zfs dmu_read: loosen the assertion.
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Authored by kib on Mar 6 2020, 1:28 PM.

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markj
jeff
avg

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rS358719: zfs dmu_read: loosen the assertion.

Summary

Since switch to the lockless grab, shared busy for ahead/behind pages allows other threads to validate and map the pages readonly.

P.S. Alternative could be to change to exclusive busy for the said pages. This should be fine both from the locking PoV (we use NOWAIT) and correctness (no overwrite of the valid data). But it reduces the parallelism for zfs_getpages().

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Repository

rS FreeBSD src repository - subversion

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Event Timeline

kib created this revision.Mar 6 2020, 1:28 PM

Herald added subscribers: delphij, imp. · View Herald TranscriptMar 6 2020, 1:28 PM

Harbormaster completed remote builds in B29825: Diff 69262.Mar 6 2020, 1:28 PM

kib edited the summary of this revision. (Show Details)Mar 6 2020, 1:35 PM

Looks good as far as my knowledge of the recent VM changes goes.
Thank you very much!

This revision is now accepted and ready to land.Mar 6 2020, 1:52 PM

markj accepted this revision.Mar 6 2020, 3:04 PM

I am ok with this but eventually it likely should not be shared busy.

Closed by commit rS358719: zfs dmu_read: loosen the assertion. (authored by kib). · Explain WhyMar 6 2020, 9:15 PM

This revision was automatically updated to reflect the committed changes.

kib added a commit: rS358719: zfs dmu_read: loosen the assertion..

Revision Contents
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Path

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head/

sys/

cddl/

contrib/

opensolaris/

uts/

common/

fs/

zfs/

dmu.c

4 lines

Diff 69279

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head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu.c

zfs dmu_read: loosen the assertion.ClosedPublicActions