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/quotaops.h>
  29#include <linux/module.h>
  30#include <linux/writeback.h>
  31#include <linux/buffer_head.h>
  32#include <linux/mpage.h>
  33#include <linux/fiemap.h>
  34#include <linux/namei.h>
 
  35#include "ext2.h"
  36#include "acl.h"
  37#include "xip.h"
  38
  39MODULE_AUTHOR("Remy Card and others");
  40MODULE_DESCRIPTION("Second Extended Filesystem");
  41MODULE_LICENSE("GPL");
  42
  43static int __ext2_write_inode(struct inode *inode, int do_sync);
  44
  45/*
  46 * Test whether an inode is a fast symlink.
  47 */
  48static inline int ext2_inode_is_fast_symlink(struct inode *inode)
  49{
  50	int ea_blocks = EXT2_I(inode)->i_file_acl ?
  51		(inode->i_sb->s_blocksize >> 9) : 0;
  52
  53	return (S_ISLNK(inode->i_mode) &&
  54		inode->i_blocks - ea_blocks == 0);
  55}
  56
  57static void ext2_truncate_blocks(struct inode *inode, loff_t offset);
  58
  59static void ext2_write_failed(struct address_space *mapping, loff_t to)
  60{
  61	struct inode *inode = mapping->host;
  62
  63	if (to > inode->i_size) {
  64		truncate_pagecache(inode, to, inode->i_size);
  65		ext2_truncate_blocks(inode, inode->i_size);
  66	}
  67}
  68
  69/*
  70 * Called at the last iput() if i_nlink is zero.
  71 */
  72void ext2_evict_inode(struct inode * inode)
  73{
  74	struct ext2_block_alloc_info *rsv;
  75	int want_delete = 0;
  76
  77	if (!inode->i_nlink && !is_bad_inode(inode)) {
  78		want_delete = 1;
  79		dquot_initialize(inode);
  80	} else {
  81		dquot_drop(inode);
  82	}
  83
  84	truncate_inode_pages(&inode->i_data, 0);
  85
  86	if (want_delete) {
 
  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	}
  96
  97	invalidate_inode_buffers(inode);
  98	end_writeback(inode);
  99
 100	ext2_discard_reservation(inode);
 101	rsv = EXT2_I(inode)->i_block_alloc_info;
 102	EXT2_I(inode)->i_block_alloc_info = NULL;
 103	if (unlikely(rsv))
 104		kfree(rsv);
 105
 106	if (want_delete)
 107		ext2_free_inode(inode);
 
 
 108}
 109
 110typedef struct {
 111	__le32	*p;
 112	__le32	key;
 113	struct buffer_head *bh;
 114} Indirect;
 115
 116static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
 117{
 118	p->key = *(p->p = v);
 119	p->bh = bh;
 120}
 121
 122static inline int verify_chain(Indirect *from, Indirect *to)
 123{
 124	while (from <= to && from->key == *from->p)
 125		from++;
 126	return (from > to);
 127}
 128
 129/**
 130 *	ext2_block_to_path - parse the block number into array of offsets
 131 *	@inode: inode in question (we are only interested in its superblock)
 132 *	@i_block: block number to be parsed
 133 *	@offsets: array to store the offsets in
 134 *      @boundary: set this non-zero if the referred-to block is likely to be
 135 *             followed (on disk) by an indirect block.
 136 *	To store the locations of file's data ext2 uses a data structure common
 137 *	for UNIX filesystems - tree of pointers anchored in the inode, with
 138 *	data blocks at leaves and indirect blocks in intermediate nodes.
 139 *	This function translates the block number into path in that tree -
 140 *	return value is the path length and @offsets[n] is the offset of
 141 *	pointer to (n+1)th node in the nth one. If @block is out of range
 142 *	(negative or too large) warning is printed and zero returned.
 143 *
 144 *	Note: function doesn't find node addresses, so no IO is needed. All
 145 *	we need to know is the capacity of indirect blocks (taken from the
 146 *	inode->i_sb).
 147 */
 148
 149/*
 150 * Portability note: the last comparison (check that we fit into triple
 151 * indirect block) is spelled differently, because otherwise on an
 152 * architecture with 32-bit longs and 8Kb pages we might get into trouble
 153 * if our filesystem had 8Kb blocks. We might use long long, but that would
 154 * kill us on x86. Oh, well, at least the sign propagation does not matter -
 155 * i_block would have to be negative in the very beginning, so we would not
 156 * get there at all.
 157 */
 158
 159static int ext2_block_to_path(struct inode *inode,
 160			long i_block, int offsets[4], int *boundary)
 161{
 162	int ptrs = EXT2_ADDR_PER_BLOCK(inode->i_sb);
 163	int ptrs_bits = EXT2_ADDR_PER_BLOCK_BITS(inode->i_sb);
 164	const long direct_blocks = EXT2_NDIR_BLOCKS,
 165		indirect_blocks = ptrs,
 166		double_blocks = (1 << (ptrs_bits * 2));
 167	int n = 0;
 168	int final = 0;
 169
 170	if (i_block < 0) {
 171		ext2_msg(inode->i_sb, KERN_WARNING,
 172			"warning: %s: block < 0", __func__);
 173	} else if (i_block < direct_blocks) {
 174		offsets[n++] = i_block;
 175		final = direct_blocks;
 176	} else if ( (i_block -= direct_blocks) < indirect_blocks) {
 177		offsets[n++] = EXT2_IND_BLOCK;
 178		offsets[n++] = i_block;
 179		final = ptrs;
 180	} else if ((i_block -= indirect_blocks) < double_blocks) {
 181		offsets[n++] = EXT2_DIND_BLOCK;
 182		offsets[n++] = i_block >> ptrs_bits;
 183		offsets[n++] = i_block & (ptrs - 1);
 184		final = ptrs;
 185	} else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
 186		offsets[n++] = EXT2_TIND_BLOCK;
 187		offsets[n++] = i_block >> (ptrs_bits * 2);
 188		offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
 189		offsets[n++] = i_block & (ptrs - 1);
 190		final = ptrs;
 191	} else {
 192		ext2_msg(inode->i_sb, KERN_WARNING,
 193			"warning: %s: block is too big", __func__);
 194	}
 195	if (boundary)
 196		*boundary = final - 1 - (i_block & (ptrs - 1));
 197
 198	return n;
 199}
 200
 201/**
 202 *	ext2_get_branch - read the chain of indirect blocks leading to data
 203 *	@inode: inode in question
 204 *	@depth: depth of the chain (1 - direct pointer, etc.)
 205 *	@offsets: offsets of pointers in inode/indirect blocks
 206 *	@chain: place to store the result
 207 *	@err: here we store the error value
 208 *
 209 *	Function fills the array of triples <key, p, bh> and returns %NULL
 210 *	if everything went OK or the pointer to the last filled triple
 211 *	(incomplete one) otherwise. Upon the return chain[i].key contains
 212 *	the number of (i+1)-th block in the chain (as it is stored in memory,
 213 *	i.e. little-endian 32-bit), chain[i].p contains the address of that
 214 *	number (it points into struct inode for i==0 and into the bh->b_data
 215 *	for i>0) and chain[i].bh points to the buffer_head of i-th indirect
 216 *	block for i>0 and NULL for i==0. In other words, it holds the block
 217 *	numbers of the chain, addresses they were taken from (and where we can
 218 *	verify that chain did not change) and buffer_heads hosting these
 219 *	numbers.
