg:
1189	if (budgeted)
1190		ubifs_release_budget(c, &req);
1191	else {
1192		c->bi.nospace = c->bi.nospace_rp = 0;
1193		smp_wmb();
1194	}
1195	return err;
1196}
1197
1198/**
1199 * do_setattr - change inode attributes.
1200 * @c: UBIFS file-system description object
1201 * @inode: inode to change attributes for
1202 * @attr: inode attribute changes description
1203 *
1204 * This function implements VFS '->setattr()' call for all cases except
1205 * truncations to smaller size. Returns zero in case of success and a negative
 
 
1206 * error code in case of failure.
1207 */
1208static int do_setattr(struct ubifs_info *c, struct inode *inode,
1209		      const struct iattr *attr)
1210{
1211	int err, release;
1212	loff_t new_size = attr->ia_size;
1213	struct ubifs_inode *ui = ubifs_inode(inode);
1214	struct ubifs_budget_req req = { .dirtied_ino = 1,
1215				.dirtied_ino_d = ALIGN(ui->data_len, 8) };
1216
1217	err = ubifs_budget_space(c, &req);
1218	if (err)
1219		return err;
1220
1221	if (attr->ia_valid & ATTR_SIZE) {
1222		dbg_gen("size %lld -> %lld", inode->i_size, new_size);
1223		truncate_setsize(inode, new_size);
1224	}
1225
1226	mutex_lock(&ui->ui_mutex);
1227	if (attr->ia_valid & ATTR_SIZE) {
1228		/* Truncation changes inode [mc]time */
1229		inode->i_mtime = inode->i_ctime = ubifs_current_time(inode);
1230		/* 'truncate_setsize()' changed @i_size, update @ui_size */
1231		ui->ui_size = inode->i_size;
1232	}
1233
1234	do_attr_changes(inode, attr);
1235
1236	release = ui->dirty;
1237	if (attr->ia_valid & ATTR_SIZE)
1238		/*
1239		 * Inode length changed, so we have to make sure
1240		 * @I_DIRTY_DATASYNC is set.
1241		 */
1242		 __mark_inode_dirty(inode, I_DIRTY_SYNC | I_DIRTY_DATASYNC);
1243	else
1244		mark_inode_dirty_sync(inode);
1245	mutex_unlock(&ui->ui_mutex);
1246
1247	if (release)
1248		ubifs_release_budget(c, &req);
1249	if (IS_SYNC(inode))
1250		err = inode->i_sb->s_op->write_inode(inode, NULL);
1251	return err;
1252}
1253
1254int ubifs_setattr(struct dentry *dentry, struct iattr *attr)
 
1255{
1256	int err;
1257	struct inode *inode = dentry->d_inode;
1258	struct ubifs_info *c = inode->i_sb->s_fs_info;
1259
1260	dbg_gen("ino %lu, mode %#x, ia_valid %#x",
1261		inode->i_ino, inode->i_mode, attr->ia_valid);
1262	err = inode_change_ok(inode, attr);
1263	if (err)
1264		return err;
1265
1266	err = dbg_check_synced_i_size(c, inode);
1267	if (err)
1268		return err;
1269
 
 
 
 
1270	if ((attr->ia_valid & ATTR_SIZE) && attr->ia_size < inode->i_size)
1271		/* Truncation to a smaller size */
1272		err = do_truncation(c, inode, attr);
1273	else
1274		err = do_setattr(c, inode, attr);
1275
1276	return err;
1277}
1278
1279static void ubifs_invalidatepage(struct page *page, unsigned long offset)
 
1280{
1281	struct inode *inode = page->mapping->host;
1282	struct ubifs_info *c = inode->i_sb->s_fs_info;
1283
1284	ubifs_assert(PagePrivate(page));
1285	if (offset)
1286		/* Partial page remains dirty */
1287		return;
1288
1289	if (PageChecked(page))
1290		release_new_page_budget(c);
1291	else
1292		release_existing_page_budget(c);
1293
1294	atomic_long_dec(&c->dirty_pg_cnt);
1295	ClearPagePrivate(page);
1296	ClearPageChecked(page);
1297}
1298
1299static void *ubifs_follow_link(struct dentry *dentry, struct nameidata *nd)
1300{
1301	struct ubifs_inode *ui = ubifs_inode(dentry->d_inode);
1302
1303	nd_set_link(nd, ui->data);
1304	return NULL;
1305}
1306
1307int ubifs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
1308{
1309	struct inode *inode = file->f_mapping->host;
1310	struct ubifs_info *c = inode->i_sb->s_fs_info;
1311	int err;
1312
1313	dbg_gen("syncing inode %lu", inode->i_ino);
1314
1315	if (c->ro_mount)
1316		/*
1317		 * For some really strange reasons VFS does not filter out
1318		 * 'fsync()' for R/O mounted file-systems as per 2.6.39.
1319		 */
1320		return 0;
1321
1322	err = filemap_write_and_wait_range(inode->i_mapping, start, end);
1323	if (err)
1324		return err;
1325	mutex_lock(&inode->i_mutex);
1326
1327	/* Synchronize the inode unless this is a 'datasync()' call. */
1328	if (!datasync || (inode->i_state & I_DIRTY_DATASYNC)) {
1329		err = inode->i_sb->s_op->write_inode(inode, NULL);
1330		if (err)
1331			goto out;
1332	}
1333
1334	/*
1335	 * Nodes related to this inode may still sit in a write-buffer. Flush
1336	 * them.
1337	 */
1338	err = ubifs_sync_wbufs_by_inode(c, inode);
1339out:
1340	mutex_unlock(&inode->i_mutex);
1341	return err;
1342}
1343
1344/**
1345 * mctime_update_needed - check if mtime or ctime update is needed.
1346 * @inode: the inode to do the check for
1347 * @now: current time
1348 *
1349 * This helper function checks if the inode mtime/ctime should be updated or
1350 * not. If current values of the time-stamps are within the UBIFS inode time
1351 * granularity, they are not updated. This is an optimization.
 
