Initial import

1 files changed, 1117 insertions, 0 deletions

diff --git a/fs/ext3/resize.c b/fs/ext3/resize.c
new file mode 100644
index 000000000..271056555
--- /dev/null
+++ b/fs/ext3/resize.c
@@ -0,0 +1,1117 @@
+/*
+ *  linux/fs/ext3/resize.c
+ *
+ * Support for resizing an ext3 filesystem while it is mounted.
+ *
+ * Copyright (C) 2001, 2002 Andreas Dilger <adilger@clusterfs.com>
+ *
+ * This could probably be made into a module, because it is not often in use.
+ */
+
+
+#define EXT3FS_DEBUG
+
+#include "ext3.h"
+
+
+#define outside(b, first, last)	((b) < (first) || (b) >= (last))
+#define inside(b, first, last)	((b) >= (first) && (b) < (last))
+
+static int verify_group_input(struct super_block *sb,
+			      struct ext3_new_group_data *input)
+{
+	struct ext3_sb_info *sbi = EXT3_SB(sb);
+	struct ext3_super_block *es = sbi->s_es;
+	ext3_fsblk_t start = le32_to_cpu(es->s_blocks_count);
+	ext3_fsblk_t end = start + input->blocks_count;
+	unsigned group = input->group;
+	ext3_fsblk_t itend = input->inode_table + sbi->s_itb_per_group;
+	unsigned overhead = ext3_bg_has_super(sb, group) ?
+		(1 + ext3_bg_num_gdb(sb, group) +
+		 le16_to_cpu(es->s_reserved_gdt_blocks)) : 0;
+	ext3_fsblk_t metaend = start + overhead;
+	struct buffer_head *bh = NULL;
+	ext3_grpblk_t free_blocks_count;
+	int err = -EINVAL;
+
+	input->free_blocks_count = free_blocks_count =
+		input->blocks_count - 2 - overhead - sbi->s_itb_per_group;
+
+	if (test_opt(sb, DEBUG))
+		printk(KERN_DEBUG "EXT3-fs: adding %s group %u: %u blocks "
+		       "(%d free, %u reserved)\n",
+		       ext3_bg_has_super(sb, input->group) ? "normal" :
+		       "no-super", input->group, input->blocks_count,
+		       free_blocks_count, input->reserved_blocks);
+
+	if (group != sbi->s_groups_count)
+		ext3_warning(sb, __func__,
+			     "Cannot add at group %u (only %lu groups)",
+			     input->group, sbi->s_groups_count);
+	else if ((start - le32_to_cpu(es->s_first_data_block)) %
+		 EXT3_BLOCKS_PER_GROUP(sb))
+		ext3_warning(sb, __func__, "Last group not full");
+	else if (input->reserved_blocks > input->blocks_count / 5)
+		ext3_warning(sb, __func__, "Reserved blocks too high (%u)",
+			     input->reserved_blocks);
+	else if (free_blocks_count < 0)
+		ext3_warning(sb, __func__, "Bad blocks count %u",
+			     input->blocks_count);
+	else if (!(bh = sb_bread(sb, end - 1)))
+		ext3_warning(sb, __func__,
+			     "Cannot read last block ("E3FSBLK")",
+			     end - 1);
+	else if (outside(input->block_bitmap, start, end))
+		ext3_warning(sb, __func__,
+			     "Block bitmap not in group (block %u)",
+			     input->block_bitmap);
+	else if (outside(input->inode_bitmap, start, end))
+		ext3_warning(sb, __func__,
+			     "Inode bitmap not in group (block %u)",
+			     input->inode_bitmap);
+	else if (outside(input->inode_table, start, end) ||
+	         outside(itend - 1, start, end))
+		ext3_warning(sb, __func__,
+			     "Inode table not in group (blocks %u-"E3FSBLK")",
+			     input->inode_table, itend - 1);
+	else if (input->inode_bitmap == input->block_bitmap)
+		ext3_warning(sb, __func__,
+			     "Block bitmap same as inode bitmap (%u)",
+			     input->block_bitmap);
+	else if (inside(input->block_bitmap, input->inode_table, itend))
+		ext3_warning(sb, __func__,
+			     "Block bitmap (%u) in inode table (%u-"E3FSBLK")",
+			     input->block_bitmap, input->inode_table, itend-1);
+	else if (inside(input->inode_bitmap, input->inode_table, itend))
+		ext3_warning(sb, __func__,
+			     "Inode bitmap (%u) in inode table (%u-"E3FSBLK")",
+			     input->inode_bitmap, input->inode_table, itend-1);
+	else if (inside(input->block_bitmap, start, metaend))
+		ext3_warning(sb, __func__,
+			     "Block bitmap (%u) in GDT table"
+			     " ("E3FSBLK"-"E3FSBLK")",
+			     input->block_bitmap, start, metaend - 1);
+	else if (inside(input->inode_bitmap, start, metaend))
+		ext3_warning(sb, __func__,
+			     "Inode bitmap (%u) in GDT table"
+			     " ("E3FSBLK"-"E3FSBLK")",
+			     input->inode_bitmap, start, metaend - 1);
+	else if (inside(input->inode_table, start, metaend) ||
+	         inside(itend - 1, start, metaend))
+		ext3_warning(sb, __func__,
+			     "Inode table (%u-"E3FSBLK") overlaps"
+			     "GDT table ("E3FSBLK"-"E3FSBLK")",
+			     input->inode_table, itend - 1, start, metaend - 1);
+	else
+		err = 0;
+	brelse(bh);
+
+	return err;
+}
+
+static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
+				  ext3_fsblk_t blk)
+{
+	struct buffer_head *bh;
+	int err;
+
+	bh = sb_getblk(sb, blk);
+	if (unlikely(!bh))
+		return ERR_PTR(-ENOMEM);
+	if ((err = ext3_journal_get_write_access(handle, bh))) {
+		brelse(bh);
+		bh = ERR_PTR(err);
+	} else {
+		lock_buffer(bh);
+		memset(bh->b_data, 0, sb->s_blocksize);
+		set_buffer_uptodate(bh);
+		unlock_buffer(bh);
+	}
+
+	return bh;
+}
+
+/*
+ * To avoid calling the atomic setbit hundreds or thousands of times, we only
+ * need to use it within a single byte (to ensure we get endianness right).
