1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *  linux/fs/ext4/resize.c
   4 *
   5 * Support for resizing an ext4 filesystem while it is mounted.
   6 *
   7 * Copyright (C) 2001, 2002 Andreas Dilger <adilger@clusterfs.com>
   8 *
   9 * This could probably be made into a module, because it is not often in use.
  10 */
  11
  12
  13#define EXT4FS_DEBUG
  14
  15#include <linux/errno.h>
  16#include <linux/slab.h>
  17
  18#include "ext4_jbd2.h"
  19
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  20int ext4_resize_begin(struct super_block *sb)
  21{
  22	struct ext4_sb_info *sbi = EXT4_SB(sb);
  23	int ret = 0;
  24
  25	if (!capable(CAP_SYS_RESOURCE))
  26		return -EPERM;
  27
  28	/*
  29	 * If we are not using the primary superblock/GDT copy don't resize,
  30         * because the user tools have no way of handling this.  Probably a
  31         * bad time to do it anyways.
  32         */
  33	if (EXT4_B2C(sbi, sbi->s_sbh->b_blocknr) !=
  34	    le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) {
  35		ext4_warning(sb, "won't resize using backup superblock at %llu",
  36			(unsigned long long)EXT4_SB(sb)->s_sbh->b_blocknr);
  37		return -EPERM;
  38	}
  39
  40	/*
  41	 * We are not allowed to do online-resizing on a filesystem mounted
  42	 * with error, because it can destroy the filesystem easily.
  43	 */
  44	if (EXT4_SB(sb)->s_mount_state & EXT4_ERROR_FS) {
  45		ext4_warning(sb, "There are errors in the filesystem, "
  46			     "so online resizing is not allowed");
  47		return -EPERM;
  48	}
  49
 
 
 
 
 
