Messages in this thread | | | From | Andreas Grünbacher <> | Date | Fri, 20 Aug 2021 16:43:34 +0200 | Subject | Re: [Cluster-devel] [PATCH v6 10/19] gfs2: Introduce flag for glock holder auto-demotion |
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Am Fr., 20. Aug. 2021 um 15:49 Uhr schrieb Steven Whitehouse <swhiteho@redhat.com>: > We always used to manage to avoid holding fs locks when copying to/from userspace > to avoid these complications.
I realize the intent, but that goal has never actually been achieved. Direct I/O has *always* been calling get_user_pages() while holding the inode glock in deferred mode.
The situation is slightly different for buffered I/O, but we have the same problem there at least since switching to iomap. (And it's a fundamental property of iomap that we want to hold the inode glock across multi-page mappings, not an implementation deficit.)
Here's a slightly outdated version of a test case that makes all versions of gfs2 prior to this patch queue unhappy: https://lore.kernel.org/fstests/20210531152604.240462-1-agruenba@redhat.com/
Thanks, Andreas
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