+ * We can use memset for the rest of the bitmap as there are no other users.
+ */
+static void mark_bitmap_end(int start_bit, int end_bit, char *bitmap)
+{
+	int i;
+
+	if (start_bit >= end_bit)
+		return;
+
+	ext3_debug("mark end bits +%d through +%d used\n", start_bit, end_bit);
+	for (i = start_bit; i < ((start_bit + 7) & ~7UL); i++)
+		ext3_set_bit(i, bitmap);
+	if (i < end_bit)
+		memset(bitmap + (i >> 3), 0xff, (end_bit - i) >> 3);
+}
+
+/*
+ * If we have fewer than thresh credits, extend by EXT3_MAX_TRANS_DATA.
+ * If that fails, restart the transaction & regain write access for the
+ * buffer head which is used for block_bitmap modifications.
+ */
+static int extend_or_restart_transaction(handle_t *handle, int thresh,
+					 struct buffer_head *bh)
+{
+	int err;
+
+	if (handle->h_buffer_credits >= thresh)
+		return 0;
+
+	err = ext3_journal_extend(handle, EXT3_MAX_TRANS_DATA);
+	if (err < 0)
+		return err;
+	if (err) {
+		err = ext3_journal_restart(handle, EXT3_MAX_TRANS_DATA);
+		if (err)
+			return err;
+		err = ext3_journal_get_write_access(handle, bh);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+/*
+ * Set up the block and inode bitmaps, and the inode table for the new group.
+ * This doesn't need to be part of the main transaction, since we are only
+ * changing blocks outside the actual filesystem.  We still do journaling to
+ * ensure the recovery is correct in case of a failure just after resize.
+ * If any part of this fails, we simply abort the resize.
+ */
+static int setup_new_group_blocks(struct super_block *sb,
+				  struct ext3_new_group_data *input)
+{
+	struct ext3_sb_info *sbi = EXT3_SB(sb);
+	ext3_fsblk_t start = ext3_group_first_block_no(sb, input->group);
+	int reserved_gdb = ext3_bg_has_super(sb, input->group) ?
+		le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks) : 0;
+	unsigned long gdblocks = ext3_bg_num_gdb(sb, input->group);
+	struct buffer_head *bh;
+	handle_t *handle;
+	ext3_fsblk_t block;
+	ext3_grpblk_t bit;
+	int i;
+	int err = 0, err2;
+
+	/* This transaction may be extended/restarted along the way */
+	handle = ext3_journal_start_sb(sb, EXT3_MAX_TRANS_DATA);
+
+	if (IS_ERR(handle))
+		return PTR_ERR(handle);
+
+	mutex_lock(&sbi->s_resize_lock);
+	if (input->group != sbi->s_groups_count) {
+		err = -EBUSY;
+		goto exit_journal;
+	}
+
+	if (IS_ERR(bh = bclean(handle, sb, input->block_bitmap))) {
+		err = PTR_ERR(bh);
+		goto exit_journal;
+	}
+
+	if (ext3_bg_has_super(sb, input->group)) {
+		ext3_debug("mark backup superblock %#04lx (+0)\n", start);
+		ext3_set_bit(0, bh->b_data);
+	}
+
+	/* Copy all of the GDT blocks into the backup in this group */
+	for (i = 0, bit = 1, block = start + 1;
+	     i < gdblocks; i++, block++, bit++) {
+		struct buffer_head *gdb;
+
+		ext3_debug("update backup group %#04lx (+%d)\n", block, bit);
+
+		err = extend_or_restart_transaction(handle, 1, bh);
+		if (err)
+			goto exit_bh;
+
+		gdb = sb_getblk(sb, block);
+		if (unlikely(!gdb)) {
+			err = -ENOMEM;
+			goto exit_bh;
+		}
+		if ((err = ext3_journal_get_write_access(handle, gdb))) {
+			brelse(gdb);
+			goto exit_bh;
+		}
+		lock_buffer(gdb);
+		memcpy(gdb->b_data, sbi->s_group_desc[i]->b_data, gdb->b_size);
+		set_buffer_uptodate(gdb);
+		unlock_buffer(gdb);
+		err = ext3_journal_dirty_metadata(handle, gdb);
+		if (err) {
+			brelse(gdb);
+			goto exit_bh;
+		}
+		ext3_set_bit(bit, bh->b_data);
+		brelse(gdb);
+	}
+
+	/* Zero out all of the reserved backup group descriptor table blocks */
+	for (i = 0, bit = gdblocks + 1, block = start + bit;
+	     i < reserved_gdb; i++, block++, bit++) {
+		struct buffer_head *gdb;
+
+		ext3_debug("clear reserved block %#04lx (+%d)\n", block, bit);
+
+		err = extend_or_restart_transaction(handle, 1, bh);
+		if (err)
+			goto exit_bh;
+
+		if (IS_ERR(gdb = bclean(handle, sb, block))) {
+			err = PTR_ERR(gdb);
+			goto exit_bh;
+		}
+		err = ext3_journal_dirty_metadata(handle, gdb);
+		if (err) {
+			brelse(gdb);
+			goto exit_bh;
+		}
+		ext3_set_bit(bit, bh->b_data);
+		brelse(gdb);
+	}
+	ext3_debug("mark block bitmap %#04x (+%ld)\n", input->block_bitmap,
+		   input->block_bitmap - start);
+	ext3_set_bit(input->block_bitmap - start, bh->b_data);