 220 *
 221 *	Function stops when it stumbles upon zero pointer (absent block)
 222 *		(pointer to last triple returned, *@err == 0)
 223 *	or when it gets an IO error reading an indirect block
 224 *		(ditto, *@err == -EIO)
 225 *	or when it notices that chain had been changed while it was reading
 226 *		(ditto, *@err == -EAGAIN)
 227 *	or when it reads all @depth-1 indirect blocks successfully and finds
 228 *	the whole chain, all way to the data (returns %NULL, *err == 0).
 229 */
 230static Indirect *ext2_get_branch(struct inode *inode,
 231				 int depth,
 232				 int *offsets,
 233				 Indirect chain[4],
 234				 int *err)
 235{
 236	struct super_block *sb = inode->i_sb;
 237	Indirect *p = chain;
 238	struct buffer_head *bh;
 239
 240	*err = 0;
 241	/* i_data is not going away, no lock needed */
 242	add_chain (chain, NULL, EXT2_I(inode)->i_data + *offsets);
 243	if (!p->key)
 244		goto no_block;
 245	while (--depth) {
 246		bh = sb_bread(sb, le32_to_cpu(p->key));
 247		if (!bh)
 248			goto failure;
 249		read_lock(&EXT2_I(inode)->i_meta_lock);
 250		if (!verify_chain(chain, p))
 251			goto changed;
 252		add_chain(++p, bh, (__le32*)bh->b_data + *++offsets);
 253		read_unlock(&EXT2_I(inode)->i_meta_lock);
 254		if (!p->key)
 255			goto no_block;
 256	}
 257	return NULL;
 258
 259changed:
 260	read_unlock(&EXT2_I(inode)->i_meta_lock);
 261	brelse(bh);
 262	*err = -EAGAIN;
 263	goto no_block;
 264failure:
 265	*err = -EIO;
 266no_block:
 267	return p;
 268}
 269
 270/**
 271 *	ext2_find_near - find a place for allocation with sufficient locality
 272 *	@inode: owner
 273 *	@ind: descriptor of indirect block.
 274 *
 275 *	This function returns the preferred place for block allocation.
 276 *	It is used when heuristic for sequential allocation fails.
 277 *	Rules are:
 278 *	  + if there is a block to the left of our position - allocate near it.
 279 *	  + if pointer will live in indirect block - allocate near that block.
 280 *	  + if pointer will live in inode - allocate in the same cylinder group.
 281 *
 282 * In the latter case we colour the starting block by the callers PID to
 283 * prevent it from clashing with concurrent allocations for a different inode
 284 * in the same block group.   The PID is used here so that functionally related
 285 * files will be close-by on-disk.
 286 *
 287 *	Caller must make sure that @ind is valid and will stay that way.
 288 */
 289
 290static ext2_fsblk_t ext2_find_near(struct inode *inode, Indirect *ind)
 291{
 292	struct ext2_inode_info *ei = EXT2_I(inode);
 293	__le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
 294	__le32 *p;
 295	ext2_fsblk_t bg_start;
 296	ext2_fsblk_t colour;
 297
 298	/* Try to find previous block */
 299	for (p = ind->p - 1; p >= start; p--)
 300		if (*p)
 301			return le32_to_cpu(*p);
 302
 303	/* No such thing, so let's try location of indirect block */
 304	if (ind->bh)
 305		return ind->bh->b_blocknr;
 306
 307	/*
 308	 * It is going to be referred from inode itself? OK, just put it into
 309	 * the same cylinder group then.
 310	 */
 311	bg_start = ext2_group_first_block_no(inode->i_sb, ei->i_block_group);
 312	colour = (current->pid % 16) *
 313			(EXT2_BLOCKS_PER_GROUP(inode->i_sb) / 16);
 314	return bg_start + colour;
 315}
 316
 317/**
 318 *	ext2_find_goal - find a preferred place for allocation.
 319 *	@inode: owner
 320 *	@block:  block we want
 321 *	@partial: pointer to the last triple within a chain
 322 *
 323 *	Returns preferred place for a block (the goal).
 324 */
 325
 326static inline ext2_fsblk_t ext2_find_goal(struct inode *inode, long block,
 327					  Indirect *partial)
 328{
 329	struct ext2_block_alloc_info *block_i;
 330
 331	block_i = EXT2_I(inode)->i_block_alloc_info;
 332
 333	/*
 334	 * try the heuristic for sequential allocation,
 335	 * failing that at least try to get decent locality.
 336	 */
 337	if (block_i && (block == block_i->last_alloc_logical_block + 1)
 338		&& (block_i->last_alloc_physical_block != 0)) {
 339		return block_i->last_alloc_physical_block + 1;
 340	}
 341
 342	return ext2_find_near(inode, partial);
 343}
 344
 345/**
 346 *	ext2_blks_to_allocate: Look up the block map and count the number
 347 *	of direct blocks need to be allocated for the given branch.
 348 *
 349 * 	@branch: chain of indirect blocks
 350 *	@k: number of blocks need for indirect blocks
 351 *	@blks: number of data blocks to be mapped.
 352 *	@blocks_to_boundary:  the offset in the indirect block
 353 *
 354 *	return the total number of blocks to be allocate, including the
 355 *	direct and indirect blocks.
 356 */
 357static int
 358ext2_blks_to_allocate(Indirect * branch, int k, unsigned long blks,
 359		int blocks_to_boundary)
 360{
 361	unsigned long count = 0;
 362
 363	/*
 364	 * Simple case, [t,d]Indirect block(s) has not allocated yet
 365	 * then it's clear blocks on that path have not allocated
 366	 */
 367	if (k > 0) {
 368		/* right now don't hanel cross boundary allocation */
 369		if (blks < blocks_to_boundary + 1)
 370			count += blks;
 371		else
 372			count += blocks_to_boundary + 1;
 373		return count;
 374	}
 375
 376	count++;
 377	while (count < blks && count <= blocks_to_boundary
 378		&& le32_to_cpu(*(branch[0].p + count)) == 0) {
 379		count++;
 380	}
 381	return count;
 382}
 383
 384/**
 385 *	ext2_alloc_blocks: multiple allocate blocks needed for a branch
 386 *	@indirect_blks: the number of blocks need to allocate for indirect
 387 *			blocks
 388 *
 389 *	@new_blocks: on return it will store the new block numbers for
 390 *	the indirect blocks(if needed) and the first direct block,
 391 *	@blks:	on return it will store the total number of allocated
 392 *		direct blocks
 393 */
 394static int ext2_alloc_blocks(struct inode *inode,
 395			ext2_fsblk_t goal, int indirect_blks, int blks,
 396			ext2_fsblk_t new_blocks[4], int *err)
 397{
 398	int target, i;
 399	unsigned long count = 0;
 400	int index = 0;
 401	ext2_fsblk_t current_block = 0;
 402	int ret = 0;
 403
 404	/*
 405	 * Here we try to allocate the requested multiple blocks at once,
 406	 * on a best-effort basis.
