1/*
   2 *  linux/fs/ext2/inode.c
   3 *
   4 * Copyright (C) 1992, 1993, 1994, 1995
   5 * Remy Card (card@masi.ibp.fr)
   6 * Laboratoire MASI - Institut Blaise Pascal
   7 * Universite Pierre et Marie Curie (Paris VI)
   8 *
   9 *  from
  10 *
  11 *  linux/fs/minix/inode.c
  12 *
  13 *  Copyright (C) 1991, 1992  Linus Torvalds
  14 *
  15 *  Goal-directed block allocation by Stephen Tweedie
  16 * 	(sct@dcs.ed.ac.uk), 1993, 1998
  17 *  Big-endian to little-endian byte-swapping/bitmaps by
  18 *        David S. Miller (davem@caip.rutgers.edu), 1995
  19 *  64-bit file support on 64-bit platforms by Jakub Jelinek
  20 * 	(jj@sunsite.ms.mff.cuni.cz)
  21 *
  22 *  Assorted race fixes, rewrite of ext2_get_block() by Al Viro, 2000
  23 */
  24
  25#include <linux/time.h>
  26#include <linux/highuid.h>
  27#include <linux/pagemap.h>
  28#include <linux/dax.h>
  29#include <linux/blkdev.h>
  30#include <linux/quotaops.h>
  31#include <linux/writeback.h>
  32#include <linux/buffer_head.h>
  33#include <linux/mpage.h>
  34#include <linux/fiemap.h>
  35#include <linux/iomap.h>
  36#include <linux/namei.h>
  37#include <linux/uio.h>
  38#include "ext2.h"
  39#include "acl.h"
  40#include "xattr.h"
  41
  42static int __ext2_write_inode(struct inode *inode, int do_sync);
  43
  44/*
  45 * Test whether an inode is a fast symlink.
  46 */
  47static inline int ext2_inode_is_fast_symlink(struct inode *inode)
  48{
  49	int ea_blocks = EXT2_I(inode)->i_file_acl ?
  50		(inode->i_sb->s_blocksize >> 9) : 0;
  51
  52	return (S_ISLNK(inode->i_mode) &&
  53		inode->i_blocks - ea_blocks == 0);
  54}
  55
  56static void ext2_truncate_blocks(struct inode *inode, loff_t offset);
  57
  58static void ext2_write_failed(struct address_space *mapping, loff_t to)
  59{
  60	struct inode *inode = mapping->host;
  61
  62	if (to > inode->i_size) {
  63		truncate_pagecache(inode, inode->i_size);
  64		ext2_truncate_blocks(inode, inode->i_size);
  65	}
  66}
  67
  68/*
  69 * Called at the last iput() if i_nlink is zero.
  70 */
  71void ext2_evict_inode(struct inode * inode)
  72{
  73	struct ext2_block_alloc_info *rsv;
  74	int want_delete = 0;
  75
  76	if (!inode->i_nlink && !is_bad_inode(inode)) {
  77		want_delete = 1;
  78		dquot_initialize(inode);
  79	} else {
  80		dquot_drop(inode);
  81	}
  82
  83	truncate_inode_pages_final(&inode->i_data);
  84
  85	if (want_delete) {
  86		sb_start_intwrite(inode->i_sb);
  87		/* set dtime */
  88		EXT2_I(inode)->i_dtime	= get_seconds();
  89		mark_inode_dirty(inode);
  90		__ext2_write_inode(inode, inode_needs_sync(inode));
  91		/* truncate to 0 */
  92		inode->i_size = 0;
  93		if (inode->i_blocks)
  94			ext2_truncate_blocks(inode, 0);
  95		ext2_xattr_delete_inode(inode);
  96	}
  97
  98	invalidate_inode_buffers(inode);
  99	clear_inode(inode);
 100
 101	ext2_discard_reservation(inode);
 102	rsv = EXT2_I(inode)->i_block_alloc_info;
 103	EXT2_I(inode)->i_block_alloc_info = NULL;
 104	if (unlikely(rsv))
 105		kfree(rsv);
 106
 107	if (want_delete) {
 108		ext2_free_inode(inode);
 109		sb_end_intwrite(inode->i_sb);
 110	}
 111}
 112
 113typedef struct {
 114	__le32	*p;
 115	__le32	key;
 116	struct buffer_head *bh;
 117} Indirect;
 118
 119static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
 120{
 121	p->key = *(p->p = v);
 122	p->bh = bh;
 123}
 124
 125static inline int verify_chain(Indirect *from, Indirect *to)
 126{
 127	while (from <= to && from->key == *from->p)
 128		from++;
 129	return (from > to);
 130}
 131
 132/**
 133 *	ext2_block_to_path - parse the block number into array of offsets
 134 *	@inode: inode in question (we are only interested in its superblock)
 135 *	@i_block: block number to be parsed
 136 *	@offsets: array to store the offsets in
 137 *      @boundary: set this non-zero if the referred-to block is likely to be
 138 *             followed (on disk) by an indirect block.
 139 *	To store the locations of file's data ext2 uses a data structure common
 140 *	for UNIX filesystems - tree of pointers anchored in the inode, with
 141 *	data blocks at leaves and indirect blocks in intermediate nodes.
 142 *	This function translates the block number into path in that tree -
 143 *	return value is the path length and @offsets[n] is the offset of
 144 *	pointer to (n+1)th node in the nth one. If @block is out of range
 145 *	(negative or too large) warning is printed and zero returned.
 146 *
 147 *	Note: function doesn't find node addresses, so no IO is needed. All
 148 *	we need to know is the capacity of indirect blocks (taken from the
 149 *	inode->i_sb).
 150 */
 151
 152/*
 153 * Portability note: the last comparison (check that we fit into triple
 154 * indirect block) is spelled differently, because otherwise on an
 155 * architecture with 32-bit longs and 8Kb pages we might get into trouble
 156 * if our filesystem had 8Kb blocks. We might use long long, but that would
 157 * kill us on x86. Oh, well, at least the sign propagation does not matter -
 158 * i_block would have to be negative in the very beginning, so we would not
 159 * get there at all.
 160 */
 161
 162static int ext2_block_to_path(struct inode *inode,
 163			long i_block, int offsets[4], int *boundary)
 164{
 165	int ptrs = EXT2_ADDR_PER_BLOCK(inode->i_sb);
 166	int ptrs_bits = EXT2_ADDR_PER_BLOCK_BITS(inode->i_sb);
 167	const long direct_blocks = EXT2_NDIR_BLOCKS,
 168		indirect_blocks = ptrs,
 169		double_blocks = (1 << (ptrs_bits * 2));
 170	int n = 0;
 171	int final = 0;
 172
 173	if (i_block < 0) {
 174		ext2_msg(inode->i_sb, KERN_WARNING,
 175			"warning: %s: block < 0", __func__);
 176	} else if (i_block < direct_blocks) {
 177		offsets[n++] = i_block;
 178		final = direct_blocks;
 179	} else if ( (i_block -= direct_blocks) < indirect_blocks) {
 180		offsets[n++] = EXT2_IND_BLOCK;
 181		offsets[n++] = i_block;
 182		final = ptrs;
 183	} else if ((i_block -= indirect_blocks) < double_blocks) {
 184		offsets[n++] = EXT2_DIND_BLOCK;
 185		offsets[n++] = i_block >> ptrs_bits;
 186		offsets[n++] = i_block & (ptrs - 1);
 187		final = ptrs;
 188	} else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
 189		offsets[n++] = EXT2_TIND_BLOCK;
 190		offsets[n++] = i_block >> (ptrs_bits * 2);
 191		offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
 192		offsets[n++] = i_block & (ptrs - 1);
 193		final = ptrs;
 194	} else {
 195		ext2_msg(inode->i_sb, KERN_WARNING,
 196			"warning: %s: block is too big", __func__);
 197	}
 198	if (boundary)
 199		*boundary = final - 1 - (i_block & (ptrs - 1));
 200
 201	return n;
 202}
 203
 204/**
 205 *	ext2_get_branch - read the chain of indirect blocks leading to data
 206 *	@inode: inode in question
 207 *	@depth: depth of the chain (1 - direct pointer, etc.)
