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.j...@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 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
