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
  20struct ext4_rcu_ptr {
  21	struct rcu_head rcu;
  22	void *ptr;
  23};
  24
  25static void ext4_rcu_ptr_callback(struct rcu_head *head)
  26{
  27	struct ext4_rcu_ptr *ptr;
  28
  29	ptr = container_of(head, struct ext4_rcu_ptr, rcu);
  30	kvfree(ptr->ptr);
  31	kfree(ptr);
  32}
  33
  34void ext4_kvfree_array_rcu(void *to_free)
  35{
  36	struct ext4_rcu_ptr *ptr = kzalloc(sizeof(*ptr), GFP_KERNEL);
  37
  38	if (ptr) {
  39		ptr->ptr = to_free;
  40		call_rcu(&ptr->rcu, ext4_rcu_ptr_callback);
  41		return;
  42	}
  43	synchronize_rcu();
  44	kvfree(to_free);
  45}
  46
  47int ext4_resize_begin(struct super_block *sb)
  48{
  49	struct ext4_sb_info *sbi = EXT4_SB(sb);
  50	int ret = 0;
  51
  52	if (!capable(CAP_SYS_RESOURCE))
  53		return -EPERM;
  54
  55	/*
  56	 * If we are not using the primary superblock/GDT copy don't resize,
  57         * because the user tools have no way of handling this.  Probably a
  58         * bad time to do it anyways.
  59         */
  60	if (EXT4_B2C(sbi, sbi->s_sbh->b_blocknr) !=
  61	    le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) {
  62		ext4_warning(sb, "won't resize using backup superblock at %llu",
  63			(unsigned long long)EXT4_SB(sb)->s_sbh->b_blocknr);
  64		return -EPERM;
  65	}
  66
  67	/*
  68	 * We are not allowed to do online-resizing on a filesystem mounted
  69	 * with error, because it can destroy the filesystem easily.
  70	 */
  71	if (EXT4_SB(sb)->s_mount_state & EXT4_ERROR_FS) {
  72		ext4_warning(sb, "There are errors in the filesystem, "
  73			     "so online resizing is not allowed");
  74		return -EPERM;
  75	}
  76
  77	if (ext4_has_feature_sparse_super2(sb)) {
  78		ext4_msg(sb, KERN_ERR, "Online resizing not supported with sparse_super2");
  79		return -EOPNOTSUPP;
  80	}
  81
  82	if (test_and_set_bit_lock(EXT4_FLAGS_RESIZING,
  83				  &EXT4_SB(sb)->s_ext4_flags))
  84		ret = -EBUSY;
  85
  86	return ret;
  87}
  88
  89void ext4_resize_end(struct super_block *sb)
  90{
  91	clear_bit_unlock(EXT4_FLAGS_RESIZING, &EXT4_SB(sb)->s_ext4_flags);
  92	smp_mb__after_atomic();
  93}
  94
  95static ext4_group_t ext4_meta_bg_first_group(struct super_block *sb,
  96					     ext4_group_t group) {
  97	return (group >> EXT4_DESC_PER_BLOCK_BITS(sb)) <<
  98	       EXT4_DESC_PER_BLOCK_BITS(sb);
  99}
 100
 101static ext4_fsblk_t ext4_meta_bg_first_block_no(struct super_block *sb,
 102					     ext4_group_t group) {
 103	group = ext4_meta_bg_first_group(sb, group);
 104	return ext4_group_first_block_no(sb, group);
 105}
 106
 107static ext4_grpblk_t ext4_group_overhead_blocks(struct super_block *sb,
 108						ext4_group_t group) {
 109	ext4_grpblk_t overhead;
 110	overhead = ext4_bg_num_gdb(sb, group);
 111	if (ext4_bg_has_super(sb, group))
 112		overhead += 1 +
 113			  le16_to_cpu(EXT4_SB(sb)->s_es->s_reserved_gdt_blocks);
 114	return overhead;
 115}
 116
 117#define outside(b, first, last)	((b) < (first) || (b) >= (last))
 118#define inside(b, first, last)	((b) >= (first) && (b) < (last))
 119
 120static int verify_group_input(struct super_block *sb,
 121			      struct ext4_new_group_data *input)
 122{
 123	struct ext4_sb_info *sbi = EXT4_SB(sb);
 124	struct ext4_super_block *es = sbi->s_es;
 125	ext4_fsblk_t start = ext4_blocks_count(es);
 126	ext4_fsblk_t end = start + input->blocks_count;
 127	ext4_group_t group = input->group;
 128	ext4_fsblk_t itend = input->inode_table + sbi->s_itb_per_group;
 129	unsigned overhead;
 130	ext4_fsblk_t metaend;
 131	struct buffer_head *bh = NULL;
 132	ext4_grpblk_t free_blocks_count, offset;
 133	int err = -EINVAL;
 134
 135	if (group != sbi->s_groups_count) {
 136		ext4_warning(sb, "Cannot add at group %u (only %u groups)",
 137			     input->group, sbi->s_groups_count);
 138		return -EINVAL;
 139	}
 140
 141	overhead = ext4_group_overhead_blocks(sb, group);
 142	metaend = start + overhead;
 143	input->free_clusters_count = free_blocks_count =
 144		input->blocks_count - 2 - overhead - sbi->s_itb_per_group;
 145
 146	if (test_opt(sb, DEBUG))
 147		printk(KERN_DEBUG "EXT4-fs: adding %s group %u: %u blocks "
 148		       "(%d free, %u reserved)\n",
 149		       ext4_bg_has_super(sb, input->group) ? "normal" :
 150		       "no-super", input->group, input->blocks_count,
 151		       free_blocks_count, input->reserved_blocks);
 152
 153	ext4_get_group_no_and_offset(sb, start, NULL, &offset);
 154	if (offset != 0)
 155			ext4_warning(sb, "Last group not full");
 156	else if (input->reserved_blocks > input->blocks_count / 5)
 157		ext4_warning(sb, "Reserved blocks too high (%u)",
 158			     input->reserved_blocks);
 159	else if (free_blocks_count < 0)
 160		ext4_warning(sb, "Bad blocks count %u",
 161			     input->blocks_count);
 162	else if (IS_ERR(bh = ext4_sb_bread(sb, end - 1, 0))) {
 163		err = PTR_ERR(bh);
 164		bh = NULL;
 165		ext4_warning(sb, "Cannot read last block (%llu)",
 166			     end - 1);
 167	} else if (outside(input->block_bitmap, start, end))
 168		ext4_warning(sb, "Block bitmap not in group (block %llu)",
 169			     (unsigned long long)input->block_bitmap);
 170	else if (outside(input->inode_bitmap, start, end))
 171		ext4_warning(sb, "Inode bitmap not in group (block %llu)",
 172			     (unsigned long long)input->inode_bitmap);
 173	else if (outside(input->inode_table, start, end) ||
 174		 outside(itend - 1, start, end))
 175		ext4_warning(sb, "Inode table not in group (blocks %llu-%llu)",
 176			     (unsigned long long)input->inode_table, itend - 1);
 177	else if (input->inode_bitmap == input->block_bitmap)
 178		ext4_warning(sb, "Block bitmap same as inode bitmap (%llu)",
 179			     (unsigned long long)input->block_bitmap);
 180	else if (inside(input->block_bitmap, input->inode_table, itend))
 181		ext4_warning(sb, "Block bitmap (%llu) in inode table "
 182			     "(%llu-%llu)",
 183			     (unsigned long long)input->block_bitmap,
 184			     (unsigned long long)input->inode_table, itend - 1);
 185	else if (inside(input->inode_bitmap, input->inode_table, itend))
 186		ext4_warning(sb, "Inode bitmap (%llu) in inode table "
 187			     "(%llu-%llu)",
 188			     (unsigned long long)input->inode_bitmap,
 189			     (unsigned long long)input->inode_table, itend - 1);
 190	else if (inside(input->block_bitmap, start, metaend))
 191		ext4_warning(sb, "Block bitmap (%llu) in GDT table (%llu-%llu)",
 192			     (unsigned long long)input->block_bitmap,
 193			     start, metaend - 1);
 194	else if (inside(input->inode_bitmap, start, metaend))
 195		ext4_warning(sb, "Inode bitmap (%llu) in GDT table (%llu-%llu)",
 196			     (unsigned long long)input->inode_bitmap,
 197			     start, metaend - 1);
 198	else if (inside(input->inode_table, start, metaend) ||
 199		 inside(itend - 1, start, metaend))
 200		ext4_warning(sb, "Inode table (%llu-%llu) overlaps GDT table "
 201			     "(%llu-%llu)",