  50	if (test_and_set_bit_lock(EXT4_FLAGS_RESIZING,
  51				  &EXT4_SB(sb)->s_ext4_flags))
  52		ret = -EBUSY;
  53
  54	return ret;
  55}
  56
  57void ext4_resize_end(struct super_block *sb)
  58{
  59	clear_bit_unlock(EXT4_FLAGS_RESIZING, &EXT4_SB(sb)->s_ext4_flags);
  60	smp_mb__after_atomic();
  61}
  62
  63static ext4_group_t ext4_meta_bg_first_group(struct super_block *sb,
  64					     ext4_group_t group) {
  65	return (group >> EXT4_DESC_PER_BLOCK_BITS(sb)) <<
  66	       EXT4_DESC_PER_BLOCK_BITS(sb);
  67}
  68
  69static ext4_fsblk_t ext4_meta_bg_first_block_no(struct super_block *sb,
  70					     ext4_group_t group) {
  71	group = ext4_meta_bg_first_group(sb, group);
  72	return ext4_group_first_block_no(sb, group);
  73}
  74
  75static ext4_grpblk_t ext4_group_overhead_blocks(struct super_block *sb,
  76						ext4_group_t group) {
  77	ext4_grpblk_t overhead;
  78	overhead = ext4_bg_num_gdb(sb, group);
  79	if (ext4_bg_has_super(sb, group))
  80		overhead += 1 +
  81			  le16_to_cpu(EXT4_SB(sb)->s_es->s_reserved_gdt_blocks);
  82	return overhead;
  83}
  84
  85#define outside(b, first, last)	((b) < (first) || (b) >= (last))
  86#define inside(b, first, last)	((b) >= (first) && (b) < (last))
  87
  88static int verify_group_input(struct super_block *sb,
  89			      struct ext4_new_group_data *input)
  90{
  91	struct ext4_sb_info *sbi = EXT4_SB(sb);
  92	struct ext4_super_block *es = sbi->s_es;
  93	ext4_fsblk_t start = ext4_blocks_count(es);
  94	ext4_fsblk_t end = start + input->blocks_count;
  95	ext4_group_t group = input->group;
  96	ext4_fsblk_t itend = input->inode_table + sbi->s_itb_per_group;
  97	unsigned overhead;
  98	ext4_fsblk_t metaend;
  99	struct buffer_head *bh = NULL;
 100	ext4_grpblk_t free_blocks_count, offset;
 101	int err = -EINVAL;
 102
 103	if (group != sbi->s_groups_count) {
 104		ext4_warning(sb, "Cannot add at group %u (only %u groups)",
 105			     input->group, sbi->s_groups_count);
 106		return -EINVAL;
 107	}
 108
 109	overhead = ext4_group_overhead_blocks(sb, group);
 110	metaend = start + overhead;
 111	input->free_clusters_count = free_blocks_count =
 112		input->blocks_count - 2 - overhead - sbi->s_itb_per_group;
 113
 114	if (test_opt(sb, DEBUG))
 115		printk(KERN_DEBUG "EXT4-fs: adding %s group %u: %u blocks "
 116		       "(%d free, %u reserved)\n",
 117		       ext4_bg_has_super(sb, input->group) ? "normal" :
 118		       "no-super", input->group, input->blocks_count,
 119		       free_blocks_count, input->reserved_blocks);
 120
 121	ext4_get_group_no_and_offset(sb, start, NULL, &offset);
 122	if (offset != 0)
 123			ext4_warning(sb, "Last group not full");
 124	else if (input->reserved_blocks > input->blocks_count / 5)
 125		ext4_warning(sb, "Reserved blocks too high (%u)",
 126			     input->reserved_blocks);
 127	else if (free_blocks_count < 0)
 128		ext4_warning(sb, "Bad blocks count %u",
 129			     input->blocks_count);
 130	else if (IS_ERR(bh = ext4_sb_bread(sb, end - 1, 0))) {
 131		err = PTR_ERR(bh);
 132		bh = NULL;
 133		ext4_warning(sb, "Cannot read last block (%llu)",
 134			     end - 1);
 135	} else if (outside(input->block_bitmap, start, end))
 136		ext4_warning(sb, "Block bitmap not in group (block %llu)",
 137			     (unsigned long long)input->block_bitmap);
 138	else if (outside(input->inode_bitmap, start, end))
 139		ext4_warning(sb, "Inode bitmap not in group (block %llu)",
 140			     (unsigned long long)input->inode_bitmap);
 141	else if (outside(input->inode_table, start, end) ||
 142		 outside(itend - 1, start, end))
 143		ext4_warning(sb, "Inode table not in group (blocks %llu-%llu)",
 144			     (unsigned long long)input->inode_table, itend - 1);
 145	else if (input->inode_bitmap == input->block_bitmap)
 146		ext4_warning(sb, "Block bitmap same as inode bitmap (%llu)",
 147			     (unsigned long long)input->block_bitmap);
 148	else if (inside(input->block_bitmap, input->inode_table, itend))
 149		ext4_warning(sb, "Block bitmap (%llu) in inode table "
 150			     "(%llu-%llu)",
 151			     (unsigned long long)input->block_bitmap,
 152			     (unsigned long long)input->inode_table, itend - 1);
 153	else if (inside(input->inode_bitmap, input->inode_table, itend))
 154		ext4_warning(sb, "Inode bitmap (%llu) in inode table "
 155			     "(%llu-%llu)",
 156			     (unsigned long long)input->inode_bitmap,
 157			     (unsigned long long)input->inode_table, itend - 1);
 158	else if (inside(input->block_bitmap, start, metaend))
 159		ext4_warning(sb, "Block bitmap (%llu) in GDT table (%llu-%llu)",
 160			     (unsigned long long)input->block_bitmap,
 161			     start, metaend - 1);
 162	else if (inside(input->inode_bitmap, start, metaend))
 163		ext4_warning(sb, "Inode bitmap (%llu) in GDT table (%llu-%llu)",
 164			     (unsigned long long)input->inode_bitmap,
 165			     start, metaend - 1);
 166	else if (inside(input->inode_table, start, metaend) ||
 167		 inside(itend - 1, start, metaend))
 168		ext4_warning(sb, "Inode table (%llu-%llu) overlaps GDT table "
 169			     "(%llu-%llu)",
 170			     (unsigned long long)input->inode_table,
 171			     itend - 1, start, metaend - 1);
 172	else
 173		err = 0;
 174	brelse(bh);
 175
 176	return err;
 177}
 178
 179/*
 180 * ext4_new_flex_group_data is used by 64bit-resize interface to add a flex
 181 * group each time.
 182 */
 183struct ext4_new_flex_group_data {
 184	struct ext4_new_group_data *groups;	/* new_group_data for groups
 185						   in the flex group */
 186	__u16 *bg_flags;			/* block group flags of groups
 187						   in @groups */
 188	ext4_group_t count;			/* number of groups in @groups
 189						 */
 190};
 191
 192/*
 193 * alloc_flex_gd() allocates a ext4_new_flex_group_data with size of
 194 * @flexbg_size.
 195 *
 196 * Returns NULL on failure otherwise address of the allocated structure.
 197 */
 198static struct ext4_new_flex_group_data *alloc_flex_gd(unsigned long flexbg_size)
 199{
 200	struct ext4_new_flex_group_data *flex_gd;
 201
 202	flex_gd = kmalloc(sizeof(*flex_gd), GFP_NOFS);
 203	if (flex_gd == NULL)
 204		goto out3;
 205
 206	if (flexbg_size >= UINT_MAX / sizeof(struct ext4_new_group_data))
 207		goto out2;
 208	flex_gd->count = flexbg_size;
 209
 210	flex_gd->groups = kmalloc_array(flexbg_size,
 211					sizeof(struct ext4_new_group_data),
 212					GFP_NOFS);
 213	if (flex_gd->groups == NULL)
 214		goto out2;
 215
 216	flex_gd->bg_flags = kmalloc_array(flexbg_size, sizeof(__u16),
 217					  GFP_NOFS);
 218	if (flex_gd->bg_flags == NULL)
 219		goto out1;
 220
 221	return flex_gd;
 222
 223out1:
 224	kfree(flex_gd->groups);
 225out2:
 226	kfree(flex_gd);
 227out3:
 228	return NULL;
 229}
 230
 231static void free_flex_gd(struct ext4_new_flex_group_data *flex_gd)
 232{
 233	kfree(flex_gd->bg_flags);
 234	kfree(flex_gd->groups);
 235	kfree(flex_gd);
 236}
 237
 238/*
 239 * ext4_alloc_group_tables() allocates block bitmaps, inode bitmaps
 240 * and inode tables for a flex group.
 241 *
 242 * This function is used by 64bit-resize.  Note that this function allocates
 243 * group tables from the 1st group of groups contained by @flexgd, which may
 244 * be a partial of a flex group.
 245 *
 246 * @sb: super block of fs to which the groups belongs
 247 *
 248 * Returns 0 on a successful allocation of the metadata blocks in the
 249 * block group.
 250 */
 251static int ext4_alloc_group_tables(struct super_block *sb,
 252				struct ext4_new_flex_group_data *flex_gd,
 253				int flexbg_size)
 254{
 255	struct ext4_new_group_data *group_data = flex_gd->groups;
 256	ext4_fsblk_t start_blk;
 257	ext4_fsblk_t last_blk;
 258	ext4_group_t src_group;
 259	ext4_group_t bb_index = 0;
 260	ext4_group_t ib_index = 0;
 261	ext4_group_t it_index = 0;
 262	ext4_group_t group;
 263	ext4_group_t last_group;
 264	unsigned overhead;
 265	__u16 uninit_mask = (flexbg_size > 1) ? ~EXT4_BG_BLOCK_UNINIT : ~0;
 266	int i;
 267
 268	BUG_ON(flex_gd->count == 0 || group_data == NULL);
 269
 270	src_group = group_data[0].group;
 271	last_group  = src_group + flex_gd->count - 1;
 272
 273	BUG_ON((flexbg_size > 1) && ((src_group & ~(flexbg_size - 1)) !=
 274	       (last_group & ~(flexbg_size - 1))));
 275next_group:
 276	group = group_data[0].group;
 277	if (src_group >= group_data[0].group + flex_gd->count)
 278		return -ENOSPC;
 279	start_blk = ext4_group_first_block_no(sb, src_group);
 280	last_blk = start_blk + group_data[src_group - group].blocks_count;
 281
 282	overhead = ext4_group_overhead_blocks(sb, src_group);
 283
 284	start_blk += overhead;
 285
 286	/* We collect contiguous blocks as much as possible. */
 287	src_group++;
 288	for (; src_group <= last_group; src_group++) {
 289		overhead = ext4_group_overhead_blocks(sb, src_group);
 290		if (overhead == 0)
 291			last_blk += group_data[src_group - group].blocks_count;
 292		else
 293			break;
 294	}
 295
 296	/* Allocate block bitmaps */
 297	for (; bb_index < flex_gd->count; bb_index++) {
 298		if (start_blk >= last_blk)
 299			goto next_group;
 300		group_data[bb_index].block_bitmap = start_blk++;
 301		group = ext4_get_group_number(sb, start_blk - 1);
 302		group -= group_data[0].group;
 303		group_data[group].mdata_blocks++;
 304		flex_gd->bg_flags[group] &= uninit_mask;
 305	}
 306
 307	/* Allocate inode bitmaps */
 308	for (; ib_index < flex_gd->count; ib_index++) {
 309		if (start_blk >= last_blk)
 310			goto next_group;
 311		group_data[ib_index].inode_bitmap = start_blk++;
 312		group = ext4_get_group_number(sb, start_blk - 1);
 313		group -= group_data[0].group;
 314		group_data[group].mdata_blocks++;
 315		flex_gd->bg_flags[group] &= uninit_mask;
 316	}
 317
 318	/* Allocate inode tables */
 319	for (; it_index < flex_gd->count; it_index++) {
 320		unsigned int itb = EXT4_SB(sb)->s_itb_per_group;
 321		ext4_fsblk_t next_group_start;
 322
 323		if (start_blk + itb > last_blk)
 324			goto next_group;
 325		group_data[it_index].inode_table = start_blk;
 326		group = ext4_get_group_number(sb, start_blk);
 327		next_group_start = ext4_group_first_block_no(sb, group + 1);
 328		group -= group_data[0].group;
 329
 330		if (start_blk + itb > next_group_start) {
 331			flex_gd->bg_flags[group + 1] &= uninit_mask;
 332			overhead = start_blk + itb - next_group_start;
 333			group_data[group + 1].mdata_blocks += overhead;
 334			itb -= overhead;
 335		}
 336
 337		group_data[group].mdata_blocks += itb;
 338		flex_gd->bg_flags[group] &= uninit_mask;
 339		start_blk += EXT4_SB(sb)->s_itb_per_group;
 340	}
 341
 342	/* Update free clusters count to exclude metadata blocks */
 343	for (i = 0; i < flex_gd->count; i++) {
 344		group_data[i].free_clusters_count -=
 345				EXT4_NUM_B2C(EXT4_SB(sb),
 346					     group_data[i].mdata_blocks);
 347	}
 348
 349	if (test_opt(sb, DEBUG)) {
 350		int i;
 351		group = group_data[0].group;
 352
 353		printk(KERN_DEBUG "EXT4-fs: adding a flex group with "
 354		       "%d groups, flexbg size is %d:\n", flex_gd->count,
 355		       flexbg_size);
 356
 357		for (i = 0; i < flex_gd->count; i++) {
 358			ext4_debug(
 359			       "adding %s group %u: %u blocks (%d free, %d mdata blocks)\n",
 360			       ext4_bg_has_super(sb, group + i) ? "normal" :
 361			       "no-super", group + i,
 362			       group_data[i].blocks_count,
 363			       group_data[i].free_clusters_count,
 364			       group_data[i].mdata_blocks);
 365		}
 366	}
 367	return 0;
 368}
 369
 370static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
 371				  ext4_fsblk_t blk)
 372{
 373	struct buffer_head *bh;
 374	int err;
 375
 376	bh = sb_getblk(sb, blk);
 377	if (unlikely(!bh))
 378		return ERR_PTR(-ENOMEM);
 379	BUFFER_TRACE(bh, "get_write_access");
 380	if ((err = ext4_journal_get_write_access(handle, bh))) {
 381		brelse(bh);
 382		bh = ERR_PTR(err);
 383	} else {
 384		memset(bh->b_data, 0, sb->s_blocksize);
 385		set_buffer_uptodate(bh);
 386	}
 387
 388	return bh;
 389}
 390
 391/*
 392 * If we have fewer than thresh credits, extend by EXT4_MAX_TRANS_DATA.
 393 * If that fails, restart the transaction & regain write access for the
 394 * buffer head which is used for block_bitmap modifications.
 395 */
 396static int extend_or_restart_transaction(handle_t *handle, int thresh)
 397{
 398	int err;
 399
 400	if (ext4_handle_has_enough_credits(handle, thresh))
 401		return 0;
 402
 403	err = ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA);
 404	if (err < 0)
 405		return err;
 406	if (err) {
 407		err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA);
 408		if (err)
 409			return err;
 410	}
 411
 412	return 0;
 413}
 414
 415/*
 416 * set_flexbg_block_bitmap() mark clusters [@first_cluster, @last_cluster] used.
 417 *
 418 * Helper function for ext4_setup_new_group_blocks() which set .
 419 *
 420 * @sb: super block
 421 * @handle: journal handle
 422 * @flex_gd: flex group data
 423 */
 424static int set_flexbg_block_bitmap(struct super_block *sb, handle_t *handle,
 425			struct ext4_new_flex_group_data *flex_gd,
 426			ext4_fsblk_t first_cluster, ext4_fsblk_t last_cluster)
 427{
 428	struct ext4_sb_info *sbi = EXT4_SB(sb);
 429	ext4_group_t count = last_cluster - first_cluster + 1;
 430	ext4_group_t count2;
 431
 432	ext4_debug("mark clusters [%llu-%llu] used\n", first_cluster,
 433		   last_cluster);
 434	for (count2 = count; count > 0;
 435	     count -= count2, first_cluster += count2) {
 436		ext4_fsblk_t start;
 437		struct buffer_head *bh;
 438		ext4_group_t group;
 439		int err;
 440
 441		group = ext4_get_group_number(sb, EXT4_C2B(sbi, first_cluster));
 442		start = EXT4_B2C(sbi, ext4_group_first_block_no(sb, group));
 443		group -= flex_gd->groups[0].group;
 444
 445		count2 = EXT4_CLUSTERS_PER_GROUP(sb) - (first_cluster - start);
 446		if (count2 > count)
 447			count2 = count;
 448
 449		if (flex_gd->bg_flags[group] & EXT4_BG_BLOCK_UNINIT) {
 450			BUG_ON(flex_gd->count > 1);
 451			continue;
 452		}
 453
 454		err = extend_or_restart_transaction(handle, 1);
 455		if (err)
 456			return err;
 457
 458		bh = sb_getblk(sb, flex_gd->groups[group].block_bitmap);
 459		if (unlikely(!bh))
 460			return -ENOMEM;
 461
 462		BUFFER_TRACE(bh, "get_write_access");
 463		err = ext4_journal_get_write_access(handle, bh);
 464		if (err) {
 465			brelse(bh);
 466			return err;
 467		}
 468		ext4_debug("mark block bitmap %#04llx (+%llu/%u)\n",
 469			   first_cluster, first_cluster - start, count2);
 470		ext4_set_bits(bh->b_data, first_cluster - start, count2);
 471
 472		err = ext4_handle_dirty_metadata(handle, NULL, bh);
 473		brelse(bh);
 474		if (unlikely(err))
 475			return err;
 476	}
 477
 478	return 0;
 479}
 480
 481/*
 482 * Set up the block and inode bitmaps, and the inode table for the new groups.
 483 * This doesn't need to be part of the main transaction, since we are only
 484 * changing blocks outside the actual filesystem.  We still do journaling to
 485 * ensure the recovery is correct in case of a failure just after resize.
 486 * If any part of this fails, we simply abort the resize.
 487 *
 488 * setup_new_flex_group_blocks handles a flex group as follow:
 489 *  1. copy super block and GDT, and initialize group tables if necessary.
 490 *     In this step, we only set bits in blocks bitmaps for blocks taken by
 491 *     super block and GDT.
 492 *  2. allocate group tables in block bitmaps, that is, set bits in block
 493 *     bitmap for blocks taken by group tables.
 494 */
 495static int setup_new_flex_group_blocks(struct super_block *sb,
 496				struct ext4_new_flex_group_data *flex_gd)
 497{
 498	int group_table_count[] = {1, 1, EXT4_SB(sb)->s_itb_per_group};
 499	ext4_fsblk_t start;
 500	ext4_fsblk_t block;
 501	struct ext4_sb_info *sbi = EXT4_SB(sb);
 502	struct ext4_super_block *es = sbi->s_es;
 503	struct ext4_new_group_data *group_data = flex_gd->groups;
 504	__u16 *bg_flags = flex_gd->bg_flags;
 505	handle_t *handle;
 506	ext4_group_t group, count;
 507	struct buffer_head *bh = NULL;
 508	int reserved_gdb, i, j, err = 0, err2;
 509	int meta_bg;
 510
 511	BUG_ON(!flex_gd->count || !group_data ||
 512	       group_data[0].group != sbi->s_groups_count);
 513
 514	reserved_gdb = le16_to_cpu(es->s_reserved_gdt_blocks);
 515	meta_bg = ext4_has_feature_meta_bg(sb);
 516
 517	/* This transaction may be extended/restarted along the way */
 518	handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, EXT4_MAX_TRANS_DATA);
 519	if (IS_ERR(handle))
 520		return PTR_ERR(handle);
 521
 522	group = group_data[0].group;
 523	for (i = 0; i < flex_gd->count; i++, group++) {
 524		unsigned long gdblocks;
 525		ext4_grpblk_t overhead;
 526
 527		gdblocks = ext4_bg_num_gdb(sb, group);
 528		start = ext4_group_first_block_no(sb, group);
 529
 530		if (meta_bg == 0 && !ext4_bg_has_super(sb, group))
 531			goto handle_itb;
 532
 533		if (meta_bg == 1) {
 534			ext4_group_t first_group;
 535			first_group = ext4_meta_bg_first_group(sb, group);
 536			if (first_group != group + 1 &&
 537			    first_group != group + EXT4_DESC_PER_BLOCK(sb) - 1)
 538				goto handle_itb;
 539		}
 540
 541		block = start + ext4_bg_has_super(sb, group);
 542		/* Copy all of the GDT blocks into the backup in this group */
 543		for (j = 0; j < gdblocks; j++, block++) {
 544			struct buffer_head *gdb;
 545
 546			ext4_debug("update backup group %#04llx\n", block);
 547			err = extend_or_restart_transaction(handle, 1);
 548			if (err)
 549				goto out;
 550
 551			gdb = sb_getblk(sb, block);
 552			if (unlikely(!gdb)) {
 553				err = -ENOMEM;
 554				goto out;
 555			}
 556
 557			BUFFER_TRACE(gdb, "get_write_access");
 558			err = ext4_journal_get_write_access(handle, gdb);
 559			if (err) {
 560				brelse(gdb);
 561				goto out;
 562			}
 563			memcpy(gdb->b_data, sbi->s_group_desc[j]->b_data,
 564			       gdb->b_size);
 565			set_buffer_uptodate(gdb);
 566
 567			err = ext4_handle_dirty_metadata(handle, NULL, gdb);
 568			if (unlikely(err)) {
 569				brelse(gdb);
 570				goto out;
 571			}
 572			brelse(gdb);
 573		}
 574
 575		/* Zero out all of the reserved backup group descriptor
 576		 * table blocks
 577		 */
 578		if (ext4_bg_has_super(sb, group)) {
 579			err = sb_issue_zeroout(sb, gdblocks + start + 1,
 580					reserved_gdb, GFP_NOFS);
 581			if (err)
 582				goto out;
 583		}
 584
 585handle_itb:
 586		/* Initialize group tables of the grop @group */
 587		if (!(bg_flags[i] & EXT4_BG_INODE_ZEROED))
 588			goto handle_bb;
 589
 590		/* Zero out all of the inode table blocks */
 591		block = group_data[i].inode_table;
 592		ext4_debug("clear inode table blocks %#04llx -> %#04lx\n",
 593			   block, sbi->s_itb_per_group);
 594		err = sb_issue_zeroout(sb, block, sbi->s_itb_per_group,
 595				       GFP_NOFS);
 596		if (err)
 597			goto out;
 598
 599handle_bb:
 600		if (bg_flags[i] & EXT4_BG_BLOCK_UNINIT)
 601			goto handle_ib;
 602
 603		/* Initialize block bitmap of the @group */
 604		block = group_data[i].block_bitmap;
 605		err = extend_or_restart_transaction(handle, 1);
 606		if (err)
 607			goto out;
 608
 609		bh = bclean(handle, sb, block);
 610		if (IS_ERR(bh)) {
 611			err = PTR_ERR(bh);
 612			goto out;
 613		}
 614		overhead = ext4_group_overhead_blocks(sb, group);
 615		if (overhead != 0) {
 616			ext4_debug("mark backup superblock %#04llx (+0)\n",
 617				   start);
 618			ext4_set_bits(bh->b_data, 0,
 619				      EXT4_NUM_B2C(sbi, overhead));
 620		}
 621		ext4_mark_bitmap_end(EXT4_B2C(sbi, group_data[i].blocks_count),
 622				     sb->s_blocksize * 8, bh->b_data);
 623		err = ext4_handle_dirty_metadata(handle, NULL, bh);
 624		brelse(bh);
 625		if (err)
 626			goto out;
 627
 628handle_ib:
 629		if (bg_flags[i] & EXT4_BG_INODE_UNINIT)
 630			continue;
 631
 632		/* Initialize inode bitmap of the @group */
 633		block = group_data[i].inode_bitmap;
 634		err = extend_or_restart_transaction(handle, 1);
 635		if (err)
 636			goto out;
 637		/* Mark unused entries in inode bitmap used */
 638		bh = bclean(handle, sb, block);
 639		if (IS_ERR(bh)) {
 640			err = PTR_ERR(bh);
 641			goto out;
 642		}
 643
 644		ext4_mark_bitmap_end(EXT4_INODES_PER_GROUP(sb),
 645				     sb->s_blocksize * 8, bh->b_data);
 646		err = ext4_handle_dirty_metadata(handle, NULL, bh);
 647		brelse(bh);
 648		if (err)
 649			goto out;
 650	}
 651
 652	/* Mark group tables in block bitmap */
 653	for (j = 0; j < GROUP_TABLE_COUNT; j++) {
 654		count = group_table_count[j];
 655		start = (&group_data[0].block_bitmap)[j];
 656		block = start;
 657		for (i = 1; i < flex_gd->count; i++) {
 658			block += group_table_count[j];
 659			if (block == (&group_data[i].block_bitmap)[j]) {
 660				count += group_table_count[j];
 661				continue;
 662			}
 663			err = set_flexbg_block_bitmap(sb, handle,
 664						      flex_gd,
 665						      EXT4_B2C(sbi, start),
 666						      EXT4_B2C(sbi,
 667							       start + count
 668							       - 1));
 669			if (err)
 670				goto out;
 671			count = group_table_count[j];
 672			start = (&group_data[i].block_bitmap)[j];
 673			block = start;
 674		}
 675
 676		if (count) {
 677			err = set_flexbg_block_bitmap(sb, handle,
 678						      flex_gd,
 679						      EXT4_B2C(sbi, start),
 680						      EXT4_B2C(sbi,
 681							       start + count
 682							       - 1));
 683			if (err)
 684				goto out;
 685		}
 686	}
 687
 688out:
 689	err2 = ext4_journal_stop(handle);
 690	if (err2 && !err)
 691		err = err2;
 692
 693	return err;
 694}
 695
 696/*
 697 * Iterate through the groups which hold BACKUP superblock/GDT copies in an
 698 * ext4 filesystem.  The counters should be initialized to 1, 5, and 7 before
 699 * calling this for the first time.  In a sparse filesystem it will be the
 700 * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
 701 * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
 702 */
 703static unsigned ext4_list_backups(struct super_block *sb, unsigned *three,
 704				  unsigned *five, unsigned *seven)
 705{
 706	unsigned *min = three;
 707	int mult = 3;
 708	unsigned ret;
 709
 710	if (!ext4_has_feature_sparse_super(sb)) {
 711		ret = *min;
 712		*min += 1;
 713		return ret;
 714	}
 715
 716	if (*five < *min) {
 717		min = five;
 718		mult = 5;
 719	}
 720	if (*seven < *min) {
 721		min = seven;
 722		mult = 7;
 723	}
 724
 725	ret = *min;
 726	*min *= mult;
 727
 728	return ret;
 729}
 730
 731/*
 732 * Check that all of the backup GDT blocks are held in the primary GDT block.
 733 * It is assumed that they are stored in group order.  Returns the number of
 734 * groups in current filesystem that have BACKUPS, or -ve error code.
 735 */
 736static int verify_reserved_gdb(struct super_block *sb,
 737			       ext4_group_t end,
 738			       struct buffer_head *primary)
 739{
 740	const ext4_fsblk_t blk = primary->b_blocknr;
 741	unsigned three = 1;
 742	unsigned five = 5;
 743	unsigned seven = 7;
 744	unsigned grp;
 745	__le32 *p = (__le32 *)primary->b_data;
 746	int gdbackups = 0;
 747
 748	while ((grp = ext4_list_backups(sb, &three, &five, &seven)) < end) {
 749		if (le32_to_cpu(*p++) !=
 750		    grp * EXT4_BLOCKS_PER_GROUP(sb) + blk){
 751			ext4_warning(sb, "reserved GDT %llu"
 752				     " missing grp %d (%llu)",
 753				     blk, grp,
 754				     grp *
 755				     (ext4_fsblk_t)EXT4_BLOCKS_PER_GROUP(sb) +
 756				     blk);
 757			return -EINVAL;
 758		}
 759		if (++gdbackups > EXT4_ADDR_PER_BLOCK(sb))
 760			return -EFBIG;
 761	}
 762
 763	return gdbackups;
 764}
 765
 766/*
 767 * Called when we need to bring a reserved group descriptor table block into
 768 * use from the resize inode.  The primary copy of the new GDT block currently
 769 * is an indirect block (under the double indirect block in the resize inode).
 770 * The new backup GDT blocks will be stored as leaf blocks in this indirect
 771 * block, in group order.  Even though we know all the block numbers we need,
 772 * we check to ensure that the resize inode has actually reserved these blocks.
 773 *
 774 * Don't need to update the block bitmaps because the blocks are still in use.
 775 *
 776 * We get all of the error cases out of the way, so that we are sure to not
 777 * fail once we start modifying the data on disk, because JBD has no rollback.
 778 */
 779static int add_new_gdb(handle_t *handle, struct inode *inode,
 780		       ext4_group_t group)
 781{
 782	struct super_block *sb = inode->i_sb;
 783	struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 784	unsigned long gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
 785	ext4_fsblk_t gdblock = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + gdb_num;
 786	struct buffer_head **o_group_desc, **n_group_desc = NULL;
 787	struct buffer_head *dind = NULL;
 788	struct buffer_head *gdb_bh = NULL;
 789	int gdbackups;
 790	struct ext4_iloc iloc = { .bh = NULL };
 791	__le32 *data;
 792	int err;
 793
 794	if (test_opt(sb, DEBUG))
 795		printk(KERN_DEBUG
 796		       "EXT4-fs: ext4_add_new_gdb: adding group block %lu\n",
 797		       gdb_num);
 798
 799	gdb_bh = ext4_sb_bread(sb, gdblock, 0);
 800	if (IS_ERR(gdb_bh))
 801		return PTR_ERR(gdb_bh);
 802
 803	gdbackups = verify_reserved_gdb(sb, group, gdb_bh);
 804	if (gdbackups < 0) {
 805		err = gdbackups;
 806		goto errout;
 807	}
 808
 809	data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
 810	dind = ext4_sb_bread(sb, le32_to_cpu(*data), 0);
 811	if (IS_ERR(dind)) {
 812		err = PTR_ERR(dind);
 813		dind = NULL;
 814		goto errout;
 815	}
 816
 817	data = (__le32 *)dind->b_data;
 818	if (le32_to_cpu(data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)]) != gdblock) {
 819		ext4_warning(sb, "new group %u GDT block %llu not reserved",
 820			     group, gdblock);
 821		err = -EINVAL;
 822		goto errout;
 823	}
 824
 825	BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
 826	err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
 827	if (unlikely(err))
 828		goto errout;
 829
 830	BUFFER_TRACE(gdb_bh, "get_write_access");
 831	err = ext4_journal_get_write_access(handle, gdb_bh);
 832	if (unlikely(err))
 833		goto errout;
 834
 835	BUFFER_TRACE(dind, "get_write_access");
 836	err = ext4_journal_get_write_access(handle, dind);
 837	if (unlikely(err))
 838		ext4_std_error(sb, err);
 