+	ext3_debug("mark inode bitmap %#04x (+%ld)\n", input->inode_bitmap,
+		   input->inode_bitmap - start);
+	ext3_set_bit(input->inode_bitmap - start, bh->b_data);
+
+	/* Zero out all of the inode table blocks */
+	for (i = 0, block = input->inode_table, bit = block - start;
+	     i < sbi->s_itb_per_group; i++, bit++, block++) {
+		struct buffer_head *it;
+
+		ext3_debug("clear inode block %#04lx (+%d)\n", block, bit);
+
+		err = extend_or_restart_transaction(handle, 1, bh);
+		if (err)
+			goto exit_bh;
+
+		if (IS_ERR(it = bclean(handle, sb, block))) {
+			err = PTR_ERR(it);
+			goto exit_bh;
+		}
+		err = ext3_journal_dirty_metadata(handle, it);
+		if (err) {
+			brelse(it);
+			goto exit_bh;
+		}
+		brelse(it);
+		ext3_set_bit(bit, bh->b_data);
+	}
+
+	err = extend_or_restart_transaction(handle, 2, bh);
+	if (err)
+		goto exit_bh;
+
+	mark_bitmap_end(input->blocks_count, EXT3_BLOCKS_PER_GROUP(sb),
+			bh->b_data);
+	err = ext3_journal_dirty_metadata(handle, bh);
+	if (err)
+		goto exit_bh;
+	brelse(bh);
+
+	/* Mark unused entries in inode bitmap used */
+	ext3_debug("clear inode bitmap %#04x (+%ld)\n",
+		   input->inode_bitmap, input->inode_bitmap - start);
+	if (IS_ERR(bh = bclean(handle, sb, input->inode_bitmap))) {
+		err = PTR_ERR(bh);
+		goto exit_journal;
+	}
+
+	mark_bitmap_end(EXT3_INODES_PER_GROUP(sb), EXT3_BLOCKS_PER_GROUP(sb),
+			bh->b_data);
+	err = ext3_journal_dirty_metadata(handle, bh);
+exit_bh:
+	brelse(bh);
+
+exit_journal:
+	mutex_unlock(&sbi->s_resize_lock);
+	if ((err2 = ext3_journal_stop(handle)) && !err)
+		err = err2;
+
+	return err;
+}
+
+/*
+ * Iterate through the groups which hold BACKUP superblock/GDT copies in an
+ * ext3 filesystem.  The counters should be initialized to 1, 5, and 7 before
+ * calling this for the first time.  In a sparse filesystem it will be the
+ * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
+ * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
+ */
+static unsigned ext3_list_backups(struct super_block *sb, unsigned *three,
+				  unsigned *five, unsigned *seven)
+{
+	unsigned *min = three;
+	int mult = 3;
+	unsigned ret;
+
+	if (!EXT3_HAS_RO_COMPAT_FEATURE(sb,
+					EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
+		ret = *min;
+		*min += 1;
+		return ret;
+	}
+
+	if (*five < *min) {
+		min = five;
+		mult = 5;
+	}
+	if (*seven < *min) {
+		min = seven;
+		mult = 7;
+	}
+
+	ret = *min;
+	*min *= mult;
+
+	return ret;
+}
+
+/*
+ * Check that all of the backup GDT blocks are held in the primary GDT block.
+ * It is assumed that they are stored in group order.  Returns the number of
+ * groups in current filesystem that have BACKUPS, or -ve error code.
+ */
+static int verify_reserved_gdb(struct super_block *sb,
+			       struct buffer_head *primary)
+{
+	const ext3_fsblk_t blk = primary->b_blocknr;
+	const unsigned long end = EXT3_SB(sb)->s_groups_count;
+	unsigned three = 1;
+	unsigned five = 5;
+	unsigned seven = 7;
+	unsigned grp;
+	__le32 *p = (__le32 *)primary->b_data;
+	int gdbackups = 0;
+
+	while ((grp = ext3_list_backups(sb, &three, &five, &seven)) < end) {
+		if (le32_to_cpu(*p++) != grp * EXT3_BLOCKS_PER_GROUP(sb) + blk){
+			ext3_warning(sb, __func__,
+				     "reserved GDT "E3FSBLK
+				     " missing grp %d ("E3FSBLK")",
+				     blk, grp,
+				     grp * EXT3_BLOCKS_PER_GROUP(sb) + blk);
+			return -EINVAL;
+		}
+		if (++gdbackups > EXT3_ADDR_PER_BLOCK(sb))
+			return -EFBIG;
+	}
+
+	return gdbackups;
+}
+
+/*
+ * Called when we need to bring a reserved group descriptor table block into
+ * use from the resize inode.  The primary copy of the new GDT block currently
+ * is an indirect block (under the double indirect block in the resize inode).
+ * The new backup GDT blocks will be stored as leaf blocks in this indirect
+ * block, in group order.  Even though we know all the block numbers we need,
+ * we check to ensure that the resize inode has actually reserved these blocks.
+ *
+ * Don't need to update the block bitmaps because the blocks are still in use.
+ *
+ * We get all of the error cases out of the way, so that we are sure to not
+ * fail once we start modifying the data on disk, because JBD has no rollback.