 202			     (unsigned long long)input->inode_table,
 203			     itend - 1, start, metaend - 1);
 204	else
 205		err = 0;
 206	brelse(bh);
 207
 208	return err;
 209}
 210
 211/*
 212 * ext4_new_flex_group_data is used by 64bit-resize interface to add a flex
 213 * group each time.
 214 */
 215struct ext4_new_flex_group_data {
 216	struct ext4_new_group_data *groups;	/* new_group_data for groups
 217						   in the flex group */
 218	__u16 *bg_flags;			/* block group flags of groups
 219						   in @groups */
 220	ext4_group_t count;			/* number of groups in @groups
 221						 */
 222};
 223
 224/*
 225 * alloc_flex_gd() allocates a ext4_new_flex_group_data with size of
 226 * @flexbg_size.
 227 *
 228 * Returns NULL on failure otherwise address of the allocated structure.
 229 */
 230static struct ext4_new_flex_group_data *alloc_flex_gd(unsigned long flexbg_size)
 231{
 232	struct ext4_new_flex_group_data *flex_gd;
 233
 234	flex_gd = kmalloc(sizeof(*flex_gd), GFP_NOFS);
 235	if (flex_gd == NULL)
 236		goto out3;
 237
 238	if (flexbg_size >= UINT_MAX / sizeof(struct ext4_new_group_data))
 239		goto out2;
 240	flex_gd->count = flexbg_size;
 241
 242	flex_gd->groups = kmalloc_array(flexbg_size,
 243					sizeof(struct ext4_new_group_data),
 244					GFP_NOFS);
 245	if (flex_gd->groups == NULL)
 246		goto out2;
 247
 248	flex_gd->bg_flags = kmalloc_array(flexbg_size, sizeof(__u16),
 249					  GFP_NOFS);
 250	if (flex_gd->bg_flags == NULL)
 251		goto out1;
 252
 253	return flex_gd;
 254
 255out1:
 256	kfree(flex_gd->groups);
 257out2:
 258	kfree(flex_gd);
 259out3:
 260	return NULL;
 261}
 262
 263static void free_flex_gd(struct ext4_new_flex_group_data *flex_gd)
 264{
 265	kfree(flex_gd->bg_flags);
 266	kfree(flex_gd->groups);
 267	kfree(flex_gd);
 268}
 269
 270/*
 271 * ext4_alloc_group_tables() allocates block bitmaps, inode bitmaps
 272 * and inode tables for a flex group.
 273 *
 274 * This function is used by 64bit-resize.  Note that this function allocates
 275 * group tables from the 1st group of groups contained by @flexgd, which may
 276 * be a partial of a flex group.
 277 *
 278 * @sb: super block of fs to which the groups belongs
 279 *
 280 * Returns 0 on a successful allocation of the metadata blocks in the
 281 * block group.
 282 */
 283static int ext4_alloc_group_tables(struct super_block *sb,
 284				struct ext4_new_flex_group_data *flex_gd,
 285				int flexbg_size)
 286{
 287	struct ext4_new_group_data *group_data = flex_gd->groups;
 288	ext4_fsblk_t start_blk;
 289	ext4_fsblk_t last_blk;
 290	ext4_group_t src_group;
 291	ext4_group_t bb_index = 0;
 292	ext4_group_t ib_index = 0;
 293	ext4_group_t it_index = 0;
 294	ext4_group_t group;
 295	ext4_group_t last_group;
 296	unsigned overhead;
 297	__u16 uninit_mask = (flexbg_size > 1) ? ~EXT4_BG_BLOCK_UNINIT : ~0;
 298	int i;
 299
 300	BUG_ON(flex_gd->count == 0 || group_data == NULL);
 301
 302	src_group = group_data[0].group;
 303	last_group  = src_group + flex_gd->count - 1;
 304
 305	BUG_ON((flexbg_size > 1) && ((src_group & ~(flexbg_size - 1)) !=
 306	       (last_group & ~(flexbg_size - 1))));
 307next_group:
 308	group = group_data[0].group;
 309	if (src_group >= group_data[0].group + flex_gd->count)
 310		return -ENOSPC;
 311	start_blk = ext4_group_first_block_no(sb, src_group);
 312	last_blk = start_blk + group_data[src_group - group].blocks_count;
 313
 314	overhead = ext4_group_overhead_blocks(sb, src_group);
 315
 316	start_blk += overhead;
 317
 318	/* We collect contiguous blocks as much as possible. */
 319	src_group++;
 320	for (; src_group <= last_group; src_group++) {
 321		overhead = ext4_group_overhead_blocks(sb, src_group);
 322		if (overhead == 0)
 323			last_blk += group_data[src_group - group].blocks_count;
 324		else
 325			break;
 326	}
 327
 328	/* Allocate block bitmaps */
 329	for (; bb_index < flex_gd->count; bb_index++) {
 330		if (start_blk >= last_blk)
 331			goto next_group;
 332		group_data[bb_index].block_bitmap = start_blk++;
 333		group = ext4_get_group_number(sb, start_blk - 1);
 334		group -= group_data[0].group;
 335		group_data[group].mdata_blocks++;
 336		flex_gd->bg_flags[group] &= uninit_mask;
 337	}
 338
 339	/* Allocate inode bitmaps */
 340	for (; ib_index < flex_gd->count; ib_index++) {
 341		if (start_blk >= last_blk)
 342			goto next_group;
 343		group_data[ib_index].inode_bitmap = start_blk++;
 344		group = ext4_get_group_number(sb, start_blk - 1);
 345		group -= group_data[0].group;
 346		group_data[group].mdata_blocks++;
 347		flex_gd->bg_flags[group] &= uninit_mask;
 348	}
 349
 350	/* Allocate inode tables */
 351	for (; it_index < flex_gd->count; it_index++) {
 352		unsigned int itb = EXT4_SB(sb)->s_itb_per_group;
 353		ext4_fsblk_t next_group_start;
 354
 355		if (start_blk + itb > last_blk)
 356			goto next_group;
 357		group_data[it_index].inode_table = start_blk;
 358		group = ext4_get_group_number(sb, start_blk);
 359		next_group_start = ext4_group_first_block_no(sb, group + 1);
 360		group -= group_data[0].group;
 361
 362		if (start_blk + itb > next_group_start) {
 363			flex_gd->bg_flags[group + 1] &= uninit_mask;
 364			overhead = start_blk + itb - next_group_start;
 365			group_data[group + 1].mdata_blocks += overhead;
 366			itb -= overhead;
 367		}
 368
 369		group_data[group].mdata_blocks += itb;
 370		flex_gd->bg_flags[group] &= uninit_mask;
 371		start_blk += EXT4_SB(sb)->s_itb_per_group;
 372	}
 373
 374	/* Update free clusters count to exclude metadata blocks */
 375	for (i = 0; i < flex_gd->count; i++) {
 376		group_data[i].free_clusters_count -=
 377				EXT4_NUM_B2C(EXT4_SB(sb),
 378					     group_data[i].mdata_blocks);
 379	}
 380
 381	if (test_opt(sb, DEBUG)) {
 382		int i;
 383		group = group_data[0].group;
 384
 385		printk(KERN_DEBUG "EXT4-fs: adding a flex group with "
 386		       "%d groups, flexbg size is %d:\n", flex_gd->count,
 387		       flexbg_size);
 388
 389		for (i = 0; i < flex_gd->count; i++) {
 390			ext4_debug(
 391			       "adding %s group %u: %u blocks (%d free, %d mdata blocks)\n",
 392			       ext4_bg_has_super(sb, group + i) ? "normal" :
 393			       "no-super", group + i,
 394			       group_data[i].blocks_count,
 395			       group_data[i].free_clusters_count,
 396			       group_data[i].mdata_blocks);
 397		}
 398	}
 399	return 0;
 400}
 401
 402static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
 403				  ext4_fsblk_t blk)
 404{
 405	struct buffer_head *bh;
 406	int err;
 407
 408	bh = sb_getblk(sb, blk);
 409	if (unlikely(!bh))
 410		return ERR_PTR(-ENOMEM);
 411	BUFFER_TRACE(bh, "get_write_access");
 412	if ((err = ext4_journal_get_write_access(handle, bh))) {
 413		brelse(bh);
 414		bh = ERR_PTR(err);
 415	} else {
 416		memset(bh->b_data, 0, sb->s_blocksize);
 417		set_buffer_uptodate(bh);
 418	}
 419
 420	return bh;
 421}
 422
 423static int ext4_resize_ensure_credits_batch(handle_t *handle, int credits)
 