 
 839
 840	/* ext4_reserve_inode_write() gets a reference on the iloc */
 841	err = ext4_reserve_inode_write(handle, inode, &iloc);
 842	if (unlikely(err))
 843		goto errout;
 844
 845	n_group_desc = ext4_kvmalloc((gdb_num + 1) *
 846				     sizeof(struct buffer_head *),
 847				     GFP_NOFS);
 848	if (!n_group_desc) {
 849		err = -ENOMEM;
 850		ext4_warning(sb, "not enough memory for %lu groups",
 851			     gdb_num + 1);
 852		goto errout;
 853	}
 854
 855	/*
 856	 * Finally, we have all of the possible failures behind us...
 857	 *
 858	 * Remove new GDT block from inode double-indirect block and clear out
 859	 * the new GDT block for use (which also "frees" the backup GDT blocks
 860	 * from the reserved inode).  We don't need to change the bitmaps for
 861	 * these blocks, because they are marked as in-use from being in the
 862	 * reserved inode, and will become GDT blocks (primary and backup).
 863	 */
 864	data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)] = 0;
 865	err = ext4_handle_dirty_metadata(handle, NULL, dind);
 866	if (unlikely(err)) {
 867		ext4_std_error(sb, err);
 868		goto errout;
 869	}
 870	inode->i_blocks -= (gdbackups + 1) * sb->s_blocksize >>
 871			   (9 - EXT4_SB(sb)->s_cluster_bits);
 872	ext4_mark_iloc_dirty(handle, inode, &iloc);
 873	memset(gdb_bh->b_data, 0, sb->s_blocksize);
 874	err = ext4_handle_dirty_metadata(handle, NULL, gdb_bh);
 875	if (unlikely(err)) {
 876		ext4_std_error(sb, err);
 877		iloc.bh = NULL;
 878		goto errout;
 879	}
 880	brelse(dind);
 881
 882	o_group_desc = EXT4_SB(sb)->s_group_desc;
 