 407	 * To build a branch, we should allocate blocks for
 408	 * the indirect blocks(if not allocated yet), and at least
 409	 * the first direct block of this branch.  That's the
 410	 * minimum number of blocks need to allocate(required)
 411	 */
 412	target = blks + indirect_blks;
 413
 414	while (1) {
 415		count = target;
 416		/* allocating blocks for indirect blocks and direct blocks */
 417		current_block = ext2_new_blocks(inode,goal,&count,err);
 418		if (*err)
 419			goto failed_out;
 420
 421		target -= count;
 422		/* allocate blocks for indirect blocks */
 423		while (index < indirect_blks && count) {
 424			new_blocks[index++] = current_block++;
 425			count--;
 426		}
 427
 428		if (count > 0)
 429			break;
 430	}
 431
 432	/* save the new block number for the first direct block */
 433	new_blocks[index] = current_block;
 434
 435	/* total number of blocks allocated for direct blocks */
 436	ret = count;
 437	*err = 0;
 438	return ret;
 439failed_out:
 440	for (i = 0; i <index; i++)
 441		ext2_free_blocks(inode, new_blocks[i], 1);
 442	if (index)
 443		mark_inode_dirty(inode);
 444	return ret;
 445}
 446
 447/**
 448 *	ext2_alloc_branch - allocate and set up a chain of blocks.
 449 *	@inode: owner
 450 *	@num: depth of the chain (number of blocks to allocate)
 451 *	@offsets: offsets (in the blocks) to store the pointers to next.
 452 *	@branch: place to store the chain in.
 453 *
 454 *	This function allocates @num blocks, zeroes out all but the last one,
 455 *	links them into chain and (if we are synchronous) writes them to disk.
 456 *	In other words, it prepares a branch that can be spliced onto the
 457 *	inode. It stores the information about that chain in the branch[], in
 458 *	the same format as ext2_get_branch() would do. We are calling it after
 459 *	we had read the existing part of chain and partial points to the last
 460 *	triple of that (one with zero ->key). Upon the exit we have the same
 461 *	picture as after the successful ext2_get_block(), except that in one
 462 *	place chain is disconnected - *branch->p is still zero (we did not
 463 *	set the last link), but branch->key contains the number that should
 464 *	be placed into *branch->p to fill that gap.
 465 *
 466 *	If allocation fails we free all blocks we've allocated (and forget
 467 *	their buffer_heads) and return the error value the from failed
 468 *	ext2_alloc_block() (normally -ENOSPC). Otherwise we set the chain
 469 *	as described above and return 0.
 470 */
 471
 472static int ext2_alloc_branch(struct inode *inode,
 473			int indirect_blks, int *blks, ext2_fsblk_t goal,
 474			int *offsets, Indirect *branch)
 475{
 476	int blocksize = inode->i_sb->s_blocksize;
 477	int i, n = 0;
 478	int err = 0;
 479	struct buffer_head *bh;
 480	int num;
 481	ext2_fsblk_t new_blocks[4];
 482	ext2_fsblk_t current_block;
 483
 484	num = ext2_alloc_blocks(inode, goal, indirect_blks,
 485				*blks, new_blocks, &err);
 486	if (err)
 487		return err;
 488
 489	branch[0].key = cpu_to_le32(new_blocks[0]);
 490	/*
 491	 * metadata blocks and data blocks are allocated.
 492	 */
 493	for (n = 1; n <= indirect_blks;  n++) {
 494		/*
 495		 * Get buffer_head for parent block, zero it out
 496		 * and set the pointer to new one, then send
 497		 * parent to disk.
 498		 */
 499		bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
 
 
 
 
 500		branch[n].bh = bh;
 501		lock_buffer(bh);
 502		memset(bh->b_data, 0, blocksize);
 503		branch[n].p = (__le32 *) bh->b_data + offsets[n];
 504		branch[n].key = cpu_to_le32(new_blocks[n]);
 505		*branch[n].p = branch[n].key;
 506		if ( n == indirect_blks) {
 507			current_block = new_blocks[n];
 508			/*
 509			 * End of chain, update the last new metablock of
 510			 * the chain to point to the new allocated
 511			 * data blocks numbers
 512			 */
 513			for (i=1; i < num; i++)
 514				*(branch[n].p + i) = cpu_to_le32(++current_block);
 515		}
 516		set_buffer_uptodate(bh);
 517		unlock_buffer(bh);
 518		mark_buffer_dirty_inode(bh, inode);
 519		/* We used to sync bh here if IS_SYNC(inode).
 520		 * But we now rely upon generic_write_sync()
 521		 * and b_inode_buffers.  But not for directories.
 522		 */
 523		if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
 524			sync_dirty_buffer(bh);
 525	}
 526	*blks = num;
 527	return err;
 
 
 
 
 
 
 
 
 528}
 529
 530/**
 531 * ext2_splice_branch - splice the allocated branch onto inode.
 532 * @inode: owner
 533 * @block: (logical) number of block we are adding
 534 * @where: location of missing link
 535 * @num:   number of indirect blocks we are adding
 536 * @blks:  number of direct blocks we are adding
 537 *
 538 * This function fills the missing link and does all housekeeping needed in
 539 * inode (->i_blocks, etc.). In case of success we end up with the full
 540 * chain to new block and return 0.
 541 */
 542static void ext2_splice_branch(struct inode *inode,
 543			long block, Indirect *where, int num, int blks)
 544{
 545	int i;
 546	struct ext2_block_alloc_info *block_i;
 547	ext2_fsblk_t current_block;
 548
 549	block_i = EXT2_I(inode)->i_block_alloc_info;
 550
 551	/* XXX LOCKING probably should have i_meta_lock ?*/
 552	/* That's it */
 553
 554	*where->p = where->key;
 555
 556	/*
 557	 * Update the host buffer_head or inode to point to more just allocated
 558	 * direct blocks blocks
 559	 */
 560	if (num == 0 && blks > 1) {
 561		current_block = le32_to_cpu(where->key) + 1;
 562		for (i = 1; i < blks; i++)
 563			*(where->p + i ) = cpu_to_le32(current_block++);
 564	}
 565
 566	/*
 567	 * update the most recently allocated logical & physical block
 568	 * in i_block_alloc_info, to assist find the proper goal block for next
 569	 * allocation
 570	 */
 571	if (block_i) {
 572		block_i->last_alloc_logical_block = block + blks - 1;
 573		block_i->last_alloc_physical_block =
 574				le32_to_cpu(where[num].key) + blks - 1;
 575	}
 576
 577	/* We are done with atomic stuff, now do the rest of housekeeping */
 578
 579	/* had we spliced it onto indirect block? */
 580	if (where->bh)
 581		mark_buffer_dirty_inode(where->bh, inode);
 582
 583	inode->i_ctime = CURRENT_TIME_SEC;
 584	mark_inode_dirty(inode);
 585}
 586
 587/*
 588 * Allocation strategy is simple: if we have to allocate something, we will
 589 * have to go the whole way to leaf. So let's do it before attaching anything
 590 * to tree, set linkage between the newborn blocks, write them if sync is
 591 * required, recheck the path, free and repeat if check fails, otherwise
 592 * set the last missing link (that will protect us from any truncate-generated
 593 * removals - all blocks on the path are immune now) and possibly force the
 594 * write on the parent block.
 595 * That has a nice additional property: no special recovery from the failed
 596 * allocations is needed - we simply release blocks and do not touch anything
 597 * reachable from inode.
 598 *
 599 * `handle' can be NULL if create == 0.
 600 *
 601 * return > 0, # of blocks mapped or allocated.
 602 * return = 0, if plain lookup failed.
 603 * return < 0, error case.