 208 *	@offsets: offsets of pointers in inode/indirect blocks
 209 *	@chain: place to store the result
 210 *	@err: here we store the error value
 211 *
 212 *	Function fills the array of triples <key, p, bh> and returns %NULL
 213 *	if everything went OK or the pointer to the last filled triple
 214 *	(incomplete one) otherwise. Upon the return chain[i].key contains
 215 *	the number of (i+1)-th block in the chain (as it is stored in memory,
 216 *	i.e. little-endian 32-bit), chain[i].p contains the address of that
 217 *	number (it points into struct inode for i==0 and into the bh->b_data
 218 *	for i>0) and chain[i].bh points to the buffer_head of i-th indirect
 219 *	block for i>0 and NULL for i==0. In other words, it holds the block
 220 *	numbers of the chain, addresses they were taken from (and where we can
 221 *	verify that chain did not change) and buffer_heads hosting these
 222 *	numbers.
 223 *
 224 *	Function stops when it stumbles upon zero pointer (absent block)
 225 *		(pointer to last triple returned, *@err == 0)
 226 *	or when it gets an IO error reading an indirect block
 227 *		(ditto, *@err == -EIO)
 228 *	or when it notices that chain had been changed while it was reading
 229 *		(ditto, *@err == -EAGAIN)
 230 *	or when it reads all @depth-1 indirect blocks successfully and finds
 231 *	the whole chain, all way to the data (returns %NULL, *err == 0).
 232 */
 233static Indirect *ext2_get_branch(struct inode *inode,
 234				 int depth,
 235				 int *offsets,
 236				 Indirect chain[4],
 237				 int *err)
 238{
 239	struct super_block *sb = inode->i_sb;
 240	Indirect *p = chain;
 241	struct buffer_head *bh;
 242
 243	*err = 0;
 244	/* i_data is not going away, no lock needed */
 245	add_chain (chain, NULL, EXT2_I(inode)->i_data + *offsets);
 246	if (!p->key)
 247		goto no_block;
 248	while (--depth) {
 249		bh = sb_bread(sb, le32_to_cpu(p->key));
 250		if (!bh)
 251			goto failure;
 252		read_lock(&EXT2_I(inode)->i_meta_lock);
 253		if (!verify_chain(chain, p))
 254			goto changed;
 255		add_chain(++p, bh, (__le32*)bh->b_data + *++offsets);
 256		read_unlock(&EXT2_I(inode)->i_meta_lock);
 257		if (!p->key)
 258			goto no_block;
 259	}
 260	return NULL;
 261
 262changed:
 263	read_unlock(&EXT2_I(inode)->i_meta_lock);
 264	brelse(bh);
 265	*err = -EAGAIN;
 266	goto no_block;
 267failure:
 268	*err = -EIO;
 269no_block:
 270	return p;
 271}
 272
 273/**
 274 *	ext2_find_near - find a place for allocation with sufficient locality
 275 *	@inode: owner
 276 *	@ind: descriptor of indirect block.
 277 *
 278 *	This function returns the preferred place for block allocation.
 279 *	It is used when heuristic for sequential allocation fails.
 280 *	Rules are:
 281 *	  + if there is a block to the left of our position - allocate near it.
 282 *	  + if pointer will live in indirect block - allocate near that block.
 283 *	  + if pointer will live in inode - allocate in the same cylinder group.
 284 *
 285 * In the latter case we colour the starting block by the callers PID to
 286 * prevent it from clashing with concurrent allocations for a different inode
 287 * in the same block group.   The PID is used here so that functionally related
 288 * files will be close-by on-disk.
 289 *
 290 *	Caller must make sure that @ind is valid and will stay that way.
 291 */
 292
 293static ext2_fsblk_t ext2_find_near(struct inode *inode, Indirect *ind)
 294{
 295	struct ext2_inode_info *ei = EXT2_I(inode);
 296	__le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
 297	__le32 *p;
 298	ext2_fsblk_t bg_start;
 299	ext2_fsblk_t colour;
 300
 301	/* Try to find previous block */
 302	for (p = ind->p - 1; p >= start; p--)
 303		if (*p)
 304			return le32_to_cpu(*p);
 305
 306	/* No such thing, so let's try location of indirect block */
 307	if (ind->bh)
 308		return ind->bh->b_blocknr;
 309
 310	/*
 311	 * It is going to be referred from inode itself? OK, just put it into
 312	 * the same cylinder group then.
 313	 */
 314	bg_start = ext2_group_first_block_no(inode->i_sb, ei->i_block_group);
 315	colour = (current->pid % 16) *
 316			(EXT2_BLOCKS_PER_GROUP(inode->i_sb) / 16);
 317	return bg_start + colour;
 318}
 319
 320/**
 321 *	ext2_find_goal - find a preferred place for allocation.
 322 *	@inode: owner
 323 *	@block:  block we want
 324 *	@partial: pointer to the last triple within a chain
 325 *
 326 *	Returns preferred place for a block (the goal).
 327 */
 328
 329static inline ext2_fsblk_t ext2_find_goal(struct inode *inode, long block,
 330					  Indirect *partial)
 331{
 332	struct ext2_block_alloc_info *block_i;
 333
 334	block_i = EXT2_I(inode)->i_block_alloc_info;
 335
 336	/*
 337	 * try the heuristic for sequential allocation,
 338	 * failing that at least try to get decent locality.
 339	 */
 340	if (block_i && (block == block_i->last_alloc_logical_block + 1)
 341		&& (block_i->last_alloc_physical_block != 0)) {
 342		return block_i->last_alloc_physical_block + 1;
 343	}
 344
 345	return ext2_find_near(inode, partial);
 346}
 347
 348/**
 349 *	ext2_blks_to_allocate: Look up the block map and count the number
 350 *	of direct blocks need to be allocated for the given branch.
 351 *
 352 * 	@branch: chain of indirect blocks
 353 *	@k: number of blocks need for indirect blocks
 354 *	@blks: number of data blocks to be mapped.
 355 *	@blocks_to_boundary:  the offset in the indirect block
 356 *
 357 *	return the total number of blocks to be allocate, including the
 358 *	direct and indirect blocks.
 359 */
 360static int
 361ext2_blks_to_allocate(Indirect * branch, int k, unsigned long blks,
 362		int blocks_to_boundary)
 363{
 364	unsigned long count = 0;
 365
 366	/*
 367	 * Simple case, [t,d]Indirect block(s) has not allocated yet
 368	 * then it's clear blocks on that path have not allocated
 369	 */
 370	if (k > 0) {
 371		/* right now don't hanel cross boundary allocation */
 372		if (blks < blocks_to_boundary + 1)
 373			count += blks;
 374		else
 375			count += blocks_to_boundary + 1;
 376		return count;
 377	}
 378
 379	count++;
 380	while (count < blks && count <= blocks_to_boundary
 381		&& le32_to_cpu(*(branch[0].p + count)) == 0) {
 382		count++;
 383	}
 384	return count;
 385}
 386
 387/**
 388 *	ext2_alloc_blocks: multiple allocate blocks needed for a branch
 389 *	@indirect_blks: the number of blocks need to allocate for indirect
 390 *			blocks
 391 *
 392 *	@new_blocks: on return it will store the new block numbers for
 393 *	the indirect blocks(if needed) and the first direct block,
 394 *	@blks:	on return it will store the total number of allocated
 395 *		direct blocks
 396 */
 397static int ext2_alloc_blocks(struct inode *inode,
 398			ext2_fsblk_t goal, int indirect_blks, int blks,
 399			ext2_fsblk_t new_blocks[4], int *err)
 400{
 401	int target, i;
 402	unsigned long count = 0;
 403	int index = 0;
 404	ext2_fsblk_t current_block = 0;
 405	int ret = 0;
 406
 407	/*
 408	 * Here we try to allocate the requested multiple blocks at once,
 409	 * on a best-effort basis.
