Fix race in dnode_check_slots_free() #8005
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Currently, dnode_check_slots_free() works by checking dn->dn_type in the dnode to determine if the dnode is reclaimable. However, there is a small window of time between dnode_free_sync() in the first call to dsl_dataset_sync() and when the useraccounting code is run when the type is set DMU_OT_NONE, but the dnode is not yet evictable, leading to crashes. This patch adds the ability for dnodes to track which txg they were last dirtied in and adds a check for this before performing the reclaim. This patch also corrects several instances when dn_dirty_link was treated as a list_node_t when it is technically a multilist_node_t. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tom Caputi <tcaputi@datto.com> Requires-spl: spl-0.7-release Issue openzfs#7147 Issue openzfs#7388 Issue openzfs#7997
Codecov Report
@@ Coverage Diff @@
## zfs-0.7-release #8005 +/- ##
==================================================
+ Coverage 72.49% 72.89% +0.4%
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Files 289 289
Lines 89767 89780 +13
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+ Hits 65077 65448 +371
+ Misses 24690 24332 -358 |
tonyhutter
approved these changes
Oct 10, 2018
behlendorf
added
Status: Accepted
janlam7
reviewed
Oct 12, 2018
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Closing. Will be included in 0.7.12. |
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Don't see this issue in the release notes of 0.7.12 |
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This patch was included via commit b32f127 which is included in the 0.7.12 branch. |
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@bunder2015 Thanks! |
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I still see this happening with Ubuntu 19.04 and the included zfs v0.7.12-1ubuntu5. Is there any known workaround for this? |
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Motivation and Context
Backport of edc1e71 for the 0.7 release branch. See issue #7997.
Description
Currently, dnode_check_slots_free() works by checking dn->dn_type
in the dnode to determine if the dnode is reclaimable. However,
there is a small window of time between dnode_free_sync() in the
first call to dsl_dataset_sync() and when the useraccounting code
is run when the type is set DMU_OT_NONE, but the dnode is not yet
evictable, leading to crashes. This patch adds the ability for
dnodes to track which txg they were last dirtied in and adds a
check for this before performing the reclaim.
This patch also corrects several instances when dn_dirty_link was
treated as a list_node_t when it is technically a multilist_node_t.
How Has This Been Tested?
This same issue was observed in master and fix was integrated in April,
this is a clean backport of that change. I've built it locally but I'm pushing
it to the bots for additional testing.
Types of changes
Checklist:
Signed-off-by.