 604 */
 605static int ext2_get_blocks(struct inode *inode,
 606			   sector_t iblock, unsigned long maxblocks,
 607			   struct buffer_head *bh_result,
 608			   int create)
 609{
 610	int err = -EIO;
 611	int offsets[4];
 612	Indirect chain[4];
 613	Indirect *partial;
 614	ext2_fsblk_t goal;
 615	int indirect_blks;
 616	int blocks_to_boundary = 0;
 617	int depth;
 618	struct ext2_inode_info *ei = EXT2_I(inode);
 619	int count = 0;
 620	ext2_fsblk_t first_block = 0;
 621
 
 
 622	depth = ext2_block_to_path(inode,iblock,offsets,&blocks_to_boundary);
 623
 624	if (depth == 0)
 625		return (err);
 626
 627	partial = ext2_get_branch(inode, depth, offsets, chain, &err);
 628	/* Simplest case - block found, no allocation needed */
 629	if (!partial) {
 630		first_block = le32_to_cpu(chain[depth - 1].key);
 631		clear_buffer_new(bh_result); /* What's this do? */
 632		count++;
 633		/*map more blocks*/
 634		while (count < maxblocks && count <= blocks_to_boundary) {
 635			ext2_fsblk_t blk;
 636
 637			if (!verify_chain(chain, chain + depth - 1)) {
 638				/*
 639				 * Indirect block might be removed by
 640				 * truncate while we were reading it.
 641				 * Handling of that case: forget what we've
 642				 * got now, go to reread.
 643				 */
 644				err = -EAGAIN;
 645				count = 0;
 646				break;
 647			}
 648			blk = le32_to_cpu(*(chain[depth-1].p + count));
 649			if (blk == first_block + count)
 650				count++;
 651			else
 652				break;
 653		}
 654		if (err != -EAGAIN)
 655			goto got_it;
 656	}
 657
 658	/* Next simple case - plain lookup or failed read of indirect block */
 659	if (!create || err == -EIO)
 660		goto cleanup;
 661
 662	mutex_lock(&ei->truncate_mutex);
 663	/*
 664	 * If the indirect block is missing while we are reading
 665	 * the chain(ext2_get_branch() returns -EAGAIN err), or
 666	 * if the chain has been changed after we grab the semaphore,
 667	 * (either because another process truncated this branch, or
 668	 * another get_block allocated this branch) re-grab the chain to see if
 669	 * the request block has been allocated or not.
 670	 *
 671	 * Since we already block the truncate/other get_block
 672	 * at this point, we will have the current copy of the chain when we
 673	 * splice the branch into the tree.
 674	 */
 675	if (err == -EAGAIN || !verify_chain(chain, partial)) {
 676		while (partial > chain) {
 677			brelse(partial->bh);
 678			partial--;
 679		}
 680		partial = ext2_get_branch(inode, depth, offsets, chain, &err);
 681		if (!partial) {
 682			count++;
 683			mutex_unlock(&ei->truncate_mutex);
 684			if (err)
 685				goto cleanup;
 686			clear_buffer_new(bh_result);
 687			goto got_it;
 688		}
 689	}
 690
 691	/*
 692	 * Okay, we need to do block allocation.  Lazily initialize the block
 693	 * allocation info here if necessary
 694	*/
 695	if (S_ISREG(inode->i_mode) && (!ei->i_block_alloc_info))
 696		ext2_init_block_alloc_info(inode);
 697
 698	goal = ext2_find_goal(inode, iblock, partial);
 699
 700	/* the number of blocks need to allocate for [d,t]indirect blocks */
 701	indirect_blks = (chain + depth) - partial - 1;
 702	/*
 703	 * Next look up the indirect map to count the totoal number of
 704	 * direct blocks to allocate for this branch.
 705	 */
 706	count = ext2_blks_to_allocate(partial, indirect_blks,
 707					maxblocks, blocks_to_boundary);
 708	/*
 709	 * XXX ???? Block out ext2_truncate while we alter the tree
 710	 */
 711	err = ext2_alloc_branch(inode, indirect_blks, &count, goal,
 712				offsets + (partial - chain), partial);
 713
 714	if (err) {
 715		mutex_unlock(&ei->truncate_mutex);
 716		goto cleanup;
 717	}
 718
 719	if (ext2_use_xip(inode->i_sb)) {
 720		/*
 721		 * we need to clear the block
 722		 */
 723		err = ext2_clear_xip_target (inode,
 724			le32_to_cpu(chain[depth-1].key));
 725		if (err) {
 726			mutex_unlock(&ei->truncate_mutex);
 727			goto cleanup;
 728		}
 729	}
 730
 731	ext2_splice_branch(inode, iblock, partial, indirect_blks, count);
 732	mutex_unlock(&ei->truncate_mutex);
 733	set_buffer_new(bh_result);
 734got_it:
 735	map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
 736	if (count > blocks_to_boundary)
 737		set_buffer_boundary(bh_result);
 738	err = count;
 739	/* Clean up and exit */
 740	partial = chain + depth - 1;	/* the whole chain */
 741cleanup:
 742	while (partial > chain) {
 743		brelse(partial->bh);
 744		partial--;
 745	}
 746	return err;
 747}
 748
 749int ext2_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create)
 750{
 751	unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
 752	int ret = ext2_get_blocks(inode, iblock, max_blocks,
 753			      bh_result, create);
 754	if (ret > 0) {
 755		bh_result->b_size = (ret << inode->i_blkbits);
 756		ret = 0;
 757	}
 758	return ret;
 759
 760}
 761
 762int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 763		u64 start, u64 len)
 764{
 765	return generic_block_fiemap(inode, fieinfo, start, len,
 766				    ext2_get_block);
 767}
 768
 769static int ext2_writepage(struct page *page, struct writeback_control *wbc)
 770{
 771	return block_write_full_page(page, ext2_get_block, wbc);
 772}
 773
 774static int ext2_readpage(struct file *file, struct page *page)
 775{
 776	return mpage_readpage(page, ext2_get_block);
 777}
 778
 779static int
 780ext2_readpages(struct file *file, struct address_space *mapping,
 781		struct list_head *pages, unsigned nr_pages)
 782{
 783	return mpage_readpages(mapping, pages, nr_pages, ext2_get_block);
 784}
 785
 786static int
 787ext2_write_begin(struct file *file, struct address_space *mapping,
 788		loff_t pos, unsigned len, unsigned flags,
 789		struct page **pagep, void **fsdata)
 790{
 791	int ret;
 792
 793	ret = block_write_begin(mapping, pos, len, flags, pagep,
 794				ext2_get_block);
 795	if (ret < 0)
 796		ext2_write_failed(mapping, pos + len);
 797	return ret;
 798}
 799
 800static int ext2_write_end(struct file *file, struct address_space *mapping,
 801			loff_t pos, unsigned len, unsigned copied,
 802			struct page *page, void *fsdata)
 803{
 804	int ret;
 805
 806	ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
 807	if (ret < len)
 808		ext2_write_failed(mapping, pos + len);
 809	return ret;
 810}
 811
 812static int
 813ext2_nobh_write_begin(struct file *file, struct address_space *mapping,
 814		loff_t pos, unsigned len, unsigned flags,
 815		struct page **pagep, void **fsdata)
 816{
 817	int ret;
 818
 819	ret = nobh_write_begin(mapping, pos, len, flags, pagep, fsdata,
 820			       ext2_get_block);
 821	if (ret < 0)
 822		ext2_write_failed(mapping, pos + len);
 823	return ret;
 824}
 825
 826static int ext2_nobh_writepage(struct page *page,
 827			struct writeback_control *wbc)
 828{
 829	return nobh_writepage(page, ext2_get_block, wbc);
 830}
 831
 832static sector_t ext2_bmap(struct address_space *mapping, sector_t block)
 833{