 
 
 
 
 424{
 425	return ext4_journal_ensure_credits_fn(handle, credits,
 426		EXT4_MAX_TRANS_DATA, 0, 0);
 
 
 
 
 
 
 
 
 
 
 
 
 
 427}
 428
 429/*
 430 * set_flexbg_block_bitmap() mark clusters [@first_cluster, @last_cluster] used.
 431 *
 432 * Helper function for ext4_setup_new_group_blocks() which set .
 433 *
 434 * @sb: super block
 435 * @handle: journal handle
 436 * @flex_gd: flex group data
 437 */
 438static int set_flexbg_block_bitmap(struct super_block *sb, handle_t *handle,
 439			struct ext4_new_flex_group_data *flex_gd,
 440			ext4_fsblk_t first_cluster, ext4_fsblk_t last_cluster)
 441{
 442	struct ext4_sb_info *sbi = EXT4_SB(sb);
 443	ext4_group_t count = last_cluster - first_cluster + 1;
 444	ext4_group_t count2;
 445
 446	ext4_debug("mark clusters [%llu-%llu] used\n", first_cluster,
 447		   last_cluster);
 448	for (count2 = count; count > 0;
 449	     count -= count2, first_cluster += count2) {
 450		ext4_fsblk_t start;
 451		struct buffer_head *bh;
 452		ext4_group_t group;
 453		int err;
 454
 455		group = ext4_get_group_number(sb, EXT4_C2B(sbi, first_cluster));
 456		start = EXT4_B2C(sbi, ext4_group_first_block_no(sb, group));
 457		group -= flex_gd->groups[0].group;
 458
 459		count2 = EXT4_CLUSTERS_PER_GROUP(sb) - (first_cluster - start);
 460		if (count2 > count)
 461			count2 = count;
 462
 463		if (flex_gd->bg_flags[group] & EXT4_BG_BLOCK_UNINIT) {
 464			BUG_ON(flex_gd->count > 1);
 465			continue;
 466		}
 467
 468		err = ext4_resize_ensure_credits_batch(handle, 1);
 469		if (err < 0)
 470			return err;
 471
 472		bh = sb_getblk(sb, flex_gd->groups[group].block_bitmap);
 473		if (unlikely(!bh))
 474			return -ENOMEM;
 475
 476		BUFFER_TRACE(bh, "get_write_access");
 477		err = ext4_journal_get_write_access(handle, bh);
 478		if (err) {
 479			brelse(bh);
 480			return err;
 481		}
 482		ext4_debug("mark block bitmap %#04llx (+%llu/%u)\n",
 483			   first_cluster, first_cluster - start, count2);
 484		ext4_set_bits(bh->b_data, first_cluster - start, count2);
 485
 486		err = ext4_handle_dirty_metadata(handle, NULL, bh);
 487		brelse(bh);
 488		if (unlikely(err))
 489			return err;
 