+ */
+static int add_new_gdb(handle_t *handle, struct inode *inode,
+		       struct ext3_new_group_data *input,
+		       struct buffer_head **primary)
+{
+	struct super_block *sb = inode->i_sb;
+	struct ext3_super_block *es = EXT3_SB(sb)->s_es;
+	unsigned long gdb_num = input->group / EXT3_DESC_PER_BLOCK(sb);
+	ext3_fsblk_t gdblock = EXT3_SB(sb)->s_sbh->b_blocknr + 1 + gdb_num;
+	struct buffer_head **o_group_desc, **n_group_desc;
+	struct buffer_head *dind;
+	int gdbackups;
+	struct ext3_iloc iloc;
+	__le32 *data;
+	int err;
+
+	if (test_opt(sb, DEBUG))
+		printk(KERN_DEBUG
+		       "EXT3-fs: ext3_add_new_gdb: adding group block %lu\n",
+		       gdb_num);
+
+	/*
+	 * If we are not using the primary superblock/GDT copy don't resize,
+	 * because the user tools have no way of handling this.  Probably a
+	 * bad time to do it anyways.
+	 */
+	if (EXT3_SB(sb)->s_sbh->b_blocknr !=
+	    le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block)) {
+		ext3_warning(sb, __func__,
+			"won't resize using backup superblock at %llu",
+			(unsigned long long)EXT3_SB(sb)->s_sbh->b_blocknr);
+		return -EPERM;
+	}
+
+	*primary = sb_bread(sb, gdblock);
+	if (!*primary)
+		return -EIO;
+
+	if ((gdbackups = verify_reserved_gdb(sb, *primary)) < 0) {
+		err = gdbackups;
+		goto exit_bh;
+	}
+
+	data = EXT3_I(inode)->i_data + EXT3_DIND_BLOCK;
+	dind = sb_bread(sb, le32_to_cpu(*data));
+	if (!dind) {
+		err = -EIO;
+		goto exit_bh;
+	}
+
+	data = (__le32 *)dind->b_data;
+	if (le32_to_cpu(data[gdb_num % EXT3_ADDR_PER_BLOCK(sb)]) != gdblock) {
+		ext3_warning(sb, __func__,
+			     "new group %u GDT block "E3FSBLK" not reserved",
+			     input->group, gdblock);
+		err = -EINVAL;
+		goto exit_dind;
+	}
+
+	if ((err = ext3_journal_get_write_access(handle, EXT3_SB(sb)->s_sbh)))
+		goto exit_dind;
+
+	if ((err = ext3_journal_get_write_access(handle, *primary)))
+		goto exit_sbh;
+
+	if ((err = ext3_journal_get_write_access(handle, dind)))
+		goto exit_primary;
+
+	/* ext3_reserve_inode_write() gets a reference on the iloc */
+	if ((err = ext3_reserve_inode_write(handle, inode, &iloc)))
+		goto exit_dindj;
+
+	n_group_desc = kmalloc((gdb_num + 1) * sizeof(struct buffer_head *),
+			GFP_NOFS);
+	if (!n_group_desc) {
+		err = -ENOMEM;
+		ext3_warning (sb, __func__,
+			      "not enough memory for %lu groups", gdb_num + 1);
+		goto exit_inode;
+	}
+
+	/*
+	 * Finally, we have all of the possible failures behind us...
+	 *
+	 * Remove new GDT block from inode double-indirect block and clear out
+	 * the new GDT block for use (which also "frees" the backup GDT blocks
+	 * from the reserved inode).  We don't need to change the bitmaps for
+	 * these blocks, because they are marked as in-use from being in the
+	 * reserved inode, and will become GDT blocks (primary and backup).
+	 */
+	data[gdb_num % EXT3_ADDR_PER_BLOCK(sb)] = 0;
+	err = ext3_journal_dirty_metadata(handle, dind);
+	if (err)
+		goto exit_group_desc;
+	brelse(dind);
+	dind = NULL;
+	inode->i_blocks -= (gdbackups + 1) * sb->s_blocksize >> 9;
+	err = ext3_mark_iloc_dirty(handle, inode, &iloc);
+	if (err)
+		goto exit_group_desc;
+	memset((*primary)->b_data, 0, sb->s_blocksize);
+	err = ext3_journal_dirty_metadata(handle, *primary);
+	if (err)
+		goto exit_group_desc;
+
+	o_group_desc = EXT3_SB(sb)->s_group_desc;
+	memcpy(n_group_desc, o_group_desc,
+	       EXT3_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
+	n_group_desc[gdb_num] = *primary;
+	EXT3_SB(sb)->s_group_desc = n_group_desc;
+	EXT3_SB(sb)->s_gdb_count++;
+	kfree(o_group_desc);
+
+	le16_add_cpu(&es->s_reserved_gdt_blocks, -1);
+	err = ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
+	if (err)
+		goto exit_inode;
+
+	return 0;
+
+exit_group_desc:
+	kfree(n_group_desc);
+exit_inode:
+	//ext3_journal_release_buffer(handle, iloc.bh);
+	brelse(iloc.bh);
+exit_dindj:
+	//ext3_journal_release_buffer(handle, dind);
+exit_primary:
+	//ext3_journal_release_buffer(handle, *primary);
+exit_sbh:
+	//ext3_journal_release_buffer(handle, *primary);
+exit_dind:
+	brelse(dind);
+exit_bh:
+	brelse(*primary);
+
+	ext3_debug("leaving with error %d\n", err);
+	return err;
+}
+
+/*
+ * Called when we are adding a new group which has a backup copy of each of
+ * the GDT blocks (i.e. sparse group) and there are reserved GDT blocks.