 834	return generic_block_bmap(mapping,block,ext2_get_block);
 835}
 836
 837static ssize_t
 838ext2_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
 839			loff_t offset, unsigned long nr_segs)
 840{
 841	struct file *file = iocb->ki_filp;
 842	struct address_space *mapping = file->f_mapping;
 843	struct inode *inode = mapping->host;
 844	ssize_t ret;
 845
 846	ret = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
 847				 ext2_get_block);
 848	if (ret < 0 && (rw & WRITE))
 849		ext2_write_failed(mapping, offset + iov_length(iov, nr_segs));
 850	return ret;
 851}
 852
 853static int
 854ext2_writepages(struct address_space *mapping, struct writeback_control *wbc)
 855{
 856	return mpage_writepages(mapping, wbc, ext2_get_block);
 857}
 858
 859const struct address_space_operations ext2_aops = {
 860	.readpage		= ext2_readpage,
 861	.readpages		= ext2_readpages,
 862	.writepage		= ext2_writepage,
 863	.write_begin		= ext2_write_begin,
 864	.write_end		= ext2_write_end,
 865	.bmap			= ext2_bmap,
 866	.direct_IO		= ext2_direct_IO,
 867	.writepages		= ext2_writepages,
 868	.migratepage		= buffer_migrate_page,
 869	.is_partially_uptodate	= block_is_partially_uptodate,
 870	.error_remove_page	= generic_error_remove_page,
 871};
 872
 873const struct address_space_operations ext2_aops_xip = {
 874	.bmap			= ext2_bmap,
 875	.get_xip_mem		= ext2_get_xip_mem,
 876};
 877
 878const struct address_space_operations ext2_nobh_aops = {
 879	.readpage		= ext2_readpage,
 880	.readpages		= ext2_readpages,
 881	.writepage		= ext2_nobh_writepage,
 882	.write_begin		= ext2_nobh_write_begin,
 883	.write_end		= nobh_write_end,
 884	.bmap			= ext2_bmap,
 885	.direct_IO		= ext2_direct_IO,
 886	.writepages		= ext2_writepages,
 887	.migratepage		= buffer_migrate_page,
 888	.error_remove_page	= generic_error_remove_page,
 889};
 890
 891/*
 892 * Probably it should be a library function... search for first non-zero word
 893 * or memcmp with zero_page, whatever is better for particular architecture.
 894 * Linus?
 895 */
 896static inline int all_zeroes(__le32 *p, __le32 *q)
 897{
 898	while (p < q)
 899		if (*p++)
 900			return 0;
 901	return 1;
 902}
 903
 904/**
 905 *	ext2_find_shared - find the indirect blocks for partial truncation.
 906 *	@inode:	  inode in question
 907 *	@depth:	  depth of the affected branch
 908 *	@offsets: offsets of pointers in that branch (see ext2_block_to_path)
 909 *	@chain:	  place to store the pointers to partial indirect blocks
 910 *	@top:	  place to the (detached) top of branch
 911 *
 912 *	This is a helper function used by ext2_truncate().
 913 *
 914 *	When we do truncate() we may have to clean the ends of several indirect
 915 *	blocks but leave the blocks themselves alive. Block is partially
 916 *	truncated if some data below the new i_size is referred from it (and
 917 *	it is on the path to the first completely truncated data block, indeed).
 918 *	We have to free the top of that path along with everything to the right
 919 *	of the path. Since no allocation past the truncation point is possible
 920 *	until ext2_truncate() finishes, we may safely do the latter, but top
 921 *	of branch may require special attention - pageout below the truncation
 922 *	point might try to populate it.
 923 *
 924 *	We atomically detach the top of branch from the tree, store the block
 925 *	number of its root in *@top, pointers to buffer_heads of partially
 926 *	truncated blocks - in @chain[].bh and pointers to their last elements
 927 *	that should not be removed - in @chain[].p. Return value is the pointer
 928 *	to last filled element of @chain.
 929 *
 930 *	The work left to caller to do the actual freeing of subtrees:
 931 *		a) free the subtree starting from *@top
 932 *		b) free the subtrees whose roots are stored in
 933 *			(@chain[i].p+1 .. end of @chain[i].bh->b_data)
 934 *		c) free the subtrees growing from the inode past the @chain[0].p
 935 *			(no partially truncated stuff there).
 936 */
 937
 938static Indirect *ext2_find_shared(struct inode *inode,
 939				int depth,
 940				int offsets[4],
 941				Indirect chain[4],
 942				__le32 *top)
 943{
 944	Indirect *partial, *p;
 945	int k, err;
 946
 947	*top = 0;
 948	for (k = depth; k > 1 && !offsets[k-1]; k--)
 949		;
 950	partial = ext2_get_branch(inode, k, offsets, chain, &err);
 951	if (!partial)
 952		partial = chain + k-1;
 953	/*
 954	 * If the branch acquired continuation since we've looked at it -
 955	 * fine, it should all survive and (new) top doesn't belong to us.
 956	 */
 957	write_lock(&EXT2_I(inode)->i_meta_lock);
 958	if (!partial->key && *partial->p) {
 959		write_unlock(&EXT2_I(inode)->i_meta_lock);
 960		goto no_top;
 961	}
 962	for (p=partial; p>chain && all_zeroes((__le32*)p->bh->b_data,p->p); p--)
 963		;
 964	/*
 965	 * OK, we've found the last block that must survive. The rest of our
 966	 * branch should be detached before unlocking. However, if that rest
 967	 * of branch is all ours and does not grow immediately from the inode
 968	 * it's easier to cheat and just decrement partial->p.
 969	 */
 970	if (p == chain + k - 1 && p > chain) {
 971		p->p--;
 972	} else {
 973		*top = *p->p;
 974		*p->p = 0;
 975	}
 976	write_unlock(&EXT2_I(inode)->i_meta_lock);
 977
 978	while(partial > p)
 979	{
 980		brelse(partial->bh);
 981		partial--;
 982	}
 983no_top:
 984	return partial;
 985}
 986
 987/**
 988 *	ext2_free_data - free a list of data blocks
 989 *	@inode:	inode we are dealing with
 990 *	@p:	array of block numbers
 991 *	@q:	points immediately past the end of array
 992 *
 993 *	We are freeing all blocks referred from that array (numbers are
 994 *	stored as little-endian 32-bit) and updating @inode->i_blocks
 995 *	appropriately.
 996 */
 997static inline void ext2_free_data(struct inode *inode, __le32 *p, __le32 *q)
 998{
 999	unsigned long block_to_free = 0, count = 0;
1000	unsigned long nr;
1001
1002	for ( ; p < q ; p++) {
1003		nr = le32_to_cpu(*p);
1004		if (nr) {
1005			*p = 0;
1006			/* accumulate blocks to free if they're contiguous */
1007			if (count == 0)
1008				goto free_this;
1009			else if (block_to_free == nr - count)
1010				count++;
1011			else {
1012				ext2_free_blocks (inode, block_to_free, count);
1013				mark_inode_dirty(inode);
1014			free_this:
1015				block_to_free = nr;
1016				count = 1;
1017			}
1018		}
1019	}
1020	if (count > 0) {
1021		ext2_free_blocks (inode, block_to_free, count);
1022		mark_inode_dirty(inode);
1023	}
1024}
1025
1026/**
1027 *	ext2_free_branches - free an array of branches
1028 *	@inode:	inode we are dealing with
1029 *	@p:	array of block numbers
1030 *	@q:	pointer immediately past the end of array
1031 *	@depth:	depth of the branches to free
1032 *
1033 *	We are freeing all blocks referred from these branches (numbers are
1034 *	stored as little-endian 32-bit) and updating @inode->i_blocks
1035 *	appropriately.