 
1352 */
1353static inline int mctime_update_needed(const struct inode *inode,
1354				       const struct timespec *now)
1355{
1356	if (!timespec_equal(&inode->i_mtime, now) ||
1357	    !timespec_equal(&inode->i_ctime, now))
 
 
1358		return 1;
1359	return 0;
1360}
1361
1362/**
1363 * update_ctime - update mtime and ctime of an inode.
1364 * @c: UBIFS file-system description object
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1365 * @inode: inode to update
1366 *
1367 * This function updates mtime and ctime of the inode if it is not equivalent to
1368 * current time. Returns zero in case of success and a negative error code in
 
 
1369 * case of failure.
1370 */
1371static int update_mctime(struct ubifs_info *c, struct inode *inode)
1372{
1373	struct timespec now = ubifs_current_time(inode);
1374	struct ubifs_inode *ui = ubifs_inode(inode);
 
1375
1376	if (mctime_update_needed(inode, &now)) {
1377		int err, release;
1378		struct ubifs_budget_req req = { .dirtied_ino = 1,
1379				.dirtied_ino_d = ALIGN(ui->data_len, 8) };
1380
1381		err = ubifs_budget_space(c, &req);
1382		if (err)
1383			return err;
1384
1385		mutex_lock(&ui->ui_mutex);
1386		inode->i_mtime = inode->i_ctime = ubifs_current_time(inode);
1387		release = ui->dirty;
1388		mark_inode_dirty_sync(inode);
1389		mutex_unlock(&ui->ui_mutex);
1390		if (release)
1391			ubifs_release_budget(c, &req);
1392	}
1393
1394	return 0;
1395}
1396
1397static ssize_t ubifs_aio_write(struct kiocb *iocb, const struct iovec *iov,
1398			       unsigned long nr_segs, loff_t pos)
1399{
1400	int err;
1401	struct inode *inode = iocb->ki_filp->f_mapping->host;
1402	struct ubifs_info *c = inode->i_sb->s_fs_info;
1403
1404	err = update_mctime(c, inode);
1405	if (err)
1406		return err;
1407
1408	return generic_file_aio_write(iocb, iov, nr_segs, pos);
1409}
1410
1411static int ubifs_set_page_dirty(struct page *page)
 
1412{
1413	int ret;
 
1414
1415	ret = __set_page_dirty_nobuffers(page);
1416	/*
1417	 * An attempt to dirty a page without budgeting for it - should not
1418	 * happen.
1419	 */
1420	ubifs_assert(ret == 0);
1421	return ret;
1422}
1423
1424static int ubifs_releasepage(struct page *page, gfp_t unused_gfp_flags)
1425{
 
 
 
 
 
 
1426	/*
1427	 * An attempt to release a dirty page without budgeting for it - should
1428	 * not happen.
 
 
 
1429	 */
1430	if (PageWriteback(page))
1431		return 0;
1432	ubifs_assert(PagePrivate(page));
1433	ubifs_assert(0);
1434	ClearPagePrivate(page);
1435	ClearPageChecked(page);
1436	return 1;
 
 
 
