From: Jan Kara <jack@suse.cz>
To: Roman Anufriev <dotdot@yandex-team.ru>
Cc: linux-ext4@vger.kernel.org, tytso@mit.edu, jack@suse.cz,
dmtrmonakhov@yandex-team.ru
Subject: Re: [PATCH 2/2] ext4: export quota journalling mode via sysfs attr quota_mode
Date: Thu, 15 Oct 2020 15:15:22 +0200 [thread overview]
Message-ID: <20201015131522.GF7037@quack2.suse.cz> (raw)
In-Reply-To: <1602761572-4713-2-git-send-email-dotdot@yandex-team.ru>
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@yandex-team.ru>
> Reviewed-by: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>
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@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2020-10-15 13:15 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-15 11:32 [PATCH 1/2] ext4: add helpers for checking whether quota is enabled/journalled Roman Anufriev
2020-10-15 11:32 ` [PATCH 2/2] ext4: export quota journalling mode via sysfs attr quota_mode Roman Anufriev
2020-10-15 13:15 ` Jan Kara [this message]
2020-10-17 18:26 ` Roman Anufriev
2020-10-19 8:19 ` Jan Kara
2020-10-19 9:36 ` Roman Anufriev
2020-10-15 12:24 ` [PATCH 1/2] ext4: add helpers for checking whether quota is enabled/journalled Jan Kara
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201015131522.GF7037@quack2.suse.cz \
--to=jack@suse.cz \
--cc=dmtrmonakhov@yandex-team.ru \
--cc=dotdot@yandex-team.ru \
--cc=linux-ext4@vger.kernel.org \
--cc=tytso@mit.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).