 410	 * To build a branch, we should allocate blocks for
 411	 * the indirect blocks(if not allocated yet), and at least
 412	 * the first direct block of this branch.  That's the
 413	 * minimum number of blocks need to allocate(required)
 414	 */
 415	target = blks + indirect_blks;
 416
 417	while (1) {
 418		count = target;
 419		/* allocating blocks for indirect blocks and direct blocks */
 420		current_block = ext2_new_blocks(inode,goal,&count,err);
 421		if (*err)
 422			goto failed_out;
 423
 424		target -= count;
 425		/* allocate blocks for indirect blocks */
 426		while (index < indirect_blks && count) {
 427			new_blocks[index++] = current_block++;
 428			count--;
 429		}
 430
 431		if (count > 0)
 432			break;
 433	}
 434
 435	/* save the new block number for the first direct block */
 436	new_blocks[index] = current_block;
 437
 438	/* total number of blocks allocated for direct blocks */
 439	ret = count;
 440	*err = 0;
 441	return ret;
 442failed_out:
 443	for (i = 0; i <index; i++)
 444		ext2_free_blocks(inode, new_blocks[i], 1);
 445	if (index)
 446		mark_inode_dirty(inode);
 447	return ret;
 448}
 449
 450/**
 451 *	ext2_alloc_branch - allocate and set up a chain of blocks.
 452 *	@inode: owner
 453 *	@num: depth of the chain (number of blocks to allocate)
 454 *	@offsets: offsets (in the blocks) to store the pointers to next.
 455 *	@branch: place to store the chain in.
 456 *
 457 *	This function allocates @num blocks, zeroes out all but the last one,
 458 *	links them into chain and (if we are synchronous) writes them to disk.
 459 *	In other words, it prepares a branch that can be spliced onto the
 460 *	inode. It stores the information about that chain in the branch[], in
 461 *	the same format as ext2_get_branch() would do. We are calling it after
 462 *	we had read the existing part of chain and partial points to the last
 463 *	triple of that (one with zero ->key). Upon the exit we have the same
 464 *	picture as after the successful ext2_get_block(), except that in one
 465 *	place chain is disconnected - *branch->p is still zero (we did not
 466 *	set the last link), but branch->key contains the number that should
 467 *	be placed into *branch->p to fill that gap.
 468 *
 469 *	If allocation fails we free all blocks we've allocated (and forget
 470 *	their buffer_heads) and return the error value the from failed
 471 *	ext2_alloc_block() (normally -ENOSPC). Otherwise we set the chain
 472 *	as described above and return 0.
 473 */
 474
 475static int ext2_alloc_branch(struct inode *inode,
 476			int indirect_blks, int *blks, ext2_fsblk_t goal,
 477			int *offsets, Indirect *branch)
 478{
 479	int blocksize = inode->i_sb->s_blocksize;
 480	int i, n = 0;
 481	int err = 0;
 482	struct buffer_head *bh;
 483	int num;
 484	ext2_fsblk_t new_blocks[4];
 485	ext2_fsblk_t current_block;
 486
 487	num = ext2_alloc_blocks(inode, goal, indirect_blks,
 488				*blks, new_blocks, &err);
 489	if (err)
 490		return err;
 491
 492	branch[0].key = cpu_to_le32(new_blocks[0]);
 493	/*
 494	 * metadata blocks and data blocks are allocated.
 495	 */
 496	for (n = 1; n <= indirect_blks;  n++) {
 497		/*
 498		 * Get buffer_head for parent block, zero it out
 499		 * and set the pointer to new one, then send
 500		 * parent to disk.
 501		 */
 502		bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
 503		if (unlikely(!bh)) {
 504			err = -ENOMEM;
 505			goto failed;
 506		}
 507		branch[n].bh = bh;
 508		lock_buffer(bh);
 509		memset(bh->b_data, 0, blocksize);
 510		branch[n].p = (__le32 *) bh->b_data + offsets[n];
 511		branch[n].key = cpu_to_le32(new_blocks[n]);
 512		*branch[n].p = branch[n].key;
 513		if ( n == indirect_blks) {
 514			current_block = new_blocks[n];
 515			/*
 516			 * End of chain, update the last new metablock of
 517			 * the chain to point to the new allocated
 518			 * data blocks numbers
 519			 */
 520			for (i=1; i < num; i++)
 521				*(branch[n].p + i) = cpu_to_le32(++current_block);
 522		}
 523		set_buffer_uptodate(bh);
 524		unlock_buffer(bh);
 525		mark_buffer_dirty_inode(bh, inode);
 526		/* We used to sync bh here if IS_SYNC(inode).
 527		 * But we now rely upon generic_write_sync()
 528		 * and b_inode_buffers.  But not for directories.
 529		 */
 530		if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
 531			sync_dirty_buffer(bh);
 532	}
 533	*blks = num;
 534	return err;
 535
 536failed:
 537	for (i = 1; i < n; i++)
 538		bforget(branch[i].bh);
 539	for (i = 0; i < indirect_blks; i++)
 540		ext2_free_blocks(inode, new_blocks[i], 1);
 541	ext2_free_blocks(inode, new_blocks[i], num);
 542	return err;
 543}
 544
 545/**
 546 * ext2_splice_branch - splice the allocated branch onto inode.
 547 * @inode: owner
 548 * @block: (logical) number of block we are adding
 549 * @where: location of missing link
 550 * @num:   number of indirect blocks we are adding
 551 * @blks:  number of direct blocks we are adding
 552 *
 553 * This function fills the missing link and does all housekeeping needed in
 554 * inode (->i_blocks, etc.). In case of success we end up with the full
 555 * chain to new block and return 0.
 556 */
 557static void ext2_splice_branch(struct inode *inode,
 558			long block, Indirect *where, int num, int blks)
 559{
 560	int i;
 561	struct ext2_block_alloc_info *block_i;
 562	ext2_fsblk_t current_block;
 563
 564	block_i = EXT2_I(inode)->i_block_alloc_info;
 565
 566	/* XXX LOCKING probably should have i_meta_lock ?*/
 567	/* That's it */
 568
 569	*where->p = where->key;
 570
 571	/*
 572	 * Update the host buffer_head or inode to point to more just allocated
 573	 * direct blocks blocks
 574	 */
 575	if (num == 0 && blks > 1) {
 576		current_block = le32_to_cpu(where->key) + 1;
 577		for (i = 1; i < blks; i++)
 578			*(where->p + i ) = cpu_to_le32(current_block++);
 579	}
 580
 581	/*
 582	 * update the most recently allocated logical & physical block
 583	 * in i_block_alloc_info, to assist find the proper goal block for next
 584	 * allocation
 585	 */
 586	if (block_i) {
 587		block_i->last_alloc_logical_block = block + blks - 1;
 588		block_i->last_alloc_physical_block =
 589				le32_to_cpu(where[num].key) + blks - 1;
 590	}
 591
 592	/* We are done with atomic stuff, now do the rest of housekeeping */
 593
 594	/* had we spliced it onto indirect block? */
 595	if (where->bh)
 596		mark_buffer_dirty_inode(where->bh, inode);
 597
 598	inode->i_ctime = current_time(inode);
 599	mark_inode_dirty(inode);
 600}
 601
 602/*
 603 * Allocation strategy is simple: if we have to allocate something, we will
 604 * have to go the whole way to leaf. So let's do it before attaching anything
 605 * to tree, set linkage between the newborn blocks, write them if sync is
 606 * required, recheck the path, free and repeat if check fails, otherwise
 607 * set the last missing link (that will protect us from any truncate-generated
 608 * removals - all blocks on the path are immune now) and possibly force the
 609 * write on the parent block.
 610 * That has a nice additional property: no special recovery from the failed
 611 * allocations is needed - we simply release blocks and do not touch anything
 612 * reachable from inode.
 613 *
 614 * `handle' can be NULL if create == 0.
 615 *
 616 * return > 0, # of blocks mapped or allocated.
 617 * return = 0, if plain lookup failed.
 618 * return < 0, error case.
 619 */
 620static int ext2_get_blocks(struct inode *inode,
 621			   sector_t iblock, unsigned long maxblocks,
 622			   u32 *bno, bool *new, bool *boundary,
 623			   int create)
 624{
 625	int err;
 626	int offsets[4];
 627	Indirect chain[4];
 628	Indirect *partial;
 629	ext2_fsblk_t goal;
 630	int indirect_blks;
 631	int blocks_to_boundary = 0;
 632	int depth;
 633	struct ext2_inode_info *ei = EXT2_I(inode);
 634	int count = 0;
 635	ext2_fsblk_t first_block = 0;
 636
 637	BUG_ON(maxblocks == 0);
 638
 639	depth = ext2_block_to_path(inode,iblock,offsets,&blocks_to_boundary);
 640
 641	if (depth == 0)
 642		return -EIO;
 643
 644	partial = ext2_get_branch(inode, depth, offsets, chain, &err);
 645	/* Simplest case - block found, no allocation needed */
 646	if (!partial) {
 647		first_block = le32_to_cpu(chain[depth - 1].key);
 
 648		count++;
 649		/*map more blocks*/
 650		while (count < maxblocks && count <= blocks_to_boundary) {
 651			ext2_fsblk_t blk;
 652
 653			if (!verify_chain(chain, chain + depth - 1)) {
 654				/*
 655				 * Indirect block might be removed by
 656				 * truncate while we were reading it.
