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author | NeilBrown <neilb@suse.de> | 2013-03-12 05:18:06 +0400 |
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committer | NeilBrown <neilb@suse.de> | 2013-03-20 06:20:59 +0400 |
commit | f8dfcffd0472a0f353f34a567ad3f53568914d04 (patch) | |
tree | 8e19d10fcd778cace960c49336f1323858dcb4d5 /arch | |
parent | 90584fc93d461520a888f691144f0879283b3624 (diff) | |
download | linux-f8dfcffd0472a0f353f34a567ad3f53568914d04.tar.xz |
md/raid5: ensure sync and DISCARD don't happen at the same time.
A number of problems can occur due to races between
resync/recovery and discard.
- if sync_request calls handle_stripe() while a discard is
happening on the stripe, it might call handle_stripe_clean_event
before all of the individual discard requests have completed
(so some devices are still locked, but not all).
Since commit ca64cae96037de16e4af92678814f5d4bf0c1c65
md/raid5: Make sure we clear R5_Discard when discard is finished.
this will cause R5_Discard to be cleared for the parity device,
so handle_stripe_clean_event() will not be called when the other
devices do become unlocked, so their ->written will not be cleared.
This ultimately leads to a WARN_ON in init_stripe and a lock-up.
- If handle_stripe_clean_event() does clear R5_UPTODATE at an awkward
time for resync, it can lead to s->uptodate being less than disks
in handle_parity_checks5(), which triggers a BUG (because it is
one).
So:
- keep R5_Discard on the parity device until all other devices have
completed their discard request
- make sure we don't try to have a 'discard' and a 'sync' action at
the same time.
This involves a new stripe flag to we know when a 'discard' is
happening, and the use of R5_Overlap on the parity disk so when a
discard is wanted while a sync is active, so we know to wake up
the discard at the appropriate time.
Discard support for RAID5 was added in 3.7, so this is suitable for
any -stable kernel since 3.7.
Cc: stable@vger.kernel.org (v3.7+)
Reported-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Tested-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Diffstat (limited to 'arch')
0 files changed, 0 insertions, 0 deletions