On Sat 17-10-20 21:26:37, Roman Anufriev wrote: > Hi, sorry for the delay. > > On Thu, 15 Oct 2020, Jan Kara wrote: > > > 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? > > Rationale behind this patch was mainly the addition of an easy way to check > whether quota journalled or not as this is quite wanted feature in out > production environment. TBH, I was not sure about sysfs file too, but it > seemed to me like the most natural place to put it. Maybe if sysfs is an > overkill - just add printing to dmesg on mount? At least, you'll be able to > check what quota type you can enable right after mounting. > > > 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). > > My bad! Totally forgot about the case when 'quota' mount option is present > but quota accounting is not enabled, as our helper-tool around 'quotactl()' > do remounting+enabling in one go. > > I'll rename the function to smth like 'ext4_quota_capable()' in v2. And if > printing to dmesg is OK, I'll probably still use this function to print on > mount what the quota type will be after accounting is enabled. Yeah, if a message in dmesg is fine for your purposes, I'd rather go with that than with a sysfs file. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