 657				 * Handling of that case: forget what we've
 658				 * got now, go to reread.
 659				 */
 660				err = -EAGAIN;
 661				count = 0;
 662				break;
 663			}
 664			blk = le32_to_cpu(*(chain[depth-1].p + count));
 665			if (blk == first_block + count)
 666				count++;
 667			else
 668				break;
 669		}
 670		if (err != -EAGAIN)
 671			goto got_it;
 672	}
 673
 674	/* Next simple case - plain lookup or failed read of indirect block */
 675	if (!create || err == -EIO)
 676		goto cleanup;
 677
 678	mutex_lock(&ei->truncate_mutex);
 679	/*
 680	 * If the indirect block is missing while we are reading
 681	 * the chain(ext2_get_branch() returns -EAGAIN err), or
 682	 * if the chain has been changed after we grab the semaphore,
 683	 * (either because another process truncated this branch, or
 684	 * another get_block allocated this branch) re-grab the chain to see if
 685	 * the request block has been allocated or not.
 686	 *
 687	 * Since we already block the truncate/other get_block
 688	 * at this point, we will have the current copy of the chain when we
 689	 * splice the branch into the tree.
 690	 */
 691	if (err == -EAGAIN || !verify_chain(chain, partial)) {
 692		while (partial > chain) {
 693			brelse(partial->bh);
 694			partial--;
 695		}
 696		partial = ext2_get_branch(inode, depth, offsets, chain, &err);
 697		if (!partial) {
 698			count++;
 699			mutex_unlock(&ei->truncate_mutex);
 700			if (err)
 701				goto cleanup;
 
 702			goto got_it;
 703		}
 704	}
 705
 706	/*
 707	 * Okay, we need to do block allocation.  Lazily initialize the block
 708	 * allocation info here if necessary
 709	*/
 710	if (S_ISREG(inode->i_mode) && (!ei->i_block_alloc_info))
 711		ext2_init_block_alloc_info(inode);
 712
 713	goal = ext2_find_goal(inode, iblock, partial);
 714
 715	/* the number of blocks need to allocate for [d,t]indirect blocks */
 716	indirect_blks = (chain + depth) - partial - 1;
 717	/*
 718	 * Next look up the indirect map to count the totoal number of
 719	 * direct blocks to allocate for this branch.
 720	 */
 721	count = ext2_blks_to_allocate(partial, indirect_blks,
 722					maxblocks, blocks_to_boundary);
 723	/*
 724	 * XXX ???? Block out ext2_truncate while we alter the tree
 725	 */
 726	err = ext2_alloc_branch(inode, indirect_blks, &count, goal,
 727				offsets + (partial - chain), partial);
 728
 729	if (err) {
 730		mutex_unlock(&ei->truncate_mutex);
 731		goto cleanup;
 732	}
 733
 734	if (IS_DAX(inode)) {
 735		/*
 736		 * We must unmap blocks before zeroing so that writeback cannot
 737		 * overwrite zeros with stale data from block device page cache.
 738		 */
 739		clean_bdev_aliases(inode->i_sb->s_bdev,
 740				   le32_to_cpu(chain[depth-1].key),
 741				   count);
 742		/*
 743		 * block must be initialised before we put it in the tree
 744		 * so that it's not found by another thread before it's
 745		 * initialised
 746		 */
 747		err = sb_issue_zeroout(inode->i_sb,
 748				le32_to_cpu(chain[depth-1].key), count,
 749				GFP_NOFS);
 750		if (err) {
 751			mutex_unlock(&ei->truncate_mutex);
 752			goto cleanup;
 753		}
 754	}
 755	*new = true;
 756
 757	ext2_splice_branch(inode, iblock, partial, indirect_blks, count);
 758	mutex_unlock(&ei->truncate_mutex);
 
 759got_it:
 
 760	if (count > blocks_to_boundary)
 761		*boundary = true;
 762	err = count;
 763	/* Clean up and exit */
 764	partial = chain + depth - 1;	/* the whole chain */
 765cleanup:
 766	while (partial > chain) {
 767		brelse(partial->bh);
 768		partial--;
 769	}
 770	if (err > 0)
 771		*bno = le32_to_cpu(chain[depth-1].key);
 772	return err;
 773}
 774
 775int ext2_get_block(struct inode *inode, sector_t iblock,
 776		struct buffer_head *bh_result, int create)
 777{
 778	unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
 779	bool new = false, boundary = false;
 780	u32 bno;
 781	int ret;
 782
 783	ret = ext2_get_blocks(inode, iblock, max_blocks, &bno, &new, &boundary,
 784			create);
 785	if (ret <= 0)
 786		return ret;
 787
 788	map_bh(bh_result, inode->i_sb, bno);
 789	bh_result->b_size = (ret << inode->i_blkbits);
 790	if (new)
 791		set_buffer_new(bh_result);
 792	if (boundary)
 793		set_buffer_boundary(bh_result);
 794	return 0;
 795
 796}
 797
 798#ifdef CONFIG_FS_DAX
 799static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 800		unsigned flags, struct iomap *iomap)
 801{
 802	unsigned int blkbits = inode->i_blkbits;
 803	unsigned long first_block = offset >> blkbits;
 804	unsigned long max_blocks = (length + (1 << blkbits) - 1) >> blkbits;
 805	bool new = false, boundary = false;
 806	u32 bno;
 807	int ret;
 808
 809	ret = ext2_get_blocks(inode, first_block, max_blocks,
 810			&bno, &new, &boundary, flags & IOMAP_WRITE);
 811	if (ret < 0)
 812		return ret;
 813
 814	iomap->flags = 0;
 815	iomap->bdev = inode->i_sb->s_bdev;
 816	iomap->offset = (u64)first_block << blkbits;
 817
 818	if (ret == 0) {
 819		iomap->type = IOMAP_HOLE;
 820		iomap->blkno = IOMAP_NULL_BLOCK;
 821		iomap->length = 1 << blkbits;
 822	} else {
 823		iomap->type = IOMAP_MAPPED;
 824		iomap->blkno = (sector_t)bno << (blkbits - 9);
 825		iomap->length = (u64)ret << blkbits;
 826		iomap->flags |= IOMAP_F_MERGED;
 827	}
 
 828
 829	if (new)
 830		iomap->flags |= IOMAP_F_NEW;
 831	return 0;
 832}
 833
 834static int
 835ext2_iomap_end(struct inode *inode, loff_t offset, loff_t length,
 836		ssize_t written, unsigned flags, struct iomap *iomap)
 837{
 838	if (iomap->type == IOMAP_MAPPED &&
 839	    written < length &&
 840	    (flags & IOMAP_WRITE))
 841		ext2_write_failed(inode->i_mapping, offset + length);
 842	return 0;
 843}
 844
 845struct iomap_ops ext2_iomap_ops = {
 846	.iomap_begin		= ext2_iomap_begin,
 847	.iomap_end		= ext2_iomap_end,
 848};
 849#else
 850/* Define empty ops for !CONFIG_FS_DAX case to avoid ugly ifdefs */
 851struct iomap_ops ext2_iomap_ops;
 852#endif /* CONFIG_FS_DAX */
 853
 854int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 855		u64 start, u64 len)
 856{
 857	return generic_block_fiemap(inode, fieinfo, start, len,
 858				    ext2_get_block);
 859}
 860
 861static int ext2_writepage(struct page *page, struct writeback_control *wbc)
 862{
 863	return block_write_full_page(page, ext2_get_block, wbc);
 864}
 865
 866static int ext2_readpage(struct file *file, struct page *page)
 867{
 868	return mpage_readpage(page, ext2_get_block);
 869}
 870
 871static int
 872ext2_readpages(struct file *file, struct address_space *mapping,
 873		struct list_head *pages, unsigned nr_pages)
 874{
 875	return mpage_readpages(mapping, pages, nr_pages, ext2_get_block);
 876}
 877
 878static int
 879ext2_write_begin(struct file *file, struct address_space *mapping,
 880		loff_t pos, unsigned len, unsigned flags,
 881		struct page **pagep, void **fsdata)
 882{
 883	int ret;
 884
 885	ret = block_write_begin(mapping, pos, len, flags, pagep,
 886				ext2_get_block);
 887	if (ret < 0)
