Re: [RFC 1/4] fs: Add generic file system event notifications

[Austin S Hemmelgarn <ahferroin7@gmail.com>]

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On 2015-04-17 09:04, Beata Michalska wrote:
> On 04/17/2015 01:31 PM, Jan Kara wrote:
>> On Wed 15-04-15 09:15:44, Beata Michalska wrote:
>> ...
>>> +static const match_table_t fs_etypes = {
>>> +	{ FS_EVENT_INFO,    "info"  },
>>> +	{ FS_EVENT_WARN,    "warn"  },
>>> +	{ FS_EVENT_THRESH,  "thr"   },
>>> +	{ FS_EVENT_ERR,     "err"   },
>>> +	{ 0, NULL },
>>> +};
>>    Why are there these generic message types? Threshold messages make good
>> sense to me. But not so much the rest. If they don't have a clear meaning,
>> it will be a mess. So I also agree with a message like - "filesystem has
>> trouble, you should probably unmount and run fsck" - that's fine. But
>> generic "info" or "warning" doesn't really carry any meaning on its own and
>> thus seems pretty useless to me. To explain a bit more, AFAIU this
>> shouldn't be a generic logging interface where something like severity
>> makes sense but rather a relatively specific interface notifying about
>> events in filesystem userspace should know about so I expect relatively low
>> number of types of events, not tens or even hundreds...
>>
>> 								Honza
>
> Getting rid of those would simplify the configuration part, indeed.
> So we would be left with 'generic' and threshold events.
> I guess I've overdone this part.

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.


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