+ * We need to add these reserved backup GDT blocks to the resize inode, so
+ * that they are kept for future resizing and not allocated to files.
+ *
+ * Each reserved backup GDT block will go into a different indirect block.
+ * The indirect blocks are actually the primary reserved GDT blocks,
+ * so we know in advance what their block numbers are.  We only get the
+ * double-indirect block to verify it is pointing to the primary reserved
+ * GDT blocks so we don't overwrite a data block by accident.  The reserved
+ * backup GDT blocks are stored in their reserved primary GDT block.
+ */
+static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
+			      struct ext3_new_group_data *input)
+{
+	struct super_block *sb = inode->i_sb;
+	int reserved_gdb =le16_to_cpu(EXT3_SB(sb)->s_es->s_reserved_gdt_blocks);
+	struct buffer_head **primary;
+	struct buffer_head *dind;
+	struct ext3_iloc iloc;
+	ext3_fsblk_t blk;
+	__le32 *data, *end;
+	int gdbackups = 0;
+	int res, i;
+	int err;
+
+	primary = kmalloc(reserved_gdb * sizeof(*primary), GFP_NOFS);
+	if (!primary)
+		return -ENOMEM;
+
+	data = EXT3_I(inode)->i_data + EXT3_DIND_BLOCK;
+	dind = sb_bread(sb, le32_to_cpu(*data));
+	if (!dind) {
+		err = -EIO;
+		goto exit_free;
+	}
+
+	blk = EXT3_SB(sb)->s_sbh->b_blocknr + 1 + EXT3_SB(sb)->s_gdb_count;
+	data = (__le32 *)dind->b_data + (EXT3_SB(sb)->s_gdb_count %
+					 EXT3_ADDR_PER_BLOCK(sb));
+	end = (__le32 *)dind->b_data + EXT3_ADDR_PER_BLOCK(sb);
+
+	/* Get each reserved primary GDT block and verify it holds backups */
+	for (res = 0; res < reserved_gdb; res++, blk++) {
+		if (le32_to_cpu(*data) != blk) {
+			ext3_warning(sb, __func__,
+				     "reserved block "E3FSBLK
+				     " not at offset %ld",
+				     blk,
+				     (long)(data - (__le32 *)dind->b_data));
+			err = -EINVAL;
+			goto exit_bh;
+		}
+		primary[res] = sb_bread(sb, blk);
+		if (!primary[res]) {
+			err = -EIO;
+			goto exit_bh;
+		}
+		if ((gdbackups = verify_reserved_gdb(sb, primary[res])) < 0) {
+			brelse(primary[res]);
+			err = gdbackups;
+			goto exit_bh;
+		}
+		if (++data >= end)
+			data = (__le32 *)dind->b_data;
+	}
+
+	for (i = 0; i < reserved_gdb; i++) {
+		if ((err = ext3_journal_get_write_access(handle, primary[i]))) {
+			/*
+			int j;
+			for (j = 0; j < i; j++)
+				ext3_journal_release_buffer(handle, primary[j]);
+			 */
+			goto exit_bh;
+		}
+	}
+
+	if ((err = ext3_reserve_inode_write(handle, inode, &iloc)))
+		goto exit_bh;
+
+	/*
+	 * Finally we can add each of the reserved backup GDT blocks from
+	 * the new group to its reserved primary GDT block.
+	 */
+	blk = input->group * EXT3_BLOCKS_PER_GROUP(sb);
+	for (i = 0; i < reserved_gdb; i++) {
+		int err2;
+		data = (__le32 *)primary[i]->b_data;
+		/* printk("reserving backup %lu[%u] = %lu\n",
+		       primary[i]->b_blocknr, gdbackups,
+		       blk + primary[i]->b_blocknr); */
+		data[gdbackups] = cpu_to_le32(blk + primary[i]->b_blocknr);
+		err2 = ext3_journal_dirty_metadata(handle, primary[i]);
+		if (!err)
+			err = err2;
+	}
+	inode->i_blocks += reserved_gdb * sb->s_blocksize >> 9;
+	ext3_mark_iloc_dirty(handle, inode, &iloc);
+
+exit_bh:
+	while (--res >= 0)
+		brelse(primary[res]);
+	brelse(dind);
+
+exit_free:
+	kfree(primary);
+
+	return err;
+}
+
+/*
+ * Update the backup copies of the ext3 metadata.  These don't need to be part
+ * of the main resize transaction, because e2fsck will re-write them if there
+ * is a problem (basically only OOM will cause a problem).  However, we
+ * _should_ update the backups if possible, in case the primary gets trashed
+ * for some reason and we need to run e2fsck from a backup superblock.  The
+ * important part is that the new block and inode counts are in the backup
+ * superblocks, and the location of the new group metadata in the GDT backups.
+ *
+ * We do not need take the s_resize_lock for this, because these
+ * blocks are not otherwise touched by the filesystem code when it is
+ * mounted.  We don't need to worry about last changing from
+ * sbi->s_groups_count, because the worst that can happen is that we
+ * do not copy the full number of backups at this time.  The resize
+ * which changed s_groups_count will backup again.