 888		ext2_write_failed(mapping, pos + len);
 889	return ret;
 890}
 891
 892static int ext2_write_end(struct file *file, struct address_space *mapping,
 893			loff_t pos, unsigned len, unsigned copied,
 894			struct page *page, void *fsdata)
 895{
 896	int ret;
 897
 898	ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
 899	if (ret < len)
 900		ext2_write_failed(mapping, pos + len);
 901	return ret;
 902}
 903
 904static int
 905ext2_nobh_write_begin(struct file *file, struct address_space *mapping,
 906		loff_t pos, unsigned len, unsigned flags,
 907		struct page **pagep, void **fsdata)
 908{
 909	int ret;
 910
 911	ret = nobh_write_begin(mapping, pos, len, flags, pagep, fsdata,
 912			       ext2_get_block);
 913	if (ret < 0)
 914		ext2_write_failed(mapping, pos + len);
 915	return ret;
 916}
 917
 918static int ext2_nobh_writepage(struct page *page,
 919			struct writeback_control *wbc)
 920{
 921	return nobh_writepage(page, ext2_get_block, wbc);
 922}
 923
 924static sector_t ext2_bmap(struct address_space *mapping, sector_t block)
 925{
 926	return generic_block_bmap(mapping,block,ext2_get_block);
 927}
 928
 929static ssize_t
 930ext2_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 
 931{
 932	struct file *file = iocb->ki_filp;
 933	struct address_space *mapping = file->f_mapping;
 934	struct inode *inode = mapping->host;
 935	size_t count = iov_iter_count(iter);
 936	loff_t offset = iocb->ki_pos;
 937	ssize_t ret;
 938
 939	if (WARN_ON_ONCE(IS_DAX(inode)))
 940		return -EIO;
 941
 942	ret = blockdev_direct_IO(iocb, inode, iter, ext2_get_block);
 943	if (ret < 0 && iov_iter_rw(iter) == WRITE)
 944		ext2_write_failed(mapping, offset + count);
 945	return ret;
 946}
 947
 948static int
 949ext2_writepages(struct address_space *mapping, struct writeback_control *wbc)
 950{
 951#ifdef CONFIG_FS_DAX
 952	if (dax_mapping(mapping)) {
 953		return dax_writeback_mapping_range(mapping,
 954						   mapping->host->i_sb->s_bdev,
 955						   wbc);
 956	}
 957#endif
 958
 959	return mpage_writepages(mapping, wbc, ext2_get_block);
 960}
 961
 962const struct address_space_operations ext2_aops = {
 963	.readpage		= ext2_readpage,
 964	.readpages		= ext2_readpages,
 965	.writepage		= ext2_writepage,
 966	.write_begin		= ext2_write_begin,
 967	.write_end		= ext2_write_end,
 968	.bmap			= ext2_bmap,
 969	.direct_IO		= ext2_direct_IO,
 970	.writepages		= ext2_writepages,
 971	.migratepage		= buffer_migrate_page,
 972	.is_partially_uptodate	= block_is_partially_uptodate,
 973	.error_remove_page	= generic_error_remove_page,
 974};
 975
 
 
 
 
 
 976const struct address_space_operations ext2_nobh_aops = {
 977	.readpage		= ext2_readpage,
 978	.readpages		= ext2_readpages,
 979	.writepage		= ext2_nobh_writepage,
 980	.write_begin		= ext2_nobh_write_begin,
 981	.write_end		= nobh_write_end,
 982	.bmap			= ext2_bmap,
 983	.direct_IO		= ext2_direct_IO,
 984	.writepages		= ext2_writepages,
 985	.migratepage		= buffer_migrate_page,
 986	.error_remove_page	= generic_error_remove_page,
 987};
 988
 989/*
 990 * Probably it should be a library function... search for first non-zero word
 991 * or memcmp with zero_page, whatever is better for particular architecture.
 992 * Linus?
 993 */
 994static inline int all_zeroes(__le32 *p, __le32 *q)
 995{
 996	while (p < q)
 997		if (*p++)
 998			return 0;
 999	return 1;
1000}
1001
1002/**
1003 *	ext2_find_shared - find the indirect blocks for partial truncation.
1004 *	@inode:	  inode in question
1005 *	@depth:	  depth of the affected branch
1006 *	@offsets: offsets of pointers in that branch (see ext2_block_to_path)
1007 *	@chain:	  place to store the pointers to partial indirect blocks
1008 *	@top:	  place to the (detached) top of branch
1009 *
1010 *	This is a helper function used by ext2_truncate().
1011 *
1012 *	When we do truncate() we may have to clean the ends of several indirect
1013 *	blocks but leave the blocks themselves alive. Block is partially
1014 *	truncated if some data below the new i_size is referred from it (and
1015 *	it is on the path to the first completely truncated data block, indeed).
1016 *	We have to free the top of that path along with everything to the right
1017 *	of the path. Since no allocation past the truncation point is possible
1018 *	until ext2_truncate() finishes, we may safely do the latter, but top
1019 *	of branch may require special attention - pageout below the truncation
1020 *	point might try to populate it.
1021 *
1022 *	We atomically detach the top of branch from the tree, store the block
1023 *	number of its root in *@top, pointers to buffer_heads of partially
1024 *	truncated blocks - in @chain[].bh and pointers to their last elements
1025 *	that should not be removed - in @chain[].p. Return value is the pointer
1026 *	to last filled element of @chain.
1027 *
1028 *	The work left to caller to do the actual freeing of subtrees:
1029 *		a) free the subtree starting from *@top
1030 *		b) free the subtrees whose roots are stored in
1031 *			(@chain[i].p+1 .. end of @chain[i].bh->b_data)
1032 *		c) free the subtrees growing from the inode past the @chain[0].p
1033 *			(no partially truncated stuff there).
1034 */
1035
1036static Indirect *ext2_find_shared(struct inode *inode,
1037				int depth,
1038				int offsets[4],
1039				Indirect chain[4],
1040				__le32 *top)
1041{
1042	Indirect *partial, *p;
1043	int k, err;
1044
1045	*top = 0;
1046	for (k = depth; k > 1 && !offsets[k-1]; k--)
1047		;
1048	partial = ext2_get_branch(inode, k, offsets, chain, &err);
1049	if (!partial)
1050		partial = chain + k-1;
1051	/*
1052	 * If the branch acquired continuation since we've looked at it -
1053	 * fine, it should all survive and (new) top doesn't belong to us.
1054	 */
1055	write_lock(&EXT2_I(inode)->i_meta_lock);
1056	if (!partial->key && *partial->p) {
1057		write_unlock(&EXT2_I(inode)->i_meta_lock);
1058		goto no_top;
1059	}
1060	for (p=partial; p>chain && all_zeroes((__le32*)p->bh->b_data,p->p); p--)
1061		;
1062	/*
1063	 * OK, we've found the last block that must survive. The rest of our
1064	 * branch should be detached before unlocking. However, if that rest
1065	 * of branch is all ours and does not grow immediately from the inode
1066	 * it's easier to cheat and just decrement partial->p.
1067	 */
1068	if (p == chain + k - 1 && p > chain) {
1069		p->p--;
1070	} else {
1071		*top = *p->p;
1072		*p->p = 0;
1073	}
1074	write_unlock(&EXT2_I(inode)->i_meta_lock);
1075
1076	while(partial > p)
1077	{
1078		brelse(partial->bh);
1079		partial--;
1080	}
1081no_top:
1082	return partial;
1083}
1084
1085/**
1086 *	ext2_free_data - free a list of data blocks
1087 *	@inode:	inode we are dealing with
1088 *	@p:	array of block numbers
1089 *	@q:	points immediately past the end of array
1090 *
1091 *	We are freeing all blocks referred from that array (numbers are
1092 *	stored as little-endian 32-bit) and updating @inode->i_blocks
1093 *	appropriately.
