The commit is pushed to "branch-rh7-3.10.0-957.10.1.vz7.85.x-ovz" and will
appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-957.10.1.vz7.85.7
------>
commit 82c8b74a4a99d705be295da09d7fa578f85dbef5
Author: Kirill Tkhai <[email protected]>
Date: Fri Mar 29 11:47:41 2019 +0300
ploop: Fix race between .prepare_merge and .submit_alloc
submit_alloc may change alloc_head in parallel,
and this may lead to data corruption, when we
read inode size before submit_alloc and update
the size after submit_alloc.
Signed-off-by: Kirill Tkhai <[email protected]>
---
drivers/block/ploop/dev.c | 5 +++++
drivers/block/ploop/fmt_ploop1.c | 4 ++++
2 files changed, 9 insertions(+)
diff --git a/drivers/block/ploop/dev.c b/drivers/block/ploop/dev.c
index 1d2167552b26..131ec72b1a1e 100644
--- a/drivers/block/ploop/dev.c
+++ b/drivers/block/ploop/dev.c
@@ -3782,6 +3782,11 @@ static void ploop_merge_cleanup(struct ploop_device *
plo,
ploop_relax(plo);
}
+/*
+ * Calls format and io callbacks. Should not be called
+ * in quiesce state, since it may enter quiesce state
+ * itself (in fmt_prepare_merge callback).
+ */
static int ploop_prepare_merge(struct ploop_delta *next,
struct ploop_snapdata *sd)
{
diff --git a/drivers/block/ploop/fmt_ploop1.c b/drivers/block/ploop/fmt_ploop1.c
index 4a4aa6bf7ae2..59ba493db9ec 100644
--- a/drivers/block/ploop/fmt_ploop1.c
+++ b/drivers/block/ploop/fmt_ploop1.c
@@ -379,6 +379,7 @@ ploop1_prepare_merge(struct ploop_delta * delta, struct
ploop_snapdata * sd)
int err;
struct ploop_pvd_header *vh;
struct ploop1_private * ph = delta->priv;
+ struct ploop_device *plo = delta->plo;
vh = (struct ploop_pvd_header *)page_address(ph->dyn_page);
@@ -389,9 +390,12 @@ ploop1_prepare_merge(struct ploop_delta * delta, struct
ploop_snapdata * sd)
if (pvd_header_is_disk_in_use(vh))
return -EBUSY;
+ /* Close race with submit_alloc */
+ ploop_quiesce(plo);
ph->alloc_head = delta->io.ops->i_size_read(&delta->io) >>
(delta->io.plo->cluster_log + 9);
delta->io.alloc_head = ph->alloc_head;
+ ploop_relax(plo);
return 0;
}
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