+ */
+static void update_backups(struct super_block *sb,
+			   int blk_off, char *data, int size)
+{
+	struct ext3_sb_info *sbi = EXT3_SB(sb);
+	const unsigned long last = sbi->s_groups_count;
+	const int bpg = EXT3_BLOCKS_PER_GROUP(sb);
+	unsigned three = 1;
+	unsigned five = 5;
+	unsigned seven = 7;
+	unsigned group;
+	int rest = sb->s_blocksize - size;
+	handle_t *handle;
+	int err = 0, err2;
+
+	handle = ext3_journal_start_sb(sb, EXT3_MAX_TRANS_DATA);
+	if (IS_ERR(handle)) {
+		group = 1;
+		err = PTR_ERR(handle);
+		goto exit_err;
+	}
+
+	while ((group = ext3_list_backups(sb, &three, &five, &seven)) < last) {
+		struct buffer_head *bh;
+
+		/* Out of journal space, and can't get more - abort - so sad */
+		if (handle->h_buffer_credits == 0 &&
+		    ext3_journal_extend(handle, EXT3_MAX_TRANS_DATA) &&
+		    (err = ext3_journal_restart(handle, EXT3_MAX_TRANS_DATA)))
+			break;
+
+		bh = sb_getblk(sb, group * bpg + blk_off);
+		if (unlikely(!bh)) {
+			err = -ENOMEM;
+			break;
+		}
+		ext3_debug("update metadata backup %#04lx\n",
+			  (unsigned long)bh->b_blocknr);
+		if ((err = ext3_journal_get_write_access(handle, bh))) {
+			brelse(bh);
+			break;
+		}
+		lock_buffer(bh);
+		memcpy(bh->b_data, data, size);
+		if (rest)
+			memset(bh->b_data + size, 0, rest);
+		set_buffer_uptodate(bh);
+		unlock_buffer(bh);
+		err = ext3_journal_dirty_metadata(handle, bh);
+		brelse(bh);
+		if (err)
+			break;
+	}
+	if ((err2 = ext3_journal_stop(handle)) && !err)
+		err = err2;
+
+	/*
+	 * Ugh! Need to have e2fsck write the backup copies.  It is too
+	 * late to revert the resize, we shouldn't fail just because of
+	 * the backup copies (they are only needed in case of corruption).
+	 *
+	 * However, if we got here we have a journal problem too, so we
+	 * can't really start a transaction to mark the superblock.
+	 * Chicken out and just set the flag on the hope it will be written
+	 * to disk, and if not - we will simply wait until next fsck.
+	 */
+exit_err:
+	if (err) {
+		ext3_warning(sb, __func__,
+			     "can't update backup for group %d (err %d), "
+			     "forcing fsck on next reboot", group, err);
+		sbi->s_mount_state &= ~EXT3_VALID_FS;
+		sbi->s_es->s_state &= cpu_to_le16(~EXT3_VALID_FS);
+		mark_buffer_dirty(sbi->s_sbh);
+	}
+}
+
+/* Add group descriptor data to an existing or new group descriptor block.
+ * Ensure we handle all possible error conditions _before_ we start modifying
+ * the filesystem, because we cannot abort the transaction and not have it
+ * write the data to disk.
+ *
+ * If we are on a GDT block boundary, we need to get the reserved GDT block.
+ * Otherwise, we may need to add backup GDT blocks for a sparse group.
+ *
+ * We only need to hold the superblock lock while we are actually adding
+ * in the new group's counts to the superblock.  Prior to that we have
+ * not really "added" the group at all.  We re-check that we are still
+ * adding in the last group in case things have changed since verifying.
+ */
+int ext3_group_add(struct super_block *sb, struct ext3_new_group_data *input)
+{
+	struct ext3_sb_info *sbi = EXT3_SB(sb);
+	struct ext3_super_block *es = sbi->s_es;
+	int reserved_gdb = ext3_bg_has_super(sb, input->group) ?
+		le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
+	struct buffer_head *primary = NULL;
+	struct ext3_group_desc *gdp;
+	struct inode *inode = NULL;
+	handle_t *handle;
+	int gdb_off, gdb_num;
+	int err, err2;
+
+	gdb_num = input->group / EXT3_DESC_PER_BLOCK(sb);
+	gdb_off = input->group % EXT3_DESC_PER_BLOCK(sb);
+
+	if (gdb_off == 0 && !EXT3_HAS_RO_COMPAT_FEATURE(sb,
+					EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
+		ext3_warning(sb, __func__,
+			     "Can't resize non-sparse filesystem further");
+		return -EPERM;
+	}
+
+	if (le32_to_cpu(es->s_blocks_count) + input->blocks_count <
+	    le32_to_cpu(es->s_blocks_count)) {
+		ext3_warning(sb, __func__, "blocks_count overflow\n");
+		return -EINVAL;
+	}
+
+	if (le32_to_cpu(es->s_inodes_count) + EXT3_INODES_PER_GROUP(sb) <
+	    le32_to_cpu(es->s_inodes_count)) {
+		ext3_warning(sb, __func__, "inodes_count overflow\n");
+		return -EINVAL;
+	}
+
+	if (reserved_gdb || gdb_off == 0) {
+		if (!EXT3_HAS_COMPAT_FEATURE(sb,
+					     EXT3_FEATURE_COMPAT_RESIZE_INODE)
+		    || !le16_to_cpu(es->s_reserved_gdt_blocks)) {
+			ext3_warning(sb, __func__,
+				     "No reserved GDT blocks, can't resize");
+			return -EPERM;
+		}
+		inode = ext3_iget(sb, EXT3_RESIZE_INO);
+		if (IS_ERR(inode)) {
+			ext3_warning(sb, __func__,
+				     "Error opening resize inode");
+			return PTR_ERR(inode);
+		}
+	}
+
+	if ((err = verify_group_input(sb, input)))
+		goto exit_put;
+
+	if ((err = setup_new_group_blocks(sb, input)))
+		goto exit_put;
+
+	/*
+	 * We will always be modifying at least the superblock and a GDT
+	 * block.  If we are adding a group past the last current GDT block,
+	 * we will also modify the inode and the dindirect block.  If we
+	 * are adding a group with superblock/GDT backups  we will also
+	 * modify each of the reserved GDT dindirect blocks.