1094 */
1095static inline void ext2_free_data(struct inode *inode, __le32 *p, __le32 *q)
1096{
1097	unsigned long block_to_free = 0, count = 0;
1098	unsigned long nr;
1099
1100	for ( ; p < q ; p++) {
1101		nr = le32_to_cpu(*p);
1102		if (nr) {
1103			*p = 0;
1104			/* accumulate blocks to free if they're contiguous */
1105			if (count == 0)
1106				goto free_this;
1107			else if (block_to_free == nr - count)
1108				count++;
1109			else {
1110				ext2_free_blocks (inode, block_to_free, count);
1111				mark_inode_dirty(inode);
1112			free_this:
1113				block_to_free = nr;
1114				count = 1;
1115			}
1116		}
1117	}
1118	if (count > 0) {
1119		ext2_free_blocks (inode, block_to_free, count);
1120		mark_inode_dirty(inode);
1121	}
1122}
1123
1124/**
1125 *	ext2_free_branches - free an array of branches
1126 *	@inode:	inode we are dealing with
1127 *	@p:	array of block numbers
1128 *	@q:	pointer immediately past the end of array
1129 *	@depth:	depth of the branches to free
1130 *
1131 *	We are freeing all blocks referred from these branches (numbers are
1132 *	stored as little-endian 32-bit) and updating @inode->i_blocks
1133 *	appropriately.
1134 */
1135static void ext2_free_branches(struct inode *inode, __le32 *p, __le32 *q, int depth)
1136{
1137	struct buffer_head * bh;
1138	unsigned long nr;
1139
1140	if (depth--) {
1141		int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
1142		for ( ; p < q ; p++) {
1143			nr = le32_to_cpu(*p);
1144			if (!nr)
1145				continue;
1146			*p = 0;
1147			bh = sb_bread(inode->i_sb, nr);
1148			/*
1149			 * A read failure? Report error and clear slot
1150			 * (should be rare).
1151			 */ 
1152			if (!bh) {
1153				ext2_error(inode->i_sb, "ext2_free_branches",
1154					"Read failure, inode=%ld, block=%ld",
1155					inode->i_ino, nr);
1156				continue;
1157			}
1158			ext2_free_branches(inode,
1159					   (__le32*)bh->b_data,
1160					   (__le32*)bh->b_data + addr_per_block,
1161					   depth);
1162			bforget(bh);
1163			ext2_free_blocks(inode, nr, 1);
1164			mark_inode_dirty(inode);
1165		}
1166	} else
1167		ext2_free_data(inode, p, q);
1168}
1169
1170/* dax_sem must be held when calling this function */
1171static void __ext2_truncate_blocks(struct inode *inode, loff_t offset)
1172{
1173	__le32 *i_data = EXT2_I(inode)->i_data;
1174	struct ext2_inode_info *ei = EXT2_I(inode);
1175	int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
1176	int offsets[4];
1177	Indirect chain[4];
1178	Indirect *partial;
1179	__le32 nr = 0;
1180	int n;
1181	long iblock;
1182	unsigned blocksize;
1183	blocksize = inode->i_sb->s_blocksize;
1184	iblock = (offset + blocksize-1) >> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
1185
1186#ifdef CONFIG_FS_DAX
1187	WARN_ON(!rwsem_is_locked(&ei->dax_sem));
1188#endif
1189
1190	n = ext2_block_to_path(inode, iblock, offsets, NULL);
1191	if (n == 0)
1192		return;
1193
1194	/*
1195	 * From here we block out all ext2_get_block() callers who want to
1196	 * modify the block allocation tree.
1197	 */
1198	mutex_lock(&ei->truncate_mutex);
1199
1200	if (n == 1) {
1201		ext2_free_data(inode, i_data+offsets[0],
1202					i_data + EXT2_NDIR_BLOCKS);
1203		goto do_indirects;
1204	}
1205
1206	partial = ext2_find_shared(inode, n, offsets, chain, &nr);
1207	/* Kill the top of shared branch (already detached) */
1208	if (nr) {
1209		if (partial == chain)
1210			mark_inode_dirty(inode);
1211		else
1212			mark_buffer_dirty_inode(partial->bh, inode);
1213		ext2_free_branches(inode, &nr, &nr+1, (chain+n-1) - partial);
1214	}
1215	/* Clear the ends of indirect blocks on the shared branch */
1216	while (partial > chain) {
1217		ext2_free_branches(inode,
1218				   partial->p + 1,
1219				   (__le32*)partial->bh->b_data+addr_per_block,
1220				   (chain+n-1) - partial);
1221		mark_buffer_dirty_inode(partial->bh, inode);
1222		brelse (partial->bh);
1223		partial--;
1224	}
1225do_indirects:
1226	/* Kill the remaining (whole) subtrees */
1227	switch (offsets[0]) {
1228		default:
1229			nr = i_data[EXT2_IND_BLOCK];
1230			if (nr) {
1231				i_data[EXT2_IND_BLOCK] = 0;
1232				mark_inode_dirty(inode);
1233				ext2_free_branches(inode, &nr, &nr+1, 1);
1234			}
1235		case EXT2_IND_BLOCK:
1236			nr = i_data[EXT2_DIND_BLOCK];
1237			if (nr) {
1238				i_data[EXT2_DIND_BLOCK] = 0;
1239				mark_inode_dirty(inode);
1240				ext2_free_branches(inode, &nr, &nr+1, 2);
1241			}
1242		case EXT2_DIND_BLOCK:
1243			nr = i_data[EXT2_TIND_BLOCK];
1244			if (nr) {
1245				i_data[EXT2_TIND_BLOCK] = 0;
1246				mark_inode_dirty(inode);
1247				ext2_free_branches(inode, &nr, &nr+1, 3);
1248			}
1249		case EXT2_TIND_BLOCK:
1250			;
1251	}
1252
1253	ext2_discard_reservation(inode);
1254
1255	mutex_unlock(&ei->truncate_mutex);
1256}
1257
1258static void ext2_truncate_blocks(struct inode *inode, loff_t offset)
1259{
1260	/*
1261	 * XXX: it seems like a bug here that we don't allow
1262	 * IS_APPEND inode to have blocks-past-i_size trimmed off.
1263	 * review and fix this.
1264	 *
1265	 * Also would be nice to be able to handle IO errors and such,
1266	 * but that's probably too much to ask.
