xref: /openbmc/linux/fs/ext4/resize.c (revision abfbd895)
1 /*
2  *  linux/fs/ext4/resize.c
3  *
4  * Support for resizing an ext4 filesystem while it is mounted.
5  *
6  * Copyright (C) 2001, 2002 Andreas Dilger <adilger@clusterfs.com>
7  *
8  * This could probably be made into a module, because it is not often in use.
9  */
10 
11 
12 #define EXT4FS_DEBUG
13 
14 #include <linux/errno.h>
15 #include <linux/slab.h>
16 
17 #include "ext4_jbd2.h"
18 
19 int ext4_resize_begin(struct super_block *sb)
20 {
21 	int ret = 0;
22 
23 	if (!capable(CAP_SYS_RESOURCE))
24 		return -EPERM;
25 
26 	/*
27 	 * If we are not using the primary superblock/GDT copy don't resize,
28          * because the user tools have no way of handling this.  Probably a
29          * bad time to do it anyways.
30          */
31 	if (EXT4_SB(sb)->s_sbh->b_blocknr !=
32 	    le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) {
33 		ext4_warning(sb, "won't resize using backup superblock at %llu",
34 			(unsigned long long)EXT4_SB(sb)->s_sbh->b_blocknr);
35 		return -EPERM;
36 	}
37 
38 	/*
39 	 * We are not allowed to do online-resizing on a filesystem mounted
40 	 * with error, because it can destroy the filesystem easily.
41 	 */
42 	if (EXT4_SB(sb)->s_mount_state & EXT4_ERROR_FS) {
43 		ext4_warning(sb, "There are errors in the filesystem, "
44 			     "so online resizing is not allowed\n");
45 		return -EPERM;
46 	}
47 
48 	if (test_and_set_bit_lock(EXT4_RESIZING, &EXT4_SB(sb)->s_resize_flags))
49 		ret = -EBUSY;
50 
51 	return ret;
52 }
53 
54 void ext4_resize_end(struct super_block *sb)
55 {
56 	clear_bit_unlock(EXT4_RESIZING, &EXT4_SB(sb)->s_resize_flags);
57 	smp_mb__after_atomic();
58 }
59 
60 static ext4_group_t ext4_meta_bg_first_group(struct super_block *sb,
61 					     ext4_group_t group) {
62 	return (group >> EXT4_DESC_PER_BLOCK_BITS(sb)) <<
63 	       EXT4_DESC_PER_BLOCK_BITS(sb);
64 }
65 
66 static ext4_fsblk_t ext4_meta_bg_first_block_no(struct super_block *sb,
67 					     ext4_group_t group) {
68 	group = ext4_meta_bg_first_group(sb, group);
69 	return ext4_group_first_block_no(sb, group);
70 }
71 
72 static ext4_grpblk_t ext4_group_overhead_blocks(struct super_block *sb,
73 						ext4_group_t group) {
74 	ext4_grpblk_t overhead;
75 	overhead = ext4_bg_num_gdb(sb, group);
76 	if (ext4_bg_has_super(sb, group))
77 		overhead += 1 +
78 			  le16_to_cpu(EXT4_SB(sb)->s_es->s_reserved_gdt_blocks);
79 	return overhead;
80 }
81 
82 #define outside(b, first, last)	((b) < (first) || (b) >= (last))
83 #define inside(b, first, last)	((b) >= (first) && (b) < (last))
84 
85 static int verify_group_input(struct super_block *sb,
86 			      struct ext4_new_group_data *input)
87 {
88 	struct ext4_sb_info *sbi = EXT4_SB(sb);
89 	struct ext4_super_block *es = sbi->s_es;
90 	ext4_fsblk_t start = ext4_blocks_count(es);
91 	ext4_fsblk_t end = start + input->blocks_count;
92 	ext4_group_t group = input->group;
93 	ext4_fsblk_t itend = input->inode_table + sbi->s_itb_per_group;
94 	unsigned overhead;
95 	ext4_fsblk_t metaend;
96 	struct buffer_head *bh = NULL;
97 	ext4_grpblk_t free_blocks_count, offset;
98 	int err = -EINVAL;
99 
100 	if (group != sbi->s_groups_count) {
101 		ext4_warning(sb, "Cannot add at group %u (only %u groups)",
102 			     input->group, sbi->s_groups_count);
103 		return -EINVAL;
104 	}
105 
106 	overhead = ext4_group_overhead_blocks(sb, group);
107 	metaend = start + overhead;
108 	input->free_blocks_count = free_blocks_count =
109 		input->blocks_count - 2 - overhead - sbi->s_itb_per_group;
110 
111 	if (test_opt(sb, DEBUG))
112 		printk(KERN_DEBUG "EXT4-fs: adding %s group %u: %u blocks "
113 		       "(%d free, %u reserved)\n",
114 		       ext4_bg_has_super(sb, input->group) ? "normal" :
115 		       "no-super", input->group, input->blocks_count,
116 		       free_blocks_count, input->reserved_blocks);
117 
118 	ext4_get_group_no_and_offset(sb, start, NULL, &offset);
119 	if (offset != 0)
120 			ext4_warning(sb, "Last group not full");
121 	else if (input->reserved_blocks > input->blocks_count / 5)
122 		ext4_warning(sb, "Reserved blocks too high (%u)",
123 			     input->reserved_blocks);
124 	else if (free_blocks_count < 0)
125 		ext4_warning(sb, "Bad blocks count %u",
126 			     input->blocks_count);
127 	else if (!(bh = sb_bread(sb, end - 1)))
128 		ext4_warning(sb, "Cannot read last block (%llu)",
129 			     end - 1);
130 	else if (outside(input->block_bitmap, start, end))
131 		ext4_warning(sb, "Block bitmap not in group (block %llu)",
132 			     (unsigned long long)input->block_bitmap);
133 	else if (outside(input->inode_bitmap, start, end))
134 		ext4_warning(sb, "Inode bitmap not in group (block %llu)",
135 			     (unsigned long long)input->inode_bitmap);
136 	else if (outside(input->inode_table, start, end) ||
137 		 outside(itend - 1, start, end))
138 		ext4_warning(sb, "Inode table not in group (blocks %llu-%llu)",
139 			     (unsigned long long)input->inode_table, itend - 1);
140 	else if (input->inode_bitmap == input->block_bitmap)
141 		ext4_warning(sb, "Block bitmap same as inode bitmap (%llu)",
142 			     (unsigned long long)input->block_bitmap);
143 	else if (inside(input->block_bitmap, input->inode_table, itend))
144 		ext4_warning(sb, "Block bitmap (%llu) in inode table "
145 			     "(%llu-%llu)",
146 			     (unsigned long long)input->block_bitmap,
147 			     (unsigned long long)input->inode_table, itend - 1);
148 	else if (inside(input->inode_bitmap, input->inode_table, itend))
149 		ext4_warning(sb, "Inode bitmap (%llu) in inode table "
150 			     "(%llu-%llu)",
151 			     (unsigned long long)input->inode_bitmap,
152 			     (unsigned long long)input->inode_table, itend - 1);
153 	else if (inside(input->block_bitmap, start, metaend))
154 		ext4_warning(sb, "Block bitmap (%llu) in GDT table (%llu-%llu)",
155 			     (unsigned long long)input->block_bitmap,
156 			     start, metaend - 1);
157 	else if (inside(input->inode_bitmap, start, metaend))
158 		ext4_warning(sb, "Inode bitmap (%llu) in GDT table (%llu-%llu)",
159 			     (unsigned long long)input->inode_bitmap,
160 			     start, metaend - 1);
161 	else if (inside(input->inode_table, start, metaend) ||
162 		 inside(itend - 1, start, metaend))
163 		ext4_warning(sb, "Inode table (%llu-%llu) overlaps GDT table "
164 			     "(%llu-%llu)",
165 			     (unsigned long long)input->inode_table,
166 			     itend - 1, start, metaend - 1);
167 	else
168 		err = 0;
169 	brelse(bh);
170 
171 	return err;
172 }
173 
174 /*
175  * ext4_new_flex_group_data is used by 64bit-resize interface to add a flex
176  * group each time.
177  */
178 struct ext4_new_flex_group_data {
179 	struct ext4_new_group_data *groups;	/* new_group_data for groups
180 						   in the flex group */
181 	__u16 *bg_flags;			/* block group flags of groups
182 						   in @groups */
183 	ext4_group_t count;			/* number of groups in @groups
184 						 */
185 };
186 
187 /*
188  * alloc_flex_gd() allocates a ext4_new_flex_group_data with size of
189  * @flexbg_size.
190  *
191  * Returns NULL on failure otherwise address of the allocated structure.
192  */
193 static struct ext4_new_flex_group_data *alloc_flex_gd(unsigned long flexbg_size)
194 {
195 	struct ext4_new_flex_group_data *flex_gd;
196 
197 	flex_gd = kmalloc(sizeof(*flex_gd), GFP_NOFS);
198 	if (flex_gd == NULL)
199 		goto out3;
200 
201 	if (flexbg_size >= UINT_MAX / sizeof(struct ext4_new_flex_group_data))
202 		goto out2;
203 	flex_gd->count = flexbg_size;
204 
205 	flex_gd->groups = kmalloc(sizeof(struct ext4_new_group_data) *
206 				  flexbg_size, GFP_NOFS);
207 	if (flex_gd->groups == NULL)
208 		goto out2;
209 
210 	flex_gd->bg_flags = kmalloc(flexbg_size * sizeof(__u16), GFP_NOFS);
211 	if (flex_gd->bg_flags == NULL)
212 		goto out1;
213 
214 	return flex_gd;
215 
216 out1:
217 	kfree(flex_gd->groups);
218 out2:
219 	kfree(flex_gd);
220 out3:
221 	return NULL;
222 }
223 
224 static void free_flex_gd(struct ext4_new_flex_group_data *flex_gd)
225 {
226 	kfree(flex_gd->bg_flags);
227 	kfree(flex_gd->groups);
228 	kfree(flex_gd);
229 }
230 
231 /*
232  * ext4_alloc_group_tables() allocates block bitmaps, inode bitmaps
233  * and inode tables for a flex group.
234  *
235  * This function is used by 64bit-resize.  Note that this function allocates
236  * group tables from the 1st group of groups contained by @flexgd, which may
237  * be a partial of a flex group.
238  *
239  * @sb: super block of fs to which the groups belongs
240  *
241  * Returns 0 on a successful allocation of the metadata blocks in the
242  * block group.
243  */
244 static int ext4_alloc_group_tables(struct super_block *sb,
245 				struct ext4_new_flex_group_data *flex_gd,
246 				int flexbg_size)
247 {
248 	struct ext4_new_group_data *group_data = flex_gd->groups;
249 	ext4_fsblk_t start_blk;
250 	ext4_fsblk_t last_blk;
251 	ext4_group_t src_group;
252 	ext4_group_t bb_index = 0;
253 	ext4_group_t ib_index = 0;
254 	ext4_group_t it_index = 0;
255 	ext4_group_t group;
256 	ext4_group_t last_group;
257 	unsigned overhead;
258 	__u16 uninit_mask = (flexbg_size > 1) ? ~EXT4_BG_BLOCK_UNINIT : ~0;
259 
260 	BUG_ON(flex_gd->count == 0 || group_data == NULL);
261 
262 	src_group = group_data[0].group;
263 	last_group  = src_group + flex_gd->count - 1;
264 
265 	BUG_ON((flexbg_size > 1) && ((src_group & ~(flexbg_size - 1)) !=
266 	       (last_group & ~(flexbg_size - 1))));
267 next_group:
268 	group = group_data[0].group;
269 	if (src_group >= group_data[0].group + flex_gd->count)
270 		return -ENOSPC;
271 	start_blk = ext4_group_first_block_no(sb, src_group);
272 	last_blk = start_blk + group_data[src_group - group].blocks_count;
273 
274 	overhead = ext4_group_overhead_blocks(sb, src_group);
275 
276 	start_blk += overhead;
277 
278 	/* We collect contiguous blocks as much as possible. */
279 	src_group++;
280 	for (; src_group <= last_group; src_group++) {
281 		overhead = ext4_group_overhead_blocks(sb, src_group);
282 		if (overhead == 0)
283 			last_blk += group_data[src_group - group].blocks_count;
284 		else
285 			break;
286 	}
287 
288 	/* Allocate block bitmaps */
289 	for (; bb_index < flex_gd->count; bb_index++) {
290 		if (start_blk >= last_blk)
291 			goto next_group;
292 		group_data[bb_index].block_bitmap = start_blk++;
293 		group = ext4_get_group_number(sb, start_blk - 1);
294 		group -= group_data[0].group;
295 		group_data[group].free_blocks_count--;
296 		flex_gd->bg_flags[group] &= uninit_mask;
297 	}
298 
299 	/* Allocate inode bitmaps */
300 	for (; ib_index < flex_gd->count; ib_index++) {
301 		if (start_blk >= last_blk)
302 			goto next_group;
303 		group_data[ib_index].inode_bitmap = start_blk++;
304 		group = ext4_get_group_number(sb, start_blk - 1);
305 		group -= group_data[0].group;
306 		group_data[group].free_blocks_count--;
307 		flex_gd->bg_flags[group] &= uninit_mask;
308 	}
309 
310 	/* Allocate inode tables */
311 	for (; it_index < flex_gd->count; it_index++) {
312 		unsigned int itb = EXT4_SB(sb)->s_itb_per_group;
313 		ext4_fsblk_t next_group_start;
314 
315 		if (start_blk + itb > last_blk)
316 			goto next_group;
317 		group_data[it_index].inode_table = start_blk;
318 		group = ext4_get_group_number(sb, start_blk);
319 		next_group_start = ext4_group_first_block_no(sb, group + 1);
320 		group -= group_data[0].group;
321 
322 		if (start_blk + itb > next_group_start) {
323 			flex_gd->bg_flags[group + 1] &= uninit_mask;
324 			overhead = start_blk + itb - next_group_start;
325 			group_data[group + 1].free_blocks_count -= overhead;
326 			itb -= overhead;
327 		}
328 
329 		group_data[group].free_blocks_count -= itb;
330 		flex_gd->bg_flags[group] &= uninit_mask;
331 		start_blk += EXT4_SB(sb)->s_itb_per_group;
332 	}
333 
334 	if (test_opt(sb, DEBUG)) {
335 		int i;
336 		group = group_data[0].group;
337 
338 		printk(KERN_DEBUG "EXT4-fs: adding a flex group with "
339 		       "%d groups, flexbg size is %d:\n", flex_gd->count,
340 		       flexbg_size);
341 
342 		for (i = 0; i < flex_gd->count; i++) {
343 			printk(KERN_DEBUG "adding %s group %u: %u "
344 			       "blocks (%d free)\n",
345 			       ext4_bg_has_super(sb, group + i) ? "normal" :
346 			       "no-super", group + i,
347 			       group_data[i].blocks_count,
348 			       group_data[i].free_blocks_count);
349 		}
350 	}
351 	return 0;
352 }
353 
354 static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
355 				  ext4_fsblk_t blk)
356 {
357 	struct buffer_head *bh;
358 	int err;
359 
360 	bh = sb_getblk(sb, blk);
361 	if (unlikely(!bh))
362 		return ERR_PTR(-ENOMEM);
363 	BUFFER_TRACE(bh, "get_write_access");
364 	if ((err = ext4_journal_get_write_access(handle, bh))) {
365 		brelse(bh);
366 		bh = ERR_PTR(err);
367 	} else {
368 		memset(bh->b_data, 0, sb->s_blocksize);
369 		set_buffer_uptodate(bh);
370 	}
371 
372 	return bh;
373 }
374 
375 /*
376  * If we have fewer than thresh credits, extend by EXT4_MAX_TRANS_DATA.
377  * If that fails, restart the transaction & regain write access for the
378  * buffer head which is used for block_bitmap modifications.
379  */
380 static int extend_or_restart_transaction(handle_t *handle, int thresh)
381 {
382 	int err;
383 
384 	if (ext4_handle_has_enough_credits(handle, thresh))
385 		return 0;
386 
387 	err = ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA);
388 	if (err < 0)
389 		return err;
390 	if (err) {
391 		err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA);
392 		if (err)
393 			return err;
394 	}
395 
396 	return 0;
397 }
398 
399 /*
400  * set_flexbg_block_bitmap() mark @count blocks starting from @block used.
401  *
402  * Helper function for ext4_setup_new_group_blocks() which set .
403  *
404  * @sb: super block
405  * @handle: journal handle
406  * @flex_gd: flex group data
407  */
408 static int set_flexbg_block_bitmap(struct super_block *sb, handle_t *handle,
409 			struct ext4_new_flex_group_data *flex_gd,
410 			ext4_fsblk_t block, ext4_group_t count)
411 {
412 	ext4_group_t count2;
413 
414 	ext4_debug("mark blocks [%llu/%u] used\n", block, count);
415 	for (count2 = count; count > 0; count -= count2, block += count2) {
416 		ext4_fsblk_t start;
417 		struct buffer_head *bh;
418 		ext4_group_t group;
419 		int err;
420 
421 		group = ext4_get_group_number(sb, block);
422 		start = ext4_group_first_block_no(sb, group);
423 		group -= flex_gd->groups[0].group;
424 
425 		count2 = EXT4_BLOCKS_PER_GROUP(sb) - (block - start);
426 		if (count2 > count)
427 			count2 = count;
428 
429 		if (flex_gd->bg_flags[group] & EXT4_BG_BLOCK_UNINIT) {
430 			BUG_ON(flex_gd->count > 1);
431 			continue;
432 		}
433 
434 		err = extend_or_restart_transaction(handle, 1);
435 		if (err)
436 			return err;
437 
438 		bh = sb_getblk(sb, flex_gd->groups[group].block_bitmap);
439 		if (unlikely(!bh))
440 			return -ENOMEM;
441 
442 		BUFFER_TRACE(bh, "get_write_access");
443 		err = ext4_journal_get_write_access(handle, bh);
444 		if (err)
445 			return err;
446 		ext4_debug("mark block bitmap %#04llx (+%llu/%u)\n", block,
447 			   block - start, count2);
448 		ext4_set_bits(bh->b_data, block - start, count2);
449 
450 		err = ext4_handle_dirty_metadata(handle, NULL, bh);
451 		if (unlikely(err))
452 			return err;
453 		brelse(bh);
454 	}
455 
456 	return 0;
457 }
458 
459 /*
460  * Set up the block and inode bitmaps, and the inode table for the new groups.
461  * This doesn't need to be part of the main transaction, since we are only
462  * changing blocks outside the actual filesystem.  We still do journaling to
463  * ensure the recovery is correct in case of a failure just after resize.
464  * If any part of this fails, we simply abort the resize.
465  *
466  * setup_new_flex_group_blocks handles a flex group as follow:
467  *  1. copy super block and GDT, and initialize group tables if necessary.
468  *     In this step, we only set bits in blocks bitmaps for blocks taken by
469  *     super block and GDT.
470  *  2. allocate group tables in block bitmaps, that is, set bits in block
471  *     bitmap for blocks taken by group tables.
