[PATCH 0/2] Fix bio_set copy

[PATCH 0/2] Fix bio_set copy

[Jens Axboe]

After a recent change, dm ends up doing a straight copy of a
bio_set. This breaks for various items in that bio_set,
most notably lists. Provide a proper helper for it, and use it.

-- 
Jens Axboe

[PATCH 1/2] block: add bioset_init_from_src() helper

[Jens Axboe]

Add a helper that allows a caller to initialize a new bio_set,
using the settings from an existing bio_set.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 block/bio.c         | 18 ++++++++++++++++++
 include/linux/bio.h |  1 +
 2 files changed, 19 insertions(+)

diff --git a/block/bio.c b/block/bio.c
index 595663e0281a..bf516d873ce9 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1967,6 +1967,24 @@ int bioset_init(struct bio_set *bs,
 }
 EXPORT_SYMBOL(bioset_init);
 
+/*
+ * Initialize and setup a new bio_set, based on the settings from
+ * another bio_set.
+ */
+int bioset_init_from_src(struct bio_set *bs, struct bio_set *src)
+{
+	int flags;
+
+	flags = 0;
+	if (src->bvec_pool.min_nr)
+		flags |= BIOSET_NEED_BVECS;
+	if (src->rescue_workqueue)
+		flags |= BIOSET_NEED_RESCUER;
+
+	return bioset_init(bs, src->bio_pool.min_nr, src->front_pad, flags);
+}
+EXPORT_SYMBOL(bioset_init_from_src);
+
 #ifdef CONFIG_BLK_CGROUP
 
 /**
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 810a8bee8f85..84abd1706dcb 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -417,6 +417,7 @@ enum {
 extern int bioset_init(struct bio_set *, unsigned int, unsigned int, int flags);
 extern void bioset_exit(struct bio_set *);
 extern int biovec_init_pool(mempool_t *pool, int pool_entries);
+extern int bioset_init_from_src(struct bio_set *bs, struct bio_set *src);
 
 extern struct bio *bio_alloc_bioset(gfp_t, unsigned int, struct bio_set *);
 extern void bio_put(struct bio *);
-- 
2.17.1

[PATCH 2/2] dm: use bioset_init_from_src() to copy bio_set

[Jens Axboe]

We can't just copy and clear a bio_set, use the bio helper to
setup a new bio_set with the settings from another one.

Fixes: 6f1c819c219f ("dm: convert to bioset_init()/mempool_init()")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 drivers/md/dm.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 98dff36b89a3..20a8d63754bf 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1953,9 +1953,10 @@ static void free_dev(struct mapped_device *md)
 	kvfree(md);
 }
 
-static void __bind_mempools(struct mapped_device *md, struct dm_table *t)
+static int __bind_mempools(struct mapped_device *md, struct dm_table *t)
 {
 	struct dm_md_mempools *p = dm_table_get_md_mempools(t);
+	int ret = 0;
 
 	if (dm_table_bio_based(t)) {
 		/*
@@ -1982,13 +1983,16 @@ static void __bind_mempools(struct mapped_device *md, struct dm_table *t)
 	       bioset_initialized(&md->bs) ||
 	       bioset_initialized(&md->io_bs));
 
-	md->bs = p->bs;
-	memset(&p->bs, 0, sizeof(p->bs));
-	md->io_bs = p->io_bs;
-	memset(&p->io_bs, 0, sizeof(p->io_bs));
+	ret = bioset_init_from_src(&md->bs, &p->bs);
+	if (ret)
+		goto out;
+	ret = bioset_init_from_src(&md->io_bs, &p->io_bs);
+	if (ret)
+		bioset_exit(&md->bs);
 out:
 	/* mempool bind completed, no longer need any mempools in the table */
 	dm_table_free_md_mempools(t);
+	return ret;
 }
 
 /*
@@ -2033,6 +2037,7 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
 	struct request_queue *q = md->queue;
 	bool request_based = dm_table_request_based(t);
 	sector_t size;
+	int ret;
 
 	lockdep_assert_held(&md->suspend_lock);
 