+	 */
+	handle = ext3_journal_start_sb(sb,
+				       ext3_bg_has_super(sb, input->group) ?
+				       3 + reserved_gdb : 4);
+	if (IS_ERR(handle)) {
+		err = PTR_ERR(handle);
+		goto exit_put;
+	}
+
+	mutex_lock(&sbi->s_resize_lock);
+	if (input->group != sbi->s_groups_count) {
+		ext3_warning(sb, __func__,
+			     "multiple resizers run on filesystem!");
+		err = -EBUSY;
+		goto exit_journal;
+	}
+
+	if ((err = ext3_journal_get_write_access(handle, sbi->s_sbh)))
+		goto exit_journal;
+
+	/*
+	 * We will only either add reserved group blocks to a backup group
+	 * or remove reserved blocks for the first group in a new group block.
+	 * Doing both would be mean more complex code, and sane people don't
+	 * use non-sparse filesystems anymore.  This is already checked above.
+	 */
+	if (gdb_off) {
+		primary = sbi->s_group_desc[gdb_num];
+		if ((err = ext3_journal_get_write_access(handle, primary)))
+			goto exit_journal;
+
+		if (reserved_gdb && ext3_bg_num_gdb(sb, input->group) &&
+		    (err = reserve_backup_gdb(handle, inode, input)))
+			goto exit_journal;
+	} else if ((err = add_new_gdb(handle, inode, input, &primary)))
+		goto exit_journal;
+
+	/*
+	 * OK, now we've set up the new group.  Time to make it active.
+	 *
+	 * We do not lock all allocations via s_resize_lock
+	 * so we have to be safe wrt. concurrent accesses the group
+	 * data.  So we need to be careful to set all of the relevant
+	 * group descriptor data etc. *before* we enable the group.
+	 *
+	 * The key field here is sbi->s_groups_count: as long as
+	 * that retains its old value, nobody is going to access the new
+	 * group.
+	 *
+	 * So first we update all the descriptor metadata for the new
+	 * group; then we update the total disk blocks count; then we
+	 * update the groups count to enable the group; then finally we
+	 * update the free space counts so that the system can start
+	 * using the new disk blocks.
+	 */
+
+	/* Update group descriptor block for new group */
+	gdp = (struct ext3_group_desc *)primary->b_data + gdb_off;
+
+	gdp->bg_block_bitmap = cpu_to_le32(input->block_bitmap);
+	gdp->bg_inode_bitmap = cpu_to_le32(input->inode_bitmap);
+	gdp->bg_inode_table = cpu_to_le32(input->inode_table);
+	gdp->bg_free_blocks_count = cpu_to_le16(input->free_blocks_count);
+	gdp->bg_free_inodes_count = cpu_to_le16(EXT3_INODES_PER_GROUP(sb));
+
+	/*
+	 * Make the new blocks and inodes valid next.  We do this before
+	 * increasing the group count so that once the group is enabled,
+	 * all of its blocks and inodes are already valid.
+	 *
+	 * We always allocate group-by-group, then block-by-block or
+	 * inode-by-inode within a group, so enabling these
+	 * blocks/inodes before the group is live won't actually let us
+	 * allocate the new space yet.
+	 */
+	le32_add_cpu(&es->s_blocks_count, input->blocks_count);
+	le32_add_cpu(&es->s_inodes_count, EXT3_INODES_PER_GROUP(sb));
+
+	/*
+	 * We need to protect s_groups_count against other CPUs seeing
+	 * inconsistent state in the superblock.
+	 *
+	 * The precise rules we use are:
+	 *
+	 * * Writers of s_groups_count *must* hold s_resize_lock
+	 * AND
+	 * * Writers must perform a smp_wmb() after updating all dependent
+	 *   data and before modifying the groups count
+	 *
+	 * * Readers must hold s_resize_lock over the access
+	 * OR
+	 * * Readers must perform an smp_rmb() after reading the groups count
+	 *   and before reading any dependent data.
+	 *
+	 * NB. These rules can be relaxed when checking the group count
+	 * while freeing data, as we can only allocate from a block
+	 * group after serialising against the group count, and we can
+	 * only then free after serialising in turn against that
+	 * allocation.
+	 */
+	smp_wmb();
+
+	/* Update the global fs size fields */
+	sbi->s_groups_count++;
+
+	err = ext3_journal_dirty_metadata(handle, primary);
+	if (err)
+		goto exit_journal;
+
+	/* Update the reserved block counts only once the new group is
+	 * active. */
+	le32_add_cpu(&es->s_r_blocks_count, input->reserved_blocks);
+
+	/* Update the free space counts */
+	percpu_counter_add(&sbi->s_freeblocks_counter,
+			   input->free_blocks_count);
+	percpu_counter_add(&sbi->s_freeinodes_counter,
+			   EXT3_INODES_PER_GROUP(sb));
+
+	err = ext3_journal_dirty_metadata(handle, sbi->s_sbh);
+
+exit_journal:
+	mutex_unlock(&sbi->s_resize_lock);
+	if ((err2 = ext3_journal_stop(handle)) && !err)
+		err = err2;
+	if (!err) {
+		update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
+			       sizeof(struct ext3_super_block));
+		update_backups(sb, primary->b_blocknr, primary->b_data,
+			       primary->b_size);
+	}
+exit_put:
+	iput(inode);
+	return err;
+} /* ext3_group_add */
+
+/* Extend the filesystem to the new number of blocks specified.  This entry
+ * point is only used to extend the current filesystem to the end of the last
+ * existing group.  It can be accessed via ioctl, or by "remount,resize=<size>"
+ * for emergencies (because it has no dependencies on reserved blocks).