1036 */
1037static void ext2_free_branches(struct inode *inode, __le32 *p, __le32 *q, int depth)
1038{
1039	struct buffer_head * bh;
1040	unsigned long nr;
1041
1042	if (depth--) {
1043		int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
1044		for ( ; p < q ; p++) {
1045			nr = le32_to_cpu(*p);
1046			if (!nr)
1047				continue;
1048			*p = 0;
1049			bh = sb_bread(inode->i_sb, nr);
1050			/*
1051			 * A read failure? Report error and clear slot
1052			 * (should be rare).
1053			 */ 
1054			if (!bh) {
1055				ext2_error(inode->i_sb, "ext2_free_branches",
1056					"Read failure, inode=%ld, block=%ld",
1057					inode->i_ino, nr);
1058				continue;
1059			}
1060			ext2_free_branches(inode,
1061					   (__le32*)bh->b_data,
1062					   (__le32*)bh->b_data + addr_per_block,
1063					   depth);
1064			bforget(bh);
1065			ext2_free_blocks(inode, nr, 1);
1066			mark_inode_dirty(inode);
1067		}
1068	} else
1069		ext2_free_data(inode, p, q);
1070}
1071
1072static void __ext2_truncate_blocks(struct inode *inode, loff_t offset)
1073{
1074	__le32 *i_data = EXT2_I(inode)->i_data;
1075	struct ext2_inode_info *ei = EXT2_I(inode);
1076	int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
1077	int offsets[4];
1078	Indirect chain[4];
1079	Indirect *partial;
1080	__le32 nr = 0;
1081	int n;
1082	long iblock;
1083	unsigned blocksize;
1084	blocksize = inode->i_sb->s_blocksize;
1085	iblock = (offset + blocksize-1) >> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
1086
1087	n = ext2_block_to_path(inode, iblock, offsets, NULL);
1088	if (n == 0)
1089		return;
1090
1091	/*
1092	 * From here we block out all ext2_get_block() callers who want to
1093	 * modify the block allocation tree.
1094	 */
1095	mutex_lock(&ei->truncate_mutex);
1096
1097	if (n == 1) {
1098		ext2_free_data(inode, i_data+offsets[0],
1099					i_data + EXT2_NDIR_BLOCKS);
1100		goto do_indirects;
1101	}
1102
1103	partial = ext2_find_shared(inode, n, offsets, chain, &nr);
1104	/* Kill the top of shared branch (already detached) */
1105	if (nr) {
1106		if (partial == chain)
1107			mark_inode_dirty(inode);
1108		else
1109			mark_buffer_dirty_inode(partial->bh, inode);
1110		ext2_free_branches(inode, &nr, &nr+1, (chain+n-1) - partial);
1111	}
1112	/* Clear the ends of indirect blocks on the shared branch */
1113	while (partial > chain) {
1114		ext2_free_branches(inode,
1115				   partial->p + 1,
1116				   (__le32*)partial->bh->b_data+addr_per_block,
1117				   (chain+n-1) - partial);
1118		mark_buffer_dirty_inode(partial->bh, inode);
1119		brelse (partial->bh);
1120		partial--;
1121	}
1122do_indirects:
1123	/* Kill the remaining (whole) subtrees */
1124	switch (offsets[0]) {
1125		default:
1126			nr = i_data[EXT2_IND_BLOCK];
1127			if (nr) {
1128				i_data[EXT2_IND_BLOCK] = 0;
1129				mark_inode_dirty(inode);
1130				ext2_free_branches(inode, &nr, &nr+1, 1);
1131			}
1132		case EXT2_IND_BLOCK:
1133			nr = i_data[EXT2_DIND_BLOCK];
1134			if (nr) {
1135				i_data[EXT2_DIND_BLOCK] = 0;
1136				mark_inode_dirty(inode);
1137				ext2_free_branches(inode, &nr, &nr+1, 2);
1138			}
1139		case EXT2_DIND_BLOCK:
1140			nr = i_data[EXT2_TIND_BLOCK];
1141			if (nr) {
1142				i_data[EXT2_TIND_BLOCK] = 0;
1143				mark_inode_dirty(inode);
1144				ext2_free_branches(inode, &nr, &nr+1, 3);
1145			}
1146		case EXT2_TIND_BLOCK:
1147			;
1148	}
1149
1150	ext2_discard_reservation(inode);
1151
1152	mutex_unlock(&ei->truncate_mutex);
1153}
1154
1155static void ext2_truncate_blocks(struct inode *inode, loff_t offset)
1156{
1157	/*
1158	 * XXX: it seems like a bug here that we don't allow
1159	 * IS_APPEND inode to have blocks-past-i_size trimmed off.
1160	 * review and fix this.
1161	 *
1162	 * Also would be nice to be able to handle IO errors and such,
1163	 * but that's probably too much to ask.
