The commit is pushed to "branch-rh7-3.10.0-229.7.2-ovz" and will appear at
https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-229.7.2.vz7.6.3
------>
commit 9202d063a35d9317b1c16ef9641687d73765f996
Author: Maxim Patlasov <[email protected]>
Date: Sat Aug 29 02:33:28 2015 +0400
ploop: fix race on prealloc request
kaio_submit_alloc() sometimes piggybacks ploop request with additional work:
set preq->prealloc_size, pass preq to fsync_thread, perform preallocation
there, get it back to kaio_submit_alloc(), move preallocation from
preq->prealloc_size to io->prealloced_size.
The problem happens when such a request does not get back to
kaio_submit_alloc.
For example, it may happen if ploop shrink or compact is in progress: by the
time the request is re-scheduled after preallocation, free blocks emerges,
and ploop_entry_request() use one of them calling kaio_submit intead of
kaio_submit_alloc.
To solve this case and other similar ones, the patch moves the code
transferring preq->prealloc_size to ploop_req_state_process(). Now, this
transfer will be done independently on how ploop state machine decides to
handle that preq.
https://jira.sw.ru/browse/PSBM-35095
Signed-off-by: Maxim Patlasov <[email protected]>
Acked-by: Dmitry Monakhov <[email protected]>
---
drivers/block/ploop/dev.c | 13 +++++++++++++
drivers/block/ploop/io_kaio.c | 9 +--------
2 files changed, 14 insertions(+), 8 deletions(-)
diff --git a/drivers/block/ploop/dev.c b/drivers/block/ploop/dev.c
index 30eb8a7..97e75a7 100644
--- a/drivers/block/ploop/dev.c
+++ b/drivers/block/ploop/dev.c
@@ -2275,6 +2275,19 @@ static void ploop_req_state_process(struct ploop_request
* preq)
ploop_tracker_notify(plo, sec);
}
+ /* trick: preq->prealloc_size is actually new pos of eof */
+ if (unlikely(preq->prealloc_size && !preq->error)) {
+ struct ploop_io *io = &ploop_top_delta(plo)->io;
+ int log = preq->plo->cluster_log + 9;
+
+ BUG_ON(preq != io->prealloc_preq);
+ io->prealloc_preq = NULL;
+
+ io->prealloced_size = preq->prealloc_size -
+ ((loff_t)io->alloc_head << log);
+ preq->prealloc_size = 0; /* only for sanity */
+ }
+
restart:
__TRACE("ST %p %u %lu\n", preq, preq->req_cluster, preq->eng_state);
switch (preq->eng_state) {
diff --git a/drivers/block/ploop/io_kaio.c b/drivers/block/ploop/io_kaio.c
index ccdf1f4..db900a3 100644
--- a/drivers/block/ploop/io_kaio.c
+++ b/drivers/block/ploop/io_kaio.c
@@ -460,14 +460,7 @@ kaio_submit_alloc(struct ploop_io *io, struct
ploop_request * preq,
return;
}
- /* trick: preq->prealloc_size is actually new pos of eof */
- if (unlikely(preq->prealloc_size)) {
- BUG_ON(preq != io->prealloc_preq);
- io->prealloc_preq = NULL;
-
- io->prealloced_size = preq->prealloc_size - ((loff_t)iblk <<
log);
- preq->prealloc_size = 0; /* only for sanity */
- }
+ BUG_ON(preq->prealloc_size);
if (unlikely(io->prealloced_size < clu_siz)) {
if (!io->prealloc_preq) {
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