472  */
473 static int setup_new_flex_group_blocks(struct super_block *sb,
474 				struct ext4_new_flex_group_data *flex_gd)
475 {
476 	int group_table_count[] = {1, 1, EXT4_SB(sb)->s_itb_per_group};
477 	ext4_fsblk_t start;
478 	ext4_fsblk_t block;
479 	struct ext4_sb_info *sbi = EXT4_SB(sb);
480 	struct ext4_super_block *es = sbi->s_es;
481 	struct ext4_new_group_data *group_data = flex_gd->groups;
482 	__u16 *bg_flags = flex_gd->bg_flags;
483 	handle_t *handle;
484 	ext4_group_t group, count;
485 	struct buffer_head *bh = NULL;
486 	int reserved_gdb, i, j, err = 0, err2;
487 	int meta_bg;
488 
489 	BUG_ON(!flex_gd->count || !group_data ||
490 	       group_data[0].group != sbi->s_groups_count);
491 
492 	reserved_gdb = le16_to_cpu(es->s_reserved_gdt_blocks);
493 	meta_bg = ext4_has_feature_meta_bg(sb);
494 
495 	/* This transaction may be extended/restarted along the way */
496 	handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, EXT4_MAX_TRANS_DATA);
497 	if (IS_ERR(handle))
498 		return PTR_ERR(handle);
499 
500 	group = group_data[0].group;
501 	for (i = 0; i < flex_gd->count; i++, group++) {
502 		unsigned long gdblocks;
503 		ext4_grpblk_t overhead;
504 
505 		gdblocks = ext4_bg_num_gdb(sb, group);
506 		start = ext4_group_first_block_no(sb, group);
507 
508 		if (meta_bg == 0 && !ext4_bg_has_super(sb, group))
509 			goto handle_itb;
510 
511 		if (meta_bg == 1) {
512 			ext4_group_t first_group;
513 			first_group = ext4_meta_bg_first_group(sb, group);
514 			if (first_group != group + 1 &&
515 			    first_group != group + EXT4_DESC_PER_BLOCK(sb) - 1)
516 				goto handle_itb;
517 		}
518 
519 		block = start + ext4_bg_has_super(sb, group);
520 		/* Copy all of the GDT blocks into the backup in this group */
521 		for (j = 0; j < gdblocks; j++, block++) {
522 			struct buffer_head *gdb;
523 
524 			ext4_debug("update backup group %#04llx\n", block);
525 			err = extend_or_restart_transaction(handle, 1);
526 			if (err)
527 				goto out;
528 
529 			gdb = sb_getblk(sb, block);
530 			if (unlikely(!gdb)) {
531 				err = -ENOMEM;
532 				goto out;
533 			}
534 
535 			BUFFER_TRACE(gdb, "get_write_access");
536 			err = ext4_journal_get_write_access(handle, gdb);
537 			if (err) {
538 				brelse(gdb);
539 				goto out;
540 			}
541 			memcpy(gdb->b_data, sbi->s_group_desc[j]->b_data,
542 			       gdb->b_size);
543 			set_buffer_uptodate(gdb);
544 
545 			err = ext4_handle_dirty_metadata(handle, NULL, gdb);
546 			if (unlikely(err)) {
547 				brelse(gdb);
548 				goto out;
549 			}
550 			brelse(gdb);
551 		}
552 
553 		/* Zero out all of the reserved backup group descriptor
554 		 * table blocks
555 		 */
556 		if (ext4_bg_has_super(sb, group)) {
557 			err = sb_issue_zeroout(sb, gdblocks + start + 1,
558 					reserved_gdb, GFP_NOFS);
559 			if (err)
560 				goto out;
561 		}
562 
563 handle_itb:
564 		/* Initialize group tables of the grop @group */
565 		if (!(bg_flags[i] & EXT4_BG_INODE_ZEROED))
566 			goto handle_bb;
567 
568 		/* Zero out all of the inode table blocks */
569 		block = group_data[i].inode_table;
570 		ext4_debug("clear inode table blocks %#04llx -> %#04lx\n",
571 			   block, sbi->s_itb_per_group);
572 		err = sb_issue_zeroout(sb, block, sbi->s_itb_per_group,
573 				       GFP_NOFS);
574 		if (err)
575 			goto out;
576 
577 handle_bb:
578 		if (bg_flags[i] & EXT4_BG_BLOCK_UNINIT)
579 			goto handle_ib;
580 
581 		/* Initialize block bitmap of the @group */
582 		block = group_data[i].block_bitmap;
583 		err = extend_or_restart_transaction(handle, 1);
584 		if (err)
585 			goto out;
586 
587 		bh = bclean(handle, sb, block);
588 		if (IS_ERR(bh)) {
589 			err = PTR_ERR(bh);
590 			bh = NULL;
591 			goto out;
592 		}
593 		overhead = ext4_group_overhead_blocks(sb, group);
594 		if (overhead != 0) {
595 			ext4_debug("mark backup superblock %#04llx (+0)\n",
596 				   start);
597 			ext4_set_bits(bh->b_data, 0, overhead);
598 		}
599 		ext4_mark_bitmap_end(group_data[i].blocks_count,
600 				     sb->s_blocksize * 8, bh->b_data);
601 		err = ext4_handle_dirty_metadata(handle, NULL, bh);
602 		if (err)
603 			goto out;
604 		brelse(bh);
605 
606 handle_ib:
607 		if (bg_flags[i] & EXT4_BG_INODE_UNINIT)
608 			continue;
609 
610 		/* Initialize inode bitmap of the @group */
611 		block = group_data[i].inode_bitmap;
612 		err = extend_or_restart_transaction(handle, 1);
613 		if (err)
614 			goto out;
615 		/* Mark unused entries in inode bitmap used */
616 		bh = bclean(handle, sb, block);
617 		if (IS_ERR(bh)) {
618 			err = PTR_ERR(bh);
619 			bh = NULL;
620 			goto out;
621 		}
622 
623 		ext4_mark_bitmap_end(EXT4_INODES_PER_GROUP(sb),
624 				     sb->s_blocksize * 8, bh->b_data);
625 		err = ext4_handle_dirty_metadata(handle, NULL, bh);
626 		if (err)
627 			goto out;
628 		brelse(bh);
629 	}
630 	bh = NULL;
631 
632 	/* Mark group tables in block bitmap */
633 	for (j = 0; j < GROUP_TABLE_COUNT; j++) {
634 		count = group_table_count[j];
635 		start = (&group_data[0].block_bitmap)[j];
636 		block = start;
637 		for (i = 1; i < flex_gd->count; i++) {
638 			block += group_table_count[j];
639 			if (block == (&group_data[i].block_bitmap)[j]) {
640 				count += group_table_count[j];
641 				continue;
642 			}
643 			err = set_flexbg_block_bitmap(sb, handle,
644 						flex_gd, start, count);
645 			if (err)
646 				goto out;
647 			count = group_table_count[j];
648 			start = (&group_data[i].block_bitmap)[j];
649 			block = start;
650 		}
651 
652 		if (count) {
653 			err = set_flexbg_block_bitmap(sb, handle,
654 						flex_gd, start, count);
655 			if (err)
656 				goto out;
657 		}
658 	}
659 
660 out:
661 	brelse(bh);
662 	err2 = ext4_journal_stop(handle);
663 	if (err2 && !err)
664 		err = err2;
665 
666 	return err;
667 }
668 
669 /*
670  * Iterate through the groups which hold BACKUP superblock/GDT copies in an
671  * ext4 filesystem.  The counters should be initialized to 1, 5, and 7 before
672  * calling this for the first time.  In a sparse filesystem it will be the
673  * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
674  * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
675  */
676 static unsigned ext4_list_backups(struct super_block *sb, unsigned *three,
677 				  unsigned *five, unsigned *seven)
678 {
679 	unsigned *min = three;
680 	int mult = 3;
681 	unsigned ret;
682 
683 	if (!ext4_has_feature_sparse_super(sb)) {
684 		ret = *min;
685 		*min += 1;
686 		return ret;
687 	}
688 
689 	if (*five < *min) {
690 		min = five;
691 		mult = 5;
692 	}
693 	if (*seven < *min) {
694 		min = seven;
695 		mult = 7;
696 	}
697 
698 	ret = *min;
699 	*min *= mult;
700 
701 	return ret;
702 }
703 
704 /*
705  * Check that all of the backup GDT blocks are held in the primary GDT block.
706  * It is assumed that they are stored in group order.  Returns the number of
707  * groups in current filesystem that have BACKUPS, or -ve error code.
708  */
709 static int verify_reserved_gdb(struct super_block *sb,
710 			       ext4_group_t end,
711 			       struct buffer_head *primary)
712 {
713 	const ext4_fsblk_t blk = primary->b_blocknr;
714 	unsigned three = 1;
715 	unsigned five = 5;
716 	unsigned seven = 7;
717 	unsigned grp;
718 	__le32 *p = (__le32 *)primary->b_data;
719 	int gdbackups = 0;
720 
721 	while ((grp = ext4_list_backups(sb, &three, &five, &seven)) < end) {
722 		if (le32_to_cpu(*p++) !=
723 		    grp * EXT4_BLOCKS_PER_GROUP(sb) + blk){
724 			ext4_warning(sb, "reserved GDT %llu"
725 				     " missing grp %d (%llu)",
726 				     blk, grp,
727 				     grp *
728 				     (ext4_fsblk_t)EXT4_BLOCKS_PER_GROUP(sb) +
729 				     blk);
730 			return -EINVAL;
731 		}
732 		if (++gdbackups > EXT4_ADDR_PER_BLOCK(sb))
733 			return -EFBIG;
734 	}
735 
736 	return gdbackups;
737 }
738 
739 /*
740  * Called when we need to bring a reserved group descriptor table block into
741  * use from the resize inode.  The primary copy of the new GDT block currently
742  * is an indirect block (under the double indirect block in the resize inode).
743  * The new backup GDT blocks will be stored as leaf blocks in this indirect
744  * block, in group order.  Even though we know all the block numbers we need,
745  * we check to ensure that the resize inode has actually reserved these blocks.
746  *
747  * Don't need to update the block bitmaps because the blocks are still in use.
748  *
749  * We get all of the error cases out of the way, so that we are sure to not
750  * fail once we start modifying the data on disk, because JBD has no rollback.
751  */
752 static int add_new_gdb(handle_t *handle, struct inode *inode,
753 		       ext4_group_t group)
754 {
755 	struct super_block *sb = inode->i_sb;
756 	struct ext4_super_block *es = EXT4_SB(sb)->s_es;
757 	unsigned long gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
758 	ext4_fsblk_t gdblock = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + gdb_num;
759 	struct buffer_head **o_group_desc, **n_group_desc;
760 	struct buffer_head *dind;
761 	struct buffer_head *gdb_bh;
762 	int gdbackups;
763 	struct ext4_iloc iloc;
764 	__le32 *data;
765 	int err;
766 
767 	if (test_opt(sb, DEBUG))
768 		printk(KERN_DEBUG
769 		       "EXT4-fs: ext4_add_new_gdb: adding group block %lu\n",
770 		       gdb_num);
771 
772 	gdb_bh = sb_bread(sb, gdblock);
773 	if (!gdb_bh)
774 		return -EIO;
775 
776 	gdbackups = verify_reserved_gdb(sb, group, gdb_bh);
777 	if (gdbackups < 0) {
778 		err = gdbackups;
779 		goto exit_bh;
780 	}
781 
782 	data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
783 	dind = sb_bread(sb, le32_to_cpu(*data));
784 	if (!dind) {
785 		err = -EIO;
786 		goto exit_bh;
787 	}
788 
789 	data = (__le32 *)dind->b_data;
790 	if (le32_to_cpu(data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)]) != gdblock) {
791 		ext4_warning(sb, "new group %u GDT block %llu not reserved",
792 			     group, gdblock);
793 		err = -EINVAL;
794 		goto exit_dind;
795 	}
796 
797 	BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
798 	err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
799 	if (unlikely(err))
800 		goto exit_dind;
801 
802 	BUFFER_TRACE(gdb_bh, "get_write_access");
803 	err = ext4_journal_get_write_access(handle, gdb_bh);
804 	if (unlikely(err))
805 		goto exit_dind;
806 
807 	BUFFER_TRACE(dind, "get_write_access");
808 	err = ext4_journal_get_write_access(handle, dind);
809 	if (unlikely(err))
810 		ext4_std_error(sb, err);
811 
812 	/* ext4_reserve_inode_write() gets a reference on the iloc */
813 	err = ext4_reserve_inode_write(handle, inode, &iloc);
814 	if (unlikely(err))
815 		goto exit_dind;
816 
817 	n_group_desc = ext4_kvmalloc((gdb_num + 1) *
818 				     sizeof(struct buffer_head *),
819 				     GFP_NOFS);
820 	if (!n_group_desc) {
821 		err = -ENOMEM;
822 		ext4_warning(sb, "not enough memory for %lu groups",
823 			     gdb_num + 1);
824 		goto exit_inode;
825 	}
826 
827 	/*
828 	 * Finally, we have all of the possible failures behind us...