1164	 */
1165	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
1166	    S_ISLNK(inode->i_mode)))
1167		return;
1168	if (ext2_inode_is_fast_symlink(inode))
1169		return;
1170	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
1171		return;
1172	__ext2_truncate_blocks(inode, offset);
1173}
1174
1175static int ext2_setsize(struct inode *inode, loff_t newsize)
1176{
1177	int error;
1178
1179	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
1180	    S_ISLNK(inode->i_mode)))
1181		return -EINVAL;
1182	if (ext2_inode_is_fast_symlink(inode))
1183		return -EINVAL;
1184	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
1185		return -EPERM;
1186
1187	inode_dio_wait(inode);
1188
1189	if (mapping_is_xip(inode->i_mapping))
1190		error = xip_truncate_page(inode->i_mapping, newsize);
1191	else if (test_opt(inode->i_sb, NOBH))
1192		error = nobh_truncate_page(inode->i_mapping,
1193				newsize, ext2_get_block);
1194	else
1195		error = block_truncate_page(inode->i_mapping,
1196				newsize, ext2_get_block);
1197	if (error)
1198		return error;
1199
1200	truncate_setsize(inode, newsize);
1201	__ext2_truncate_blocks(inode, newsize);
1202
1203	inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
1204	if (inode_needs_sync(inode)) {
1205		sync_mapping_buffers(inode->i_mapping);
1206		sync_inode_metadata(inode, 1);
1207	} else {
1208		mark_inode_dirty(inode);
1209	}
1210
1211	return 0;
1212}
1213
1214static struct ext2_inode *ext2_get_inode(struct super_block *sb, ino_t ino,
1215					struct buffer_head **p)
1216{
1217	struct buffer_head * bh;
1218	unsigned long block_group;
1219	unsigned long block;
1220	unsigned long offset;
1221	struct ext2_group_desc * gdp;
1222
1223	*p = NULL;
1224	if ((ino != EXT2_ROOT_INO && ino < EXT2_FIRST_INO(sb)) ||
1225	    ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
1226		goto Einval;
1227
1228	block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb);
1229	gdp = ext2_get_group_desc(sb, block_group, NULL);
1230	if (!gdp)
1231		goto Egdp;
1232	/*
1233	 * Figure out the offset within the block group inode table
1234	 */
1235	offset = ((ino - 1) % EXT2_INODES_PER_GROUP(sb)) * EXT2_INODE_SIZE(sb);
1236	block = le32_to_cpu(gdp->bg_inode_table) +
1237		(offset >> EXT2_BLOCK_SIZE_BITS(sb));
1238	if (!(bh = sb_bread(sb, block)))
1239		goto Eio;
1240
1241	*p = bh;
1242	offset &= (EXT2_BLOCK_SIZE(sb) - 1);
1243	return (struct ext2_inode *) (bh->b_data + offset);
1244
1245Einval:
1246	ext2_error(sb, "ext2_get_inode", "bad inode number: %lu",
1247		   (unsigned long) ino);
1248	return ERR_PTR(-EINVAL);
1249Eio:
1250	ext2_error(sb, "ext2_get_inode",
1251		   "unable to read inode block - inode=%lu, block=%lu",
1252		   (unsigned long) ino, block);
1253Egdp:
1254	return ERR_PTR(-EIO);
1255}
1256
1257void ext2_set_inode_flags(struct inode *inode)
1258{
1259	unsigned int flags = EXT2_I(inode)->i_flags;
1260
1261	inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
1262	if (flags & EXT2_SYNC_FL)
1263		inode->i_flags |= S_SYNC;
1264	if (flags & EXT2_APPEND_FL)
1265		inode->i_flags |= S_APPEND;
1266	if (flags & EXT2_IMMUTABLE_FL)
1267		inode->i_flags |= S_IMMUTABLE;
1268	if (flags & EXT2_NOATIME_FL)
1269		inode->i_flags |= S_NOATIME;
1270	if (flags & EXT2_DIRSYNC_FL)
1271		inode->i_flags |= S_DIRSYNC;
1272}
1273
1274/* Propagate flags from i_flags to EXT2_I(inode)->i_flags */
1275void ext2_get_inode_flags(struct ext2_inode_info *ei)
1276{
1277	unsigned int flags = ei->vfs_inode.i_flags;
1278
1279	ei->i_flags &= ~(EXT2_SYNC_FL|EXT2_APPEND_FL|
1280			EXT2_IMMUTABLE_FL|EXT2_NOATIME_FL|EXT2_DIRSYNC_FL);
1281	if (flags & S_SYNC)
1282		ei->i_flags |= EXT2_SYNC_FL;
1283	if (flags & S_APPEND)
1284		ei->i_flags |= EXT2_APPEND_FL;
1285	if (flags & S_IMMUTABLE)
1286		ei->i_flags |= EXT2_IMMUTABLE_FL;
1287	if (flags & S_NOATIME)
1288		ei->i_flags |= EXT2_NOATIME_FL;
1289	if (flags & S_DIRSYNC)
1290		ei->i_flags |= EXT2_DIRSYNC_FL;
1291}
1292
1293struct inode *ext2_iget (struct super_block *sb, unsigned long ino)
1294{
1295	struct ext2_inode_info *ei;
1296	struct buffer_head * bh;
1297	struct ext2_inode *raw_inode;
1298	struct inode *inode;
1299	long ret = -EIO;
1300	int n;
 
 
1301
1302	inode = iget_locked(sb, ino);
1303	if (!inode)
1304		return ERR_PTR(-ENOMEM);
1305	if (!(inode->i_state & I_NEW))
1306		return inode;
1307
1308	ei = EXT2_I(inode);
1309	ei->i_block_alloc_info = NULL;
1310
1311	raw_inode = ext2_get_inode(inode->i_sb, ino, &bh);
1312	if (IS_ERR(raw_inode)) {
1313		ret = PTR_ERR(raw_inode);
1314 		goto bad_inode;
1315	}
1316
1317	inode->i_mode = le16_to_cpu(raw_inode->i_mode);
1318	inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
1319	inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
1320	if (!(test_opt (inode->i_sb, NO_UID32))) {
1321		inode->i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
1322		inode->i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
1323	}
1324	inode->i_nlink = le16_to_cpu(raw_inode->i_links_count);
 
 
1325	inode->i_size = le32_to_cpu(raw_inode->i_size);
1326	inode->i_atime.tv_sec = (signed)le32_to_cpu(raw_inode->i_atime);
1327	inode->i_ctime.tv_sec = (signed)le32_to_cpu(raw_inode->i_ctime);
1328	inode->i_mtime.tv_sec = (signed)le32_to_cpu(raw_inode->i_mtime);
1329	inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1330	ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
1331	/* We now have enough fields to check if the inode was active or not.
1332	 * This is needed because nfsd might try to access dead inodes
1333	 * the test is that same one that e2fsck uses
1334	 * NeilBrown 1999oct15
1335	 */
1336	if (inode->i_nlink == 0 && (inode->i_mode == 0 || ei->i_dtime)) {
1337		/* this inode is deleted */
1338		brelse (bh);
1339		ret = -ESTALE;
1340		goto bad_inode;
1341	}
1342	inode->i_blocks = le32_to_cpu(raw_inode->i_blocks);
1343	ei->i_flags = le32_to_cpu(raw_inode->i_flags);
1344	ei->i_faddr = le32_to_cpu(raw_inode->i_faddr);
1345	ei->i_frag_no = raw_inode->i_frag;
1346	ei->i_frag_size = raw_inode->i_fsize;
1347	ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl);
1348	ei->i_dir_acl = 0;
1349	if (S_ISREG(inode->i_mode))
1350		inode->i_size |= ((__u64)le32_to_cpu(raw_inode->i_size_high)) << 32;
1351	else
1352		ei->i_dir_acl = le32_to_cpu(raw_inode->i_dir_acl);
1353	ei->i_dtime = 0;
1354	inode->i_generation = le32_to_cpu(raw_inode->i_generation);
1355	ei->i_state = 0;
1356	ei->i_block_group = (ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);
1357	ei->i_dir_start_lookup = 0;
1358
1359	/*
1360	 * NOTE! The in-memory inode i_data array is in little-endian order
1361	 * even on big-endian machines: we do NOT byteswap the block numbers!