+ *
+ * If we _really_ wanted, we could use default values to call ext3_group_add()
+ * allow the "remount" trick to work for arbitrary resizing, assuming enough
+ * GDT blocks are reserved to grow to the desired size.
+ */
+int ext3_group_extend(struct super_block *sb, struct ext3_super_block *es,
+		      ext3_fsblk_t n_blocks_count)
+{
+	ext3_fsblk_t o_blocks_count;
+	ext3_grpblk_t last;
+	ext3_grpblk_t add;
+	struct buffer_head * bh;
+	handle_t *handle;
+	int err;
+	unsigned long freed_blocks;
+
+	/* We don't need to worry about locking wrt other resizers just
+	 * yet: we're going to revalidate es->s_blocks_count after
+	 * taking the s_resize_lock below. */
+	o_blocks_count = le32_to_cpu(es->s_blocks_count);
+
+	if (test_opt(sb, DEBUG))
+		printk(KERN_DEBUG "EXT3-fs: extending last group from "E3FSBLK
+		       " up to "E3FSBLK" blocks\n",
+		       o_blocks_count, n_blocks_count);
+
+	if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
+		return 0;
+
+	if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
+		printk(KERN_ERR "EXT3-fs: filesystem on %s:"
+			" too large to resize to "E3FSBLK" blocks safely\n",
+			sb->s_id, n_blocks_count);
+		if (sizeof(sector_t) < 8)
+			ext3_warning(sb, __func__,
+			"CONFIG_LBDAF not enabled\n");
+		return -EINVAL;
+	}
+
+	if (n_blocks_count < o_blocks_count) {
+		ext3_warning(sb, __func__,
+			     "can't shrink FS - resize aborted");
+		return -EBUSY;
+	}
+
+	/* Handle the remaining blocks in the last group only. */
+	last = (o_blocks_count - le32_to_cpu(es->s_first_data_block)) %
+		EXT3_BLOCKS_PER_GROUP(sb);
+
+	if (last == 0) {
+		ext3_warning(sb, __func__,
+			     "need to use ext2online to resize further");
+		return -EPERM;
+	}
+
+	add = EXT3_BLOCKS_PER_GROUP(sb) - last;
+
+	if (o_blocks_count + add < o_blocks_count) {
+		ext3_warning(sb, __func__, "blocks_count overflow");
+		return -EINVAL;
+	}
+
+	if (o_blocks_count + add > n_blocks_count)
+		add = n_blocks_count - o_blocks_count;
+
+	if (o_blocks_count + add < n_blocks_count)
+		ext3_warning(sb, __func__,
+			     "will only finish group ("E3FSBLK
+			     " blocks, %u new)",
+			     o_blocks_count + add, add);
+
+	/* See if the device is actually as big as what was requested */
+	bh = sb_bread(sb, o_blocks_count + add -1);
+	if (!bh) {
+		ext3_warning(sb, __func__,
+			     "can't read last block, resize aborted");
+		return -ENOSPC;
+	}
+	brelse(bh);
+
+	/* We will update the superblock, one block bitmap, and
+	 * one group descriptor via ext3_free_blocks().
+	 */
+	handle = ext3_journal_start_sb(sb, 3);
+	if (IS_ERR(handle)) {
+		err = PTR_ERR(handle);
+		ext3_warning(sb, __func__, "error %d on journal start",err);
+		goto exit_put;
+	}
+
+	mutex_lock(&EXT3_SB(sb)->s_resize_lock);
+	if (o_blocks_count != le32_to_cpu(es->s_blocks_count)) {
+		ext3_warning(sb, __func__,
+			     "multiple resizers run on filesystem!");
+		mutex_unlock(&EXT3_SB(sb)->s_resize_lock);
+		ext3_journal_stop(handle);
+		err = -EBUSY;
+		goto exit_put;
+	}
+
+	if ((err = ext3_journal_get_write_access(handle,
+						 EXT3_SB(sb)->s_sbh))) {
+		ext3_warning(sb, __func__,
+			     "error %d on journal write access", err);
+		mutex_unlock(&EXT3_SB(sb)->s_resize_lock);
+		ext3_journal_stop(handle);
+		goto exit_put;
+	}
+	es->s_blocks_count = cpu_to_le32(o_blocks_count + add);
+	err = ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
+	mutex_unlock(&EXT3_SB(sb)->s_resize_lock);
+	if (err) {
+		ext3_warning(sb, __func__,
+			     "error %d on journal dirty metadata", err);
+		ext3_journal_stop(handle);
+		goto exit_put;
+	}
+	ext3_debug("freeing blocks "E3FSBLK" through "E3FSBLK"\n",
+		   o_blocks_count, o_blocks_count + add);
+	ext3_free_blocks_sb(handle, sb, o_blocks_count, add, &freed_blocks);
+	ext3_debug("freed blocks "E3FSBLK" through "E3FSBLK"\n",
+		   o_blocks_count, o_blocks_count + add);
+	if ((err = ext3_journal_stop(handle)))
+		goto exit_put;
+	if (test_opt(sb, DEBUG))
+		printk(KERN_DEBUG "EXT3-fs: extended group to %u blocks\n",
+		       le32_to_cpu(es->s_blocks_count));
+	update_backups(sb, EXT3_SB(sb)->s_sbh->b_blocknr, (char *)es,
+		       sizeof(struct ext3_super_block));
+exit_put:
+	return err;
+} /* ext3_group_extend */