1437}
1438
1439/*
1440 * mmap()d file has taken write protection fault and is being made writable.
1441 * UBIFS must ensure page is budgeted for.
1442 */
1443static int ubifs_vm_page_mkwrite(struct vm_area_struct *vma,
1444				 struct vm_fault *vmf)
1445{
1446	struct page *page = vmf->page;
1447	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
1448	struct ubifs_info *c = inode->i_sb->s_fs_info;
1449	struct timespec now = ubifs_current_time(inode);
1450	struct ubifs_budget_req req = { .new_page = 1 };
1451	int err, update_time;
1452
1453	dbg_gen("ino %lu, pg %lu, i_size %lld",	inode->i_ino, page->index,
1454		i_size_read(inode));
1455	ubifs_assert(!c->ro_media && !c->ro_mount);
1456
1457	if (unlikely(c->ro_error))
1458		return VM_FAULT_SIGBUS; /* -EROFS */
1459
1460	/*
1461	 * We have not locked @page so far so we may budget for changing the
1462	 * page. Note, we cannot do this after we locked the page, because
1463	 * budgeting may cause write-back which would cause deadlock.
1464	 *
1465	 * At the moment we do not know whether the page is dirty or not, so we
1466	 * assume that it is not and budget for a new page. We could look at
1467	 * the @PG_private flag and figure this out, but we may race with write
1468	 * back and the page state may change by the time we lock it, so this
1469	 * would need additional care. We do not bother with this at the
1470	 * moment, although it might be good idea to do. Instead, we allocate
1471	 * budget for a new page and amend it later on if the page was in fact
1472	 * dirty.
1473	 *
1474	 * The budgeting-related logic of this function is similar to what we
1475	 * do in 'ubifs_write_begin()' and 'ubifs_write_end()'. Glance there
1476	 * for more comments.
1477	 */
1478	update_time = mctime_update_needed(inode, &now);
1479	if (update_time)
1480		/*
1481		 * We have to change inode time stamp which requires extra
1482		 * budgeting.
1483		 */
1484		req.dirtied_ino = 1;
1485
1486	err = ubifs_budget_space(c, &req);
1487	if (unlikely(err)) {
1488		if (err == -ENOSPC)
1489			ubifs_warn("out of space for mmapped file "
1490				   "(inode number %lu)", inode->i_ino);
1491		return VM_FAULT_SIGBUS;
1492	}
1493
1494	lock_page(page);
1495	if (unlikely(page->mapping != inode->i_mapping ||
1496		     page_offset(page) > i_size_read(inode))) {
1497		/* Page got truncated out from underneath us */
1498		err = -EINVAL;
1499		goto out_unlock;
1500	}
1501
1502	if (PagePrivate(page))
1503		release_new_page_budget(c);
1504	else {
1505		if (!PageChecked(page))
1506			ubifs_convert_page_budget(c);
1507		SetPagePrivate(page);
1508		atomic_long_inc(&c->dirty_pg_cnt);
1509		__set_page_dirty_nobuffers(page);
1510	}
1511
1512	if (update_time) {
1513		int release;
1514		struct ubifs_inode *ui = ubifs_inode(inode);
1515
1516		mutex_lock(&ui->ui_mutex);
1517		inode->i_mtime = inode->i_ctime = ubifs_current_time(inode);
1518		release = ui->dirty;
1519		mark_inode_dirty_sync(inode);
1520		mutex_unlock(&ui->ui_mutex);
1521		if (release)
1522			ubifs_release_dirty_inode_budget(c, ui);
1523	}
1524
1525	unlock_page(page);
1526	return 0;
1527
1528out_unlock:
1529	unlock_page(page);
1530	ubifs_release_budget(c, &req);
1531	if (err)
1532		err = VM_FAULT_SIGBUS;
1533	return err;
1534}
1535
1536static const struct vm_operations_struct ubifs_file_vm_ops = {
1537	.fault        = filemap_fault,
 
1538	.page_mkwrite = ubifs_vm_page_mkwrite,
1539};
1540
1541static int ubifs_file_mmap(struct file *file, struct vm_area_struct *vma)
1542{
1543	int err;
1544
1545	err = generic_file_mmap(file, vma);
1546	if (err)
1547		return err;
1548	vma->vm_ops = &ubifs_file_vm_ops;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1549	return 0;
1550}
1551
1552const struct address_space_operations ubifs_file_address_operations = {
1553	.readpage       = ubifs_readpage,
1554	.writepage      = ubifs_writepage,
1555	.write_begin    = ubifs_write_begin,
1556	.write_end      = ubifs_write_end,
1557	.invalidatepage = ubifs_invalidatepage,
1558	.set_page_dirty = ubifs_set_page_dirty,
1559	.releasepage    = ubifs_releasepage,
 
1560};
1561
1562const struct inode_operations ubifs_file_inode_operations = {
1563	.setattr     = ubifs_setattr,
1564	.getattr     = ubifs_getattr,
1565#ifdef CONFIG_UBIFS_FS_XATTR
1566	.setxattr    = ubifs_setxattr,
1567	.getxattr    = ubifs_getxattr,
1568	.listxattr   = ubifs_listxattr,
1569	.removexattr = ubifs_removexattr,
1570#endif
 
1571};
1572
1573const struct inode_operations ubifs_symlink_inode_operations = {
1574	.readlink    = generic_readlink,
1575	.follow_link = ubifs_follow_link,
1576	.setattr     = ubifs_setattr,
1577	.getattr     = ubifs_getattr,
 
 
1578};
1579
1580const struct file_operations ubifs_file_operations = {
1581	.llseek         = generic_file_llseek,
1582	.read           = do_sync_read,
1583	.write          = do_sync_write,
1584	.aio_read       = generic_file_aio_read,
1585	.aio_write      = ubifs_aio_write,
1586	.mmap           = ubifs_file_mmap,
1587	.fsync          = ubifs_fsync,
1588	.unlocked_ioctl = ubifs_ioctl,
1589	.splice_read	= generic_file_splice_read,
1590	.splice_write	= generic_file_splice_write,
 
1591#ifdef CONFIG_COMPAT
1592	.compat_ioctl   = ubifs_compat_ioctl,
1593#endif
1594};