 883	memcpy(n_group_desc, o_group_desc,
 884	       EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
 
 885	n_group_desc[gdb_num] = gdb_bh;
 886	EXT4_SB(sb)->s_group_desc = n_group_desc;
 887	EXT4_SB(sb)->s_gdb_count++;
 888	kvfree(o_group_desc);
 889
 
 890	le16_add_cpu(&es->s_reserved_gdt_blocks, -1);
 891	err = ext4_handle_dirty_super(handle, sb);
 
 
 892	if (err)
 893		ext4_std_error(sb, err);
 894	return err;
 895errout:
 896	kvfree(n_group_desc);
 897	brelse(iloc.bh);
 898	brelse(dind);
 899	brelse(gdb_bh);
 900
 901	ext4_debug("leaving with error %d\n", err);
 902	return err;
 903}
 904
 905/*
 906 * add_new_gdb_meta_bg is the sister of add_new_gdb.
 907 */
 908static int add_new_gdb_meta_bg(struct super_block *sb,
 909			       handle_t *handle, ext4_group_t group) {
 910	ext4_fsblk_t gdblock;
 911	struct buffer_head *gdb_bh;
 912	struct buffer_head **o_group_desc, **n_group_desc;
 913	unsigned long gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
 914	int err;
 915
 916	gdblock = ext4_meta_bg_first_block_no(sb, group) +
 917		   ext4_bg_has_super(sb, group);
 918	gdb_bh = ext4_sb_bread(sb, gdblock, 0);
 919	if (IS_ERR(gdb_bh))
 920		return PTR_ERR(gdb_bh);
 921	n_group_desc = ext4_kvmalloc((gdb_num + 1) *
 922				     sizeof(struct buffer_head *),
 923				     GFP_NOFS);
 924	if (!n_group_desc) {
 925		brelse(gdb_bh);
 926		err = -ENOMEM;
 927		ext4_warning(sb, "not enough memory for %lu groups",
 928			     gdb_num + 1);
 929		return err;
 930	}
 931
 932	o_group_desc = EXT4_SB(sb)->s_group_desc;
 
 933	memcpy(n_group_desc, o_group_desc,
 934	       EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
 