829 	 *
830 	 * Remove new GDT block from inode double-indirect block and clear out
831 	 * the new GDT block for use (which also "frees" the backup GDT blocks
832 	 * from the reserved inode).  We don't need to change the bitmaps for
833 	 * these blocks, because they are marked as in-use from being in the
834 	 * reserved inode, and will become GDT blocks (primary and backup).
835 	 */
836 	data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)] = 0;
837 	err = ext4_handle_dirty_metadata(handle, NULL, dind);
838 	if (unlikely(err)) {
839 		ext4_std_error(sb, err);
840 		goto exit_inode;
841 	}
842 	inode->i_blocks -= (gdbackups + 1) * sb->s_blocksize >> 9;
843 	ext4_mark_iloc_dirty(handle, inode, &iloc);
844 	memset(gdb_bh->b_data, 0, sb->s_blocksize);
845 	err = ext4_handle_dirty_metadata(handle, NULL, gdb_bh);
846 	if (unlikely(err)) {
847 		ext4_std_error(sb, err);
848 		goto exit_inode;
849 	}
850 	brelse(dind);
851 
852 	o_group_desc = EXT4_SB(sb)->s_group_desc;
853 	memcpy(n_group_desc, o_group_desc,
854 	       EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
855 	n_group_desc[gdb_num] = gdb_bh;
856 	EXT4_SB(sb)->s_group_desc = n_group_desc;
857 	EXT4_SB(sb)->s_gdb_count++;
858 	kvfree(o_group_desc);
859 
860 	le16_add_cpu(&es->s_reserved_gdt_blocks, -1);
861 	err = ext4_handle_dirty_super(handle, sb);
862 	if (err)
863 		ext4_std_error(sb, err);
864 
865 	return err;
866 
867 exit_inode:
868 	kvfree(n_group_desc);
869 	brelse(iloc.bh);
870 exit_dind:
871 	brelse(dind);
872 exit_bh:
873 	brelse(gdb_bh);
874 
875 	ext4_debug("leaving with error %d\n", err);
876 	return err;
877 }
878 
879 /*
880  * add_new_gdb_meta_bg is the sister of add_new_gdb.
881  */
882 static int add_new_gdb_meta_bg(struct super_block *sb,
883 			       handle_t *handle, ext4_group_t group) {
884 	ext4_fsblk_t gdblock;
885 	struct buffer_head *gdb_bh;
886 	struct buffer_head **o_group_desc, **n_group_desc;
887 	unsigned long gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
888 	int err;
889 
890 	gdblock = ext4_meta_bg_first_block_no(sb, group) +
891 		   ext4_bg_has_super(sb, group);
892 	gdb_bh = sb_bread(sb, gdblock);
893 	if (!gdb_bh)
894 		return -EIO;
895 	n_group_desc = ext4_kvmalloc((gdb_num + 1) *
896 				     sizeof(struct buffer_head *),
897 				     GFP_NOFS);
898 	if (!n_group_desc) {
899 		err = -ENOMEM;
900 		ext4_warning(sb, "not enough memory for %lu groups",
901 			     gdb_num + 1);
902 		return err;
903 	}
904 
905 	o_group_desc = EXT4_SB(sb)->s_group_desc;
906 	memcpy(n_group_desc, o_group_desc,
907 	       EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
908 	n_group_desc[gdb_num] = gdb_bh;
909 	EXT4_SB(sb)->s_group_desc = n_group_desc;
910 	EXT4_SB(sb)->s_gdb_count++;
911 	kvfree(o_group_desc);
912 	BUFFER_TRACE(gdb_bh, "get_write_access");
913 	err = ext4_journal_get_write_access(handle, gdb_bh);
914 	if (unlikely(err))
915 		brelse(gdb_bh);
916 	return err;
917 }
918 
919 /*
920  * Called when we are adding a new group which has a backup copy of each of
921  * the GDT blocks (i.e. sparse group) and there are reserved GDT blocks.
922  * We need to add these reserved backup GDT blocks to the resize inode, so
923  * that they are kept for future resizing and not allocated to files.
924  *
925  * Each reserved backup GDT block will go into a different indirect block.
926  * The indirect blocks are actually the primary reserved GDT blocks,
927  * so we know in advance what their block numbers are.  We only get the
928  * double-indirect block to verify it is pointing to the primary reserved
929  * GDT blocks so we don't overwrite a data block by accident.  The reserved
930  * backup GDT blocks are stored in their reserved primary GDT block.
931  */
932 static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
933 			      ext4_group_t group)
934 {
935 	struct super_block *sb = inode->i_sb;
936 	int reserved_gdb =le16_to_cpu(EXT4_SB(sb)->s_es->s_reserved_gdt_blocks);
937 	struct buffer_head **primary;
938 	struct buffer_head *dind;
939 	struct ext4_iloc iloc;
940 	ext4_fsblk_t blk;
941 	__le32 *data, *end;
942 	int gdbackups = 0;
943 	int res, i;
944 	int err;
945 
946 	primary = kmalloc(reserved_gdb * sizeof(*primary), GFP_NOFS);
947 	if (!primary)
948 		return -ENOMEM;
949 
950 	data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
951 	dind = sb_bread(sb, le32_to_cpu(*data));
952 	if (!dind) {
953 		err = -EIO;
954 		goto exit_free;
955 	}
956 
957 	blk = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + EXT4_SB(sb)->s_gdb_count;
958 	data = (__le32 *)dind->b_data + (EXT4_SB(sb)->s_gdb_count %
959 					 EXT4_ADDR_PER_BLOCK(sb));
960 	end = (__le32 *)dind->b_data + EXT4_ADDR_PER_BLOCK(sb);
961 
962 	/* Get each reserved primary GDT block and verify it holds backups */
963 	for (res = 0; res < reserved_gdb; res++, blk++) {
964 		if (le32_to_cpu(*data) != blk) {
965 			ext4_warning(sb, "reserved block %llu"
966 				     " not at offset %ld",
967 				     blk,
968 				     (long)(data - (__le32 *)dind->b_data));
969 			err = -EINVAL;
970 			goto exit_bh;
971 		}
972 		primary[res] = sb_bread(sb, blk);
973 		if (!primary[res]) {
974 			err = -EIO;
975 			goto exit_bh;
976 		}
977 		gdbackups = verify_reserved_gdb(sb, group, primary[res]);
978 		if (gdbackups < 0) {
979 			brelse(primary[res]);
980 			err = gdbackups;
981 			goto exit_bh;
982 		}
983 		if (++data >= end)
984 			data = (__le32 *)dind->b_data;
985 	}
986 
987 	for (i = 0; i < reserved_gdb; i++) {
988 		BUFFER_TRACE(primary[i], "get_write_access");
989 		if ((err = ext4_journal_get_write_access(handle, primary[i])))
990 			goto exit_bh;
991 	}
992 
993 	if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
994 		goto exit_bh;
995 
996 	/*
997 	 * Finally we can add each of the reserved backup GDT blocks from
998 	 * the new group to its reserved primary GDT block.
999 	 */
1000 	blk = group * EXT4_BLOCKS_PER_GROUP(sb);
1001 	for (i = 0; i < reserved_gdb; i++) {
1002 		int err2;
1003 		data = (__le32 *)primary[i]->b_data;
1004 		/* printk("reserving backup %lu[%u] = %lu\n",
1005 		       primary[i]->b_blocknr, gdbackups,
1006 		       blk + primary[i]->b_blocknr); */
1007 		data[gdbackups] = cpu_to_le32(blk + primary[i]->b_blocknr);
1008 		err2 = ext4_handle_dirty_metadata(handle, NULL, primary[i]);
1009 		if (!err)
1010 			err = err2;
1011 	}
1012 	inode->i_blocks += reserved_gdb * sb->s_blocksize >> 9;
1013 	ext4_mark_iloc_dirty(handle, inode, &iloc);
1014 
1015 exit_bh:
1016 	while (--res >= 0)
1017 		brelse(primary[res]);
1018 	brelse(dind);
1019 
1020 exit_free:
1021 	kfree(primary);
1022 
1023 	return err;
1024 }
1025 
1026 /*
1027  * Update the backup copies of the ext4 metadata.  These don't need to be part
1028  * of the main resize transaction, because e2fsck will re-write them if there
1029  * is a problem (basically only OOM will cause a problem).  However, we
1030  * _should_ update the backups if possible, in case the primary gets trashed
1031  * for some reason and we need to run e2fsck from a backup superblock.  The
1032  * important part is that the new block and inode counts are in the backup
1033  * superblocks, and the location of the new group metadata in the GDT backups.
1034  *
1035  * We do not need take the s_resize_lock for this, because these
1036  * blocks are not otherwise touched by the filesystem code when it is
1037  * mounted.  We don't need to worry about last changing from
1038  * sbi->s_groups_count, because the worst that can happen is that we
1039  * do not copy the full number of backups at this time.  The resize
1040  * which changed s_groups_count will backup again.