1362	 */
1363	for (n = 0; n < EXT2_N_BLOCKS; n++)
1364		ei->i_data[n] = raw_inode->i_block[n];
1365
1366	if (S_ISREG(inode->i_mode)) {
1367		inode->i_op = &ext2_file_inode_operations;
1368		if (ext2_use_xip(inode->i_sb)) {
1369			inode->i_mapping->a_ops = &ext2_aops_xip;
1370			inode->i_fop = &ext2_xip_file_operations;
1371		} else if (test_opt(inode->i_sb, NOBH)) {
1372			inode->i_mapping->a_ops = &ext2_nobh_aops;
1373			inode->i_fop = &ext2_file_operations;
1374		} else {
1375			inode->i_mapping->a_ops = &ext2_aops;
1376			inode->i_fop = &ext2_file_operations;
1377		}
1378	} else if (S_ISDIR(inode->i_mode)) {
1379		inode->i_op = &ext2_dir_inode_operations;
1380		inode->i_fop = &ext2_dir_operations;
1381		if (test_opt(inode->i_sb, NOBH))
1382			inode->i_mapping->a_ops = &ext2_nobh_aops;
1383		else
1384			inode->i_mapping->a_ops = &ext2_aops;
1385	} else if (S_ISLNK(inode->i_mode)) {
1386		if (ext2_inode_is_fast_symlink(inode)) {
1387			inode->i_op = &ext2_fast_symlink_inode_operations;
1388			nd_terminate_link(ei->i_data, inode->i_size,
1389				sizeof(ei->i_data) - 1);
1390		} else {
1391			inode->i_op = &ext2_symlink_inode_operations;
1392			if (test_opt(inode->i_sb, NOBH))
1393				inode->i_mapping->a_ops = &ext2_nobh_aops;
1394			else
1395				inode->i_mapping->a_ops = &ext2_aops;
1396		}
1397	} else {
1398		inode->i_op = &ext2_special_inode_operations;
1399		if (raw_inode->i_block[0])
1400			init_special_inode(inode, inode->i_mode,
1401			   old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
1402		else 
1403			init_special_inode(inode, inode->i_mode,
1404			   new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
1405	}
1406	brelse (bh);
1407	ext2_set_inode_flags(inode);
1408	unlock_new_inode(inode);
1409	return inode;
1410	
1411bad_inode:
1412	iget_failed(inode);
1413	return ERR_PTR(ret);
1414}
1415
1416static int __ext2_write_inode(struct inode *inode, int do_sync)
1417{
1418	struct ext2_inode_info *ei = EXT2_I(inode);
1419	struct super_block *sb = inode->i_sb;
1420	ino_t ino = inode->i_ino;
1421	uid_t uid = inode->i_uid;
1422	gid_t gid = inode->i_gid;
1423	struct buffer_head * bh;
1424	struct ext2_inode * raw_inode = ext2_get_inode(sb, ino, &bh);
1425	int n;
1426	int err = 0;
1427
1428	if (IS_ERR(raw_inode))
1429 		return -EIO;
1430
1431	/* For fields not not tracking in the in-memory inode,
1432	 * initialise them to zero for new inodes. */
1433	if (ei->i_state & EXT2_STATE_NEW)
1434		memset(raw_inode, 0, EXT2_SB(sb)->s_inode_size);
1435
1436	ext2_get_inode_flags(ei);
1437	raw_inode->i_mode = cpu_to_le16(inode->i_mode);
1438	if (!(test_opt(sb, NO_UID32))) {
1439		raw_inode->i_uid_low = cpu_to_le16(low_16_bits(uid));
1440		raw_inode->i_gid_low = cpu_to_le16(low_16_bits(gid));
1441/*
1442 * Fix up interoperability with old kernels. Otherwise, old inodes get
1443 * re-used with the upper 16 bits of the uid/gid intact
1444 */
1445		if (!ei->i_dtime) {
1446			raw_inode->i_uid_high = cpu_to_le16(high_16_bits(uid));
1447			raw_inode->i_gid_high = cpu_to_le16(high_16_bits(gid));
1448		} else {
1449			raw_inode->i_uid_high = 0;
1450			raw_inode->i_gid_high = 0;
1451		}
1452	} else {
1453		raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(uid));
1454		raw_inode->i_gid_low = cpu_to_le16(fs_high2lowgid(gid));
1455		raw_inode->i_uid_high = 0;
1456		raw_inode->i_gid_high = 0;
1457	}
1458	raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
1459	raw_inode->i_size = cpu_to_le32(inode->i_size);
1460	raw_inode->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
1461	raw_inode->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
1462	raw_inode->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
1463
1464	raw_inode->i_blocks = cpu_to_le32(inode->i_blocks);
1465	raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
1466	raw_inode->i_flags = cpu_to_le32(ei->i_flags);
1467	raw_inode->i_faddr = cpu_to_le32(ei->i_faddr);
1468	raw_inode->i_frag = ei->i_frag_no;
1469	raw_inode->i_fsize = ei->i_frag_size;
1470	raw_inode->i_file_acl = cpu_to_le32(ei->i_file_acl);
1471	if (!S_ISREG(inode->i_mode))
1472		raw_inode->i_dir_acl = cpu_to_le32(ei->i_dir_acl);
1473	else {
1474		raw_inode->i_size_high = cpu_to_le32(inode->i_size >> 32);
1475		if (inode->i_size > 0x7fffffffULL) {
1476			if (!EXT2_HAS_RO_COMPAT_FEATURE(sb,
1477					EXT2_FEATURE_RO_COMPAT_LARGE_FILE) ||
1478			    EXT2_SB(sb)->s_es->s_rev_level ==
1479					cpu_to_le32(EXT2_GOOD_OLD_REV)) {
1480			       /* If this is the first large file
1481				* created, add a flag to the superblock.
1482				*/
1483				spin_lock(&EXT2_SB(sb)->s_lock);
1484				ext2_update_dynamic_rev(sb);
1485				EXT2_SET_RO_COMPAT_FEATURE(sb,
1486					EXT2_FEATURE_RO_COMPAT_LARGE_FILE);
1487				spin_unlock(&EXT2_SB(sb)->s_lock);
1488				ext2_write_super(sb);
1489			}
1490		}
1491	}
1492	
1493	raw_inode->i_generation = cpu_to_le32(inode->i_generation);
1494	if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
1495		if (old_valid_dev(inode->i_rdev)) {
1496			raw_inode->i_block[0] =
1497				cpu_to_le32(old_encode_dev(inode->i_rdev));
1498			raw_inode->i_block[1] = 0;
1499		} else {
1500			raw_inode->i_block[0] = 0;
1501			raw_inode->i_block[1] =
1502				cpu_to_le32(new_encode_dev(inode->i_rdev));
1503			raw_inode->i_block[2] = 0;
1504		}
1505	} else for (n = 0; n < EXT2_N_BLOCKS; n++)
1506		raw_inode->i_block[n] = ei->i_data[n];
1507	mark_buffer_dirty(bh);
1508	if (do_sync) {
1509		sync_dirty_buffer(bh);
1510		if (buffer_req(bh) && !buffer_uptodate(bh)) {
1511			printk ("IO error syncing ext2 inode [%s:%08lx]\n",
1512				sb->s_id, (unsigned long) ino);
1513			err = -EIO;
1514		}
1515	}
1516	ei->i_state &= ~EXT2_STATE_NEW;
1517	brelse (bh);
1518	return err;
1519}
1520
1521int ext2_write_inode(struct inode *inode, struct writeback_control *wbc)
1522{
1523	return __ext2_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
1524}
1525
1526int ext2_setattr(struct dentry *dentry, struct iattr *iattr)
1527{
1528	struct inode *inode = dentry->d_inode;
1529	int error;
1530
1531	error = inode_change_ok(inode, iattr);
1532	if (error)
1533		return error;
1534
1535	if (is_quota_modification(inode, iattr))
1536		dquot_initialize(inode);
1537	if ((iattr->ia_valid & ATTR_UID && iattr->ia_uid != inode->i_uid) ||
1538	    (iattr->ia_valid & ATTR_GID && iattr->ia_gid != inode->i_gid)) {
1539		error = dquot_transfer(inode, iattr);
1540		if (error)
1541			return error;
1542	}
1543	if (iattr->ia_valid & ATTR_SIZE && iattr->ia_size != inode->i_size) {
1544		error = ext2_setsize(inode, iattr->ia_size);
1545		if (error)
1546			return error;
1547	}
1548	setattr_copy(inode, iattr);
1549	if (iattr->ia_valid & ATTR_MODE)
1550		error = ext2_acl_chmod(inode);
1551	mark_inode_dirty(inode);
1552
1553	return error;
1554}