The commit is pushed to "branch-rh7-3.10.0-327.18.2.vz7.14.x-ovz" and will
appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-327.18.2.vz7.14.11
------>
commit 06e75864374f0bc36a31ef17f64911a5fb9ba0df
Author: Maxim Patlasov <[email protected]>
Date: Fri Jun 3 16:11:04 2016 +0400
Revert "ploop: push_backup must pass READs intact"
Patchset description:
ploop: push_backup: implement separate lockout tree
The patch set firstly reverts ALLOW_READS hack that was needed to
reuse plo->lockout_tree for push_backup needs, then adds new lockout
tree for push_backup needs: plo->lockout_pb_tree.
This solves an issue revealed by PSBM-47680: it is possible that
plo->lockout_tree is already occupied by a WRITE request waiting for ACK
from backup tool, but then the tool generates a READ request that wants
to occupy that slot already busy by the WRITE. See per-patch descriptions
for details
https://jira.sw.ru/browse/PSBM-47680
Maxim Patlasov (2):
ploop: push_backup: roll back ALLOW_READS patch
ploop: push_backup: rework lockout machinery
=====================================================
This patch description:
The patch reverts:
Subject: [PATCH rh7] ploop: push_backup must pass READs intact
If push_backup is in progress (doesn't matter "full" or "incremental") and
ploop state-machine detects incoming WRITE request to the cluster-block that
was not push_backup-ed yet, it suspends the request until userspace reports
it
as "processed".
The above is fine, but while such a WRITE request is suspended, only
subsequent WRITEs (to given cluster-block) must be suspended too. READs must
not. Otherwise userspace backup tool will be blocked infinintely trying
to push_backup given cluster-block.
Passing READs while blocking WRITEs must be OK because: 1) ploop has not
finalized that first WRITE yet; 2) given cluster-block will be kept
intact (non-modified) while the WRITE is suspended.
https://jira.sw.ru/browse/PSBM-46775
Signed-off-by: Maxim Patlasov <[email protected]>
---
drivers/block/ploop/dev.c | 7 -------
include/linux/ploop/ploop.h | 1 -
2 files changed, 8 deletions(-)
diff --git a/drivers/block/ploop/dev.c b/drivers/block/ploop/dev.c
index 96f7850..d3f0ec0 100644
--- a/drivers/block/ploop/dev.c
+++ b/drivers/block/ploop/dev.c
@@ -1137,11 +1137,6 @@ static int check_lockout(struct ploop_request *preq)
else if (preq->req_cluster > p->req_cluster)
n = n->rb_right;
else {
- /* do not block backup tool READs from /dev/ploop */
- if (!(preq->req_rw & REQ_WRITE) &&
- test_bit(PLOOP_REQ_ALLOW_READS, &p->state))
- return 0;
-
list_add_tail(&preq->list, &p->delay_list);
plo->st.bio_lockouts++;
trace_preq_lockout(preq, p);
@@ -2053,7 +2048,6 @@ restart:
ploop_pb_clear_bit(plo->pbd, preq->req_cluster);
} else {
spin_lock_irq(&plo->lock);
- __set_bit(PLOOP_REQ_ALLOW_READS, &preq->state);
ploop_add_lockout(preq, 0);
spin_unlock_irq(&plo->lock);
/*
@@ -2072,7 +2066,6 @@ restart:
spin_lock_irq(&plo->lock);
del_lockout(preq);
- __clear_bit(PLOOP_REQ_ALLOW_READS, &preq->state);
if (!list_empty(&preq->delay_list))
list_splice_init(&preq->delay_list,
plo->ready_queue.prev);
spin_unlock_irq(&plo->lock);
diff --git a/include/linux/ploop/ploop.h b/include/linux/ploop/ploop.h
index 0fba25e..77fd833 100644
--- a/include/linux/ploop/ploop.h
+++ b/include/linux/ploop/ploop.h
@@ -470,7 +470,6 @@ enum
PLOOP_REQ_KAIO_FSYNC, /*force image fsync by KAIO module */
PLOOP_REQ_POST_SUBMIT, /* preq needs post_submit processing */
PLOOP_REQ_PUSH_BACKUP, /* preq was ACKed by userspace push_backup */
- PLOOP_REQ_ALLOW_READS, /* READs are allowed for given req_cluster */
PLOOP_REQ_FSYNC_DONE, /* fsync_thread() performed f_op->fsync() */
};
_______________________________________________
Devel mailing list
[email protected]
https://lists.openvz.org/mailman/listinfo/devel
