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| author | NeilBrown <neilb@suse.com> | 2016-03-09 02:58:25 +0100 |
|---|---|---|
| committer | Shaohua Li <shli@fb.com> | 2016-03-09 18:31:41 +0100 |
| commit | 550da24f8d62fe81f3c13e3ec27602d6e44d43dc (patch) | |
| tree | a5403f9c30d4d284ced5ae211df4e171ec32f91c /drivers/md | |
| parent | Update MD git tree URL (diff) | |
| download | linux-550da24f8d62fe81f3c13e3ec27602d6e44d43dc.tar.xz linux-550da24f8d62fe81f3c13e3ec27602d6e44d43dc.zip | |
md/raid5: preserve STRIPE_PREREAD_ACTIVE in break_stripe_batch_list
break_stripe_batch_list breaks up a batch and copies some flags from
the batch head to the members, preserving others.
It doesn't preserve or copy STRIPE_PREREAD_ACTIVE. This is not
normally a problem as STRIPE_PREREAD_ACTIVE is cleared when a
stripe_head is added to a batch, and is not set on stripe_heads
already in a batch.
However there is no locking to ensure one thread doesn't set the flag
after it has just been cleared in another. This does occasionally happen.
md/raid5 maintains a count of the number of stripe_heads with
STRIPE_PREREAD_ACTIVE set: conf->preread_active_stripes. When
break_stripe_batch_list clears STRIPE_PREREAD_ACTIVE inadvertently
this could becomes incorrect and will never again return to zero.
md/raid5 delays the handling of some stripe_heads until
preread_active_stripes becomes zero. So when the above mention race
happens, those stripe_heads become blocked and never progress,
resulting is write to the array handing.
So: change break_stripe_batch_list to preserve STRIPE_PREREAD_ACTIVE
in the members of a batch.
URL: https://bugzilla.kernel.org/show_bug.cgi?id=108741
URL: https://bugzilla.redhat.com/show_bug.cgi?id=1258153
URL: http://thread.gmane.org/5649C0E9.2030204@zoner.cz
Reported-by: Martin Svec <martin.svec@zoner.cz> (and others)
Tested-by: Tom Weber <linux@junkyard.4t2.com>
Fixes: 1b956f7a8f9a ("md/raid5: be more selective about distributing flags across batch.")
Cc: stable@vger.kernel.org (v4.1 and later)
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/raid5.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index c25f2fb2e567..32d52878f182 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -4239,7 +4239,6 @@ static void break_stripe_batch_list(struct stripe_head *head_sh, WARN_ON_ONCE(sh->state & ((1 << STRIPE_ACTIVE) | (1 << STRIPE_SYNCING) | (1 << STRIPE_REPLACED) | - (1 << STRIPE_PREREAD_ACTIVE) | (1 << STRIPE_DELAYED) | (1 << STRIPE_BIT_DELAY) | (1 << STRIPE_FULL_WRITE) | @@ -4254,6 +4253,7 @@ static void break_stripe_batch_list(struct stripe_head *head_sh, (1 << STRIPE_REPLACED))); set_mask_bits(&sh->state, ~(STRIPE_EXPAND_SYNC_FLAGS | + (1 << STRIPE_PREREAD_ACTIVE) | (1 << STRIPE_DEGRADED)), head_sh->state & (1 << STRIPE_INSYNC)); |