1267	 */
1268	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
1269	    S_ISLNK(inode->i_mode)))
1270		return;
1271	if (ext2_inode_is_fast_symlink(inode))
1272		return;
1273	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
1274		return;
1275
1276	dax_sem_down_write(EXT2_I(inode));
1277	__ext2_truncate_blocks(inode, offset);
1278	dax_sem_up_write(EXT2_I(inode));
1279}
1280
1281static int ext2_setsize(struct inode *inode, loff_t newsize)
1282{
1283	int error;
1284
1285	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
1286	    S_ISLNK(inode->i_mode)))
1287		return -EINVAL;
1288	if (ext2_inode_is_fast_symlink(inode))
1289		return -EINVAL;
1290	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
1291		return -EPERM;
1292
1293	inode_dio_wait(inode);
1294
1295	if (IS_DAX(inode)) {
1296		error = iomap_zero_range(inode, newsize,
1297					 PAGE_ALIGN(newsize) - newsize, NULL,
1298					 &ext2_iomap_ops);
1299	} else if (test_opt(inode->i_sb, NOBH))
1300		error = nobh_truncate_page(inode->i_mapping,
1301				newsize, ext2_get_block);
1302	else
1303		error = block_truncate_page(inode->i_mapping,
1304				newsize, ext2_get_block);
1305	if (error)
1306		return error;
1307
1308	dax_sem_down_write(EXT2_I(inode));
1309	truncate_setsize(inode, newsize);
1310	__ext2_truncate_blocks(inode, newsize);
1311	dax_sem_up_write(EXT2_I(inode));
1312
1313	inode->i_mtime = inode->i_ctime = current_time(inode);
1314	if (inode_needs_sync(inode)) {
1315		sync_mapping_buffers(inode->i_mapping);
1316		sync_inode_metadata(inode, 1);
1317	} else {
1318		mark_inode_dirty(inode);
1319	}
1320
1321	return 0;
1322}
1323
1324static struct ext2_inode *ext2_get_inode(struct super_block *sb, ino_t ino,
1325					struct buffer_head **p)
1326{
1327	struct buffer_head * bh;
1328	unsigned long block_group;
1329	unsigned long block;
1330	unsigned long offset;
1331	struct ext2_group_desc * gdp;
1332
1333	*p = NULL;
1334	if ((ino != EXT2_ROOT_INO && ino < EXT2_FIRST_INO(sb)) ||
1335	    ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
1336		goto Einval;
1337
1338	block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb);
1339	gdp = ext2_get_group_desc(sb, block_group, NULL);
1340	if (!gdp)
1341		goto Egdp;
1342	/*
1343	 * Figure out the offset within the block group inode table
1344	 */
1345	offset = ((ino - 1) % EXT2_INODES_PER_GROUP(sb)) * EXT2_INODE_SIZE(sb);
1346	block = le32_to_cpu(gdp->bg_inode_table) +
1347		(offset >> EXT2_BLOCK_SIZE_BITS(sb));
1348	if (!(bh = sb_bread(sb, block)))
1349		goto Eio;
1350
1351	*p = bh;
1352	offset &= (EXT2_BLOCK_SIZE(sb) - 1);
1353	return (struct ext2_inode *) (bh->b_data + offset);
1354
1355Einval:
1356	ext2_error(sb, "ext2_get_inode", "bad inode number: %lu",
1357		   (unsigned long) ino);
1358	return ERR_PTR(-EINVAL);
1359Eio:
1360	ext2_error(sb, "ext2_get_inode",
1361		   "unable to read inode block - inode=%lu, block=%lu",
1362		   (unsigned long) ino, block);
1363Egdp:
1364	return ERR_PTR(-EIO);
1365}
1366
1367void ext2_set_inode_flags(struct inode *inode)
1368{
1369	unsigned int flags = EXT2_I(inode)->i_flags;
1370
1371	inode->i_flags &= ~(S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME |
1372				S_DIRSYNC | S_DAX);
1373	if (flags & EXT2_SYNC_FL)
1374		inode->i_flags |= S_SYNC;
1375	if (flags & EXT2_APPEND_FL)
1376		inode->i_flags |= S_APPEND;
1377	if (flags & EXT2_IMMUTABLE_FL)
1378		inode->i_flags |= S_IMMUTABLE;
1379	if (flags & EXT2_NOATIME_FL)
1380		inode->i_flags |= S_NOATIME;
1381	if (flags & EXT2_DIRSYNC_FL)
1382		inode->i_flags |= S_DIRSYNC;
1383	if (test_opt(inode->i_sb, DAX) && S_ISREG(inode->i_mode))
1384		inode->i_flags |= S_DAX;
1385}
1386
1387/* Propagate flags from i_flags to EXT2_I(inode)->i_flags */
1388void ext2_get_inode_flags(struct ext2_inode_info *ei)
1389{
1390	unsigned int flags = ei->vfs_inode.i_flags;
1391
1392	ei->i_flags &= ~(EXT2_SYNC_FL|EXT2_APPEND_FL|
1393			EXT2_IMMUTABLE_FL|EXT2_NOATIME_FL|EXT2_DIRSYNC_FL);
1394	if (flags & S_SYNC)
1395		ei->i_flags |= EXT2_SYNC_FL;
1396	if (flags & S_APPEND)
1397		ei->i_flags |= EXT2_APPEND_FL;
1398	if (flags & S_IMMUTABLE)
1399		ei->i_flags |= EXT2_IMMUTABLE_FL;
1400	if (flags & S_NOATIME)
1401		ei->i_flags |= EXT2_NOATIME_FL;
1402	if (flags & S_DIRSYNC)
1403		ei->i_flags |= EXT2_DIRSYNC_FL;
1404}
1405
1406struct inode *ext2_iget (struct super_block *sb, unsigned long ino)
1407{
1408	struct ext2_inode_info *ei;
1409	struct buffer_head * bh;
1410	struct ext2_inode *raw_inode;
1411	struct inode *inode;
1412	long ret = -EIO;
1413	int n;
1414	uid_t i_uid;
1415	gid_t i_gid;
1416
1417	inode = iget_locked(sb, ino);
1418	if (!inode)
1419		return ERR_PTR(-ENOMEM);
1420	if (!(inode->i_state & I_NEW))
1421		return inode;
1422
1423	ei = EXT2_I(inode);
1424	ei->i_block_alloc_info = NULL;
1425
1426	raw_inode = ext2_get_inode(inode->i_sb, ino, &bh);
1427	if (IS_ERR(raw_inode)) {
1428		ret = PTR_ERR(raw_inode);
1429 		goto bad_inode;
1430	}
1431
1432	inode->i_mode = le16_to_cpu(raw_inode->i_mode);
1433	i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
1434	i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
1435	if (!(test_opt (inode->i_sb, NO_UID32))) {
1436		i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
1437		i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
1438	}
1439	i_uid_write(inode, i_uid);
1440	i_gid_write(inode, i_gid);
1441	set_nlink(inode, le16_to_cpu(raw_inode->i_links_count));
1442	inode->i_size = le32_to_cpu(raw_inode->i_size);
1443	inode->i_atime.tv_sec = (signed)le32_to_cpu(raw_inode->i_atime);
1444	inode->i_ctime.tv_sec = (signed)le32_to_cpu(raw_inode->i_ctime);
1445	inode->i_mtime.tv_sec = (signed)le32_to_cpu(raw_inode->i_mtime);
1446	inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1447	ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
1448	/* We now have enough fields to check if the inode was active or not.
1449	 * This is needed because nfsd might try to access dead inodes
1450	 * the test is that same one that e2fsck uses
1451	 * NeilBrown 1999oct15
1452	 */
1453	if (inode->i_nlink == 0 && (inode->i_mode == 0 || ei->i_dtime)) {
1454		/* this inode is deleted */
1455		brelse (bh);
1456		ret = -ESTALE;
1457		goto bad_inode;
1458	}
1459	inode->i_blocks = le32_to_cpu(raw_inode->i_blocks);
1460	ei->i_flags = le32_to_cpu(raw_inode->i_flags);
1461	ei->i_faddr = le32_to_cpu(raw_inode->i_faddr);
1462	ei->i_frag_no = raw_inode->i_frag;
1463	ei->i_frag_size = raw_inode->i_fsize;
1464	ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl);
1465	ei->i_dir_acl = 0;
1466
1467	if (ei->i_file_acl &&
1468	    !ext2_data_block_valid(EXT2_SB(sb), ei->i_file_acl, 1)) {
1469		ext2_error(sb, "ext2_iget", "bad extended attribute block %u",
1470			   ei->i_file_acl);
1471		brelse(bh);
1472		ret = -EFSCORRUPTED;
1473		goto bad_inode;
1474	}
1475
1476	if (S_ISREG(inode->i_mode))
1477		inode->i_size |= ((__u64)le32_to_cpu(raw_inode->i_size_high)) << 32;
1478	else
1479		ei->i_dir_acl = le32_to_cpu(raw_inode->i_dir_acl);
1480	if (i_size_read(inode) < 0) {
1481		ret = -EFSCORRUPTED;
1482		goto bad_inode;
1483	}
1484	ei->i_dtime = 0;
1485	inode->i_generation = le32_to_cpu(raw_inode->i_generation);
1486	ei->i_state = 0;
1487	ei->i_block_group = (ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);
1488	ei->i_dir_start_lookup = 0;
1489
1490	/*
1491	 * NOTE! The in-memory inode i_data array is in little-endian order
1492	 * even on big-endian machines: we do NOT byteswap the block numbers!
