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Commit bb08c1e7 authored by Yongqiang Yang's avatar Yongqiang Yang Committed by Theodore Ts'o
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ext4: add a function which adds a new group descriptors to a fs 



This patch adds a function named ext4_add_new_descs() which adds one
or more new group descriptors to a fs and whose code is copied from
ext4_group_add().

The function will be used by new resize implementation.

Signed-off-by: default avatarYongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 18e31438

fs/ext4/resize.c

+46 −0
Original line number Diff line number Diff line
@@ -735,6 +735,52 @@ static void update_backups(struct super_block *sb, 
	}

}



/*

 * ext4_add_new_descs() adds @count group descriptor of groups

 * starting at @group

 *

 * @handle: journal handle

 * @sb: super block

 * @group: the group no. of the first group desc to be added

 * @resize_inode: the resize inode

 * @count: number of group descriptors to be added

 */

static int ext4_add_new_descs(handle_t *handle, struct super_block *sb,

			      ext4_group_t group, struct inode *resize_inode,

			      ext4_group_t count)

{

	struct ext4_sb_info *sbi = EXT4_SB(sb);

	struct ext4_super_block *es = sbi->s_es;

	struct buffer_head *gdb_bh;

	int i, gdb_off, gdb_num, err = 0;



	for (i = 0; i < count; i++, group++) {

		int reserved_gdb = ext4_bg_has_super(sb, group) ?

			le16_to_cpu(es->s_reserved_gdt_blocks) : 0;



		gdb_off = group % EXT4_DESC_PER_BLOCK(sb);

		gdb_num = group / EXT4_DESC_PER_BLOCK(sb);



		/*

		 * 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) {

			gdb_bh = sbi->s_group_desc[gdb_num];

			err = ext4_journal_get_write_access(handle, gdb_bh);



			if (!err && reserved_gdb && ext4_bg_num_gdb(sb, group))

				err = reserve_backup_gdb(handle, resize_inode, group);

		} else

			err = add_new_gdb(handle, resize_inode, group);

		if (err)

			break;

	}

	return err;

}



/* 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