 935	n_group_desc[gdb_num] = gdb_bh;
 936
 937	BUFFER_TRACE(gdb_bh, "get_write_access");
 938	err = ext4_journal_get_write_access(handle, gdb_bh);
 939	if (err) {
 940		kvfree(n_group_desc);
 941		brelse(gdb_bh);
 942		return err;
 943	}
 944
 945	EXT4_SB(sb)->s_group_desc = n_group_desc;
 946	EXT4_SB(sb)->s_gdb_count++;
 947	kvfree(o_group_desc);
 948	return err;
 949}
 950
 951/*
 952 * Called when we are adding a new group which has a backup copy of each of
 953 * the GDT blocks (i.e. sparse group) and there are reserved GDT blocks.
 954 * We need to add these reserved backup GDT blocks to the resize inode, so
 955 * that they are kept for future resizing and not allocated to files.
 956 *
 957 * Each reserved backup GDT block will go into a different indirect block.
 958 * The indirect blocks are actually the primary reserved GDT blocks,
 959 * so we know in advance what their block numbers are.  We only get the
 960 * double-indirect block to verify it is pointing to the primary reserved
 961 * GDT blocks so we don't overwrite a data block by accident.  The reserved
 962 * backup GDT blocks are stored in their reserved primary GDT block.
 963 */
 964static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
 965			      ext4_group_t group)
 966{
 967	struct super_block *sb = inode->i_sb;
 968	int reserved_gdb =le16_to_cpu(EXT4_SB(sb)->s_es->s_reserved_gdt_blocks);
 969	int cluster_bits = EXT4_SB(sb)->s_cluster_bits;
 970	struct buffer_head **primary;
 971	struct buffer_head *dind;
 972	struct ext4_iloc iloc;
 973	ext4_fsblk_t blk;
 974	__le32 *data, *end;
 975	int gdbackups = 0;
 976	int res, i;
 977	int err;
 978
 979	primary = kmalloc_array(reserved_gdb, sizeof(*primary), GFP_NOFS);
 980	if (!primary)
 981		return -ENOMEM;
 982
 983	data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
 984	dind = ext4_sb_bread(sb, le32_to_cpu(*data), 0);
 985	if (IS_ERR(dind)) {
 986		err = PTR_ERR(dind);
 987		dind = NULL;
 988		goto exit_free;
 989	}
 990
 991	blk = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + EXT4_SB(sb)->s_gdb_count;
 992	data = (__le32 *)dind->b_data + (EXT4_SB(sb)->s_gdb_count %
 993					 EXT4_ADDR_PER_BLOCK(sb));
 994	end = (__le32 *)dind->b_data + EXT4_ADDR_PER_BLOCK(sb);
 995
 996	/* Get each reserved primary GDT block and verify it holds backups */
 997	for (res = 0; res < reserved_gdb; res++, blk++) {
 998		if (le32_to_cpu(*data) != blk) {
 999			ext4_warning(sb, "reserved block %llu"
1000				     " not at offset %ld",
1001				     blk,
1002				     (long)(data - (__le32 *)dind->b_data));
1003			err = -EINVAL;
1004			goto exit_bh;
1005		}
1006		primary[res] = ext4_sb_bread(sb, blk, 0);
1007		if (IS_ERR(primary[res])) {
1008			err = PTR_ERR(primary[res]);
1009			primary[res] = NULL;
1010			goto exit_bh;
1011		}
1012		gdbackups = verify_reserved_gdb(sb, group, primary[res]);
1013		if (gdbackups < 0) {
1014			brelse(primary[res]);
1015			err = gdbackups;
1016			goto exit_bh;
1017		}
1018		if (++data >= end)
1019			data = (__le32 *)dind->b_data;
1020	}
1021
1022	for (i = 0; i < reserved_gdb; i++) {
1023		BUFFER_TRACE(primary[i], "get_write_access");
1024		if ((err = ext4_journal_get_write_access(handle, primary[i])))
1025			goto exit_bh;
1026	}
1027
1028	if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
1029		goto exit_bh;
1030
1031	/*
1032	 * Finally we can add each of the reserved backup GDT blocks from
1033	 * the new group to its reserved primary GDT block.
1034	 */
1035	blk = group * EXT4_BLOCKS_PER_GROUP(sb);
1036	for (i = 0; i < reserved_gdb; i++) {
1037		int err2;
1038		data = (__le32 *)primary[i]->b_data;
1039		/* printk("reserving backup %lu[%u] = %lu\n",
1040		       primary[i]->b_blocknr, gdbackups,
1041		       blk + primary[i]->b_blocknr); */
1042		data[gdbackups] = cpu_to_le32(blk + primary[i]->b_blocknr);
1043		err2 = ext4_handle_dirty_metadata(handle, NULL, primary[i]);
1044		if (!err)
1045			err = err2;
1046	}
1047
1048	inode->i_blocks += reserved_gdb * sb->s_blocksize >> (9 - cluster_bits);
1049	ext4_mark_iloc_dirty(handle, inode, &iloc);
1050
1051exit_bh:
1052	while (--res >= 0)
1053		brelse(primary[res]);
1054	brelse(dind);
1055
1056exit_free:
1057	kfree(primary);
1058
1059	return err;
1060}
1061
1062/*
1063 * Update the backup copies of the ext4 metadata.  These don't need to be part
1064 * of the main resize transaction, because e2fsck will re-write them if there
1065 * is a problem (basically only OOM will cause a problem).  However, we
1066 * _should_ update the backups if possible, in case the primary gets trashed
1067 * for some reason and we need to run e2fsck from a backup superblock.  The
1068 * important part is that the new block and inode counts are in the backup
1069 * superblocks, and the location of the new group metadata in the GDT backups.
1070 *
1071 * We do not need take the s_resize_lock for this, because these
1072 * blocks are not otherwise touched by the filesystem code when it is
1073 * mounted.  We don't need to worry about last changing from
1074 * sbi->s_groups_count, because the worst that can happen is that we
1075 * do not copy the full number of backups at this time.  The resize
1076 * which changed s_groups_count will backup again.
1077 */
1078static void update_backups(struct super_block *sb, sector_t blk_off, char *data,
1079			   int size, int meta_bg)
1080{
1081	struct ext4_sb_info *sbi = EXT4_SB(sb);
1082	ext4_group_t last;
1083	const int bpg = EXT4_BLOCKS_PER_GROUP(sb);
1084	unsigned three = 1;
1085	unsigned five = 5;
1086	unsigned seven = 7;
1087	ext4_group_t group = 0;
1088	int rest = sb->s_blocksize - size;
1089	handle_t *handle;
1090	int err = 0, err2;
1091
1092	handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, EXT4_MAX_TRANS_DATA);
1093	if (IS_ERR(handle)) {
1094		group = 1;
1095		err = PTR_ERR(handle);
1096		goto exit_err;
1097	}
1098
1099	if (meta_bg == 0) {
1100		group = ext4_list_backups(sb, &three, &five, &seven);
1101		last = sbi->s_groups_count;
1102	} else {
1103		group = ext4_get_group_number(sb, blk_off) + 1;
1104		last = (ext4_group_t)(group + EXT4_DESC_PER_BLOCK(sb) - 2);
1105	}
1106
1107	while (group < sbi->s_groups_count) {
1108		struct buffer_head *bh;
1109		ext4_fsblk_t backup_block;
1110
1111		/* Out of journal space, and can't get more - abort - so sad */
1112		if (ext4_handle_valid(handle) &&
1113		    handle->h_buffer_credits == 0 &&
1114		    ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA) &&
1115		    (err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA)))
1116			break;
1117
1118		if (meta_bg == 0)
1119			backup_block = ((ext4_fsblk_t)group) * bpg + blk_off;
1120		else
1121			backup_block = (ext4_group_first_block_no(sb, group) +
1122					ext4_bg_has_super(sb, group));
1123
1124		bh = sb_getblk(sb, backup_block);
1125		if (unlikely(!bh)) {
1126			err = -ENOMEM;
1127			break;
1128		}
1129		ext4_debug("update metadata backup %llu(+%llu)\n",
1130			   backup_block, backup_block -
1131			   ext4_group_first_block_no(sb, group));
1132		BUFFER_TRACE(bh, "get_write_access");
1133		if ((err = ext4_journal_get_write_access(handle, bh))) {
1134			brelse(bh);
1135			break;
1136		}
1137		lock_buffer(bh);
1138		memcpy(bh->b_data, data, size);
1139		if (rest)
1140			memset(bh->b_data + size, 0, rest);
1141		set_buffer_uptodate(bh);
1142		unlock_buffer(bh);
1143		err = ext4_handle_dirty_metadata(handle, NULL, bh);
1144		if (unlikely(err))
1145			ext4_std_error(sb, err);
1146		brelse(bh);
1147
1148		if (meta_bg == 0)
1149			group = ext4_list_backups(sb, &three, &five, &seven);
1150		else if (group == last)
1151			break;
1152		else
1153			group = last;
1154	}
1155	if ((err2 = ext4_journal_stop(handle)) && !err)
1156		err = err2;
1157
1158	/*
1159	 * Ugh! Need to have e2fsck write the backup copies.  It is too
1160	 * late to revert the resize, we shouldn't fail just because of
1161	 * the backup copies (they are only needed in case of corruption).
1162	 *
1163	 * However, if we got here we have a journal problem too, so we
1164	 * can't really start a transaction to mark the superblock.
1165	 * Chicken out and just set the flag on the hope it will be written
1166	 * to disk, and if not - we will simply wait until next fsck.
1167	 */
1168exit_err:
1169	if (err) {
1170		ext4_warning(sb, "can't update backup for group %u (err %d), "
1171			     "forcing fsck on next reboot", group, err);
1172		sbi->s_mount_state &= ~EXT4_VALID_FS;
1173		sbi->s_es->s_state &= cpu_to_le16(~EXT4_VALID_FS);
1174		mark_buffer_dirty(sbi->s_sbh);
1175	}
1176}
1177
1178/*
1179 * ext4_add_new_descs() adds @count group descriptor of groups
1180 * starting at @group
1181 *
1182 * @handle: journal handle
1183 * @sb: super block
1184 * @group: the group no. of the first group desc to be added
1185 * @resize_inode: the resize inode
1186 * @count: number of group descriptors to be added
1187 */
1188static int ext4_add_new_descs(handle_t *handle, struct super_block *sb,
1189			      ext4_group_t group, struct inode *resize_inode,
1190			      ext4_group_t count)
1191{
1192	struct ext4_sb_info *sbi = EXT4_SB(sb);
1193	struct ext4_super_block *es = sbi->s_es;
1194	struct buffer_head *gdb_bh;
1195	int i, gdb_off, gdb_num, err = 0;
1196	int meta_bg;
1197
1198	meta_bg = ext4_has_feature_meta_bg(sb);
1199	for (i = 0; i < count; i++, group++) {
1200		int reserved_gdb = ext4_bg_has_super(sb, group) ?
1201			le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
1202
1203		gdb_off = group % EXT4_DESC_PER_BLOCK(sb);
1204		gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
1205
1206		/*
1207		 * We will only either add reserved group blocks to a backup group
1208		 * or remove reserved blocks for the first group in a new group block.
1209		 * Doing both would be mean more complex code, and sane people don't
1210		 * use non-sparse filesystems anymore.  This is already checked above.
1211		 */
1212		if (gdb_off) {
1213			gdb_bh = sbi->s_group_desc[gdb_num];
 
1214			BUFFER_TRACE(gdb_bh, "get_write_access");
1215			err = ext4_journal_get_write_access(handle, gdb_bh);
1216
1217			if (!err && reserved_gdb && ext4_bg_num_gdb(sb, group))
1218				err = reserve_backup_gdb(handle, resize_inode, group);
1219		} else if (meta_bg != 0) {
1220			err = add_new_gdb_meta_bg(sb, handle, group);
1221		} else {
1222			err = add_new_gdb(handle, resize_inode, group);
1223		}
1224		if (err)
1225			break;
1226	}
1227	return err;
1228}
1229
1230static struct buffer_head *ext4_get_bitmap(struct super_block *sb, __u64 block)
1231{
1232	struct buffer_head *bh = sb_getblk(sb, block);
1233	if (unlikely(!bh))
1234		return NULL;
1235	if (!bh_uptodate_or_lock(bh)) {
1236		if (bh_submit_read(bh) < 0) {
1237			brelse(bh);
1238			return NULL;
1239		}
1240	}
1241
1242	return bh;
1243}
1244
1245static int ext4_set_bitmap_checksums(struct super_block *sb,
1246				     ext4_group_t group,
1247				     struct ext4_group_desc *gdp,
1248				     struct ext4_new_group_data *group_data)
1249{
1250	struct buffer_head *bh;
1251
1252	if (!ext4_has_metadata_csum(sb))
1253		return 0;
1254
1255	bh = ext4_get_bitmap(sb, group_data->inode_bitmap);
1256	if (!bh)
1257		return -EIO;
1258	ext4_inode_bitmap_csum_set(sb, group, gdp, bh,
1259				   EXT4_INODES_PER_GROUP(sb) / 8);
1260	brelse(bh);
1261
1262	bh = ext4_get_bitmap(sb, group_data->block_bitmap);
1263	if (!bh)
1264		return -EIO;
1265	ext4_block_bitmap_csum_set(sb, group, gdp, bh);
1266	brelse(bh);
1267
1268	return 0;
1269}
1270
1271/*
1272 * ext4_setup_new_descs() will set up the group descriptor descriptors of a flex bg
1273 */
1274static int ext4_setup_new_descs(handle_t *handle, struct super_block *sb,
1275				struct ext4_new_flex_group_data *flex_gd)
1276{
1277	struct ext4_new_group_data	*group_data = flex_gd->groups;
1278	struct ext4_group_desc		*gdp;
1279	struct ext4_sb_info		*sbi = EXT4_SB(sb);
1280	struct buffer_head		*gdb_bh;
1281	ext4_group_t			group;
1282	__u16				*bg_flags = flex_gd->bg_flags;
1283	int				i, gdb_off, gdb_num, err = 0;
1284
1285
1286	for (i = 0; i < flex_gd->count; i++, group_data++, bg_flags++) {
1287		group = group_data->group;
1288
1289		gdb_off = group % EXT4_DESC_PER_BLOCK(sb);
1290		gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
1291
1292		/*
1293		 * get_write_access() has been called on gdb_bh by ext4_add_new_desc().
1294		 */
1295		gdb_bh = sbi->s_group_desc[gdb_num];
1296		/* Update group descriptor block for new group */
1297		gdp = (struct ext4_group_desc *)(gdb_bh->b_data +
1298						 gdb_off * EXT4_DESC_SIZE(sb));
1299
1300		memset(gdp, 0, EXT4_DESC_SIZE(sb));
1301		ext4_block_bitmap_set(sb, gdp, group_data->block_bitmap);
1302		ext4_inode_bitmap_set(sb, gdp, group_data->inode_bitmap);
1303		err = ext4_set_bitmap_checksums(sb, group, gdp, group_data);
1304		if (err) {
1305			ext4_std_error(sb, err);
1306			break;
1307		}
1308
1309		ext4_inode_table_set(sb, gdp, group_data->inode_table);
1310		ext4_free_group_clusters_set(sb, gdp,
1311					     group_data->free_clusters_count);
1312		ext4_free_inodes_set(sb, gdp, EXT4_INODES_PER_GROUP(sb));
1313		if (ext4_has_group_desc_csum(sb))
1314			ext4_itable_unused_set(sb, gdp,
1315					       EXT4_INODES_PER_GROUP(sb));
1316		gdp->bg_flags = cpu_to_le16(*bg_flags);
1317		ext4_group_desc_csum_set(sb, group, gdp);
1318
1319		err = ext4_handle_dirty_metadata(handle, NULL, gdb_bh);
1320		if (unlikely(err)) {
1321			ext4_std_error(sb, err);
1322			break;
1323		}
1324
1325		/*
1326		 * We can allocate memory for mb_alloc based on the new group
1327		 * descriptor
1328		 */
1329		err = ext4_mb_add_groupinfo(sb, group, gdp);
1330		if (err)
1331			break;
1332	}
1333	return err;
1334}
1335
1336/*
1337 * ext4_update_super() updates the super block so that the newly added
1338 * groups can be seen by the filesystem.
1339 *
1340 * @sb: super block
1341 * @flex_gd: new added groups
1342 */
1343static void ext4_update_super(struct super_block *sb,
1344			     struct ext4_new_flex_group_data *flex_gd)
1345{
1346	ext4_fsblk_t blocks_count = 0;
1347	ext4_fsblk_t free_blocks = 0;
1348	ext4_fsblk_t reserved_blocks = 0;
1349	struct ext4_new_group_data *group_data = flex_gd->groups;
1350	struct ext4_sb_info *sbi = EXT4_SB(sb);
1351	struct ext4_super_block *es = sbi->s_es;
1352	int i;
1353
1354	BUG_ON(flex_gd->count == 0 || group_data == NULL);
1355	/*
1356	 * Make the new blocks and inodes valid next.  We do this before
1357	 * increasing the group count so that once the group is enabled,
1358	 * all of its blocks and inodes are already valid.
1359	 *
1360	 * We always allocate group-by-group, then block-by-block or
1361	 * inode-by-inode within a group, so enabling these
1362	 * blocks/inodes before the group is live won't actually let us
1363	 * allocate the new space yet.
1364	 */
1365	for (i = 0; i < flex_gd->count; i++) {
1366		blocks_count += group_data[i].blocks_count;
1367		free_blocks += EXT4_C2B(sbi, group_data[i].free_clusters_count);
1368	}
1369
1370	reserved_blocks = ext4_r_blocks_count(es) * 100;
1371	reserved_blocks = div64_u64(reserved_blocks, ext4_blocks_count(es));
1372	reserved_blocks *= blocks_count;
1373	do_div(reserved_blocks, 100);
1374
 
1375	ext4_blocks_count_set(es, ext4_blocks_count(es) + blocks_count);
1376	ext4_free_blocks_count_set(es, ext4_free_blocks_count(es) + free_blocks);
1377	le32_add_cpu(&es->s_inodes_count, EXT4_INODES_PER_GROUP(sb) *
1378		     flex_gd->count);
1379	le32_add_cpu(&es->s_free_inodes_count, EXT4_INODES_PER_GROUP(sb) *
1380		     flex_gd->count);
1381
1382	ext4_debug("free blocks count %llu", ext4_free_blocks_count(es));
1383	/*
1384	 * We need to protect s_groups_count against other CPUs seeing
1385	 * inconsistent state in the superblock.
1386	 *
1387	 * The precise rules we use are:
1388	 *
1389	 * * Writers must perform a smp_wmb() after updating all
1390	 *   dependent data and before modifying the groups count
1391	 *
1392	 * * Readers must perform an smp_rmb() after reading the groups
1393	 *   count and before reading any dependent data.
1394	 *
1395	 * NB. These rules can be relaxed when checking the group count
1396	 * while freeing data, as we can only allocate from a block
1397	 * group after serialising against the group count, and we can
1398	 * only then free after serialising in turn against that
1399	 * allocation.
1400	 */
1401	smp_wmb();
1402
1403	/* Update the global fs size fields */
1404	sbi->s_groups_count += flex_gd->count;
1405	sbi->s_blockfile_groups = min_t(ext4_group_t, sbi->s_groups_count,
1406			(EXT4_MAX_BLOCK_FILE_PHYS / EXT4_BLOCKS_PER_GROUP(sb)));
1407
1408	/* Update the reserved block counts only once the new group is
1409	 * active. */
1410	ext4_r_blocks_count_set(es, ext4_r_blocks_count(es) +
1411				reserved_blocks);
 
 
1412
1413	/* Update the free space counts */
1414	percpu_counter_add(&sbi->s_freeclusters_counter,
1415			   EXT4_NUM_B2C(sbi, free_blocks));
1416	percpu_counter_add(&sbi->s_freeinodes_counter,
1417			   EXT4_INODES_PER_GROUP(sb) * flex_gd->count);
1418
1419	ext4_debug("free blocks count %llu",
1420		   percpu_counter_read(&sbi->s_freeclusters_counter));
1421	if (ext4_has_feature_flex_bg(sb) && sbi->s_log_groups_per_flex) {
1422		ext4_group_t flex_group;
 
 
1423		flex_group = ext4_flex_group(sbi, group_data[0].group);
 
1424		atomic64_add(EXT4_NUM_B2C(sbi, free_blocks),
1425			     &sbi->s_flex_groups[flex_group].free_clusters);
1426		atomic_add(EXT4_INODES_PER_GROUP(sb) * flex_gd->count,
1427			   &sbi->s_flex_groups[flex_group].free_inodes);
1428	}
1429
1430	/*
1431	 * Update the fs overhead information
1432	 */
1433	ext4_calculate_overhead(sb);
1434
1435	if (test_opt(sb, DEBUG))
1436		printk(KERN_DEBUG "EXT4-fs: added group %u:"
1437		       "%llu blocks(%llu free %llu reserved)\n", flex_gd->count,
1438		       blocks_count, free_blocks, reserved_blocks);
1439}
1440
1441/* Add a flex group to an fs. Ensure we handle all possible error conditions
1442 * _before_ we start modifying the filesystem, because we cannot abort the
1443 * transaction and not have it write the data to disk.
1444 */
1445static int ext4_flex_group_add(struct super_block *sb,
1446			       struct inode *resize_inode,
1447			       struct ext4_new_flex_group_data *flex_gd)
1448{
1449	struct ext4_sb_info *sbi = EXT4_SB(sb);
1450	struct ext4_super_block *es = sbi->s_es;
1451	ext4_fsblk_t o_blocks_count;
1452	ext4_grpblk_t last;
1453	ext4_group_t group;
1454	handle_t *handle;
1455	unsigned reserved_gdb;
1456	int err = 0, err2 = 0, credit;
1457
1458	BUG_ON(!flex_gd->count || !flex_gd->groups || !flex_gd->bg_flags);
1459
1460	reserved_gdb = le16_to_cpu(es->s_reserved_gdt_blocks);
1461	o_blocks_count = ext4_blocks_count(es);
1462	ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
1463	BUG_ON(last);
1464
1465	err = setup_new_flex_group_blocks(sb, flex_gd);
1466	if (err)
1467		goto exit;
1468	/*
1469	 * We will always be modifying at least the superblock and  GDT
1470	 * blocks.  If we are adding a group past the last current GDT block,
1471	 * we will also modify the inode and the dindirect block.  If we
1472	 * are adding a group with superblock/GDT backups  we will also
1473	 * modify each of the reserved GDT dindirect blocks.
1474	 */
1475	credit = 3;	/* sb, resize inode, resize inode dindirect */
1476	/* GDT blocks */
1477	credit += 1 + DIV_ROUND_UP(flex_gd->count, EXT4_DESC_PER_BLOCK(sb));
1478	credit += reserved_gdb;	/* Reserved GDT dindirect blocks */
1479	handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, credit);
1480	if (IS_ERR(handle)) {
1481		err = PTR_ERR(handle);
1482		goto exit;
1483	}
1484
1485	BUFFER_TRACE(sbi->s_sbh, "get_write_access");
1486	err = ext4_journal_get_write_access(handle, sbi->s_sbh);
1487	if (err)
1488		goto exit_journal;
1489
1490	group = flex_gd->groups[0].group;
1491	BUG_ON(group != sbi->s_groups_count);
1492	err = ext4_add_new_descs(handle, sb, group,
1493				resize_inode, flex_gd->count);
1494	if (err)
1495		goto exit_journal;
1496
1497	err = ext4_setup_new_descs(handle, sb, flex_gd);
1498	if (err)
1499		goto exit_journal;
1500
1501	ext4_update_super(sb, flex_gd);
1502
1503	err = ext4_handle_dirty_super(handle, sb);
1504
1505exit_journal:
1506	err2 = ext4_journal_stop(handle);
1507	if (!err)
1508		err = err2;
1509
1510	if (!err) {
1511		int gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
1512		int gdb_num_end = ((group + flex_gd->count - 1) /
1513				   EXT4_DESC_PER_BLOCK(sb));
1514		int meta_bg = ext4_has_feature_meta_bg(sb);
1515		sector_t old_gdb = 0;
1516
1517		update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
1518			       sizeof(struct ext4_super_block), 0);
1519		for (; gdb_num <= gdb_num_end; gdb_num++) {
1520			struct buffer_head *gdb_bh;
1521
1522			gdb_bh = sbi->s_group_desc[gdb_num];
 