 490	}
 491
 492	return 0;
 493}
 494
 495/*
 496 * Set up the block and inode bitmaps, and the inode table for the new groups.
 497 * This doesn't need to be part of the main transaction, since we are only
 498 * changing blocks outside the actual filesystem.  We still do journaling to
 499 * ensure the recovery is correct in case of a failure just after resize.
 500 * If any part of this fails, we simply abort the resize.
 501 *
 502 * setup_new_flex_group_blocks handles a flex group as follow:
 503 *  1. copy super block and GDT, and initialize group tables if necessary.
 504 *     In this step, we only set bits in blocks bitmaps for blocks taken by
 505 *     super block and GDT.
 506 *  2. allocate group tables in block bitmaps, that is, set bits in block
 507 *     bitmap for blocks taken by group tables.
 508 */
 509static int setup_new_flex_group_blocks(struct super_block *sb,
 510				struct ext4_new_flex_group_data *flex_gd)
 511{
 512	int group_table_count[] = {1, 1, EXT4_SB(sb)->s_itb_per_group};
 513	ext4_fsblk_t start;
 514	ext4_fsblk_t block;
 515	struct ext4_sb_info *sbi = EXT4_SB(sb);
 516	struct ext4_super_block *es = sbi->s_es;
 517	struct ext4_new_group_data *group_data = flex_gd->groups;
 518	__u16 *bg_flags = flex_gd->bg_flags;
 519	handle_t *handle;
 520	ext4_group_t group, count;
 521	struct buffer_head *bh = NULL;
 522	int reserved_gdb, i, j, err = 0, err2;
 523	int meta_bg;
 524
 525	BUG_ON(!flex_gd->count || !group_data ||
 526	       group_data[0].group != sbi->s_groups_count);
 527
 528	reserved_gdb = le16_to_cpu(es->s_reserved_gdt_blocks);
 529	meta_bg = ext4_has_feature_meta_bg(sb);
 530
 531	/* This transaction may be extended/restarted along the way */
 532	handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, EXT4_MAX_TRANS_DATA);
 533	if (IS_ERR(handle))
 534		return PTR_ERR(handle);
 535
 536	group = group_data[0].group;
 537	for (i = 0; i < flex_gd->count; i++, group++) {
 538		unsigned long gdblocks;
 539		ext4_grpblk_t overhead;
 540
 541		gdblocks = ext4_bg_num_gdb(sb, group);
 542		start = ext4_group_first_block_no(sb, group);
 543
 544		if (meta_bg == 0 && !ext4_bg_has_super(sb, group))
 545			goto handle_itb;
 546
 547		if (meta_bg == 1) {
 548			ext4_group_t first_group;
 549			first_group = ext4_meta_bg_first_group(sb, group);
 550			if (first_group != group + 1 &&
 551			    first_group != group + EXT4_DESC_PER_BLOCK(sb) - 1)
 552				goto handle_itb;
 553		}
 554
 555		block = start + ext4_bg_has_super(sb, group);
 556		/* Copy all of the GDT blocks into the backup in this group */
 557		for (j = 0; j < gdblocks; j++, block++) {
 558			struct buffer_head *gdb;
 559
 560			ext4_debug("update backup group %#04llx\n", block);
 561			err = ext4_resize_ensure_credits_batch(handle, 1);
 562			if (err < 0)
 563				goto out;
 564
 565			gdb = sb_getblk(sb, block);
 566			if (unlikely(!gdb)) {
 567				err = -ENOMEM;
 568				goto out;
 569			}
 570
 571			BUFFER_TRACE(gdb, "get_write_access");
 572			err = ext4_journal_get_write_access(handle, gdb);
 573			if (err) {
 574				brelse(gdb);
 575				goto out;
 576			}
 577			memcpy(gdb->b_data, sbi_array_rcu_deref(sbi,
 578				s_group_desc, j)->b_data, gdb->b_size);
 579			set_buffer_uptodate(gdb);
 580
 581			err = ext4_handle_dirty_metadata(handle, NULL, gdb);
 582			if (unlikely(err)) {
 583				brelse(gdb);
 584				goto out;
 585			}
 586			brelse(gdb);
 587		}
 588
 589		/* Zero out all of the reserved backup group descriptor
 590		 * table blocks
 591		 */
 592		if (ext4_bg_has_super(sb, group)) {
 593			err = sb_issue_zeroout(sb, gdblocks + start + 1,
 594					reserved_gdb, GFP_NOFS);
 595			if (err)
 596				goto out;
 597		}
 598
 599handle_itb:
 600		/* Initialize group tables of the grop @group */
 601		if (!(bg_flags[i] & EXT4_BG_INODE_ZEROED))
 602			goto handle_bb;
 603
 604		/* Zero out all of the inode table blocks */
 605		block = group_data[i].inode_table;
 606		ext4_debug("clear inode table blocks %#04llx -> %#04lx\n",
 607			   block, sbi->s_itb_per_group);
 608		err = sb_issue_zeroout(sb, block, sbi->s_itb_per_group,
 609				       GFP_NOFS);
 610		if (err)
 611			goto out;
 612
 613handle_bb:
 614		if (bg_flags[i] & EXT4_BG_BLOCK_UNINIT)
 615			goto handle_ib;
 616
 617		/* Initialize block bitmap of the @group */
 618		block = group_data[i].block_bitmap;
 619		err = ext4_resize_ensure_credits_batch(handle, 1);
 620		if (err < 0)
 621			goto out;
 622
 623		bh = bclean(handle, sb, block);
 624		if (IS_ERR(bh)) {
 625			err = PTR_ERR(bh);
 
 626			goto out;
 627		}
 628		overhead = ext4_group_overhead_blocks(sb, group);
 629		if (overhead != 0) {
 630			ext4_debug("mark backup superblock %#04llx (+0)\n",
 631				   start);
 632			ext4_set_bits(bh->b_data, 0,
 633				      EXT4_NUM_B2C(sbi, overhead));
 634		}
 635		ext4_mark_bitmap_end(EXT4_B2C(sbi, group_data[i].blocks_count),
 636				     sb->s_blocksize * 8, bh->b_data);
 637		err = ext4_handle_dirty_metadata(handle, NULL, bh);
 638		brelse(bh);
 639		if (err)
 640			goto out;
 
 641
 642handle_ib:
 643		if (bg_flags[i] & EXT4_BG_INODE_UNINIT)
 644			continue;
 645
 646		/* Initialize inode bitmap of the @group */
 647		block = group_data[i].inode_bitmap;
 648		err = ext4_resize_ensure_credits_batch(handle, 1);
 649		if (err < 0)
 650			goto out;
 651		/* Mark unused entries in inode bitmap used */
 652		bh = bclean(handle, sb, block);
 653		if (IS_ERR(bh)) {
 654			err = PTR_ERR(bh);
 
 655			goto out;
 656		}
 657
 658		ext4_mark_bitmap_end(EXT4_INODES_PER_GROUP(sb),
 659				     sb->s_blocksize * 8, bh->b_data);
 660		err = ext4_handle_dirty_metadata(handle, NULL, bh);
 661		brelse(bh);
 662		if (err)
 663			goto out;
 
 664	}
 
 665
 666	/* Mark group tables in block bitmap */
 667	for (j = 0; j < GROUP_TABLE_COUNT; j++) {
 668		count = group_table_count[j];
 669		start = (&group_data[0].block_bitmap)[j];
 670		block = start;
 671		for (i = 1; i < flex_gd->count; i++) {
 672			block += group_table_count[j];
 673			if (block == (&group_data[i].block_bitmap)[j]) {
 674				count += group_table_count[j];
 675				continue;
 676			}
 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			count = group_table_count[j];
 686			start = (&group_data[i].block_bitmap)[j];
 687			block = start;
 688		}
 689
 690		if (count) {
 691			err = set_flexbg_block_bitmap(sb, handle,
 692						      flex_gd,
 693						      EXT4_B2C(sbi, start),
 694						      EXT4_B2C(sbi,
 695							       start + count
 696							       - 1));
 697			if (err)
 698				goto out;
 699		}
 700	}
 701
 702out:
 
 703	err2 = ext4_journal_stop(handle);
 704	if (err2 && !err)
 705		err = err2;
 706
 707	return err;
 708}
 709
 710/*
 711 * Iterate through the groups which hold BACKUP superblock/GDT copies in an
 712 * ext4 filesystem.  The counters should be initialized to 1, 5, and 7 before
 713 * calling this for the first time.  In a sparse filesystem it will be the
 714 * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
 715 * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
 716 */
 717static unsigned ext4_list_backups(struct super_block *sb, unsigned *three,
 718				  unsigned *five, unsigned *seven)
 719{
 720	unsigned *min = three;
 721	int mult = 3;
 722	unsigned ret;
 723
 724	if (!ext4_has_feature_sparse_super(sb)) {
 725		ret = *min;
 726		*min += 1;
 727		return ret;
 728	}
 729
 730	if (*five < *min) {
 731		min = five;
 732		mult = 5;
 733	}
 734	if (*seven < *min) {
 735		min = seven;
 736		mult = 7;
 737	}
 738
 739	ret = *min;
 740	*min *= mult;
 741
 742	return ret;
 743}
 744
 745/*
 746 * Check that all of the backup GDT blocks are held in the primary GDT block.
 747 * It is assumed that they are stored in group order.  Returns the number of
 748 * groups in current filesystem that have BACKUPS, or -ve error code.
 749 */
 750static int verify_reserved_gdb(struct super_block *sb,
 751			       ext4_group_t end,
 752			       struct buffer_head *primary)
 753{
 754	const ext4_fsblk_t blk = primary->b_blocknr;
 755	unsigned three = 1;
 756	unsigned five = 5;
 757	unsigned seven = 7;
 758	unsigned grp;
 759	__le32 *p = (__le32 *)primary->b_data;
 760	int gdbackups = 0;
 761
 762	while ((grp = ext4_list_backups(sb, &three, &five, &seven)) < end) {
 763		if (le32_to_cpu(*p++) !=
 764		    grp * EXT4_BLOCKS_PER_GROUP(sb) + blk){
 765			ext4_warning(sb, "reserved GDT %llu"
 766				     " missing grp %d (%llu)",
 767				     blk, grp,
 768				     grp *
 769				     (ext4_fsblk_t)EXT4_BLOCKS_PER_GROUP(sb) +
 770				     blk);
 771			return -EINVAL;
 772		}
 773		if (++gdbackups > EXT4_ADDR_PER_BLOCK(sb))
 774			return -EFBIG;
 775	}
 776
 777	return gdbackups;
 778}
 779
 780/*
 781 * Called when we need to bring a reserved group descriptor table block into
 782 * use from the resize inode.  The primary copy of the new GDT block currently
 783 * is an indirect block (under the double indirect block in the resize inode).
 784 * The new backup GDT blocks will be stored as leaf blocks in this indirect
 785 * block, in group order.  Even though we know all the block numbers we need,
 786 * we check to ensure that the resize inode has actually reserved these blocks.
 787 *
 788 * Don't need to update the block bitmaps because the blocks are still in use.
 789 *
 790 * We get all of the error cases out of the way, so that we are sure to not
 791 * fail once we start modifying the data on disk, because JBD has no rollback.
 792 */
 793static int add_new_gdb(handle_t *handle, struct inode *inode,
 794		       ext4_group_t group)
 795{
 796	struct super_block *sb = inode->i_sb;
 797	struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 798	unsigned long gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
 799	ext4_fsblk_t gdblock = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + gdb_num;
 800	struct buffer_head **o_group_desc, **n_group_desc = NULL;
 801	struct buffer_head *dind = NULL;
 802	struct buffer_head *gdb_bh = NULL;
 803	int gdbackups;
 804	struct ext4_iloc iloc = { .bh = NULL };
 805	__le32 *data;
 806	int err;
 807
 808	if (test_opt(sb, DEBUG))
 809		printk(KERN_DEBUG
 810		       "EXT4-fs: ext4_add_new_gdb: adding group block %lu\n",
 811		       gdb_num);
 812
 813	gdb_bh = ext4_sb_bread(sb, gdblock, 0);
 814	if (IS_ERR(gdb_bh))
 815		return PTR_ERR(gdb_bh);
 816
 817	gdbackups = verify_reserved_gdb(sb, group, gdb_bh);
 818	if (gdbackups < 0) {
 819		err = gdbackups;
 820		goto errout;
 821	}
 822
 823	data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
 824	dind = ext4_sb_bread(sb, le32_to_cpu(*data), 0);
 825	if (IS_ERR(dind)) {
 826		err = PTR_ERR(dind);
 827		dind = NULL;
 828		goto errout;
 829	}
 830
 831	data = (__le32 *)dind->b_data;
 832	if (le32_to_cpu(data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)]) != gdblock) {
 833		ext4_warning(sb, "new group %u GDT block %llu not reserved",
 834			     group, gdblock);
 835		err = -EINVAL;
 836		goto errout;
 837	}
 838
 839	BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
 840	err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
 841	if (unlikely(err))
 842		goto errout;
 843
 844	BUFFER_TRACE(gdb_bh, "get_write_access");
 845	err = ext4_journal_get_write_access(handle, gdb_bh);
 846	if (unlikely(err))
 847		goto errout;
 848
 849	BUFFER_TRACE(dind, "get_write_access");
 850	err = ext4_journal_get_write_access(handle, dind);
 851	if (unlikely(err)) {
 852		ext4_std_error(sb, err);
 853		goto errout;
 854	}
 855
 856	/* ext4_reserve_inode_write() gets a reference on the iloc */
 857	err = ext4_reserve_inode_write(handle, inode, &iloc);
 858	if (unlikely(err))
 859		goto errout;
 860
 861	n_group_desc = kvmalloc((gdb_num + 1) * sizeof(struct buffer_head *),
 862				GFP_KERNEL);
 