1493	 */
1494	for (n = 0; n < EXT2_N_BLOCKS; n++)
1495		ei->i_data[n] = raw_inode->i_block[n];
1496
1497	if (S_ISREG(inode->i_mode)) {
1498		inode->i_op = &ext2_file_inode_operations;
1499		if (test_opt(inode->i_sb, NOBH)) {
 
 
 
1500			inode->i_mapping->a_ops = &ext2_nobh_aops;
1501			inode->i_fop = &ext2_file_operations;
1502		} else {
1503			inode->i_mapping->a_ops = &ext2_aops;
1504			inode->i_fop = &ext2_file_operations;
1505		}
1506	} else if (S_ISDIR(inode->i_mode)) {
1507		inode->i_op = &ext2_dir_inode_operations;
1508		inode->i_fop = &ext2_dir_operations;
1509		if (test_opt(inode->i_sb, NOBH))
1510			inode->i_mapping->a_ops = &ext2_nobh_aops;
1511		else
1512			inode->i_mapping->a_ops = &ext2_aops;
1513	} else if (S_ISLNK(inode->i_mode)) {
1514		if (ext2_inode_is_fast_symlink(inode)) {
1515			inode->i_link = (char *)ei->i_data;
1516			inode->i_op = &ext2_fast_symlink_inode_operations;
1517			nd_terminate_link(ei->i_data, inode->i_size,
1518				sizeof(ei->i_data) - 1);
1519		} else {
1520			inode->i_op = &ext2_symlink_inode_operations;
1521			inode_nohighmem(inode);
1522			if (test_opt(inode->i_sb, NOBH))
1523				inode->i_mapping->a_ops = &ext2_nobh_aops;
1524			else
1525				inode->i_mapping->a_ops = &ext2_aops;
1526		}
1527	} else {
1528		inode->i_op = &ext2_special_inode_operations;
1529		if (raw_inode->i_block[0])
1530			init_special_inode(inode, inode->i_mode,
1531			   old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
1532		else 
1533			init_special_inode(inode, inode->i_mode,
1534			   new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
1535	}
1536	brelse (bh);
1537	ext2_set_inode_flags(inode);
1538	unlock_new_inode(inode);
1539	return inode;
1540	
1541bad_inode:
1542	iget_failed(inode);
1543	return ERR_PTR(ret);
1544}
1545
1546static int __ext2_write_inode(struct inode *inode, int do_sync)
1547{
1548	struct ext2_inode_info *ei = EXT2_I(inode);
1549	struct super_block *sb = inode->i_sb;
1550	ino_t ino = inode->i_ino;
1551	uid_t uid = i_uid_read(inode);
1552	gid_t gid = i_gid_read(inode);
1553	struct buffer_head * bh;
1554	struct ext2_inode * raw_inode = ext2_get_inode(sb, ino, &bh);
1555	int n;
1556	int err = 0;
1557
1558	if (IS_ERR(raw_inode))
1559 		return -EIO;
1560
1561	/* For fields not not tracking in the in-memory inode,
1562	 * initialise them to zero for new inodes. */
1563	if (ei->i_state & EXT2_STATE_NEW)
1564		memset(raw_inode, 0, EXT2_SB(sb)->s_inode_size);
1565
1566	ext2_get_inode_flags(ei);
1567	raw_inode->i_mode = cpu_to_le16(inode->i_mode);
1568	if (!(test_opt(sb, NO_UID32))) {
1569		raw_inode->i_uid_low = cpu_to_le16(low_16_bits(uid));
1570		raw_inode->i_gid_low = cpu_to_le16(low_16_bits(gid));
1571/*
1572 * Fix up interoperability with old kernels. Otherwise, old inodes get
1573 * re-used with the upper 16 bits of the uid/gid intact
1574 */
1575		if (!ei->i_dtime) {
1576			raw_inode->i_uid_high = cpu_to_le16(high_16_bits(uid));
1577			raw_inode->i_gid_high = cpu_to_le16(high_16_bits(gid));
1578		} else {
1579			raw_inode->i_uid_high = 0;
1580			raw_inode->i_gid_high = 0;
1581		}
1582	} else {
1583		raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(uid));
1584		raw_inode->i_gid_low = cpu_to_le16(fs_high2lowgid(gid));
1585		raw_inode->i_uid_high = 0;
1586		raw_inode->i_gid_high = 0;
1587	}
1588	raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
1589	raw_inode->i_size = cpu_to_le32(inode->i_size);
1590	raw_inode->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
1591	raw_inode->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
1592	raw_inode->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
1593
1594	raw_inode->i_blocks = cpu_to_le32(inode->i_blocks);
1595	raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
1596	raw_inode->i_flags = cpu_to_le32(ei->i_flags);
1597	raw_inode->i_faddr = cpu_to_le32(ei->i_faddr);
1598	raw_inode->i_frag = ei->i_frag_no;
1599	raw_inode->i_fsize = ei->i_frag_size;
1600	raw_inode->i_file_acl = cpu_to_le32(ei->i_file_acl);
1601	if (!S_ISREG(inode->i_mode))
1602		raw_inode->i_dir_acl = cpu_to_le32(ei->i_dir_acl);
1603	else {
1604		raw_inode->i_size_high = cpu_to_le32(inode->i_size >> 32);
1605		if (inode->i_size > 0x7fffffffULL) {
1606			if (!EXT2_HAS_RO_COMPAT_FEATURE(sb,
1607					EXT2_FEATURE_RO_COMPAT_LARGE_FILE) ||
1608			    EXT2_SB(sb)->s_es->s_rev_level ==
1609					cpu_to_le32(EXT2_GOOD_OLD_REV)) {
1610			       /* If this is the first large file
1611				* created, add a flag to the superblock.
1612				*/
1613				spin_lock(&EXT2_SB(sb)->s_lock);
1614				ext2_update_dynamic_rev(sb);
1615				EXT2_SET_RO_COMPAT_FEATURE(sb,
1616					EXT2_FEATURE_RO_COMPAT_LARGE_FILE);
1617				spin_unlock(&EXT2_SB(sb)->s_lock);
1618				ext2_write_super(sb);
1619			}
1620		}
1621	}
1622	
1623	raw_inode->i_generation = cpu_to_le32(inode->i_generation);
1624	if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
1625		if (old_valid_dev(inode->i_rdev)) {
1626			raw_inode->i_block[0] =
1627				cpu_to_le32(old_encode_dev(inode->i_rdev));
1628			raw_inode->i_block[1] = 0;
1629		} else {
1630			raw_inode->i_block[0] = 0;
1631			raw_inode->i_block[1] =
1632				cpu_to_le32(new_encode_dev(inode->i_rdev));
1633			raw_inode->i_block[2] = 0;
1634		}
1635	} else for (n = 0; n < EXT2_N_BLOCKS; n++)
1636		raw_inode->i_block[n] = ei->i_data[n];
1637	mark_buffer_dirty(bh);
1638	if (do_sync) {
1639		sync_dirty_buffer(bh);
1640		if (buffer_req(bh) && !buffer_uptodate(bh)) {
1641			printk ("IO error syncing ext2 inode [%s:%08lx]\n",
1642				sb->s_id, (unsigned long) ino);
1643			err = -EIO;
1644		}
1645	}
1646	ei->i_state &= ~EXT2_STATE_NEW;
1647	brelse (bh);
1648	return err;
1649}
1650
1651int ext2_write_inode(struct inode *inode, struct writeback_control *wbc)
1652{
1653	return __ext2_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
1654}
1655
1656int ext2_setattr(struct dentry *dentry, struct iattr *iattr)
1657{
1658	struct inode *inode = d_inode(dentry);
1659	int error;
1660
1661	error = setattr_prepare(dentry, iattr);
1662	if (error)
1663		return error;
1664
1665	if (is_quota_modification(inode, iattr)) {
1666		error = dquot_initialize(inode);
1667		if (error)
1668			return error;
1669	}
1670	if ((iattr->ia_valid & ATTR_UID && !uid_eq(iattr->ia_uid, inode->i_uid)) ||
1671	    (iattr->ia_valid & ATTR_GID && !gid_eq(iattr->ia_gid, inode->i_gid))) {
1672		error = dquot_transfer(inode, iattr);
1673		if (error)
1674			return error;
1675	}
1676	if (iattr->ia_valid & ATTR_SIZE && iattr->ia_size != inode->i_size) {
1677		error = ext2_setsize(inode, iattr->ia_size);
1678		if (error)
1679			return error;
1680	}
1681	setattr_copy(inode, iattr);
1682	if (iattr->ia_valid & ATTR_MODE)
1683		error = posix_acl_chmod(inode, inode->i_mode);
1684	mark_inode_dirty(inode);
1685
1686	return error;
1687}