@@ -2068,7 +2073,11 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
 		md->immutable_target = dm_table_get_immutable_target(t);
 	}
 
-	__bind_mempools(md, t);
+	ret = __bind_mempools(md, t);
+	if (ret) {
+		old_map = ERR_PTR(ret);
+		goto out;
+	}
 
 	old_map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock));
 	rcu_assign_pointer(md->map, (void *)t);
@@ -2078,6 +2087,7 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
 	if (old_map)
 		dm_sync_table(md);
 
+out:
 	return old_map;
 }
 
-- 
2.17.1

Re: [PATCH 0/2] Fix bio_set copy

[Li Wang]

[-- Attachment #1: Type: text/plain, Size: 437 bytes --]

Jens Axboe <axboe@kernel.dk> wrote:

> After a recent change, dm ends up doing a straight copy of a
> bio_set. This breaks for various items in that bio_set,
> most notably lists. Provide a proper helper for it, and use it.
>
> ​

I can confirm that the issue[1] was gone with this patchset applied.


   Tested-by: Li Wang <liwang@redhat.com>

​

[1] https://lkml.org/lkml/2018/6/7/36​


-- 
Regards,
Li Wang

[-- Attachment #2: Type: text/html, Size: 1721 bytes --]

Re: [PATCH 0/2] Fix bio_set copy

[vrbagal1]

On 2018-06-08 11:42, Li Wang wrote:
> Jens Axboe <axboe@kernel.dk> wrote:
> 
>> After a recent change, dm ends up doing a straight copy of a
>> bio_set. This breaks for various items in that bio_set,
>> most notably lists. Provide a proper helper for it, and use it.
> 
> ​

I am not seeing the issue, I reported with this patch applied to latest 
mainline.

JOB ID     : 5d6db9ad320b92b77cd92056fb4514c9afa0feea
JOB LOG    : 
/root/avocado-korg/korg/results/job-2018-06-08T03.49-5d6db9a/job.log
  (1/4) memhotplug.py:memstress.test_hotplug_loop: PASS (254.14 s)
  (2/4) memhotplug.py:memstress.test_hotplug_toggle: PASS (246.81 s)
  (3/4) memhotplug.py:memstress.test_dlpar_mem_hotplug: PASS (3.95 s)
  (4/4) memhotplug.py:memstress.test_hotplug_per_numa_node: PASS (223.96 
s)
RESULTS    : PASS 4 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0 | 
CANCEL 0
JOB TIME   : 734.52 s
JOB HTML   : 
/root/avocado-korg/korg/results/job-2018-06-08T03.49-5d6db9a/results.html

      Reported-by: Venkat R.B <vrbagal1@linux.vnet.ibm.com>
      Tested-by: Venkat R.B <vrbagal1@linux.vnet.ibm.com>
> 
> I can confirm that the issue[1] was gone with this patchset applied.
> 
>    Tested-by: Li Wang <liwang@redhat.com>
> 
> ​
> [1] https://lkml.org/lkml/2018/6/7/36 [1]​
> 
> --
> 
> Regards,
> 
> Li Wang
> 
> 
> Links:
> ------
> [1] https://lkml.org/lkml/2018/6/7/36

Re: [PATCH 0/2] Fix bio_set copy

[Jens Axboe]

On 6/8/18 12:12 AM, Li Wang wrote:
> Jens Axboe <axboe@kernel.dk <mailto:axboe@kernel.dk>> wrote:
> 
>     After a recent change, dm ends up doing a straight copy of a
>     bio_set. This breaks for various items in that bio_set,
>     most notably lists. Provide a proper helper for it, and use it.
> 
> ​
> 
> I can confirm that the issue[1] was gone with this patchset applied.
> 
> 
>    Tested-by: Li Wang <liwang@redhat.com <mailto:liwang@redhat.com>>

Thanks for testing, both of you, and reporting. I'll get this pushed
upstream.

-- 
Jens Axboe