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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: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Yongqiang Yang 2012-01-03 23:20:50 -05:00 committed by Theodore Ts'o
parent 18e3143848
commit bb08c1e7d8
1 changed files with 46 additions and 0 deletions
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46
fs/ext4/resize.c
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@ -735,6 +735,52 @@ exit_err:
}
}
/*
* 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