 863	if (!n_group_desc) {
 864		err = -ENOMEM;
 865		ext4_warning(sb, "not enough memory for %lu groups",
 866			     gdb_num + 1);
 867		goto errout;
 868	}
 869
 870	/*
 871	 * Finally, we have all of the possible failures behind us...
 872	 *
 873	 * Remove new GDT block from inode double-indirect block and clear out
 874	 * the new GDT block for use (which also "frees" the backup GDT blocks
 875	 * from the reserved inode).  We don't need to change the bitmaps for
 876	 * these blocks, because they are marked as in-use from being in the
 877	 * reserved inode, and will become GDT blocks (primary and backup).
 878	 */
 879	data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)] = 0;
 880	err = ext4_handle_dirty_metadata(handle, NULL, dind);
 881	if (unlikely(err)) {
 882		ext4_std_error(sb, err);
 883		goto errout;
 884	}
 885	inode->i_blocks -= (gdbackups + 1) * sb->s_blocksize >>
 886			   (9 - EXT4_SB(sb)->s_cluster_bits);
 887	ext4_mark_iloc_dirty(handle, inode, &iloc);
 888	memset(gdb_bh->b_data, 0, sb->s_blocksize);
 889	err = ext4_handle_dirty_metadata(handle, NULL, gdb_bh);
 890	if (unlikely(err)) {
 891		ext4_std_error(sb, err);
 892		iloc.bh = NULL;
 893		goto errout;
 894	}
 895	brelse(dind);
 896
 897	rcu_read_lock();
 898	o_group_desc = rcu_dereference(EXT4_SB(sb)->s_group_desc);
 899	memcpy(n_group_desc, o_group_desc,
 900	       EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
 901	rcu_read_unlock();
 902	n_group_desc[gdb_num] = gdb_bh;
 903	rcu_assign_pointer(EXT4_SB(sb)->s_group_desc, n_group_desc);
 904	EXT4_SB(sb)->s_gdb_count++;
 905	ext4_kvfree_array_rcu(o_group_desc);
 906
 907	lock_buffer(EXT4_SB(sb)->s_sbh);
 908	le16_add_cpu(&es->s_reserved_gdt_blocks, -1);
 909	ext4_superblock_csum_set(sb);
 910	unlock_buffer(EXT4_SB(sb)->s_sbh);
 911	err = ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
 912	if (err)
 913		ext4_std_error(sb, err);
 
 914	return err;
 915errout:
 
 916	kvfree(n_group_desc);
 917	brelse(iloc.bh);
 
 918	brelse(dind);
 
 919	brelse(gdb_bh);
 920
 921	ext4_debug("leaving with error %d\n", err);
 922	return err;
 923}
 924
 925/*
 926 * add_new_gdb_meta_bg is the sister of add_new_gdb.
 927 */
 928static int add_new_gdb_meta_bg(struct super_block *sb,
 929			       handle_t *handle, ext4_group_t group) {
 930	ext4_fsblk_t gdblock;
 931	struct buffer_head *gdb_bh;
 932	struct buffer_head **o_group_desc, **n_group_desc;
 933	unsigned long gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
 934	int err;
 935
 936	gdblock = ext4_meta_bg_first_block_no(sb, group) +
 937		   ext4_bg_has_super(sb, group);
 938	gdb_bh = ext4_sb_bread(sb, gdblock, 0);
 939	if (IS_ERR(gdb_bh))
 940		return PTR_ERR(gdb_bh);
 941	n_group_desc = kvmalloc((gdb_num + 1) * sizeof(struct buffer_head *),
 942				GFP_KERNEL);
 
 943	if (!n_group_desc) {
 944		brelse(gdb_bh);
 945		err = -ENOMEM;
 946		ext4_warning(sb, "not enough memory for %lu groups",
 947			     gdb_num + 1);
 948		return err;
 949	}
 950
 951	rcu_read_lock();
 952	o_group_desc = rcu_dereference(EXT4_SB(sb)->s_group_desc);
 953	memcpy(n_group_desc, o_group_desc,
 954	       EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
 955	rcu_read_unlock();
 956	n_group_desc[gdb_num] = gdb_bh;
 957
 
 
 958	BUFFER_TRACE(gdb_bh, "get_write_access");
 959	err = ext4_journal_get_write_access(handle, gdb_bh);
 960	if (err) {
 961		kvfree(n_group_desc);
 962		brelse(gdb_bh);
 963		return err;
 964	}
 965
 966	rcu_assign_pointer(EXT4_SB(sb)->s_group_desc, n_group_desc);
 967	EXT4_SB(sb)->s_gdb_count++;
 968	ext4_kvfree_array_rcu(o_group_desc);
 969	return err;
 970}
 971
 972/*
 973 * Called when we are adding a new group which has a backup copy of each of
 974 * the GDT blocks (i.e. sparse group) and there are reserved GDT blocks.
 975 * We need to add these reserved backup GDT blocks to the resize inode, so
 976 * that they are kept for future resizing and not allocated to files.
 977 *
 978 * Each reserved backup GDT block will go into a different indirect block.
 979 * The indirect blocks are actually the primary reserved GDT blocks,
 980 * so we know in advance what their block numbers are.  We only get the
 981 * double-indirect block to verify it is pointing to the primary reserved
 982 * GDT blocks so we don't overwrite a data block by accident.  The reserved
 983 * backup GDT blocks are stored in their reserved primary GDT block.
 984 */
 985static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
 986			      ext4_group_t group)
 987{
 988	struct super_block *sb = inode->i_sb;
 989	int reserved_gdb =le16_to_cpu(EXT4_SB(sb)->s_es->s_reserved_gdt_blocks);
 990	int cluster_bits = EXT4_SB(sb)->s_cluster_bits;
 991	struct buffer_head **primary;
 992	struct buffer_head *dind;
 993	struct ext4_iloc iloc;
 994	ext4_fsblk_t blk;
 995	__le32 *data, *end;
 996	int gdbackups = 0;
 997	int res, i;
 998	int err;
 999
1000	primary = kmalloc_array(reserved_gdb, sizeof(*primary), GFP_NOFS);
1001	if (!primary)
1002		return -ENOMEM;
1003
1004	data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
1005	dind = ext4_sb_bread(sb, le32_to_cpu(*data), 0);
1006	if (IS_ERR(dind)) {
1007		err = PTR_ERR(dind);
1008		dind = NULL;
1009		goto exit_free;
1010	}
1011
1012	blk = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + EXT4_SB(sb)->s_gdb_count;
1013	data = (__le32 *)dind->b_data + (EXT4_SB(sb)->s_gdb_count %
1014					 EXT4_ADDR_PER_BLOCK(sb));
1015	end = (__le32 *)dind->b_data + EXT4_ADDR_PER_BLOCK(sb);
1016
1017	/* Get each reserved primary GDT block and verify it holds backups */
1018	for (res = 0; res < reserved_gdb; res++, blk++) {
1019		if (le32_to_cpu(*data) != blk) {
1020			ext4_warning(sb, "reserved block %llu"
1021				     " not at offset %ld",
1022				     blk,
1023				     (long)(data - (__le32 *)dind->b_data));
1024			err = -EINVAL;
1025			goto exit_bh;
1026		}
1027		primary[res] = ext4_sb_bread(sb, blk, 0);
1028		if (IS_ERR(primary[res])) {
1029			err = PTR_ERR(primary[res]);
1030			primary[res] = NULL;
1031			goto exit_bh;
1032		}
1033		gdbackups = verify_reserved_gdb(sb, group, primary[res]);
1034		if (gdbackups < 0) {
1035			brelse(primary[res]);
1036			err = gdbackups;
1037			goto exit_bh;
1038		}
1039		if (++data >= end)
1040			data = (__le32 *)dind->b_data;
1041	}
1042
1043	for (i = 0; i < reserved_gdb; i++) {
1044		BUFFER_TRACE(primary[i], "get_write_access");
1045		if ((err = ext4_journal_get_write_access(handle, primary[i])))
1046			goto exit_bh;
1047	}
1048
1049	if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
1050		goto exit_bh;
1051
1052	/*
1053	 * Finally we can add each of the reserved backup GDT blocks from
1054	 * the new group to its reserved primary GDT block.
1055	 */
1056	blk = group * EXT4_BLOCKS_PER_GROUP(sb);
1057	for (i = 0; i < reserved_gdb; i++) {
1058		int err2;
1059		data = (__le32 *)primary[i]->b_data;
1060		/* printk("reserving backup %lu[%u] = %lu\n",
1061		       primary[i]->b_blocknr, gdbackups,
1062		       blk + primary[i]->b_blocknr); */
1063		data[gdbackups] = cpu_to_le32(blk + primary[i]->b_blocknr);
1064		err2 = ext4_handle_dirty_metadata(handle, NULL, primary[i]);
1065		if (!err)
1066			err = err2;
1067	}
1068
1069	inode->i_blocks += reserved_gdb * sb->s_blocksize >> (9 - cluster_bits);
1070	ext4_mark_iloc_dirty(handle, inode, &iloc);
1071
1072exit_bh:
1073	while (--res >= 0)
1074		brelse(primary[res]);
1075	brelse(dind);
1076
1077exit_free:
1078	kfree(primary);
1079
1080	return err;
1081}
1082
1083/*
1084 * Update the backup copies of the ext4 metadata.  These don't need to be part
1085 * of the main resize transaction, because e2fsck will re-write them if there
1086 * is a problem (basically only OOM will cause a problem).  However, we
1087 * _should_ update the backups if possible, in case the primary gets trashed
1088 * for some reason and we need to run e2fsck from a backup superblock.  The
1089 * important part is that the new block and inode counts are in the backup
1090 * superblocks, and the location of the new group metadata in the GDT backups.
1091 *
1092 * We do not need take the s_resize_lock for this, because these
1093 * blocks are not otherwise touched by the filesystem code when it is
1094 * mounted.  We don't need to worry about last changing from
1095 * sbi->s_groups_count, because the worst that can happen is that we
1096 * do not copy the full number of backups at this time.  The resize
1097 * which changed s_groups_count will backup again.
1098 */
1099static void update_backups(struct super_block *sb, sector_t blk_off, char *data,
1100			   int size, int meta_bg)
1101{
1102	struct ext4_sb_info *sbi = EXT4_SB(sb);
1103	ext4_group_t last;
1104	const int bpg = EXT4_BLOCKS_PER_GROUP(sb);
1105	unsigned three = 1;
1106	unsigned five = 5;
1107	unsigned seven = 7;
1108	ext4_group_t group = 0;
1109	int rest = sb->s_blocksize - size;
1110	handle_t *handle;
1111	int err = 0, err2;
1112
1113	handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, EXT4_MAX_TRANS_DATA);
1114	if (IS_ERR(handle)) {
1115		group = 1;
1116		err = PTR_ERR(handle);
1117		goto exit_err;
1118	}
1119
1120	if (meta_bg == 0) {
1121		group = ext4_list_backups(sb, &three, &five, &seven);
1122		last = sbi->s_groups_count;
1123	} else {
1124		group = ext4_get_group_number(sb, blk_off) + 1;
1125		last = (ext4_group_t)(group + EXT4_DESC_PER_BLOCK(sb) - 2);
1126	}
1127
1128	while (group < sbi->s_groups_count) {
1129		struct buffer_head *bh;
1130		ext4_fsblk_t backup_block;
1131
1132		/* Out of journal space, and can't get more - abort - so sad */
1133		err = ext4_resize_ensure_credits_batch(handle, 1);
1134		if (err < 0)
 
