Re: [PATCH v2 5/9] ext4: add new attr pointer attr_mb_order

Jan Kara
2024-03-14T10:32:15Z

On Tue 27-02-24 17:11:44, Baokun Li wrote:
> The s_mb_best_avail_max_trim_order is of type unsigned int, and has a
> range of values well beyond the normal use of the mb_order. Although the
> mballoc code is careful enough that large numbers don't matter there, but
> this can mislead the sysadmin into thinking that it's normal to set such
> values. Hence add a new attr_id attr_mb_order with values in the range
> [0, 64] to avoid storing garbage values and make us more resilient to
> surprises in the future.
>
> Suggested-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Baokun Li <libaokun1@huawei.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

Honza

> ---
> fs/ext4/sysfs.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
> index ddd71673176c..8e0473169458 100644
> --- a/fs/ext4/sysfs.c
> +++ b/fs/ext4/sysfs.c
> @@ -30,6 +30,7 @@ typedef enum {
> attr_first_error_time,
> attr_last_error_time,
> attr_clusters_in_group,
> + attr_mb_order,
> attr_feature,
> attr_pointer_ui,
> attr_pointer_ul,
> @@ -210,6 +211,8 @@ EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, inode_readahead,
> ext4_sb_info, s_inode_readahead_blks);
> EXT4_ATTR_OFFSET(mb_group_prealloc, 0644, clusters_in_group,
> ext4_sb_info, s_mb_group_prealloc);
> +EXT4_ATTR_OFFSET(mb_best_avail_max_trim_order, 0644, mb_order,
> + ext4_sb_info, s_mb_best_avail_max_trim_order);
> EXT4_RW_ATTR_SBI_UI(inode_goal, s_inode_goal);
> EXT4_RW_ATTR_SBI_UI(mb_stats, s_mb_stats);
> EXT4_RW_ATTR_SBI_UI(mb_max_to_scan, s_mb_max_to_scan);
> @@ -225,7 +228,6 @@ EXT4_RW_ATTR_SBI_UI(warning_ratelimit_interval_ms, s_warning_ratelimit_state.int
> EXT4_RW_ATTR_SBI_UI(warning_ratelimit_burst, s_warning_ratelimit_state.burst);
> EXT4_RW_ATTR_SBI_UI(msg_ratelimit_interval_ms, s_msg_ratelimit_state.interval);
> EXT4_RW_ATTR_SBI_UI(msg_ratelimit_burst, s_msg_ratelimit_state.burst);
> -EXT4_RW_ATTR_SBI_UI(mb_best_avail_max_trim_order, s_mb_best_avail_max_trim_order);
> #ifdef CONFIG_EXT4_DEBUG
> EXT4_RW_ATTR_SBI_UL(simulate_fail, s_simulate_fail);
> #endif
> @@ -379,6 +381,7 @@ static ssize_t ext4_generic_attr_show(struct ext4_attr *a,
> switch (a->attr_id) {
> case attr_inode_readahead:
> case attr_clusters_in_group:
> + case attr_mb_order:
> case attr_pointer_ui:
> if (a->attr_ptr == ptr_ext4_super_block_offset)
> return sysfs_emit(buf, "%u\n", le32_to_cpup(ptr));
> @@ -458,6 +461,14 @@ static ssize_t ext4_generic_attr_store(struct ext4_attr *a,
> else
> *((unsigned int *) ptr) = t;
> return len;
> + case attr_mb_order:
> + ret = kstrtouint(skip_spaces(buf), 0, &t);
> + if (ret)
> + return ret;
> + if (t > 64)
> + return -EINVAL;
> + *((unsigned int *) ptr) = t;
> + return len;
> case attr_clusters_in_group:
> ret = kstrtouint(skip_spaces(buf), 0, &t);
> if (ret)
> --
> 2.31.1
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR