[PATCH 3.13.y-ckt 045/108] dm space map metadata: fix ref counting bug when bootstrapping a new space map

From: Kamal Mostafa
Date: Fri Jan 22 2016 - 18:49:40 EST


3.13.11-ckt33 -stable review patch. If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Joe Thornber <ejt@xxxxxxxxxx>

commit 50dd842ad83b43bed71790efb31cfb2f6c05c9c1 upstream.

When applying block operations (BOPs) do not remove them from the
uncommitted BOP ring-buffer until after they've been applied -- in case
we recurse.

Also, perform BOP_INC operation, in dm_sm_metadata_create() and
sm_metadata_extend(), in terms of the uncommitted BOP ring-buffer rather
than using direct calls to sm_ll_inc().

Signed-off-by: Joe Thornber <ejt@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
drivers/md/persistent-data/dm-space-map-metadata.c | 32 +++++++++++++++-------
1 file changed, 22 insertions(+), 10 deletions(-)

diff --git a/drivers/md/persistent-data/dm-space-map-metadata.c b/drivers/md/persistent-data/dm-space-map-metadata.c
index 8ce970c..6b6efa7 100644
--- a/drivers/md/persistent-data/dm-space-map-metadata.c
+++ b/drivers/md/persistent-data/dm-space-map-metadata.c
@@ -136,7 +136,7 @@ static int brb_push(struct bop_ring_buffer *brb,
return 0;
}

-static int brb_pop(struct bop_ring_buffer *brb, struct block_op *result)
+static int brb_peek(struct bop_ring_buffer *brb, struct block_op *result)
{
struct block_op *bop;

@@ -147,6 +147,17 @@ static int brb_pop(struct bop_ring_buffer *brb, struct block_op *result)
result->type = bop->type;
result->block = bop->block;

+ return 0;
+}
+
+static int brb_pop(struct bop_ring_buffer *brb)
+{
+ struct block_op *bop;
+
+ if (brb_empty(brb))
+ return -ENODATA;
+
+ bop = brb->bops + brb->begin;
brb->begin = brb_next(brb, brb->begin);

return 0;
@@ -211,7 +222,7 @@ static int apply_bops(struct sm_metadata *smm)
while (!brb_empty(&smm->uncommitted)) {
struct block_op bop;

- r = brb_pop(&smm->uncommitted, &bop);
+ r = brb_peek(&smm->uncommitted, &bop);
if (r) {
DMERR("bug in bop ring buffer");
break;
@@ -220,6 +231,8 @@ static int apply_bops(struct sm_metadata *smm)
r = commit_bop(smm, &bop);
if (r)
break;
+
+ brb_pop(&smm->uncommitted);
}

return r;
@@ -679,7 +692,6 @@ static struct dm_space_map bootstrap_ops = {
static int sm_metadata_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
{
int r, i;
- enum allocation_event ev;
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
dm_block_t old_len = smm->ll.nr_blocks;

@@ -701,11 +713,12 @@ static int sm_metadata_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
* allocate any new blocks.
*/
do {
- for (i = old_len; !r && i < smm->begin; i++) {
- r = sm_ll_inc(&smm->ll, i, &ev);
- if (r)
- goto out;
- }
+ for (i = old_len; !r && i < smm->begin; i++)
+ r = add_bop(smm, BOP_INC, i);
+
+ if (r)
+ goto out;
+
old_len = smm->begin;

r = apply_bops(smm);
@@ -750,7 +763,6 @@ int dm_sm_metadata_create(struct dm_space_map *sm,
{
int r;
dm_block_t i;
- enum allocation_event ev;
struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

smm->begin = superblock + 1;
@@ -776,7 +788,7 @@ int dm_sm_metadata_create(struct dm_space_map *sm,
* allocated blocks that they were built from.
*/
for (i = superblock; !r && i < smm->begin; i++)
- r = sm_ll_inc(&smm->ll, i, &ev);
+ r = add_bop(smm, BOP_INC, i);

if (r)
return r;
--
1.9.1