 
1135			break;
1136
1137		if (meta_bg == 0)
1138			backup_block = ((ext4_fsblk_t)group) * bpg + blk_off;
1139		else
1140			backup_block = (ext4_group_first_block_no(sb, group) +
1141					ext4_bg_has_super(sb, group));
1142
1143		bh = sb_getblk(sb, backup_block);
1144		if (unlikely(!bh)) {
1145			err = -ENOMEM;
1146			break;
1147		}
1148		ext4_debug("update metadata backup %llu(+%llu)\n",
1149			   backup_block, backup_block -
1150			   ext4_group_first_block_no(sb, group));
1151		BUFFER_TRACE(bh, "get_write_access");
1152		if ((err = ext4_journal_get_write_access(handle, bh))) {
1153			brelse(bh);
1154			break;
1155		}
1156		lock_buffer(bh);
1157		memcpy(bh->b_data, data, size);
1158		if (rest)
1159			memset(bh->b_data + size, 0, rest);
1160		set_buffer_uptodate(bh);
1161		unlock_buffer(bh);
1162		err = ext4_handle_dirty_metadata(handle, NULL, bh);
1163		if (unlikely(err))
1164			ext4_std_error(sb, err);
1165		brelse(bh);
1166
1167		if (meta_bg == 0)
1168			group = ext4_list_backups(sb, &three, &five, &seven);
1169		else if (group == last)
1170			break;
1171		else
1172			group = last;
1173	}
1174	if ((err2 = ext4_journal_stop(handle)) && !err)
1175		err = err2;
1176
1177	/*
1178	 * Ugh! Need to have e2fsck write the backup copies.  It is too
1179	 * late to revert the resize, we shouldn't fail just because of
1180	 * the backup copies (they are only needed in case of corruption).
1181	 *
1182	 * However, if we got here we have a journal problem too, so we
1183	 * can't really start a transaction to mark the superblock.
1184	 * Chicken out and just set the flag on the hope it will be written
1185	 * to disk, and if not - we will simply wait until next fsck.
1186	 */
1187exit_err:
1188	if (err) {
1189		ext4_warning(sb, "can't update backup for group %u (err %d), "
1190			     "forcing fsck on next reboot", group, err);
1191		sbi->s_mount_state &= ~EXT4_VALID_FS;
1192		sbi->s_es->s_state &= cpu_to_le16(~EXT4_VALID_FS);
1193		mark_buffer_dirty(sbi->s_sbh);
1194	}
1195}
1196
1197/*
1198 * ext4_add_new_descs() adds @count group descriptor of groups
1199 * starting at @group
1200 *
1201 * @handle: journal handle
1202 * @sb: super block
1203 * @group: the group no. of the first group desc to be added
1204 * @resize_inode: the resize inode
1205 * @count: number of group descriptors to be added
1206 */
1207static int ext4_add_new_descs(handle_t *handle, struct super_block *sb,
1208			      ext4_group_t group, struct inode *resize_inode,
1209			      ext4_group_t count)
1210{
1211	struct ext4_sb_info *sbi = EXT4_SB(sb);
1212	struct ext4_super_block *es = sbi->s_es;
1213	struct buffer_head *gdb_bh;
1214	int i, gdb_off, gdb_num, err = 0;
1215	int meta_bg;
1216
1217	meta_bg = ext4_has_feature_meta_bg(sb);
1218	for (i = 0; i < count; i++, group++) {
1219		int reserved_gdb = ext4_bg_has_super(sb, group) ?
1220			le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
1221
1222		gdb_off = group % EXT4_DESC_PER_BLOCK(sb);
1223		gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
1224
1225		/*
1226		 * We will only either add reserved group blocks to a backup group
1227		 * or remove reserved blocks for the first group in a new group block.
1228		 * Doing both would be mean more complex code, and sane people don't
1229		 * use non-sparse filesystems anymore.  This is already checked above.
1230		 */
1231		if (gdb_off) {
1232			gdb_bh = sbi_array_rcu_deref(sbi, s_group_desc,
1233						     gdb_num);
1234			BUFFER_TRACE(gdb_bh, "get_write_access");
1235			err = ext4_journal_get_write_access(handle, gdb_bh);
1236
1237			if (!err && reserved_gdb && ext4_bg_num_gdb(sb, group))
1238				err = reserve_backup_gdb(handle, resize_inode, group);
1239		} else if (meta_bg != 0) {
1240			err = add_new_gdb_meta_bg(sb, handle, group);
1241		} else {
1242			err = add_new_gdb(handle, resize_inode, group);
1243		}
1244		if (err)
1245			break;
1246	}
1247	return err;
1248}
1249
1250static struct buffer_head *ext4_get_bitmap(struct super_block *sb, __u64 block)
1251{
1252	struct buffer_head *bh = sb_getblk(sb, block);
1253	if (unlikely(!bh))
1254		return NULL;
1255	if (!bh_uptodate_or_lock(bh)) {
1256		if (ext4_read_bh(bh, 0, NULL) < 0) {
1257			brelse(bh);
1258			return NULL;
1259		}
1260	}
1261
1262	return bh;
1263}
1264
1265static int ext4_set_bitmap_checksums(struct super_block *sb,
1266				     ext4_group_t group,
1267				     struct ext4_group_desc *gdp,
1268				     struct ext4_new_group_data *group_data)
1269{
1270	struct buffer_head *bh;
1271
1272	if (!ext4_has_metadata_csum(sb))
1273		return 0;
1274
1275	bh = ext4_get_bitmap(sb, group_data->inode_bitmap);
1276	if (!bh)
1277		return -EIO;
1278	ext4_inode_bitmap_csum_set(sb, group, gdp, bh,
1279				   EXT4_INODES_PER_GROUP(sb) / 8);
1280	brelse(bh);
1281
1282	bh = ext4_get_bitmap(sb, group_data->block_bitmap);
1283	if (!bh)
1284		return -EIO;
1285	ext4_block_bitmap_csum_set(sb, group, gdp, bh);
1286	brelse(bh);
1287
1288	return 0;
1289}
1290
1291/*
1292 * ext4_setup_new_descs() will set up the group descriptor descriptors of a flex bg
1293 */
1294static int ext4_setup_new_descs(handle_t *handle, struct super_block *sb,
1295				struct ext4_new_flex_group_data *flex_gd)
1296{
1297	struct ext4_new_group_data	*group_data = flex_gd->groups;
1298	struct ext4_group_desc		*gdp;
1299	struct ext4_sb_info		*sbi = EXT4_SB(sb);
1300	struct buffer_head		*gdb_bh;
1301	ext4_group_t			group;
1302	__u16				*bg_flags = flex_gd->bg_flags;
1303	int				i, gdb_off, gdb_num, err = 0;
1304
1305
1306	for (i = 0; i < flex_gd->count; i++, group_data++, bg_flags++) {
1307		group = group_data->group;
1308
1309		gdb_off = group % EXT4_DESC_PER_BLOCK(sb);
1310		gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
1311
1312		/*
1313		 * get_write_access() has been called on gdb_bh by ext4_add_new_desc().
1314		 */
1315		gdb_bh = sbi_array_rcu_deref(sbi, s_group_desc, gdb_num);
1316		/* Update group descriptor block for new group */
1317		gdp = (struct ext4_group_desc *)(gdb_bh->b_data +
1318						 gdb_off * EXT4_DESC_SIZE(sb));
1319
1320		memset(gdp, 0, EXT4_DESC_SIZE(sb));
1321		ext4_block_bitmap_set(sb, gdp, group_data->block_bitmap);
1322		ext4_inode_bitmap_set(sb, gdp, group_data->inode_bitmap);
1323		err = ext4_set_bitmap_checksums(sb, group, gdp, group_data);
1324		if (err) {
1325			ext4_std_error(sb, err);
1326			break;
1327		}
1328
1329		ext4_inode_table_set(sb, gdp, group_data->inode_table);
1330		ext4_free_group_clusters_set(sb, gdp,
1331					     group_data->free_clusters_count);
1332		ext4_free_inodes_set(sb, gdp, EXT4_INODES_PER_GROUP(sb));
1333		if (ext4_has_group_desc_csum(sb))
1334			ext4_itable_unused_set(sb, gdp,
1335					       EXT4_INODES_PER_GROUP(sb));
1336		gdp->bg_flags = cpu_to_le16(*bg_flags);
1337		ext4_group_desc_csum_set(sb, group, gdp);
1338
1339		err = ext4_handle_dirty_metadata(handle, NULL, gdb_bh);
1340		if (unlikely(err)) {
1341			ext4_std_error(sb, err);
1342			break;
1343		}
1344
1345		/*
1346		 * We can allocate memory for mb_alloc based on the new group
1347		 * descriptor
1348		 */
1349		err = ext4_mb_add_groupinfo(sb, group, gdp);
1350		if (err)
1351			break;
1352	}
1353	return err;
1354}
1355
1356/*
1357 * ext4_update_super() updates the super block so that the newly added
1358 * groups can be seen by the filesystem.
1359 *
1360 * @sb: super block
1361 * @flex_gd: new added groups
1362 */
1363static void ext4_update_super(struct super_block *sb,
1364			     struct ext4_new_flex_group_data *flex_gd)
1365{
1366	ext4_fsblk_t blocks_count = 0;
1367	ext4_fsblk_t free_blocks = 0;
1368	ext4_fsblk_t reserved_blocks = 0;
1369	struct ext4_new_group_data *group_data = flex_gd->groups;
1370	struct ext4_sb_info *sbi = EXT4_SB(sb);
1371	struct ext4_super_block *es = sbi->s_es;
1372	int i;
1373
1374	BUG_ON(flex_gd->count == 0 || group_data == NULL);
1375	/*
1376	 * Make the new blocks and inodes valid next.  We do this before
1377	 * increasing the group count so that once the group is enabled,
1378	 * all of its blocks and inodes are already valid.
1379	 *
1380	 * We always allocate group-by-group, then block-by-block or
1381	 * inode-by-inode within a group, so enabling these
1382	 * blocks/inodes before the group is live won't actually let us
1383	 * allocate the new space yet.
1384	 */
1385	for (i = 0; i < flex_gd->count; i++) {
1386		blocks_count += group_data[i].blocks_count;
1387		free_blocks += EXT4_C2B(sbi, group_data[i].free_clusters_count);
1388	}
1389
1390	reserved_blocks = ext4_r_blocks_count(es) * 100;
1391	reserved_blocks = div64_u64(reserved_blocks, ext4_blocks_count(es));
1392	reserved_blocks *= blocks_count;
1393	do_div(reserved_blocks, 100);
1394
1395	lock_buffer(sbi->s_sbh);
1396	ext4_blocks_count_set(es, ext4_blocks_count(es) + blocks_count);
1397	ext4_free_blocks_count_set(es, ext4_free_blocks_count(es) + free_blocks);
1398	le32_add_cpu(&es->s_inodes_count, EXT4_INODES_PER_GROUP(sb) *
1399		     flex_gd->count);
1400	le32_add_cpu(&es->s_free_inodes_count, EXT4_INODES_PER_GROUP(sb) *
1401		     flex_gd->count);
1402
1403	ext4_debug("free blocks count %llu", ext4_free_blocks_count(es));
1404	/*
1405	 * We need to protect s_groups_count against other CPUs seeing
1406	 * inconsistent state in the superblock.
1407	 *
1408	 * The precise rules we use are:
1409	 *
1410	 * * Writers must perform a smp_wmb() after updating all
1411	 *   dependent data and before modifying the groups count
1412	 *
1413	 * * Readers must perform an smp_rmb() after reading the groups
1414	 *   count and before reading any dependent data.
1415	 *
1416	 * NB. These rules can be relaxed when checking the group count
1417	 * while freeing data, as we can only allocate from a block
1418	 * group after serialising against the group count, and we can
1419	 * only then free after serialising in turn against that
1420	 * allocation.
1421	 */
1422	smp_wmb();
1423
1424	/* Update the global fs size fields */
1425	sbi->s_groups_count += flex_gd->count;
1426	sbi->s_blockfile_groups = min_t(ext4_group_t, sbi->s_groups_count,
1427			(EXT4_MAX_BLOCK_FILE_PHYS / EXT4_BLOCKS_PER_GROUP(sb)));
1428
1429	/* Update the reserved block counts only once the new group is
1430	 * active. */
1431	ext4_r_blocks_count_set(es, ext4_r_blocks_count(es) +
1432				reserved_blocks);
1433	ext4_superblock_csum_set(sb);
1434	unlock_buffer(sbi->s_sbh);
1435
1436	/* Update the free space counts */
1437	percpu_counter_add(&sbi->s_freeclusters_counter,
1438			   EXT4_NUM_B2C(sbi, free_blocks));
1439	percpu_counter_add(&sbi->s_freeinodes_counter,
1440			   EXT4_INODES_PER_GROUP(sb) * flex_gd->count);
1441
1442	ext4_debug("free blocks count %llu",
1443		   percpu_counter_read(&sbi->s_freeclusters_counter));
1444	if (ext4_has_feature_flex_bg(sb) && sbi->s_log_groups_per_flex) {
1445		ext4_group_t flex_group;
1446		struct flex_groups *fg;
1447
1448		flex_group = ext4_flex_group(sbi, group_data[0].group);
1449		fg = sbi_array_rcu_deref(sbi, s_flex_groups, flex_group);
1450		atomic64_add(EXT4_NUM_B2C(sbi, free_blocks),
1451			     &fg->free_clusters);
1452		atomic_add(EXT4_INODES_PER_GROUP(sb) * flex_gd->count,
1453			   &fg->free_inodes);
1454	}
1455
1456	/*
1457	 * Update the fs overhead information
1458	 */
1459	ext4_calculate_overhead(sb);
1460
1461	if (test_opt(sb, DEBUG))
1462		printk(KERN_DEBUG "EXT4-fs: added group %u:"
1463		       "%llu blocks(%llu free %llu reserved)\n", flex_gd->count,
1464		       blocks_count, free_blocks, reserved_blocks);
