On Thu 15-10-20 14:32:52, Roman Anufriev wrote:
> Right now, it is hard to understand what quota journalling type is enabled:
> you need to be quite familiar with kernel code and trace it or really
> understand what different combinations of fs flags/mount options lead to.
>
> This patch exports via sysfs attr /sys/fs/ext4/<disk>/quota_mode current
> quota jounalling mode, making it easier to check at a glance/in autotests.
> The semantics is similar to ext4 data journalling modes:
>
> * journalled - quota accounting and journaling are enabled
> * writeback - quota accounting is enabled, but journalling is disabled
> * none - quota accounting is disabled
> * disabled - kernel compiled without CONFIG_QUOTA feature
>
> Signed-off-by: Roman Anufriev <dotdot@xxxxxxxxxxxxxx>
> Reviewed-by: Dmitry Monakhov <dmtrmonakhov@xxxxxxxxxxxxxx>
Hum, I'm not sure about this. The state of quota can be found out with
"quotaon -p <mntpoint>" (or corresponding quotactl if you need this from
C). The only thing you won't learn is journalled / writeback mode and
generally you should not care about this although I agree that for fs
crash testing purposes you may care. But is that big enough usecase for a
new sysfs file when all the information is already available for userspace
just not in a convenient form?
BTW, I've now realized ext4_any_quota_enabled() has actually misleading
name in the sysfs file reports wrong information. It is rather
ext4_any_quota_may_be_enabled() since presence of QUOTA mount option only
says that quotaon(8) will enable quotas if it is run, not that quota
accounting is enabled. sb_any_quota_loaded() tells you if accounting is
actually enabled or not (however this can change anytime so that's why we
use more relaxed checks for the purpose of journal credit estimates).
Honza
> ---
> fs/ext4/sysfs.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
> index bfabb79..a46487f 100644
> --- a/fs/ext4/sysfs.c
> +++ b/fs/ext4/sysfs.c
> @@ -36,6 +36,7 @@ typedef enum {
> attr_pointer_string,
> attr_pointer_atomic,
> attr_journal_task,
> + attr_quota_mode,
> } attr_id_t;
>
> typedef enum {
> @@ -140,6 +141,23 @@ static ssize_t journal_task_show(struct ext4_sb_info *sbi, char *buf)
> task_pid_vnr(sbi->s_journal->j_task));
> }
>
> +static ssize_t quota_mode_show(struct ext4_sb_info *sbi, char *buf)
> +{
> +#ifdef CONFIG_QUOTA
> + struct super_block *sb = sbi->s_buddy_cache->i_sb;
> +
> + if (!ext4_any_quota_enabled(sb))
> + return snprintf(buf, PAGE_SIZE, "none\n");
> +
> + if (ext4_is_quota_journalled(sb))
> + return snprintf(buf, PAGE_SIZE, "journalled\n");
> + else
> + return snprintf(buf, PAGE_SIZE, "writeback\n");
> +#else
> + return snprintf(buf, PAGE_SIZE, "disabled\n");
> +#endif
> +}
> +
> #define EXT4_ATTR(_name,_mode,_id) \
> static struct ext4_attr ext4_attr_##_name = { \
> .attr = {.name = __stringify(_name), .mode = _mode }, \
> @@ -248,6 +266,7 @@ EXT4_ATTR(last_error_time, 0444, last_error_time);
> EXT4_ATTR(journal_task, 0444, journal_task);
> EXT4_RW_ATTR_SBI_UI(mb_prefetch, s_mb_prefetch);
> EXT4_RW_ATTR_SBI_UI(mb_prefetch_limit, s_mb_prefetch_limit);
> +EXT4_ATTR_FUNC(quota_mode, 0444);
>
> static unsigned int old_bump_val = 128;
> EXT4_ATTR_PTR(max_writeback_mb_bump, 0444, pointer_ui, &old_bump_val);
> @@ -296,6 +315,7 @@ static struct attribute *ext4_attrs[] = {
> #endif
> ATTR_LIST(mb_prefetch),
> ATTR_LIST(mb_prefetch_limit),
> + ATTR_LIST(quota_mode),
> NULL,
> };
> ATTRIBUTE_GROUPS(ext4);
> @@ -425,6 +445,8 @@ static ssize_t ext4_attr_show(struct kobject *kobj,
> return print_tstamp(buf, sbi->s_es, s_last_error_time);
> case attr_journal_task:
> return journal_task_show(sbi, buf);
> + case attr_quota_mode:
> + return quota_mode_show(sbi, buf);
> }
>
> return 0;
> --
> 2.7.4
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
