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Commit 1c6bd717 authored by Theodore Ts'o's avatar Theodore Ts'o
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ext4: convert file system to meta_bg if needed during resizing



If we have run out of reserved gdt blocks, then clear the resize_inode
feature and enable the meta_bg feature, so that we can continue
resizing the file system seamlessly.

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 93f90526
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+133 −17
Original line number Diff line number Diff line
@@ -1756,6 +1756,99 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
	return err;
} /* ext4_group_extend */


static int num_desc_blocks(struct super_block *sb, ext4_group_t groups)
{
	return (groups + EXT4_DESC_PER_BLOCK(sb) - 1) / EXT4_DESC_PER_BLOCK(sb);
}

/*
 * Release the resize inode and drop the resize_inode feature if there
 * are no more reserved gdt blocks, and then convert the file system
 * to enable meta_bg
 */
static int ext4_convert_meta_bg(struct super_block *sb, struct inode *inode)
{
	handle_t *handle;
	struct ext4_sb_info *sbi = EXT4_SB(sb);
	struct ext4_super_block *es = sbi->s_es;
	struct ext4_inode_info *ei = 0;
	ext4_fsblk_t nr;
	int i, ret, err = 0;
	int credits = 1;

	ext4_msg(sb, KERN_INFO, "Converting file system to meta_bg");
	if (EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_RESIZE_INODE)) {
		if (es->s_reserved_gdt_blocks) {
			ext4_error(sb, "Unexpected non-zero "
				   "s_reserved_gdt_blocks");
			return -EPERM;
		}
		if (!inode) {
			ext4_error(sb, "Unexpected NULL resize_inode");
			return -EPERM;
		}
		ei = EXT4_I(inode);

		/* Do a quick sanity check of the resize inode */
		if (inode->i_blocks != 1 << (inode->i_blkbits - 9))
			goto invalid_resize_inode;
		for (i = 0; i < EXT4_N_BLOCKS; i++) {
			if (i == EXT4_DIND_BLOCK) {
				if (ei->i_data[i])
					continue;
				else
					goto invalid_resize_inode;
			}
			if (ei->i_data[i])
				goto invalid_resize_inode;
		}
		credits += 3;	/* block bitmap, bg descriptor, resize inode */
	}

	handle = ext4_journal_start_sb(sb, credits);
	if (IS_ERR(handle))
		return PTR_ERR(handle);

	err = ext4_journal_get_write_access(handle, sbi->s_sbh);
	if (err)
		goto errout;

	EXT4_CLEAR_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_RESIZE_INODE);
	EXT4_SET_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG);
	sbi->s_es->s_first_meta_bg =
		cpu_to_le32(num_desc_blocks(sb, sbi->s_groups_count));

	err = ext4_handle_dirty_super(handle, sb);
	if (err) {
		ext4_std_error(sb, err);
		goto errout;
	}

	if (inode) {
		nr = le32_to_cpu(ei->i_data[EXT4_DIND_BLOCK]);
		ext4_free_blocks(handle, inode, NULL, nr, 1,
				 EXT4_FREE_BLOCKS_METADATA |
				 EXT4_FREE_BLOCKS_FORGET);
		ei->i_data[EXT4_DIND_BLOCK] = 0;
		inode->i_blocks = 0;

		err = ext4_mark_inode_dirty(handle, inode);
		if (err)
			ext4_std_error(sb, err);
	}

errout:
	ret = ext4_journal_stop(handle);
	if (!err)
		err = ret;
	return ret;

invalid_resize_inode:
	ext4_error(sb, "corrupted/inconsistent resize inode");
	return -EINVAL;
}

/*
 * ext4_resize_fs() resizes a fs to new size specified by @n_blocks_count
 *
@@ -1772,13 +1865,14 @@ int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
	ext4_grpblk_t add, offset;
	unsigned long n_desc_blocks;
	unsigned long o_desc_blocks;
	unsigned long desc_blocks;
	ext4_group_t o_group;
	ext4_group_t n_group;
	ext4_fsblk_t o_blocks_count;
	ext4_fsblk_t n_blocks_count_retry = 0;
	int err = 0, flexbg_size = 1 << sbi->s_log_groups_per_flex;
	int meta_bg;

retry:
	o_blocks_count = ext4_blocks_count(es);

	if (test_opt(sb, DEBUG))
@@ -1798,11 +1892,8 @@ int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
	ext4_get_group_no_and_offset(sb, n_blocks_count - 1, &n_group, &offset);
	ext4_get_group_no_and_offset(sb, o_blocks_count - 1, &o_group, &offset);

	n_desc_blocks = (n_group + EXT4_DESC_PER_BLOCK(sb)) /
			 EXT4_DESC_PER_BLOCK(sb);
	o_desc_blocks = (sbi->s_groups_count + EXT4_DESC_PER_BLOCK(sb) - 1) /
			 EXT4_DESC_PER_BLOCK(sb);
	desc_blocks = n_desc_blocks - o_desc_blocks;
	n_desc_blocks = num_desc_blocks(sb, n_group + 1);
	o_desc_blocks = num_desc_blocks(sb, sbi->s_groups_count);

	meta_bg = EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG);

@@ -1812,20 +1903,37 @@ int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
				   "simultaneously");
			return -EINVAL;
		}
		if (le16_to_cpu(es->s_reserved_gdt_blocks) < desc_blocks) {
			ext4_warning(sb,
				     "No reserved GDT blocks, can't resize");
			return -EPERM;
		if (n_desc_blocks > o_desc_blocks +
		    le16_to_cpu(es->s_reserved_gdt_blocks)) {
			n_blocks_count_retry = n_blocks_count;
			n_desc_blocks = o_desc_blocks +
				le16_to_cpu(es->s_reserved_gdt_blocks);
			n_group = n_desc_blocks * EXT4_DESC_PER_BLOCK(sb);
			n_blocks_count = n_group * EXT4_BLOCKS_PER_GROUP(sb);
			n_group--; /* set to last group number */
		}

		if (!resize_inode)
			resize_inode = ext4_iget(sb, EXT4_RESIZE_INO);
		if (IS_ERR(resize_inode)) {
			ext4_warning(sb, "Error opening resize inode");
			return PTR_ERR(resize_inode);
		}
	} else if (!meta_bg) {
		ext4_warning(sb, "File system features do not permit "
			     "online resize");
		return -EPERM;
	}

	if ((!resize_inode && !meta_bg) || n_group == o_group) {
		err = ext4_convert_meta_bg(sb, resize_inode);
		if (err)
			goto out;
		if (resize_inode) {
			iput(resize_inode);
			resize_inode = NULL;
		}
		if (n_blocks_count_retry) {
			n_blocks_count = n_blocks_count_retry;
			n_blocks_count_retry = 0;
			goto retry;
		}
	}

	/* See if the device is actually as big as what was requested */
@@ -1876,13 +1984,21 @@ int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
			break;
	}

	if (!err && n_blocks_count_retry) {
		n_blocks_count = n_blocks_count_retry;
		n_blocks_count_retry = 0;
		free_flex_gd(flex_gd);
		flex_gd = NULL;
		goto retry;
	}

out:
	if (flex_gd)
		free_flex_gd(flex_gd);
	if (resize_inode != NULL)
		iput(resize_inode);
	if (test_opt(sb, DEBUG))
		ext4_msg(sb, KERN_DEBUG, "resized filesystem from %llu "
		       "upto %llu blocks", o_blocks_count, n_blocks_count);
		ext4_msg(sb, KERN_DEBUG, "resized filesystem to %llu",
			 n_blocks_count);
	return err;
}