1465}
1466
1467/* Add a flex group to an fs. Ensure we handle all possible error conditions
1468 * _before_ we start modifying the filesystem, because we cannot abort the
1469 * transaction and not have it write the data to disk.
1470 */
1471static int ext4_flex_group_add(struct super_block *sb,
1472			       struct inode *resize_inode,
1473			       struct ext4_new_flex_group_data *flex_gd)
1474{
1475	struct ext4_sb_info *sbi = EXT4_SB(sb);
1476	struct ext4_super_block *es = sbi->s_es;
1477	ext4_fsblk_t o_blocks_count;
1478	ext4_grpblk_t last;
1479	ext4_group_t group;
1480	handle_t *handle;
1481	unsigned reserved_gdb;
1482	int err = 0, err2 = 0, credit;
1483
1484	BUG_ON(!flex_gd->count || !flex_gd->groups || !flex_gd->bg_flags);
1485
1486	reserved_gdb = le16_to_cpu(es->s_reserved_gdt_blocks);
1487	o_blocks_count = ext4_blocks_count(es);
1488	ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
1489	BUG_ON(last);
1490
1491	err = setup_new_flex_group_blocks(sb, flex_gd);
1492	if (err)
1493		goto exit;
1494	/*
1495	 * We will always be modifying at least the superblock and  GDT
1496	 * blocks.  If we are adding a group past the last current GDT block,
1497	 * we will also modify the inode and the dindirect block.  If we
1498	 * are adding a group with superblock/GDT backups  we will also
1499	 * modify each of the reserved GDT dindirect blocks.
1500	 */
1501	credit = 3;	/* sb, resize inode, resize inode dindirect */
1502	/* GDT blocks */
1503	credit += 1 + DIV_ROUND_UP(flex_gd->count, EXT4_DESC_PER_BLOCK(sb));
1504	credit += reserved_gdb;	/* Reserved GDT dindirect blocks */
1505	handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, credit);
1506	if (IS_ERR(handle)) {
1507		err = PTR_ERR(handle);
1508		goto exit;
1509	}
1510
1511	BUFFER_TRACE(sbi->s_sbh, "get_write_access");
1512	err = ext4_journal_get_write_access(handle, sbi->s_sbh);
1513	if (err)
1514		goto exit_journal;
1515
1516	group = flex_gd->groups[0].group;
1517	BUG_ON(group != sbi->s_groups_count);
1518	err = ext4_add_new_descs(handle, sb, group,
1519				resize_inode, flex_gd->count);
1520	if (err)
1521		goto exit_journal;
1522
1523	err = ext4_setup_new_descs(handle, sb, flex_gd);
1524	if (err)
1525		goto exit_journal;
1526
1527	ext4_update_super(sb, flex_gd);
1528
1529	err = ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);
1530
1531exit_journal:
1532	err2 = ext4_journal_stop(handle);
1533	if (!err)
1534		err = err2;
1535
1536	if (!err) {
1537		int gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
1538		int gdb_num_end = ((group + flex_gd->count - 1) /
1539				   EXT4_DESC_PER_BLOCK(sb));
1540		int meta_bg = ext4_has_feature_meta_bg(sb);
1541		sector_t old_gdb = 0;
1542
1543		update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
1544			       sizeof(struct ext4_super_block), 0);
1545		for (; gdb_num <= gdb_num_end; gdb_num++) {
1546			struct buffer_head *gdb_bh;
1547
1548			gdb_bh = sbi_array_rcu_deref(sbi, s_group_desc,
1549						     gdb_num);
1550			if (old_gdb == gdb_bh->b_blocknr)
1551				continue;
1552			update_backups(sb, gdb_bh->b_blocknr, gdb_bh->b_data,
1553				       gdb_bh->b_size, meta_bg);
1554			old_gdb = gdb_bh->b_blocknr;
1555		}
1556	}
1557exit:
1558	return err;
1559}
1560
1561static int ext4_setup_next_flex_gd(struct super_block *sb,
1562				    struct ext4_new_flex_group_data *flex_gd,
1563				    ext4_fsblk_t n_blocks_count,
1564				    unsigned long flexbg_size)
1565{
1566	struct ext4_sb_info *sbi = EXT4_SB(sb);
1567	struct ext4_super_block *es = sbi->s_es;
1568	struct ext4_new_group_data *group_data = flex_gd->groups;
1569	ext4_fsblk_t o_blocks_count;
1570	ext4_group_t n_group;
1571	ext4_group_t group;
1572	ext4_group_t last_group;
1573	ext4_grpblk_t last;
1574	ext4_grpblk_t clusters_per_group;
1575	unsigned long i;
1576
1577	clusters_per_group = EXT4_CLUSTERS_PER_GROUP(sb);
1578
1579	o_blocks_count = ext4_blocks_count(es);
1580
1581	if (o_blocks_count == n_blocks_count)
1582		return 0;
1583
1584	ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
1585	BUG_ON(last);
1586	ext4_get_group_no_and_offset(sb, n_blocks_count - 1, &n_group, &last);
1587
1588	last_group = group | (flexbg_size - 1);
1589	if (last_group > n_group)
1590		last_group = n_group;
1591
1592	flex_gd->count = last_group - group + 1;
1593
1594	for (i = 0; i < flex_gd->count; i++) {
1595		int overhead;
1596
1597		group_data[i].group = group + i;
1598		group_data[i].blocks_count = EXT4_BLOCKS_PER_GROUP(sb);
1599		overhead = ext4_group_overhead_blocks(sb, group + i);
1600		group_data[i].mdata_blocks = overhead;
1601		group_data[i].free_clusters_count = EXT4_CLUSTERS_PER_GROUP(sb);
1602		if (ext4_has_group_desc_csum(sb)) {
1603			flex_gd->bg_flags[i] = EXT4_BG_BLOCK_UNINIT |
1604					       EXT4_BG_INODE_UNINIT;
1605			if (!test_opt(sb, INIT_INODE_TABLE))
1606				flex_gd->bg_flags[i] |= EXT4_BG_INODE_ZEROED;
1607		} else
1608			flex_gd->bg_flags[i] = EXT4_BG_INODE_ZEROED;
1609	}
1610
1611	if (last_group == n_group && ext4_has_group_desc_csum(sb))
1612		/* We need to initialize block bitmap of last group. */
1613		flex_gd->bg_flags[i - 1] &= ~EXT4_BG_BLOCK_UNINIT;
1614
1615	if ((last_group == n_group) && (last != clusters_per_group - 1)) {
1616		group_data[i - 1].blocks_count = EXT4_C2B(sbi, last + 1);
1617		group_data[i - 1].free_clusters_count -= clusters_per_group -
1618						       last - 1;
1619	}
1620
1621	return 1;
1622}
1623
1624/* Add group descriptor data to an existing or new group descriptor block.
1625 * Ensure we handle all possible error conditions _before_ we start modifying
1626 * the filesystem, because we cannot abort the transaction and not have it
1627 * write the data to disk.
1628 *
1629 * If we are on a GDT block boundary, we need to get the reserved GDT block.
1630 * Otherwise, we may need to add backup GDT blocks for a sparse group.
1631 *
1632 * We only need to hold the superblock lock while we are actually adding
1633 * in the new group's counts to the superblock.  Prior to that we have
1634 * not really "added" the group at all.  We re-check that we are still
1635 * adding in the last group in case things have changed since verifying.
1636 */
1637int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
1638{
1639	struct ext4_new_flex_group_data flex_gd;
1640	struct ext4_sb_info *sbi = EXT4_SB(sb);
1641	struct ext4_super_block *es = sbi->s_es;
1642	int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
1643		le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
1644	struct inode *inode = NULL;
1645	int gdb_off;
1646	int err;
1647	__u16 bg_flags = 0;
1648
1649	gdb_off = input->group % EXT4_DESC_PER_BLOCK(sb);
1650
1651	if (gdb_off == 0 && !ext4_has_feature_sparse_super(sb)) {
1652		ext4_warning(sb, "Can't resize non-sparse filesystem further");
1653		return -EPERM;
1654	}
1655
1656	if (ext4_blocks_count(es) + input->blocks_count <
1657	    ext4_blocks_count(es)) {
1658		ext4_warning(sb, "blocks_count overflow");
1659		return -EINVAL;
1660	}
1661
1662	if (le32_to_cpu(es->s_inodes_count) + EXT4_INODES_PER_GROUP(sb) <
1663	    le32_to_cpu(es->s_inodes_count)) {
1664		ext4_warning(sb, "inodes_count overflow");
1665		return -EINVAL;
1666	}
1667
1668	if (reserved_gdb || gdb_off == 0) {
1669		if (!ext4_has_feature_resize_inode(sb) ||
1670		    !le16_to_cpu(es->s_reserved_gdt_blocks)) {
1671			ext4_warning(sb,
1672				     "No reserved GDT blocks, can't resize");
1673			return -EPERM;
1674		}
1675		inode = ext4_iget(sb, EXT4_RESIZE_INO, EXT4_IGET_SPECIAL);
1676		if (IS_ERR(inode)) {
1677			ext4_warning(sb, "Error opening resize inode");
1678			return PTR_ERR(inode);
1679		}
1680	}
1681
1682
1683	err = verify_group_input(sb, input);
1684	if (err)
1685		goto out;
1686
1687	err = ext4_alloc_flex_bg_array(sb, input->group + 1);
1688	if (err)
1689		goto out;
1690
1691	err = ext4_mb_alloc_groupinfo(sb, input->group + 1);
1692	if (err)
1693		goto out;
1694
1695	flex_gd.count = 1;
1696	flex_gd.groups = input;
1697	flex_gd.bg_flags = &bg_flags;
1698	err = ext4_flex_group_add(sb, inode, &flex_gd);
1699out:
1700	iput(inode);
1701	return err;
1702} /* ext4_group_add */
1703
1704/*
1705 * extend a group without checking assuming that checking has been done.
1706 */
1707static int ext4_group_extend_no_check(struct super_block *sb,
1708				      ext4_fsblk_t o_blocks_count, ext4_grpblk_t add)
1709{
1710	struct ext4_super_block *es = EXT4_SB(sb)->s_es;
1711	handle_t *handle;
1712	int err = 0, err2;
1713
1714	/* We will update the superblock, one block bitmap, and
1715	 * one group descriptor via ext4_group_add_blocks().
1716	 */
1717	handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, 3);
1718	if (IS_ERR(handle)) {
1719		err = PTR_ERR(handle);
1720		ext4_warning(sb, "error %d on journal start", err);
1721		return err;
1722	}
1723
1724	BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
1725	err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
1726	if (err) {
1727		ext4_warning(sb, "error %d on journal write access", err);
1728		goto errout;
1729	}
1730
1731	lock_buffer(EXT4_SB(sb)->s_sbh);
1732	ext4_blocks_count_set(es, o_blocks_count + add);
1733	ext4_free_blocks_count_set(es, ext4_free_blocks_count(es) + add);
1734	ext4_superblock_csum_set(sb);
1735	unlock_buffer(EXT4_SB(sb)->s_sbh);
1736	ext4_debug("freeing blocks %llu through %llu\n", o_blocks_count,
1737		   o_blocks_count + add);
1738	/* We add the blocks to the bitmap and set the group need init bit */
1739	err = ext4_group_add_blocks(handle, sb, o_blocks_count, add);
1740	if (err)
1741		goto errout;
1742	ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
1743	ext4_debug("freed blocks %llu through %llu\n", o_blocks_count,
1744		   o_blocks_count + add);
1745errout:
1746	err2 = ext4_journal_stop(handle);
1747	if (err2 && !err)
1748		err = err2;
1749
1750	if (!err) {
1751		if (test_opt(sb, DEBUG))
1752			printk(KERN_DEBUG "EXT4-fs: extended group to %llu "
1753			       "blocks\n", ext4_blocks_count(es));
1754		update_backups(sb, EXT4_SB(sb)->s_sbh->b_blocknr,
1755			       (char *)es, sizeof(struct ext4_super_block), 0);
1756	}
1757	return err;
1758}
1759
1760/*
1761 * Extend the filesystem to the new number of blocks specified.  This entry
1762 * point is only used to extend the current filesystem to the end of the last
1763 * existing group.  It can be accessed via ioctl, or by "remount,resize=<size>"
1764 * for emergencies (because it has no dependencies on reserved blocks).
1765 *
1766 * If we _really_ wanted, we could use default values to call ext4_group_add()
1767 * allow the "remount" trick to work for arbitrary resizing, assuming enough
1768 * GDT blocks are reserved to grow to the desired size.
1769 */
1770int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
1771		      ext4_fsblk_t n_blocks_count)
1772{
1773	ext4_fsblk_t o_blocks_count;
1774	ext4_grpblk_t last;
1775	ext4_grpblk_t add;
1776	struct buffer_head *bh;
1777	int err;
1778	ext4_group_t group;
1779
1780	o_blocks_count = ext4_blocks_count(es);
1781
1782	if (test_opt(sb, DEBUG))
1783		ext4_msg(sb, KERN_DEBUG,
1784			 "extending last group from %llu to %llu blocks",
1785			 o_blocks_count, n_blocks_count);
1786
1787	if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
1788		return 0;
1789
1790	if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
1791		ext4_msg(sb, KERN_ERR,
1792			 "filesystem too large to resize to %llu blocks safely",
1793			 n_blocks_count);
 
