On Fri 17-04-15 17:08:10, John Spray wrote: > > On 17/04/2015 16:43, Jan Kara wrote: > >On Fri 17-04-15 15:51:14, John Spray wrote: > >>On 17/04/2015 14:23, Austin S Hemmelgarn wrote: > >> > >>>For some filesystems, it may make sense to differentiate between a > >>>generic warning and an error. For BTRFS and ZFS for example, if > >>>there is a csum error on a block, this will get automatically > >>>corrected in many configurations, and won't require anything like > >>>fsck to be run, but monitoring applications will still probably > >>>want to be notified. > >>Another key differentiation IMHO is between transient errors (like > >>server is unavailable in a distributed filesystem) that will block > >>the filesystem but might clear on their own, vs. permanent errors > >>like unreadable drives that definitely will not clear until the > >>administrator takes some action. It's usually a reasonable > >>approximation to call transient issues warnings, and permanent > >>issues errors. > > So you can have events like FS_UNAVAILABLE and FS_AVAILABLE but what use > >would this have? I wouldn't like the interface to be dumping ground for > >random crap - we have dmesg for that :). > In that case I'm confused -- why would ENOSPC be an appropriate use > of this interface if the mount being entirely blocked would be > inappropriate? Isn't being unable to service any I/O a more > fundamental and severe thing than being up and healthy but full? > > Were you intending the interface to be exclusively for data > integrity issues like checksum failures, rather than more general > events about a mount that userspace would probably like to know > about? Well, I'm not saying we cannot have those events for fs availability / inavailability. I'm just saying I'd like to see some use for that first. I don't want events to be added just because it's possible... For ENOSPC we have thin provisioned storage and the userspace deamon shuffling real storage underneath. So there I know the usecase. Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
