Messages in this thread | | | Date | Thu, 13 Oct 2022 13:56:36 -0400 | From | Sasha Levin <> | Subject | Re: [PATCH AUTOSEL 6.0 38/46] btrfs: introduce BTRFS_QGROUP_RUNTIME_FLAG_CANCEL_RESCAN |
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On Thu, Oct 13, 2022 at 07:12:10AM +0800, Qu Wenruo wrote: > > >On 2022/10/12 20:56, David Sterba wrote: >>On Tue, Oct 11, 2022 at 10:50:06AM -0400, Sasha Levin wrote: >>>From: Qu Wenruo <wqu@suse.com> >>> >>>[ Upstream commit e562a8bdf652b010ce2525bcf15d145c9d3932bf ] >>> >>>Introduce a new runtime flag, BTRFS_QGROUP_RUNTIME_FLAG_CANCEL_RESCAN, >>>which will inform qgroup rescan to cancel its work asynchronously. >>> >>>This is to address the window when an operation makes qgroup numbers >>>inconsistent (like qgroup inheriting) while a qgroup rescan is running. >>> >>>In that case, qgroup inconsistent flag will be cleared when qgroup >>>rescan finishes. >>>But we changed the ownership of some extents, which means the rescan is >>>already meaningless, and the qgroup inconsistent flag should not be >>>cleared. >>> >>>With the new flag, each time we set INCONSISTENT flag, we also set this >>>new flag to inform any running qgroup rescan to exit immediately, and >>>leaving the INCONSISTENT flag there. >>> >>>The new runtime flag can only be cleared when a new rescan is started. >> >>Qu, does this patch make sense for stable on itself? It was part of a >>series adding some new flags and the sysfs knob. As I read it there's a >>case where it can affect how the rescan is done and that it can be >>cancelled but still am not sure if it's worth the backport. > >Considering the qgroup still lacks a way to handle large subvolume drop, >and a lot of things can mark qgroup inconsistent halfway, I think >backporting this patch itself is not that bad. > >The problem is, why only backporting this one? > >To me, it would make more sense to backport either all or none. > >Sure, if we can cancel rescan it's an improvement, but rescan itself is >already relatively cheap compared to other qgroup operations. >Thus I prefer to backport all the qgroup patches.
I'll drop this one and happily take a series if you want to send one out.
-- Thanks, Sasha
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