 
1794		return -EINVAL;
1795	}
1796
1797	if (n_blocks_count < o_blocks_count) {
1798		ext4_warning(sb, "can't shrink FS - resize aborted");
1799		return -EINVAL;
1800	}
1801
1802	/* Handle the remaining blocks in the last group only. */
1803	ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
1804
1805	if (last == 0) {
1806		ext4_warning(sb, "need to use ext2online to resize further");
1807		return -EPERM;
1808	}
1809
1810	add = EXT4_BLOCKS_PER_GROUP(sb) - last;
1811
1812	if (o_blocks_count + add < o_blocks_count) {
1813		ext4_warning(sb, "blocks_count overflow");
1814		return -EINVAL;
1815	}
1816
1817	if (o_blocks_count + add > n_blocks_count)
1818		add = n_blocks_count - o_blocks_count;
1819
1820	if (o_blocks_count + add < n_blocks_count)
1821		ext4_warning(sb, "will only finish group (%llu blocks, %u new)",
1822			     o_blocks_count + add, add);
1823
1824	/* See if the device is actually as big as what was requested */
1825	bh = ext4_sb_bread(sb, o_blocks_count + add - 1, 0);
1826	if (IS_ERR(bh)) {
1827		ext4_warning(sb, "can't read last block, resize aborted");
1828		return -ENOSPC;
1829	}
1830	brelse(bh);
1831
1832	err = ext4_group_extend_no_check(sb, o_blocks_count, add);
1833	return err;
1834} /* ext4_group_extend */
1835
1836
1837static int num_desc_blocks(struct super_block *sb, ext4_group_t groups)
1838{
1839	return (groups + EXT4_DESC_PER_BLOCK(sb) - 1) / EXT4_DESC_PER_BLOCK(sb);
1840}
1841
1842/*
1843 * Release the resize inode and drop the resize_inode feature if there
1844 * are no more reserved gdt blocks, and then convert the file system
1845 * to enable meta_bg
1846 */
1847static int ext4_convert_meta_bg(struct super_block *sb, struct inode *inode)
1848{
1849	handle_t *handle;
1850	struct ext4_sb_info *sbi = EXT4_SB(sb);
1851	struct ext4_super_block *es = sbi->s_es;
1852	struct ext4_inode_info *ei = EXT4_I(inode);
1853	ext4_fsblk_t nr;
1854	int i, ret, err = 0;
1855	int credits = 1;
1856
1857	ext4_msg(sb, KERN_INFO, "Converting file system to meta_bg");
1858	if (inode) {
1859		if (es->s_reserved_gdt_blocks) {
1860			ext4_error(sb, "Unexpected non-zero "
1861				   "s_reserved_gdt_blocks");
1862			return -EPERM;
1863		}
1864
1865		/* Do a quick sanity check of the resize inode */
1866		if (inode->i_blocks != 1 << (inode->i_blkbits -
1867					     (9 - sbi->s_cluster_bits)))
1868			goto invalid_resize_inode;
1869		for (i = 0; i < EXT4_N_BLOCKS; i++) {
1870			if (i == EXT4_DIND_BLOCK) {
1871				if (ei->i_data[i])
1872					continue;
1873				else
1874					goto invalid_resize_inode;
1875			}
1876			if (ei->i_data[i])
1877				goto invalid_resize_inode;
1878		}
1879		credits += 3;	/* block bitmap, bg descriptor, resize inode */
1880	}
1881
1882	handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, credits);
1883	if (IS_ERR(handle))
1884		return PTR_ERR(handle);
1885
1886	BUFFER_TRACE(sbi->s_sbh, "get_write_access");
1887	err = ext4_journal_get_write_access(handle, sbi->s_sbh);
1888	if (err)
1889		goto errout;
1890
1891	lock_buffer(sbi->s_sbh);
1892	ext4_clear_feature_resize_inode(sb);
1893	ext4_set_feature_meta_bg(sb);
1894	sbi->s_es->s_first_meta_bg =
1895		cpu_to_le32(num_desc_blocks(sb, sbi->s_groups_count));
1896	ext4_superblock_csum_set(sb);
1897	unlock_buffer(sbi->s_sbh);
1898
1899	err = ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);
1900	if (err) {
1901		ext4_std_error(sb, err);
1902		goto errout;
1903	}
1904
1905	if (inode) {
1906		nr = le32_to_cpu(ei->i_data[EXT4_DIND_BLOCK]);
1907		ext4_free_blocks(handle, inode, NULL, nr, 1,
1908				 EXT4_FREE_BLOCKS_METADATA |
1909				 EXT4_FREE_BLOCKS_FORGET);
1910		ei->i_data[EXT4_DIND_BLOCK] = 0;
1911		inode->i_blocks = 0;
1912
1913		err = ext4_mark_inode_dirty(handle, inode);
1914		if (err)
1915			ext4_std_error(sb, err);
1916	}
1917
1918errout:
1919	ret = ext4_journal_stop(handle);
1920	if (!err)
1921		err = ret;
1922	return ret;
1923
1924invalid_resize_inode:
1925	ext4_error(sb, "corrupted/inconsistent resize inode");
1926	return -EINVAL;
1927}
1928
1929/*
1930 * ext4_resize_fs() resizes a fs to new size specified by @n_blocks_count
1931 *
1932 * @sb: super block of the fs to be resized
1933 * @n_blocks_count: the number of blocks resides in the resized fs
1934 */
1935int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
1936{
1937	struct ext4_new_flex_group_data *flex_gd = NULL;
1938	struct ext4_sb_info *sbi = EXT4_SB(sb);
1939	struct ext4_super_block *es = sbi->s_es;
1940	struct buffer_head *bh;
1941	struct inode *resize_inode = NULL;
1942	ext4_grpblk_t add, offset;
1943	unsigned long n_desc_blocks;
1944	unsigned long o_desc_blocks;
1945	ext4_group_t o_group;
1946	ext4_group_t n_group;
1947	ext4_fsblk_t o_blocks_count;
1948	ext4_fsblk_t n_blocks_count_retry = 0;
1949	unsigned long last_update_time = 0;
1950	int err = 0, flexbg_size = 1 << sbi->s_log_groups_per_flex;
1951	int meta_bg;
1952
1953	/* See if the device is actually as big as what was requested */
1954	bh = ext4_sb_bread(sb, n_blocks_count - 1, 0);
1955	if (IS_ERR(bh)) {
1956		ext4_warning(sb, "can't read last block, resize aborted");
1957		return -ENOSPC;
1958	}
1959	brelse(bh);
1960
1961retry:
1962	o_blocks_count = ext4_blocks_count(es);
1963
1964	ext4_msg(sb, KERN_INFO, "resizing filesystem from %llu "
1965		 "to %llu blocks", o_blocks_count, n_blocks_count);
1966
1967	if (n_blocks_count < o_blocks_count) {
1968		/* On-line shrinking not supported */
1969		ext4_warning(sb, "can't shrink FS - resize aborted");
1970		return -EINVAL;
1971	}
1972
1973	if (n_blocks_count == o_blocks_count)
1974		/* Nothing need to do */
1975		return 0;
1976
1977	n_group = ext4_get_group_number(sb, n_blocks_count - 1);
1978	if (n_group >= (0xFFFFFFFFUL / EXT4_INODES_PER_GROUP(sb))) {
1979		ext4_warning(sb, "resize would cause inodes_count overflow");
1980		return -EINVAL;
1981	}
1982	ext4_get_group_no_and_offset(sb, o_blocks_count - 1, &o_group, &offset);
1983
1984	n_desc_blocks = num_desc_blocks(sb, n_group + 1);
1985	o_desc_blocks = num_desc_blocks(sb, sbi->s_groups_count);
1986
1987	meta_bg = ext4_has_feature_meta_bg(sb);
1988
1989	if (ext4_has_feature_resize_inode(sb)) {
1990		if (meta_bg) {
1991			ext4_error(sb, "resize_inode and meta_bg enabled "
1992				   "simultaneously");
1993			return -EINVAL;
1994		}
1995		if (n_desc_blocks > o_desc_blocks +
1996		    le16_to_cpu(es->s_reserved_gdt_blocks)) {
1997			n_blocks_count_retry = n_blocks_count;
1998			n_desc_blocks = o_desc_blocks +
1999				le16_to_cpu(es->s_reserved_gdt_blocks);
2000			n_group = n_desc_blocks * EXT4_DESC_PER_BLOCK(sb);
2001			n_blocks_count = (ext4_fsblk_t)n_group *
2002				EXT4_BLOCKS_PER_GROUP(sb) +
2003				le32_to_cpu(es->s_first_data_block);
2004			n_group--; /* set to last group number */
2005		}
2006
2007		if (!resize_inode)
2008			resize_inode = ext4_iget(sb, EXT4_RESIZE_INO,
2009						 EXT4_IGET_SPECIAL);
2010		if (IS_ERR(resize_inode)) {
2011			ext4_warning(sb, "Error opening resize inode");
2012			return PTR_ERR(resize_inode);
2013		}
2014	}
2015
2016	if ((!resize_inode && !meta_bg) || n_blocks_count == o_blocks_count) {
2017		err = ext4_convert_meta_bg(sb, resize_inode);
2018		if (err)
2019			goto out;
2020		if (resize_inode) {
2021			iput(resize_inode);
2022			resize_inode = NULL;
2023		}
2024		if (n_blocks_count_retry) {
2025			n_blocks_count = n_blocks_count_retry;
2026			n_blocks_count_retry = 0;
2027			goto retry;
2028		}
2029	}
2030
2031	/*
2032	 * Make sure the last group has enough space so that it's
2033	 * guaranteed to have enough space for all metadata blocks
2034	 * that it might need to hold.  (We might not need to store
2035	 * the inode table blocks in the last block group, but there
2036	 * will be cases where this might be needed.)
2037	 */
2038	if ((ext4_group_first_block_no(sb, n_group) +
2039	     ext4_group_overhead_blocks(sb, n_group) + 2 +
2040	     sbi->s_itb_per_group + sbi->s_cluster_ratio) >= n_blocks_count) {
2041		n_blocks_count = ext4_group_first_block_no(sb, n_group);
2042		n_group--;
2043		n_blocks_count_retry = 0;
2044		if (resize_inode) {
2045			iput(resize_inode);
2046			resize_inode = NULL;
2047		}
2048		goto retry;
2049	}
2050
2051	/* extend the last group */
2052	if (n_group == o_group)
2053		add = n_blocks_count - o_blocks_count;
2054	else
2055		add = EXT4_C2B(sbi, EXT4_CLUSTERS_PER_GROUP(sb) - (offset + 1));
2056	if (add > 0) {
2057		err = ext4_group_extend_no_check(sb, o_blocks_count, add);
2058		if (err)
2059			goto out;
2060	}
2061
2062	if (ext4_blocks_count(es) == n_blocks_count)
2063		goto out;
2064
2065	err = ext4_alloc_flex_bg_array(sb, n_group + 1);
2066	if (err)
2067		goto out;
2068
2069	err = ext4_mb_alloc_groupinfo(sb, n_group + 1);
2070	if (err)
2071		goto out;
2072
2073	flex_gd = alloc_flex_gd(flexbg_size);
2074	if (flex_gd == NULL) {
2075		err = -ENOMEM;
2076		goto out;
2077	}
2078
2079	/* Add flex groups. Note that a regular group is a
2080	 * flex group with 1 group.
2081	 */
2082	while (ext4_setup_next_flex_gd(sb, flex_gd, n_blocks_count,
2083					      flexbg_size)) {
2084		if (jiffies - last_update_time > HZ * 10) {
2085			if (last_update_time)
2086				ext4_msg(sb, KERN_INFO,
2087					 "resized to %llu blocks",
2088					 ext4_blocks_count(es));
2089			last_update_time = jiffies;
2090		}
2091		if (ext4_alloc_group_tables(sb, flex_gd, flexbg_size) != 0)
2092			break;
2093		err = ext4_flex_group_add(sb, resize_inode, flex_gd);
2094		if (unlikely(err))
2095			break;
2096	}
2097
2098	if (!err && n_blocks_count_retry) {
2099		n_blocks_count = n_blocks_count_retry;
2100		n_blocks_count_retry = 0;
2101		free_flex_gd(flex_gd);
2102		flex_gd = NULL;
2103		if (resize_inode) {
2104			iput(resize_inode);
2105			resize_inode = NULL;
2106		}
2107		goto retry;
2108	}
2109
2110out:
2111	if (flex_gd)
2112		free_flex_gd(flex_gd);
2113	if (resize_inode != NULL)
2114		iput(resize_inode);
2115	if (err)
2116		ext4_warning(sb, "error (%d) occurred during "
2117			     "file system resize", err);
2118	ext4_msg(sb, KERN_INFO, "resized filesystem to %llu",
2119		 ext4_blocks_count(es));
2120	return err;
2121}