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ext4: add a function which updates the super block during online resizing

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This patch adds a function named ext4_update_super() which updates
super block so the newly created block groups are visible to the file
system.  This 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 23:41:39 -05:00 committed by Theodore Ts'o
parent 083f5b24cc
commit 2e10e2f2e5
1 changed files with 94 additions and 0 deletions
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94
fs/ext4/resize.c
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@ -1142,6 +1142,100 @@ static int ext4_setup_new_descs(handle_t *handle, struct super_block *sb,
return err;
}
/*
* ext4_update_super() updates the super block so that the newly added
* groups can be seen by the filesystem.
*
* @sb: super block
* @flex_gd: new added groups
*/
static void ext4_update_super(struct super_block *sb,
struct ext4_new_flex_group_data *flex_gd)
{
ext4_fsblk_t blocks_count = 0;
ext4_fsblk_t free_blocks = 0;
ext4_fsblk_t reserved_blocks = 0;
struct ext4_new_group_data *group_data = flex_gd->groups;
struct ext4_sb_info *sbi = EXT4_SB(sb);
struct ext4_super_block *es = sbi->s_es;
int i;
BUG_ON(flex_gd->count == 0 || group_data == NULL);
/*
* 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.
*/
for (i = 0; i < flex_gd->count; i++) {
blocks_count += group_data[i].blocks_count;
free_blocks += group_data[i].free_blocks_count;
}
reserved_blocks = ext4_r_blocks_count(es) * 100;
do_div(reserved_blocks, ext4_blocks_count(es));
reserved_blocks *= blocks_count;
do_div(reserved_blocks, 100);
ext4_blocks_count_set(es, ext4_blocks_count(es) + blocks_count);
le32_add_cpu(&es->s_inodes_count, EXT4_INODES_PER_GROUP(sb) *
flex_gd->count);
/*
* We need to protect s_groups_count against other CPUs seeing
* inconsistent state in the superblock.
*
* The precise rules we use are:
*
* * Writers must perform a smp_wmb() after updating all
* dependent data and before modifying the groups count
*
* * 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 += flex_gd->count;
/* Update the reserved block counts only once the new group is
* active. */
ext4_r_blocks_count_set(es, ext4_r_blocks_count(es) +
reserved_blocks);
/* Update the free space counts */
percpu_counter_add(&sbi->s_freeclusters_counter,
EXT4_B2C(sbi, free_blocks));
percpu_counter_add(&sbi->s_freeinodes_counter,
EXT4_INODES_PER_GROUP(sb) * flex_gd->count);
if (EXT4_HAS_INCOMPAT_FEATURE(sb,
EXT4_FEATURE_INCOMPAT_FLEX_BG) &&
sbi->s_log_groups_per_flex) {
ext4_group_t flex_group;
flex_group = ext4_flex_group(sbi, group_data[0].group);
atomic_add(EXT4_B2C(sbi, free_blocks),
&sbi->s_flex_groups[flex_group].free_clusters);
atomic_add(EXT4_INODES_PER_GROUP(sb) * flex_gd->count,
&sbi->s_flex_groups[flex_group].free_inodes);
}
if (test_opt(sb, DEBUG))
printk(KERN_DEBUG "EXT4-fs: added group %u:"
"%llu blocks(%llu free %llu reserved)\n", flex_gd->count,
blocks_count, free_blocks, reserved_blocks);
}
/* 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