1523			if (old_gdb == gdb_bh->b_blocknr)
1524				continue;
1525			update_backups(sb, gdb_bh->b_blocknr, gdb_bh->b_data,
1526				       gdb_bh->b_size, meta_bg);
1527			old_gdb = gdb_bh->b_blocknr;
1528		}
1529	}
1530exit:
1531	return err;
1532}
1533
1534static int ext4_setup_next_flex_gd(struct super_block *sb,
1535				    struct ext4_new_flex_group_data *flex_gd,
1536				    ext4_fsblk_t n_blocks_count,
1537				    unsigned long flexbg_size)
1538{
1539	struct ext4_sb_info *sbi = EXT4_SB(sb);
1540	struct ext4_super_block *es = sbi->s_es;
1541	struct ext4_new_group_data *group_data = flex_gd->groups;
1542	ext4_fsblk_t o_blocks_count;
1543	ext4_group_t n_group;
1544	ext4_group_t group;
1545	ext4_group_t last_group;
1546	ext4_grpblk_t last;
1547	ext4_grpblk_t clusters_per_group;
1548	unsigned long i;
1549
1550	clusters_per_group = EXT4_CLUSTERS_PER_GROUP(sb);
1551
1552	o_blocks_count = ext4_blocks_count(es);
1553
1554	if (o_blocks_count == n_blocks_count)
1555		return 0;
1556
1557	ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
1558	BUG_ON(last);
1559	ext4_get_group_no_and_offset(sb, n_blocks_count - 1, &n_group, &last);
1560
1561	last_group = group | (flexbg_size - 1);
1562	if (last_group > n_group)
1563		last_group = n_group;
1564
1565	flex_gd->count = last_group - group + 1;
1566
1567	for (i = 0; i < flex_gd->count; i++) {
1568		int overhead;
1569
1570		group_data[i].group = group + i;
1571		group_data[i].blocks_count = EXT4_BLOCKS_PER_GROUP(sb);
1572		overhead = ext4_group_overhead_blocks(sb, group + i);
1573		group_data[i].mdata_blocks = overhead;
1574		group_data[i].free_clusters_count = EXT4_CLUSTERS_PER_GROUP(sb);
1575		if (ext4_has_group_desc_csum(sb)) {
1576			flex_gd->bg_flags[i] = EXT4_BG_BLOCK_UNINIT |
1577					       EXT4_BG_INODE_UNINIT;
1578			if (!test_opt(sb, INIT_INODE_TABLE))
1579				flex_gd->bg_flags[i] |= EXT4_BG_INODE_ZEROED;
1580		} else
1581			flex_gd->bg_flags[i] = EXT4_BG_INODE_ZEROED;
1582	}
1583
1584	if (last_group == n_group && ext4_has_group_desc_csum(sb))
1585		/* We need to initialize block bitmap of last group. */
1586		flex_gd->bg_flags[i - 1] &= ~EXT4_BG_BLOCK_UNINIT;
1587
1588	if ((last_group == n_group) && (last != clusters_per_group - 1)) {
1589		group_data[i - 1].blocks_count = EXT4_C2B(sbi, last + 1);
1590		group_data[i - 1].free_clusters_count -= clusters_per_group -
1591						       last - 1;
1592	}
1593
1594	return 1;
1595}
1596
1597/* Add group descriptor data to an existing or new group descriptor block.
1598 * Ensure we handle all possible error conditions _before_ we start modifying
1599 * the filesystem, because we cannot abort the transaction and not have it
1600 * write the data to disk.
1601 *
1602 * If we are on a GDT block boundary, we need to get the reserved GDT block.
1603 * Otherwise, we may need to add backup GDT blocks for a sparse group.
1604 *
1605 * We only need to hold the superblock lock while we are actually adding
1606 * in the new group's counts to the superblock.  Prior to that we have
1607 * not really "added" the group at all.  We re-check that we are still
1608 * adding in the last group in case things have changed since verifying.
1609 */
1610int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
1611{
1612	struct ext4_new_flex_group_data flex_gd;
1613	struct ext4_sb_info *sbi = EXT4_SB(sb);
1614	struct ext4_super_block *es = sbi->s_es;
1615	int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
1616		le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
1617	struct inode *inode = NULL;
1618	int gdb_off;
1619	int err;
1620	__u16 bg_flags = 0;
1621
1622	gdb_off = input->group % EXT4_DESC_PER_BLOCK(sb);
1623
1624	if (gdb_off == 0 && !ext4_has_feature_sparse_super(sb)) {
1625		ext4_warning(sb, "Can't resize non-sparse filesystem further");
1626		return -EPERM;
1627	}
1628
1629	if (ext4_blocks_count(es) + input->blocks_count <
1630	    ext4_blocks_count(es)) {
1631		ext4_warning(sb, "blocks_count overflow");
1632		return -EINVAL;
1633	}
1634
1635	if (le32_to_cpu(es->s_inodes_count) + EXT4_INODES_PER_GROUP(sb) <
1636	    le32_to_cpu(es->s_inodes_count)) {
1637		ext4_warning(sb, "inodes_count overflow");
1638		return -EINVAL;
1639	}
1640
1641	if (reserved_gdb || gdb_off == 0) {
1642		if (!ext4_has_feature_resize_inode(sb) ||
1643		    !le16_to_cpu(es->s_reserved_gdt_blocks)) {
1644			ext4_warning(sb,
1645				     "No reserved GDT blocks, can't resize");
1646			return -EPERM;
1647		}
1648		inode = ext4_iget(sb, EXT4_RESIZE_INO, EXT4_IGET_SPECIAL);
1649		if (IS_ERR(inode)) {
1650			ext4_warning(sb, "Error opening resize inode");
1651			return PTR_ERR(inode);
1652		}
1653	}
1654
1655
1656	err = verify_group_input(sb, input);
1657	if (err)
1658		goto out;
1659
1660	err = ext4_alloc_flex_bg_array(sb, input->group + 1);
1661	if (err)
1662		goto out;
1663
1664	err = ext4_mb_alloc_groupinfo(sb, input->group + 1);
1665	if (err)
1666		goto out;
1667
1668	flex_gd.count = 1;
1669	flex_gd.groups = input;
1670	flex_gd.bg_flags = &bg_flags;
1671	err = ext4_flex_group_add(sb, inode, &flex_gd);
1672out:
1673	iput(inode);
1674	return err;
1675} /* ext4_group_add */
1676
1677/*
1678 * extend a group without checking assuming that checking has been done.
1679 */
1680static int ext4_group_extend_no_check(struct super_block *sb,
1681				      ext4_fsblk_t o_blocks_count, ext4_grpblk_t add)
1682{
1683	struct ext4_super_block *es = EXT4_SB(sb)->s_es;
1684	handle_t *handle;
1685	int err = 0, err2;
1686
1687	/* We will update the superblock, one block bitmap, and
1688	 * one group descriptor via ext4_group_add_blocks().
1689	 */
1690	handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, 3);
1691	if (IS_ERR(handle)) {
1692		err = PTR_ERR(handle);
1693		ext4_warning(sb, "error %d on journal start", err);
1694		return err;
1695	}
1696
1697	BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
1698	err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
1699	if (err) {
1700		ext4_warning(sb, "error %d on journal write access", err);
1701		goto errout;
1702	}
1703
 
1704	ext4_blocks_count_set(es, o_blocks_count + add);
1705	ext4_free_blocks_count_set(es, ext4_free_blocks_count(es) + add);
 
 
1706	ext4_debug("freeing blocks %llu through %llu\n", o_blocks_count,
1707		   o_blocks_count + add);
1708	/* We add the blocks to the bitmap and set the group need init bit */
1709	err = ext4_group_add_blocks(handle, sb, o_blocks_count, add);
1710	if (err)
1711		goto errout;
1712	ext4_handle_dirty_super(handle, sb);
1713	ext4_debug("freed blocks %llu through %llu\n", o_blocks_count,
1714		   o_blocks_count + add);
1715errout:
1716	err2 = ext4_journal_stop(handle);
1717	if (err2 && !err)
1718		err = err2;
1719
1720	if (!err) {
1721		if (test_opt(sb, DEBUG))
1722			printk(KERN_DEBUG "EXT4-fs: extended group to %llu "
1723			       "blocks\n", ext4_blocks_count(es));
1724		update_backups(sb, EXT4_SB(sb)->s_sbh->b_blocknr,
1725			       (char *)es, sizeof(struct ext4_super_block), 0);
1726	}
1727	return err;
1728}
1729
1730/*
1731 * Extend the filesystem to the new number of blocks specified.  This entry
1732 * point is only used to extend the current filesystem to the end of the last
1733 * existing group.  It can be accessed via ioctl, or by "remount,resize=<size>"
1734 * for emergencies (because it has no dependencies on reserved blocks).
1735 *
1736 * If we _really_ wanted, we could use default values to call ext4_group_add()
1737 * allow the "remount" trick to work for arbitrary resizing, assuming enough
1738 * GDT blocks are reserved to grow to the desired size.
1739 */
1740int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
1741		      ext4_fsblk_t n_blocks_count)
1742{
1743	ext4_fsblk_t o_blocks_count;
1744	ext4_grpblk_t last;
1745	ext4_grpblk_t add;
1746	struct buffer_head *bh;
1747	int err;
1748	ext4_group_t group;
1749
1750	o_blocks_count = ext4_blocks_count(es);
1751
1752	if (test_opt(sb, DEBUG))
1753		ext4_msg(sb, KERN_DEBUG,
1754			 "extending last group from %llu to %llu blocks",
1755			 o_blocks_count, n_blocks_count);
1756
1757	if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
1758		return 0;
1759
1760	if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
1761		ext4_msg(sb, KERN_ERR,
1762			 "filesystem too large to resize to %llu blocks safely",
1763			 n_blocks_count);
1764		return -EINVAL;
1765	}
1766
1767	if (n_blocks_count < o_blocks_count) {
1768		ext4_warning(sb, "can't shrink FS - resize aborted");
1769		return -EINVAL;
1770	}
1771
1772	/* Handle the remaining blocks in the last group only. */
1773	ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
1774
1775	if (last == 0) {
1776		ext4_warning(sb, "need to use ext2online to resize further");
1777		return -EPERM;
1778	}
1779
1780	add = EXT4_BLOCKS_PER_GROUP(sb) - last;
1781
1782	if (o_blocks_count + add < o_blocks_count) {
1783		ext4_warning(sb, "blocks_count overflow");
1784		return -EINVAL;
1785	}
1786
1787	if (o_blocks_count + add > n_blocks_count)
1788		add = n_blocks_count - o_blocks_count;
1789
1790	if (o_blocks_count + add < n_blocks_count)
1791		ext4_warning(sb, "will only finish group (%llu blocks, %u new)",
1792			     o_blocks_count + add, add);
1793
1794	/* See if the device is actually as big as what was requested */
1795	bh = sb_bread(sb, o_blocks_count + add - 1);
1796	if (!bh) {
1797		ext4_warning(sb, "can't read last block, resize aborted");
1798		return -ENOSPC;
1799	}
1800	brelse(bh);
1801
1802	err = ext4_group_extend_no_check(sb, o_blocks_count, add);
1803	return err;
1804} /* ext4_group_extend */
1805
1806
1807static int num_desc_blocks(struct super_block *sb, ext4_group_t groups)
1808{
1809	return (groups + EXT4_DESC_PER_BLOCK(sb) - 1) / EXT4_DESC_PER_BLOCK(sb);
1810}
1811
1812/*
1813 * Release the resize inode and drop the resize_inode feature if there
1814 * are no more reserved gdt blocks, and then convert the file system
1815 * to enable meta_bg
1816 */
1817static int ext4_convert_meta_bg(struct super_block *sb, struct inode *inode)
1818{
1819	handle_t *handle;
1820	struct ext4_sb_info *sbi = EXT4_SB(sb);
1821	struct ext4_super_block *es = sbi->s_es;
1822	struct ext4_inode_info *ei = EXT4_I(inode);
1823	ext4_fsblk_t nr;
1824	int i, ret, err = 0;
1825	int credits = 1;
1826
1827	ext4_msg(sb, KERN_INFO, "Converting file system to meta_bg");
1828	if (inode) {
1829		if (es->s_reserved_gdt_blocks) {
1830			ext4_error(sb, "Unexpected non-zero "
1831				   "s_reserved_gdt_blocks");
1832			return -EPERM;
1833		}
1834
1835		/* Do a quick sanity check of the resize inode */
1836		if (inode->i_blocks != 1 << (inode->i_blkbits -
1837					     (9 - sbi->s_cluster_bits)))
1838			goto invalid_resize_inode;
1839		for (i = 0; i < EXT4_N_BLOCKS; i++) {
1840			if (i == EXT4_DIND_BLOCK) {
1841				if (ei->i_data[i])
1842					continue;
1843				else
1844					goto invalid_resize_inode;
1845			}
1846			if (ei->i_data[i])
1847				goto invalid_resize_inode;
1848		}
1849		credits += 3;	/* block bitmap, bg descriptor, resize inode */
1850	}
1851
1852	handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, credits);
1853	if (IS_ERR(handle))
1854		return PTR_ERR(handle);
1855
1856	BUFFER_TRACE(sbi->s_sbh, "get_write_access");
1857	err = ext4_journal_get_write_access(handle, sbi->s_sbh);
1858	if (err)
1859		goto errout;
1860
 