1041  */
1042 static void update_backups(struct super_block *sb, sector_t blk_off, char *data,
1043 			   int size, int meta_bg)
1044 {
1045 	struct ext4_sb_info *sbi = EXT4_SB(sb);
1046 	ext4_group_t last;
1047 	const int bpg = EXT4_BLOCKS_PER_GROUP(sb);
1048 	unsigned three = 1;
1049 	unsigned five = 5;
1050 	unsigned seven = 7;
1051 	ext4_group_t group = 0;
1052 	int rest = sb->s_blocksize - size;
1053 	handle_t *handle;
1054 	int err = 0, err2;
1055 
1056 	handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, EXT4_MAX_TRANS_DATA);
1057 	if (IS_ERR(handle)) {
1058 		group = 1;
1059 		err = PTR_ERR(handle);
1060 		goto exit_err;
1061 	}
1062 
1063 	if (meta_bg == 0) {
1064 		group = ext4_list_backups(sb, &three, &five, &seven);
1065 		last = sbi->s_groups_count;
1066 	} else {
1067 		group = ext4_get_group_number(sb, blk_off) + 1;
1068 		last = (ext4_group_t)(group + EXT4_DESC_PER_BLOCK(sb) - 2);
1069 	}
1070 
1071 	while (group < sbi->s_groups_count) {
1072 		struct buffer_head *bh;
1073 		ext4_fsblk_t backup_block;
1074 
1075 		/* Out of journal space, and can't get more - abort - so sad */
1076 		if (ext4_handle_valid(handle) &&
1077 		    handle->h_buffer_credits == 0 &&
1078 		    ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA) &&
1079 		    (err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA)))
1080 			break;
1081 
1082 		if (meta_bg == 0)
1083 			backup_block = ((ext4_fsblk_t)group) * bpg + blk_off;
1084 		else
1085 			backup_block = (ext4_group_first_block_no(sb, group) +
1086 					ext4_bg_has_super(sb, group));
1087 
1088 		bh = sb_getblk(sb, backup_block);
1089 		if (unlikely(!bh)) {
1090 			err = -ENOMEM;
1091 			break;
1092 		}
1093 		ext4_debug("update metadata backup %llu(+%llu)\n",
1094 			   backup_block, backup_block -
1095 			   ext4_group_first_block_no(sb, group));
1096 		BUFFER_TRACE(bh, "get_write_access");
1097 		if ((err = ext4_journal_get_write_access(handle, bh)))
1098 			break;
1099 		lock_buffer(bh);
1100 		memcpy(bh->b_data, data, size);
1101 		if (rest)
1102 			memset(bh->b_data + size, 0, rest);
1103 		set_buffer_uptodate(bh);
1104 		unlock_buffer(bh);
1105 		err = ext4_handle_dirty_metadata(handle, NULL, bh);
1106 		if (unlikely(err))
1107 			ext4_std_error(sb, err);
1108 		brelse(bh);
1109 
1110 		if (meta_bg == 0)
1111 			group = ext4_list_backups(sb, &three, &five, &seven);
1112 		else if (group == last)
1113 			break;
1114 		else
1115 			group = last;
1116 	}
1117 	if ((err2 = ext4_journal_stop(handle)) && !err)
1118 		err = err2;
1119 
1120 	/*
1121 	 * Ugh! Need to have e2fsck write the backup copies.  It is too
1122 	 * late to revert the resize, we shouldn't fail just because of
1123 	 * the backup copies (they are only needed in case of corruption).
1124 	 *
1125 	 * However, if we got here we have a journal problem too, so we
1126 	 * can't really start a transaction to mark the superblock.
1127 	 * Chicken out and just set the flag on the hope it will be written
1128 	 * to disk, and if not - we will simply wait until next fsck.
1129 	 */
1130 exit_err:
1131 	if (err) {
1132 		ext4_warning(sb, "can't update backup for group %u (err %d), "
1133 			     "forcing fsck on next reboot", group, err);
1134 		sbi->s_mount_state &= ~EXT4_VALID_FS;
1135 		sbi->s_es->s_state &= cpu_to_le16(~EXT4_VALID_FS);
1136 		mark_buffer_dirty(sbi->s_sbh);
1137 	}
1138 }
1139 
1140 /*
1141  * ext4_add_new_descs() adds @count group descriptor of groups
1142  * starting at @group
1143  *
1144  * @handle: journal handle
1145  * @sb: super block
1146  * @group: the group no. of the first group desc to be added
1147  * @resize_inode: the resize inode
1148  * @count: number of group descriptors to be added
1149  */
1150 static int ext4_add_new_descs(handle_t *handle, struct super_block *sb,
1151 			      ext4_group_t group, struct inode *resize_inode,
1152 			      ext4_group_t count)
1153 {
1154 	struct ext4_sb_info *sbi = EXT4_SB(sb);
1155 	struct ext4_super_block *es = sbi->s_es;
1156 	struct buffer_head *gdb_bh;
1157 	int i, gdb_off, gdb_num, err = 0;
1158 	int meta_bg;
1159 
1160 	meta_bg = ext4_has_feature_meta_bg(sb);
1161 	for (i = 0; i < count; i++, group++) {
1162 		int reserved_gdb = ext4_bg_has_super(sb, group) ?
1163 			le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
1164 
1165 		gdb_off = group % EXT4_DESC_PER_BLOCK(sb);
1166 		gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
1167 
1168 		/*
1169 		 * We will only either add reserved group blocks to a backup group
1170 		 * or remove reserved blocks for the first group in a new group block.
1171 		 * Doing both would be mean more complex code, and sane people don't
1172 		 * use non-sparse filesystems anymore.  This is already checked above.
1173 		 */
1174 		if (gdb_off) {
1175 			gdb_bh = sbi->s_group_desc[gdb_num];
1176 			BUFFER_TRACE(gdb_bh, "get_write_access");
1177 			err = ext4_journal_get_write_access(handle, gdb_bh);
1178 
1179 			if (!err && reserved_gdb && ext4_bg_num_gdb(sb, group))
1180 				err = reserve_backup_gdb(handle, resize_inode, group);
1181 		} else if (meta_bg != 0) {
1182 			err = add_new_gdb_meta_bg(sb, handle, group);
1183 		} else {
1184 			err = add_new_gdb(handle, resize_inode, group);
1185 		}
1186 		if (err)
1187 			break;
1188 	}
1189 	return err;
1190 }
1191 
1192 static struct buffer_head *ext4_get_bitmap(struct super_block *sb, __u64 block)
1193 {
1194 	struct buffer_head *bh = sb_getblk(sb, block);
1195 	if (unlikely(!bh))
1196 		return NULL;
1197 	if (!bh_uptodate_or_lock(bh)) {
1198 		if (bh_submit_read(bh) < 0) {
1199 			brelse(bh);
1200 			return NULL;
1201 		}
1202 	}
1203 
1204 	return bh;
1205 }
1206 
1207 static int ext4_set_bitmap_checksums(struct super_block *sb,
1208 				     ext4_group_t group,
1209 				     struct ext4_group_desc *gdp,
1210 				     struct ext4_new_group_data *group_data)
1211 {
1212 	struct buffer_head *bh;
1213 
1214 	if (!ext4_has_metadata_csum(sb))
1215 		return 0;
1216 
1217 	bh = ext4_get_bitmap(sb, group_data->inode_bitmap);
1218 	if (!bh)
1219 		return -EIO;
1220 	ext4_inode_bitmap_csum_set(sb, group, gdp, bh,
1221 				   EXT4_INODES_PER_GROUP(sb) / 8);
1222 	brelse(bh);
1223 
1224 	bh = ext4_get_bitmap(sb, group_data->block_bitmap);
1225 	if (!bh)
1226 		return -EIO;
1227 	ext4_block_bitmap_csum_set(sb, group, gdp, bh);
1228 	brelse(bh);
1229 
1230 	return 0;
1231 }
1232 
1233 /*
1234  * ext4_setup_new_descs() will set up the group descriptor descriptors of a flex bg
1235  */
1236 static int ext4_setup_new_descs(handle_t *handle, struct super_block *sb,
1237 				struct ext4_new_flex_group_data *flex_gd)
1238 {
1239 	struct ext4_new_group_data	*group_data = flex_gd->groups;
1240 	struct ext4_group_desc		*gdp;
1241 	struct ext4_sb_info		*sbi = EXT4_SB(sb);
1242 	struct buffer_head		*gdb_bh;
1243 	ext4_group_t			group;
1244 	__u16				*bg_flags = flex_gd->bg_flags;
1245 	int				i, gdb_off, gdb_num, err = 0;
1246 
1247 
1248 	for (i = 0; i < flex_gd->count; i++, group_data++, bg_flags++) {
1249 		group = group_data->group;
1250 
1251 		gdb_off = group % EXT4_DESC_PER_BLOCK(sb);
1252 		gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
1253 
1254 		/*
1255 		 * get_write_access() has been called on gdb_bh by ext4_add_new_desc().
1256 		 */
1257 		gdb_bh = sbi->s_group_desc[gdb_num];
1258 		/* Update group descriptor block for new group */
1259 		gdp = (struct ext4_group_desc *)(gdb_bh->b_data +
1260 						 gdb_off * EXT4_DESC_SIZE(sb));
1261 
1262 		memset(gdp, 0, EXT4_DESC_SIZE(sb));
1263 		ext4_block_bitmap_set(sb, gdp, group_data->block_bitmap);
1264 		ext4_inode_bitmap_set(sb, gdp, group_data->inode_bitmap);
1265 		err = ext4_set_bitmap_checksums(sb, group, gdp, group_data);
1266 		if (err) {
1267 			ext4_std_error(sb, err);
1268 			break;
1269 		}
1270 
1271 		ext4_inode_table_set(sb, gdp, group_data->inode_table);
1272 		ext4_free_group_clusters_set(sb, gdp,
1273 			EXT4_NUM_B2C(sbi, group_data->free_blocks_count));
1274 		ext4_free_inodes_set(sb, gdp, EXT4_INODES_PER_GROUP(sb));
1275 		if (ext4_has_group_desc_csum(sb))
1276 			ext4_itable_unused_set(sb, gdp,
1277 					       EXT4_INODES_PER_GROUP(sb));
1278 		gdp->bg_flags = cpu_to_le16(*bg_flags);
1279 		ext4_group_desc_csum_set(sb, group, gdp);
1280 
1281 		err = ext4_handle_dirty_metadata(handle, NULL, gdb_bh);
1282 		if (unlikely(err)) {
1283 			ext4_std_error(sb, err);
1284 			break;
1285 		}
1286 
1287 		/*
1288 		 * We can allocate memory for mb_alloc based on the new group
1289 		 * descriptor
1290 		 */
1291 		err = ext4_mb_add_groupinfo(sb, group, gdp);
1292 		if (err)
1293 			break;
1294 	}
1295 	return err;
1296 }
1297 
1298 /*
1299  * ext4_update_super() updates the super block so that the newly added
1300  * groups can be seen by the filesystem.
