From: Duncan <1i5t5.duncan@cox.net>
To: linux-btrfs@vger.kernel.org
Cc: fstests@vger.kernel.org
Subject: Re: Ideas to do custom operation just after mount?
Date: Tue, 22 Dec 2015 09:28:15 +0000 (UTC) [thread overview]
Message-ID: <pan$a07c5$8ea63042$e035dc2a$bbe2f2c1@cox.net> (raw)
In-Reply-To: 20151222011424.03247982@jupiter.sol.kaishome.de
Kai Krakow posted on Tue, 22 Dec 2015 01:14:24 +0100 as excerpted:
> Am Mon, 21 Dec 2015 13:18:22 +0800 schrieb Anand Jain
> <anand.jain@oracle.com>:
>
>
>>
>> > BTW, any good idea for btrfs to do such operation like
>> > enabling/disabling some minor features? Especially when it can be set
>> > on individual file/dirs.
>> >
>> > Features like incoming write time deduplication, is designed to be
>> > enabled/disabled for individual file/dirs, so it's not a quite good
>> > idea to use mount option to do it.
>> >
>> > Although some feature, like btrfs quota(qgroup), should be
>> > implemented by mount option though.
>> > I don't understand why qgroup is enabled/disabled by ioctl. :(
>>
>>
>> mount option won't persist across systems/computers unless remembered
>> by human.
>
> Valid point, tho here's an counter-example: space-cache is persisted.
> Once enabled, it's always there until you clear AND disable it during
> initial mount.
Data point. space_cache doesn't have to be manually enabled at all,
unless it was turned off at some point; it's automatically enabled on
mounting new btrfs.
At least, I've never specifically enabled (or disabled) space_cache on
any of my btrfs here, yet they all have it enabled.
(Years ago, with my first btrfs experiments, a corrupted space_cache
could cause the filesystem not to mount. But then I left btrfs alone for
awhile, and I guess in the mean time it learned to auto-correct such
problems, as I've never had to worry about a bad space-cache failing a
mount since I returned to using it, and that itself was two and a half
years ago, now. With the previous mount-blocker experience I was a
rather nervous when I saw it enabled without me initially enabling it,
but space_cache has basically "just worked" for me since then, tho I've
had a few other mount-blocking bugs.)
--
Duncan - List replies preferred. No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master." Richard Stallman
next prev parent reply other threads:[~2015-12-22 9:28 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-17 1:55 Ideas to do custom operation just after mount? Qu Wenruo
2015-12-21 0:16 ` Dave Chinner
2015-12-21 2:25 ` Qu Wenruo
2015-12-21 2:38 ` Qu Wenruo
2015-12-21 5:18 ` Anand Jain
2015-12-22 0:14 ` Kai Krakow
2015-12-22 9:28 ` Duncan [this message]
2015-12-23 23:17 ` Dave Chinner
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