1861	ext4_clear_feature_resize_inode(sb);
1862	ext4_set_feature_meta_bg(sb);
1863	sbi->s_es->s_first_meta_bg =
1864		cpu_to_le32(num_desc_blocks(sb, sbi->s_groups_count));
 
 
1865
1866	err = ext4_handle_dirty_super(handle, sb);
1867	if (err) {
1868		ext4_std_error(sb, err);
1869		goto errout;
1870	}
1871
1872	if (inode) {
1873		nr = le32_to_cpu(ei->i_data[EXT4_DIND_BLOCK]);
1874		ext4_free_blocks(handle, inode, NULL, nr, 1,
1875				 EXT4_FREE_BLOCKS_METADATA |
1876				 EXT4_FREE_BLOCKS_FORGET);
1877		ei->i_data[EXT4_DIND_BLOCK] = 0;
1878		inode->i_blocks = 0;
1879
1880		err = ext4_mark_inode_dirty(handle, inode);
1881		if (err)
1882			ext4_std_error(sb, err);
1883	}
1884
1885errout:
1886	ret = ext4_journal_stop(handle);
1887	if (!err)
1888		err = ret;
1889	return ret;
1890
1891invalid_resize_inode:
1892	ext4_error(sb, "corrupted/inconsistent resize inode");
1893	return -EINVAL;
1894}
1895
1896/*
1897 * ext4_resize_fs() resizes a fs to new size specified by @n_blocks_count
1898 *
1899 * @sb: super block of the fs to be resized
1900 * @n_blocks_count: the number of blocks resides in the resized fs
1901 */
1902int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
1903{
1904	struct ext4_new_flex_group_data *flex_gd = NULL;
1905	struct ext4_sb_info *sbi = EXT4_SB(sb);
1906	struct ext4_super_block *es = sbi->s_es;
1907	struct buffer_head *bh;
1908	struct inode *resize_inode = NULL;
1909	ext4_grpblk_t add, offset;
1910	unsigned long n_desc_blocks;
1911	unsigned long o_desc_blocks;
1912	ext4_group_t o_group;
1913	ext4_group_t n_group;
1914	ext4_fsblk_t o_blocks_count;
1915	ext4_fsblk_t n_blocks_count_retry = 0;
1916	unsigned long last_update_time = 0;
1917	int err = 0, flexbg_size = 1 << sbi->s_log_groups_per_flex;
1918	int meta_bg;
1919
1920	/* See if the device is actually as big as what was requested */
1921	bh = sb_bread(sb, n_blocks_count - 1);
1922	if (!bh) {
1923		ext4_warning(sb, "can't read last block, resize aborted");
1924		return -ENOSPC;
1925	}
1926	brelse(bh);
1927
1928retry:
1929	o_blocks_count = ext4_blocks_count(es);
1930
1931	ext4_msg(sb, KERN_INFO, "resizing filesystem from %llu "
1932		 "to %llu blocks", o_blocks_count, n_blocks_count);
1933
1934	if (n_blocks_count < o_blocks_count) {
1935		/* On-line shrinking not supported */
1936		ext4_warning(sb, "can't shrink FS - resize aborted");
1937		return -EINVAL;
1938	}
1939
1940	if (n_blocks_count == o_blocks_count)
1941		/* Nothing need to do */
1942		return 0;
1943
1944	n_group = ext4_get_group_number(sb, n_blocks_count - 1);
1945	if (n_group >= (0xFFFFFFFFUL / EXT4_INODES_PER_GROUP(sb))) {
1946		ext4_warning(sb, "resize would cause inodes_count overflow");
1947		return -EINVAL;
1948	}
1949	ext4_get_group_no_and_offset(sb, o_blocks_count - 1, &o_group, &offset);
1950
1951	n_desc_blocks = num_desc_blocks(sb, n_group + 1);
1952	o_desc_blocks = num_desc_blocks(sb, sbi->s_groups_count);
1953
1954	meta_bg = ext4_has_feature_meta_bg(sb);
1955
1956	if (ext4_has_feature_resize_inode(sb)) {
1957		if (meta_bg) {
1958			ext4_error(sb, "resize_inode and meta_bg enabled "
1959				   "simultaneously");
1960			return -EINVAL;
1961		}
1962		if (n_desc_blocks > o_desc_blocks +
1963		    le16_to_cpu(es->s_reserved_gdt_blocks)) {
1964			n_blocks_count_retry = n_blocks_count;
1965			n_desc_blocks = o_desc_blocks +
1966				le16_to_cpu(es->s_reserved_gdt_blocks);
1967			n_group = n_desc_blocks * EXT4_DESC_PER_BLOCK(sb);
1968			n_blocks_count = (ext4_fsblk_t)n_group *
1969				EXT4_BLOCKS_PER_GROUP(sb) +
1970				le32_to_cpu(es->s_first_data_block);
1971			n_group--; /* set to last group number */
1972		}
1973
1974		if (!resize_inode)
1975			resize_inode = ext4_iget(sb, EXT4_RESIZE_INO,
1976						 EXT4_IGET_SPECIAL);
1977		if (IS_ERR(resize_inode)) {
1978			ext4_warning(sb, "Error opening resize inode");
1979			return PTR_ERR(resize_inode);
1980		}
1981	}
1982
1983	if ((!resize_inode && !meta_bg) || n_blocks_count == o_blocks_count) {
1984		err = ext4_convert_meta_bg(sb, resize_inode);
1985		if (err)
1986			goto out;
1987		if (resize_inode) {
1988			iput(resize_inode);
1989			resize_inode = NULL;
1990		}
1991		if (n_blocks_count_retry) {
1992			n_blocks_count = n_blocks_count_retry;
1993			n_blocks_count_retry = 0;
1994			goto retry;
1995		}
1996	}
1997
1998	/*
1999	 * Make sure the last group has enough space so that it's
2000	 * guaranteed to have enough space for all metadata blocks
2001	 * that it might need to hold.  (We might not need to store
2002	 * the inode table blocks in the last block group, but there
2003	 * will be cases where this might be needed.)
2004	 */
2005	if ((ext4_group_first_block_no(sb, n_group) +
2006	     ext4_group_overhead_blocks(sb, n_group) + 2 +
2007	     sbi->s_itb_per_group + sbi->s_cluster_ratio) >= n_blocks_count) {
2008		n_blocks_count = ext4_group_first_block_no(sb, n_group);
2009		n_group--;
2010		n_blocks_count_retry = 0;
2011		if (resize_inode) {
2012			iput(resize_inode);
2013			resize_inode = NULL;
2014		}
2015		goto retry;
2016	}
2017
2018	/* extend the last group */
2019	if (n_group == o_group)
2020		add = n_blocks_count - o_blocks_count;
2021	else
2022		add = EXT4_C2B(sbi, EXT4_CLUSTERS_PER_GROUP(sb) - (offset + 1));
2023	if (add > 0) {
2024		err = ext4_group_extend_no_check(sb, o_blocks_count, add);
2025		if (err)
2026			goto out;
2027	}
2028
2029	if (ext4_blocks_count(es) == n_blocks_count)
2030		goto out;
2031
2032	err = ext4_alloc_flex_bg_array(sb, n_group + 1);
2033	if (err)
2034		goto out;
2035
2036	err = ext4_mb_alloc_groupinfo(sb, n_group + 1);
2037	if (err)
2038		goto out;
2039
2040	flex_gd = alloc_flex_gd(flexbg_size);
2041	if (flex_gd == NULL) {
2042		err = -ENOMEM;
2043		goto out;
2044	}
2045
2046	/* Add flex groups. Note that a regular group is a
2047	 * flex group with 1 group.
2048	 */
2049	while (ext4_setup_next_flex_gd(sb, flex_gd, n_blocks_count,
2050					      flexbg_size)) {
2051		if (jiffies - last_update_time > HZ * 10) {
2052			if (last_update_time)
2053				ext4_msg(sb, KERN_INFO,
2054					 "resized to %llu blocks",
2055					 ext4_blocks_count(es));
2056			last_update_time = jiffies;
2057		}
2058		if (ext4_alloc_group_tables(sb, flex_gd, flexbg_size) != 0)
2059			break;
2060		err = ext4_flex_group_add(sb, resize_inode, flex_gd);
2061		if (unlikely(err))
2062			break;
2063	}
2064
2065	if (!err && n_blocks_count_retry) {
2066		n_blocks_count = n_blocks_count_retry;
2067		n_blocks_count_retry = 0;
2068		free_flex_gd(flex_gd);
2069		flex_gd = NULL;
2070		if (resize_inode) {
2071			iput(resize_inode);
2072			resize_inode = NULL;
2073		}
2074		goto retry;
2075	}
2076
2077out:
2078	if (flex_gd)
2079		free_flex_gd(flex_gd);
2080	if (resize_inode != NULL)
2081		iput(resize_inode);
2082	if (err)
2083		ext4_warning(sb, "error (%d) occurred during "
2084			     "file system resize", err);
2085	ext4_msg(sb, KERN_INFO, "resized filesystem to %llu",
2086		 ext4_blocks_count(es));
2087	return err;
2088}