1301  *
1302  * @sb: super block
1303  * @flex_gd: new added groups
1304  */
1305 static void ext4_update_super(struct super_block *sb,
1306 			     struct ext4_new_flex_group_data *flex_gd)
1307 {
1308 	ext4_fsblk_t blocks_count = 0;
1309 	ext4_fsblk_t free_blocks = 0;
1310 	ext4_fsblk_t reserved_blocks = 0;
1311 	struct ext4_new_group_data *group_data = flex_gd->groups;
1312 	struct ext4_sb_info *sbi = EXT4_SB(sb);
1313 	struct ext4_super_block *es = sbi->s_es;
1314 	int i;
1315 
1316 	BUG_ON(flex_gd->count == 0 || group_data == NULL);
1317 	/*
1318 	 * Make the new blocks and inodes valid next.  We do this before
1319 	 * increasing the group count so that once the group is enabled,
1320 	 * all of its blocks and inodes are already valid.
1321 	 *
1322 	 * We always allocate group-by-group, then block-by-block or
1323 	 * inode-by-inode within a group, so enabling these
1324 	 * blocks/inodes before the group is live won't actually let us
1325 	 * allocate the new space yet.
1326 	 */
1327 	for (i = 0; i < flex_gd->count; i++) {
1328 		blocks_count += group_data[i].blocks_count;
1329 		free_blocks += group_data[i].free_blocks_count;
1330 	}
1331 
1332 	reserved_blocks = ext4_r_blocks_count(es) * 100;
1333 	reserved_blocks = div64_u64(reserved_blocks, ext4_blocks_count(es));
1334 	reserved_blocks *= blocks_count;
1335 	do_div(reserved_blocks, 100);
1336 
1337 	ext4_blocks_count_set(es, ext4_blocks_count(es) + blocks_count);
1338 	ext4_free_blocks_count_set(es, ext4_free_blocks_count(es) + free_blocks);
1339 	le32_add_cpu(&es->s_inodes_count, EXT4_INODES_PER_GROUP(sb) *
1340 		     flex_gd->count);
1341 	le32_add_cpu(&es->s_free_inodes_count, EXT4_INODES_PER_GROUP(sb) *
1342 		     flex_gd->count);
1343 
1344 	ext4_debug("free blocks count %llu", ext4_free_blocks_count(es));
1345 	/*
1346 	 * We need to protect s_groups_count against other CPUs seeing
1347 	 * inconsistent state in the superblock.
1348 	 *
1349 	 * The precise rules we use are:
1350 	 *
1351 	 * * Writers must perform a smp_wmb() after updating all
1352 	 *   dependent data and before modifying the groups count
1353 	 *
1354 	 * * Readers must perform an smp_rmb() after reading the groups
1355 	 *   count and before reading any dependent data.
1356 	 *
1357 	 * NB. These rules can be relaxed when checking the group count
1358 	 * while freeing data, as we can only allocate from a block
1359 	 * group after serialising against the group count, and we can
1360 	 * only then free after serialising in turn against that
1361 	 * allocation.
1362 	 */
1363 	smp_wmb();
1364 
1365 	/* Update the global fs size fields */
1366 	sbi->s_groups_count += flex_gd->count;
1367 	sbi->s_blockfile_groups = min_t(ext4_group_t, sbi->s_groups_count,
1368 			(EXT4_MAX_BLOCK_FILE_PHYS / EXT4_BLOCKS_PER_GROUP(sb)));
1369 
1370 	/* Update the reserved block counts only once the new group is
1371 	 * active. */
1372 	ext4_r_blocks_count_set(es, ext4_r_blocks_count(es) +
1373 				reserved_blocks);
1374 
1375 	/* Update the free space counts */
1376 	percpu_counter_add(&sbi->s_freeclusters_counter,
1377 			   EXT4_NUM_B2C(sbi, free_blocks));
1378 	percpu_counter_add(&sbi->s_freeinodes_counter,
1379 			   EXT4_INODES_PER_GROUP(sb) * flex_gd->count);
1380 
1381 	ext4_debug("free blocks count %llu",
1382 		   percpu_counter_read(&sbi->s_freeclusters_counter));
1383 	if (ext4_has_feature_flex_bg(sb) && sbi->s_log_groups_per_flex) {
1384 		ext4_group_t flex_group;
1385 		flex_group = ext4_flex_group(sbi, group_data[0].group);
1386 		atomic64_add(EXT4_NUM_B2C(sbi, free_blocks),
1387 			     &sbi->s_flex_groups[flex_group].free_clusters);
1388 		atomic_add(EXT4_INODES_PER_GROUP(sb) * flex_gd->count,
1389 			   &sbi->s_flex_groups[flex_group].free_inodes);
1390 	}
1391 
1392 	/*
1393 	 * Update the fs overhead information
1394 	 */
1395 	ext4_calculate_overhead(sb);
1396 
1397 	if (test_opt(sb, DEBUG))
1398 		printk(KERN_DEBUG "EXT4-fs: added group %u:"
1399 		       "%llu blocks(%llu free %llu reserved)\n", flex_gd->count,
1400 		       blocks_count, free_blocks, reserved_blocks);
1401 }
1402 
1403 /* Add a flex group to an fs. Ensure we handle all possible error conditions
1404  * _before_ we start modifying the filesystem, because we cannot abort the
1405  * transaction and not have it write the data to disk.
1406  */
1407 static int ext4_flex_group_add(struct super_block *sb,
1408 			       struct inode *resize_inode,
1409 			       struct ext4_new_flex_group_data *flex_gd)
1410 {
1411 	struct ext4_sb_info *sbi = EXT4_SB(sb);
1412 	struct ext4_super_block *es = sbi->s_es;
1413 	ext4_fsblk_t o_blocks_count;
1414 	ext4_grpblk_t last;
1415 	ext4_group_t group;
1416 	handle_t *handle;
1417 	unsigned reserved_gdb;
1418 	int err = 0, err2 = 0, credit;
1419 
1420 	BUG_ON(!flex_gd->count || !flex_gd->groups || !flex_gd->bg_flags);
1421 
1422 	reserved_gdb = le16_to_cpu(es->s_reserved_gdt_blocks);
1423 	o_blocks_count = ext4_blocks_count(es);
1424 	ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
1425 	BUG_ON(last);
1426 
1427 	err = setup_new_flex_group_blocks(sb, flex_gd);
1428 	if (err)
1429 		goto exit;
1430 	/*
1431 	 * We will always be modifying at least the superblock and  GDT
1432 	 * blocks.  If we are adding a group past the last current GDT block,
1433 	 * we will also modify the inode and the dindirect block.  If we
1434 	 * are adding a group with superblock/GDT backups  we will also
1435 	 * modify each of the reserved GDT dindirect blocks.
1436 	 */
1437 	credit = 3;	/* sb, resize inode, resize inode dindirect */
1438 	/* GDT blocks */
1439 	credit += 1 + DIV_ROUND_UP(flex_gd->count, EXT4_DESC_PER_BLOCK(sb));
1440 	credit += reserved_gdb;	/* Reserved GDT dindirect blocks */
1441 	handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, credit);
1442 	if (IS_ERR(handle)) {
1443 		err = PTR_ERR(handle);
1444 		goto exit;
1445 	}
1446 
1447 	BUFFER_TRACE(sbi->s_sbh, "get_write_access");
1448 	err = ext4_journal_get_write_access(handle, sbi->s_sbh);
1449 	if (err)
1450 		goto exit_journal;
1451 
1452 	group = flex_gd->groups[0].group;
1453 	BUG_ON(group != EXT4_SB(sb)->s_groups_count);
1454 	err = ext4_add_new_descs(handle, sb, group,
1455 				resize_inode, flex_gd->count);
1456 	if (err)
1457 		goto exit_journal;
1458 
1459 	err = ext4_setup_new_descs(handle, sb, flex_gd);
1460 	if (err)
1461 		goto exit_journal;
1462 
1463 	ext4_update_super(sb, flex_gd);
1464 
1465 	err = ext4_handle_dirty_super(handle, sb);
1466 
1467 exit_journal:
1468 	err2 = ext4_journal_stop(handle);
1469 	if (!err)
1470 		err = err2;
1471 
1472 	if (!err) {
1473 		int gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
1474 		int gdb_num_end = ((group + flex_gd->count - 1) /
1475 				   EXT4_DESC_PER_BLOCK(sb));
1476 		int meta_bg = ext4_has_feature_meta_bg(sb);
1477 		sector_t old_gdb = 0;
1478 
1479 		update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
1480 			       sizeof(struct ext4_super_block), 0);
1481 		for (; gdb_num <= gdb_num_end; gdb_num++) {
1482 			struct buffer_head *gdb_bh;
1483 
1484 			gdb_bh = sbi->s_group_desc[gdb_num];
1485 			if (old_gdb == gdb_bh->b_blocknr)
1486 				continue;
1487 			update_backups(sb, gdb_bh->b_blocknr, gdb_bh->b_data,
1488 				       gdb_bh->b_size, meta_bg);
1489 			old_gdb = gdb_bh->b_blocknr;
1490 		}
1491 	}
1492 exit:
1493 	return err;
1494 }
1495 
1496 static int ext4_setup_next_flex_gd(struct super_block *sb,
1497 				    struct ext4_new_flex_group_data *flex_gd,
1498 				    ext4_fsblk_t n_blocks_count,
1499 				    unsigned long flexbg_size)
1500 {
1501 	struct ext4_super_block *es = EXT4_SB(sb)->s_es;
1502 	struct ext4_new_group_data *group_data = flex_gd->groups;
1503 	ext4_fsblk_t o_blocks_count;
1504 	ext4_group_t n_group;
1505 	ext4_group_t group;
1506 	ext4_group_t last_group;
1507 	ext4_grpblk_t last;
1508 	ext4_grpblk_t blocks_per_group;
1509 	unsigned long i;
1510 
1511 	blocks_per_group = EXT4_BLOCKS_PER_GROUP(sb);
1512 
1513 	o_blocks_count = ext4_blocks_count(es);
1514 
1515 	if (o_blocks_count == n_blocks_count)
1516 		return 0;
1517 
1518 	ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
1519 	BUG_ON(last);
1520 	ext4_get_group_no_and_offset(sb, n_blocks_count - 1, &n_group, &last);
1521 
1522 	last_group = group | (flexbg_size - 1);
1523 	if (last_group > n_group)
1524 		last_group = n_group;
1525 
1526 	flex_gd->count = last_group - group + 1;
1527 
1528 	for (i = 0; i < flex_gd->count; i++) {
1529 		int overhead;
1530 
1531 		group_data[i].group = group + i;
1532 		group_data[i].blocks_count = blocks_per_group;
1533 		overhead = ext4_group_overhead_blocks(sb, group + i);
1534 		group_data[i].free_blocks_count = blocks_per_group - overhead;
1535 		if (ext4_has_group_desc_csum(sb)) {
1536 			flex_gd->bg_flags[i] = EXT4_BG_BLOCK_UNINIT |
1537 					       EXT4_BG_INODE_UNINIT;
1538 			if (!test_opt(sb, INIT_INODE_TABLE))
1539 				flex_gd->bg_flags[i] |= EXT4_BG_INODE_ZEROED;
1540 		} else
1541 			flex_gd->bg_flags[i] = EXT4_BG_INODE_ZEROED;
1542 	}
1543 
1544 	if (last_group == n_group && ext4_has_group_desc_csum(sb))
1545 		/* We need to initialize block bitmap of last group. */
1546 		flex_gd->bg_flags[i - 1] &= ~EXT4_BG_BLOCK_UNINIT;
1547 
1548 	if ((last_group == n_group) && (last != blocks_per_group - 1)) {
1549 		group_data[i - 1].blocks_count = last + 1;
1550 		group_data[i - 1].free_blocks_count -= blocks_per_group-
1551 					last - 1;
1552 	}
1553 
1554 	return 1;
1555 }
1556 
1557 /* Add group descriptor data to an existing or new group descriptor block.
