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Differential D41731

vfs_lookup_cross_mount(): Fix reference counting/locking on LK_UPGRADE error
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Authored by olce on Sep 5 2023, 12:58 PM.
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emaste
imp
markj

Details

Reviewers
mjg
kib
jah
Commits
rGaaeaba324335: vfs: fix reference counting/locking on LK_UPGRADE error
rGc76dfb929e70: vfs: fix reference counting/locking on LK_UPGRADE error
rG02cbc029dac9: vfs: fix reference counting/locking on LK_UPGRADE error
Summary

Factoring out this code unfortunately introduced reference and lock leaks in
case of failure in the lock upgrade path under VV_CROSSLOCK. In terms of
practical use, this impacts unionfs (and nullfs in a corner case).

Also, add under INVARIANTS a check about the return value of vn_lock() (it is
not supposed to be anything else than ENOENT).

Fixes: 80bd5ef07025 vfs: factor out mount point traversal to a dedicated routine
MFC after: 3 days
MFC to: stable/14 releng/14.0
Sponsored by: The FreeBSD Foundation

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Repository
rG FreeBSD src repository
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Unit
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Build Status
Buildable 53435
Build 50326: arc lint + arc unit

Event Timeline

olce created this revision.Sep 5 2023, 12:58 PM
Herald added a subscriber: imp. · View Herald TranscriptSep 5 2023, 12:58 PM
olce requested review of this revision.Sep 5 2023, 12:58 PM
Harbormaster completed remote builds in B53435: Diff 126882.Sep 5 2023, 12:58 PM
olce updated this revision to Diff 126986.Sep 6 2023, 7:02 PM
olce edited the summary of this revision. (Show Details)

Add an MPASS() on error, change a bit the commit message.

Harbormaster completed remote builds in B53477: Diff 126986.Sep 6 2023, 7:02 PM
olce added reviewers: mjg, kib, jah.Sep 6 2023, 7:03 PM
olce mentioned this in D40883: vfs: factor out mount point traversal to a dedicated routine.
olce added subscribers: emaste, markj.
olce edited the summary of this revision. (Show Details)Sep 6 2023, 7:17 PM
mjg added a comment.Sep 8 2023, 8:11 PM

I found the bug around hte next day after introducing it, it must have slipped through the cracks afterwards.

I'll sort this review out over the weekend, thanks for submitting.

This revision was not accepted when it landed; it landed in state Needs Review.Sep 22 2023, 9:00 PM
Closed by commit rG02cbc029dac9: vfs: fix reference counting/locking on LK_UPGRADE error (authored by olce, committed by mjg). · Explain Why
This revision was automatically updated to reflect the committed changes.
mjg added a commit: rG02cbc029dac9: vfs: fix reference counting/locking on LK_UPGRADE error.
mjg added a commit: rGc76dfb929e70: vfs: fix reference counting/locking on LK_UPGRADE error.Sep 24 2023, 10:45 AM
mjg added a commit: rGaaeaba324335: vfs: fix reference counting/locking on LK_UPGRADE error.Sep 24 2023, 9:47 PM

Revision Contents
Changeset List

PathSize
sys/
kern/
8 lines

Diff 126882

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sys/kern/vfs_lookup.c

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