1558  * Ensure we handle all possible error conditions _before_ we start modifying
1559  * the filesystem, because we cannot abort the transaction and not have it
1560  * write the data to disk.
1561  *
1562  * If we are on a GDT block boundary, we need to get the reserved GDT block.
1563  * Otherwise, we may need to add backup GDT blocks for a sparse group.
1564  *
1565  * We only need to hold the superblock lock while we are actually adding
1566  * in the new group's counts to the superblock.  Prior to that we have
1567  * not really "added" the group at all.  We re-check that we are still
1568  * adding in the last group in case things have changed since verifying.
1569  */
1570 int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
1571 {
1572 	struct ext4_new_flex_group_data flex_gd;
1573 	struct ext4_sb_info *sbi = EXT4_SB(sb);
1574 	struct ext4_super_block *es = sbi->s_es;
1575 	int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
1576 		le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
1577 	struct inode *inode = NULL;
1578 	int gdb_off;
1579 	int err;
1580 	__u16 bg_flags = 0;
1581 
1582 	gdb_off = input->group % EXT4_DESC_PER_BLOCK(sb);
1583 
1584 	if (gdb_off == 0 && !ext4_has_feature_sparse_super(sb)) {
1585 		ext4_warning(sb, "Can't resize non-sparse filesystem further");
1586 		return -EPERM;
1587 	}
1588 
1589 	if (ext4_blocks_count(es) + input->blocks_count <
1590 	    ext4_blocks_count(es)) {
1591 		ext4_warning(sb, "blocks_count overflow");
1592 		return -EINVAL;
1593 	}
1594 
1595 	if (le32_to_cpu(es->s_inodes_count) + EXT4_INODES_PER_GROUP(sb) <
1596 	    le32_to_cpu(es->s_inodes_count)) {
1597 		ext4_warning(sb, "inodes_count overflow");
1598 		return -EINVAL;
1599 	}
1600 
1601 	if (reserved_gdb || gdb_off == 0) {
1602 		if (ext4_has_feature_resize_inode(sb) ||
1603 		    !le16_to_cpu(es->s_reserved_gdt_blocks)) {
1604 			ext4_warning(sb,
1605 				     "No reserved GDT blocks, can't resize");
1606 			return -EPERM;
1607 		}
1608 		inode = ext4_iget(sb, EXT4_RESIZE_INO);
1609 		if (IS_ERR(inode)) {
1610 			ext4_warning(sb, "Error opening resize inode");
1611 			return PTR_ERR(inode);
1612 		}
1613 	}
1614 
1615 
1616 	err = verify_group_input(sb, input);
1617 	if (err)
1618 		goto out;
1619 
1620 	err = ext4_alloc_flex_bg_array(sb, input->group + 1);
1621 	if (err)
1622 		goto out;
1623 
1624 	err = ext4_mb_alloc_groupinfo(sb, input->group + 1);
1625 	if (err)
1626 		goto out;
1627 
1628 	flex_gd.count = 1;
1629 	flex_gd.groups = input;
1630 	flex_gd.bg_flags = &bg_flags;
1631 	err = ext4_flex_group_add(sb, inode, &flex_gd);
1632 out:
1633 	iput(inode);
1634 	return err;
1635 } /* ext4_group_add */
1636 
1637 /*
1638  * extend a group without checking assuming that checking has been done.
1639  */
1640 static int ext4_group_extend_no_check(struct super_block *sb,
1641 				      ext4_fsblk_t o_blocks_count, ext4_grpblk_t add)
1642 {
1643 	struct ext4_super_block *es = EXT4_SB(sb)->s_es;
1644 	handle_t *handle;
1645 	int err = 0, err2;
1646 
1647 	/* We will update the superblock, one block bitmap, and
1648 	 * one group descriptor via ext4_group_add_blocks().
1649 	 */
1650 	handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, 3);
1651 	if (IS_ERR(handle)) {
1652 		err = PTR_ERR(handle);
1653 		ext4_warning(sb, "error %d on journal start", err);
1654 		return err;
1655 	}
1656 
1657 	BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
1658 	err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
1659 	if (err) {
1660 		ext4_warning(sb, "error %d on journal write access", err);
1661 		goto errout;
1662 	}
1663 
1664 	ext4_blocks_count_set(es, o_blocks_count + add);
1665 	ext4_free_blocks_count_set(es, ext4_free_blocks_count(es) + add);
1666 	ext4_debug("freeing blocks %llu through %llu\n", o_blocks_count,
1667 		   o_blocks_count + add);
1668 	/* We add the blocks to the bitmap and set the group need init bit */
1669 	err = ext4_group_add_blocks(handle, sb, o_blocks_count, add);
1670 	if (err)
1671 		goto errout;
1672 	ext4_handle_dirty_super(handle, sb);
1673 	ext4_debug("freed blocks %llu through %llu\n", o_blocks_count,
1674 		   o_blocks_count + add);
1675 errout:
1676 	err2 = ext4_journal_stop(handle);
1677 	if (err2 && !err)
1678 		err = err2;
1679 
1680 	if (!err) {
1681 		if (test_opt(sb, DEBUG))
1682 			printk(KERN_DEBUG "EXT4-fs: extended group to %llu "
1683 			       "blocks\n", ext4_blocks_count(es));
1684 		update_backups(sb, EXT4_SB(sb)->s_sbh->b_blocknr,
1685 			       (char *)es, sizeof(struct ext4_super_block), 0);
1686 	}
1687 	return err;
1688 }
1689 
1690 /*
1691  * Extend the filesystem to the new number of blocks specified.  This entry
1692  * point is only used to extend the current filesystem to the end of the last
1693  * existing group.  It can be accessed via ioctl, or by "remount,resize=<size>"
1694  * for emergencies (because it has no dependencies on reserved blocks).
1695  *
1696  * If we _really_ wanted, we could use default values to call ext4_group_add()
1697  * allow the "remount" trick to work for arbitrary resizing, assuming enough
1698  * GDT blocks are reserved to grow to the desired size.
1699  */
1700 int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
1701 		      ext4_fsblk_t n_blocks_count)
1702 {
1703 	ext4_fsblk_t o_blocks_count;
1704 	ext4_grpblk_t last;
1705 	ext4_grpblk_t add;
1706 	struct buffer_head *bh;
1707 	int err;
1708 	ext4_group_t group;
1709 
1710 	o_blocks_count = ext4_blocks_count(es);
1711 
1712 	if (test_opt(sb, DEBUG))
1713 		ext4_msg(sb, KERN_DEBUG,
1714 			 "extending last group from %llu to %llu blocks",
1715 			 o_blocks_count, n_blocks_count);
1716 
1717 	if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
1718 		return 0;
1719 
1720 	if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
1721 		ext4_msg(sb, KERN_ERR,
1722 			 "filesystem too large to resize to %llu blocks safely",
1723 			 n_blocks_count);
1724 		if (sizeof(sector_t) < 8)
1725 			ext4_warning(sb, "CONFIG_LBDAF not enabled");
1726 		return -EINVAL;
1727 	}
1728 
1729 	if (n_blocks_count < o_blocks_count) {
1730 		ext4_warning(sb, "can't shrink FS - resize aborted");
1731 		return -EINVAL;
1732 	}
1733 
1734 	/* Handle the remaining blocks in the last group only. */
1735 	ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
1736 
1737 	if (last == 0) {
1738 		ext4_warning(sb, "need to use ext2online to resize further");
1739 		return -EPERM;
1740 	}
1741 
1742 	add = EXT4_BLOCKS_PER_GROUP(sb) - last;
1743 
1744 	if (o_blocks_count + add < o_blocks_count) {
1745 		ext4_warning(sb, "blocks_count overflow");
1746 		return -EINVAL;
1747 	}
1748 
1749 	if (o_blocks_count + add > n_blocks_count)
1750 		add = n_blocks_count - o_blocks_count;
1751 
1752 	if (o_blocks_count + add < n_blocks_count)
1753 		ext4_warning(sb, "will only finish group (%llu blocks, %u new)",
1754 			     o_blocks_count + add, add);
1755 
1756 	/* See if the device is actually as big as what was requested */
1757 	bh = sb_bread(sb, o_blocks_count + add - 1);
1758 	if (!bh) {
1759 		ext4_warning(sb, "can't read last block, resize aborted");
1760 		return -ENOSPC;
1761 	}
1762 	brelse(bh);
1763 
1764 	err = ext4_group_extend_no_check(sb, o_blocks_count, add);
1765 	return err;
1766 } /* ext4_group_extend */
1767 
1768 
1769 static int num_desc_blocks(struct super_block *sb, ext4_group_t groups)
1770 {
1771 	return (groups + EXT4_DESC_PER_BLOCK(sb) - 1) / EXT4_DESC_PER_BLOCK(sb);
1772 }
1773 
1774 /*
1775  * Release the resize inode and drop the resize_inode feature if there
1776  * are no more reserved gdt blocks, and then convert the file system
1777  * to enable meta_bg
1778  */
1779 static int ext4_convert_meta_bg(struct super_block *sb, struct inode *inode)
1780 {
1781 	handle_t *handle;
1782 	struct ext4_sb_info *sbi = EXT4_SB(sb);
1783 	struct ext4_super_block *es = sbi->s_es;
1784 	struct ext4_inode_info *ei = EXT4_I(inode);
1785 	ext4_fsblk_t nr;
1786 	int i, ret, err = 0;
1787 	int credits = 1;
1788 
1789 	ext4_msg(sb, KERN_INFO, "Converting file system to meta_bg");
1790 	if (inode) {
1791 		if (es->s_reserved_gdt_blocks) {
1792 			ext4_error(sb, "Unexpected non-zero "
1793 				   "s_reserved_gdt_blocks");
1794 			return -EPERM;
1795 		}
1796 
1797 		/* Do a quick sanity check of the resize inode */
1798 		if (inode->i_blocks != 1 << (inode->i_blkbits - 9))
1799 			goto invalid_resize_inode;
1800 		for (i = 0; i < EXT4_N_BLOCKS; i++) {
1801 			if (i == EXT4_DIND_BLOCK) {
1802 				if (ei->i_data[i])
1803 					continue;
1804 				else
1805 					goto invalid_resize_inode;
1806 			}
1807 			if (ei->i_data[i])
1808 				goto invalid_resize_inode;
1809 		}
1810 		credits += 3;	/* block bitmap, bg descriptor, resize inode */
1811 	}
1812 
1813 	handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, credits);
1814 	if (IS_ERR(handle))
1815 		return PTR_ERR(handle);
1816 
1817 	BUFFER_TRACE(sbi->s_sbh, "get_write_access");
1818 	err = ext4_journal_get_write_access(handle, sbi->s_sbh);
1819 	if (err)
1820 		goto errout;
1821 
1822 	ext4_clear_feature_resize_inode(sb);
1823 	ext4_set_feature_meta_bg(sb);
1824 	sbi->s_es->s_first_meta_bg =
1825 		cpu_to_le32(num_desc_blocks(sb, sbi->s_groups_count));
1826 
1827 	err = ext4_handle_dirty_super(handle, sb);
1828 	if (err) {
1829 		ext4_std_error(sb, err);
1830 		goto errout;
1831 	}
1832 
1833 	if (inode) {
1834 		nr = le32_to_cpu(ei->i_data[EXT4_DIND_BLOCK]);
1835 		ext4_free_blocks(handle, inode, NULL, nr, 1,
1836 				 EXT4_FREE_BLOCKS_METADATA |
1837 				 EXT4_FREE_BLOCKS_FORGET);
1838 		ei->i_data[EXT4_DIND_BLOCK] = 0;
1839 		inode->i_blocks = 0;
1840 
1841 		err = ext4_mark_inode_dirty(handle, inode);
1842 		if (err)
1843 			ext4_std_error(sb, err);
1844 	}
1845 
1846 errout:
1847 	ret = ext4_journal_stop(handle);
1848 	if (!err)
1849 		err = ret;
1850 	return ret;
1851 
1852 invalid_resize_inode:
1853 	ext4_error(sb, "corrupted/inconsistent resize inode");
1854 	return -EINVAL;
1855 }
1856 
1857 /*
1858  * ext4_resize_fs() resizes a fs to new size specified by @n_blocks_count
1859  *
1860  * @sb: super block of the fs to be resized
1861  * @n_blocks_count: the number of blocks resides in the resized fs
1862  */
1863 int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
1864 {
1865 	struct ext4_new_flex_group_data *flex_gd = NULL;
1866 	struct ext4_sb_info *sbi = EXT4_SB(sb);
1867 	struct ext4_super_block *es = sbi->s_es;
1868 	struct buffer_head *bh;
1869 	struct inode *resize_inode = NULL;
1870 	ext4_grpblk_t add, offset;
1871 	unsigned long n_desc_blocks;
1872 	unsigned long o_desc_blocks;
1873 	ext4_group_t o_group;
1874 	ext4_group_t n_group;
1875 	ext4_fsblk_t o_blocks_count;
1876 	ext4_fsblk_t n_blocks_count_retry = 0;
1877 	unsigned long last_update_time = 0;
1878 	int err = 0, flexbg_size = 1 << sbi->s_log_groups_per_flex;
1879 	int meta_bg;
1880 
1881 	/* See if the device is actually as big as what was requested */
1882 	bh = sb_bread(sb, n_blocks_count - 1);
1883 	if (!bh) {
1884 		ext4_warning(sb, "can't read last block, resize aborted");
1885 		return -ENOSPC;
1886 	}
1887 	brelse(bh);
1888 
1889 retry:
1890 	o_blocks_count = ext4_blocks_count(es);
1891 
1892 	ext4_msg(sb, KERN_INFO, "resizing filesystem from %llu "
1893 		 "to %llu blocks", o_blocks_count, n_blocks_count);
1894 
1895 	if (n_blocks_count < o_blocks_count) {
1896 		/* On-line shrinking not supported */
1897 		ext4_warning(sb, "can't shrink FS - resize aborted");
1898 		return -EINVAL;
1899 	}
1900 
1901 	if (n_blocks_count == o_blocks_count)
1902 		/* Nothing need to do */
1903 		return 0;
1904 
1905 	n_group = ext4_get_group_number(sb, n_blocks_count - 1);
1906 	if (n_group > (0xFFFFFFFFUL / EXT4_INODES_PER_GROUP(sb))) {
1907 		ext4_warning(sb, "resize would cause inodes_count overflow");
1908 		return -EINVAL;
1909 	}
1910 	ext4_get_group_no_and_offset(sb, o_blocks_count - 1, &o_group, &offset);
1911 
1912 	n_desc_blocks = num_desc_blocks(sb, n_group + 1);
1913 	o_desc_blocks = num_desc_blocks(sb, sbi->s_groups_count);
1914 
1915 	meta_bg = ext4_has_feature_meta_bg(sb);
1916 
1917 	if (ext4_has_feature_resize_inode(sb)) {
1918 		if (meta_bg) {
1919 			ext4_error(sb, "resize_inode and meta_bg enabled "
1920 				   "simultaneously");
1921 			return -EINVAL;
1922 		}
1923 		if (n_desc_blocks > o_desc_blocks +
1924 		    le16_to_cpu(es->s_reserved_gdt_blocks)) {
1925 			n_blocks_count_retry = n_blocks_count;
1926 			n_desc_blocks = o_desc_blocks +
1927 				le16_to_cpu(es->s_reserved_gdt_blocks);
1928 			n_group = n_desc_blocks * EXT4_DESC_PER_BLOCK(sb);
1929 			n_blocks_count = n_group * EXT4_BLOCKS_PER_GROUP(sb);
1930 			n_group--; /* set to last group number */
1931 		}
1932 
1933 		if (!resize_inode)
1934 			resize_inode = ext4_iget(sb, EXT4_RESIZE_INO);
1935 		if (IS_ERR(resize_inode)) {
1936 			ext4_warning(sb, "Error opening resize inode");
1937 			return PTR_ERR(resize_inode);
1938 		}
1939 	}
1940 
1941 	if ((!resize_inode && !meta_bg) || n_blocks_count == o_blocks_count) {
1942 		err = ext4_convert_meta_bg(sb, resize_inode);
1943 		if (err)
1944 			goto out;
1945 		if (resize_inode) {
1946 			iput(resize_inode);
1947 			resize_inode = NULL;
1948 		}
1949 		if (n_blocks_count_retry) {
1950 			n_blocks_count = n_blocks_count_retry;
1951 			n_blocks_count_retry = 0;
1952 			goto retry;
1953 		}
1954 	}
1955 
1956 	/* extend the last group */
1957 	if (n_group == o_group)
1958 		add = n_blocks_count - o_blocks_count;
1959 	else
1960 		add = EXT4_BLOCKS_PER_GROUP(sb) - (offset + 1);
1961 	if (add > 0) {
1962 		err = ext4_group_extend_no_check(sb, o_blocks_count, add);
1963 		if (err)
1964 			goto out;
1965 	}
1966 
1967 	if (ext4_blocks_count(es) == n_blocks_count)
1968 		goto out;
1969 
1970 	err = ext4_alloc_flex_bg_array(sb, n_group + 1);
1971 	if (err)
1972 		return err;
1973 
1974 	err = ext4_mb_alloc_groupinfo(sb, n_group + 1);
1975 	if (err)
1976 		goto out;
1977 
1978 	flex_gd = alloc_flex_gd(flexbg_size);
1979 	if (flex_gd == NULL) {
1980 		err = -ENOMEM;
1981 		goto out;
1982 	}
1983 
1984 	/* Add flex groups. Note that a regular group is a
1985 	 * flex group with 1 group.
1986 	 */
1987 	while (ext4_setup_next_flex_gd(sb, flex_gd, n_blocks_count,
1988 					      flexbg_size)) {
1989 		if (jiffies - last_update_time > HZ * 10) {
1990 			if (last_update_time)
1991 				ext4_msg(sb, KERN_INFO,
1992 					 "resized to %llu blocks",
1993 					 ext4_blocks_count(es));
1994 			last_update_time = jiffies;
1995 		}
1996 		if (ext4_alloc_group_tables(sb, flex_gd, flexbg_size) != 0)
1997 			break;
1998 		err = ext4_flex_group_add(sb, resize_inode, flex_gd);
1999 		if (unlikely(err))
2000 			break;
2001 	}
2002 
2003 	if (!err && n_blocks_count_retry) {
2004 		n_blocks_count = n_blocks_count_retry;
2005 		n_blocks_count_retry = 0;
2006 		free_flex_gd(flex_gd);
2007 		flex_gd = NULL;
2008 		goto retry;
2009 	}
2010 
2011 out:
2012 	if (flex_gd)
2013 		free_flex_gd(flex_gd);
2014 	if (resize_inode != NULL)
2015 		iput(resize_inode);
2016 	ext4_msg(sb, KERN_INFO, "resized filesystem to %llu", n_blocks_count);
2017 	return err;
2018 }
2019