Hi,
在 2025/05/12 21:36, Yu Kuai 写道:
Hi,
在 2025/05/12 21:30, Christoph Hellwig 写道:
On Mon, May 12, 2025 at 03:26:41PM +0200, Christoph Hellwig wrote:
1) bitmap bio must be done before this bio can be issued;
2) bitmap bio will be added to current->bio_list, and wait for this bio
to be issued;
Do you have a better sulution to this problem?
A bew block layer API that bypasses bio_list maybe? I.e. export
__submit_bio with a better name and a kerneldoc detailing the narrow
use case.
That won't work as we'd miss a lot of checks, cgroup handling, etc.
But maybe a flag to skip the recursion avoidance?
I think this can work, and this can also improve performance. I'll look
into this.
So, I did a quick test with old internal bitmap and make sure following
patch can work.
However, for bitmap file case, bio is issued from submit_bh(), I'll have
to change buffer_head code and I'm not sure if we want to do that.
Thanks,
Kuai
diff --git a/block/blk-core.c b/block/blk-core.c
index b862c66018f2..66ced5769694 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -745,7 +745,7 @@ void submit_bio_noacct_nocheck(struct bio *bio)
* to collect a list of requests submited by a ->submit_bio
method while
* it is active, and then process them after it returned.
*/
- if (current->bio_list)
+ if (current->bio_list && !bio_flagged(bio, BIO_STACKED_META))
bio_list_add(¤t->bio_list[0], bio);
else if (!bdev_test_flag(bio->bi_bdev, BD_HAS_SUBMIT_BIO))
__submit_bio_noacct_mq(bio);
diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index 431a3ab2e449..e0cb210a4ea4 100644
--- a/drivers/md/md-bitmap.c
+++ b/drivers/md/md-bitmap.c
@@ -1257,35 +1257,6 @@ static void __bitmap_unplug(struct bitmap *bitmap)
md_bitmap_file_kick(bitmap);
}
-struct bitmap_unplug_work {
- struct work_struct work;
- struct bitmap *bitmap;
- struct completion *done;
-};
-
-static void md_bitmap_unplug_fn(struct work_struct *work)
-{
- struct bitmap_unplug_work *unplug_work =
- container_of(work, struct bitmap_unplug_work, work);
-
- __bitmap_unplug(unplug_work->bitmap);
- complete(unplug_work->done);
-}
-
-static void bitmap_unplug_async(struct bitmap *bitmap)
-{
- DECLARE_COMPLETION_ONSTACK(done);
- struct bitmap_unplug_work unplug_work;
-
- INIT_WORK_ONSTACK(&unplug_work.work, md_bitmap_unplug_fn);
- unplug_work.bitmap = bitmap;
- unplug_work.done = &done;
-
- queue_work(md_bitmap_wq, &unplug_work.work);
- wait_for_completion(&done);
- destroy_work_on_stack(&unplug_work.work);
-}
-
static void bitmap_unplug(struct mddev *mddev, bool sync)
{
struct bitmap *bitmap = mddev->bitmap;
@@ -1293,10 +1264,7 @@ static void bitmap_unplug(struct mddev *mddev,
bool sync)
if (!bitmap)
return;
- if (sync)
- __bitmap_unplug(bitmap);
- else
- bitmap_unplug_async(bitmap);
+ __bitmap_unplug(bitmap);
}
static void md_bitmap_set_memory_bits(struct bitmap *bitmap, sector_t
offset, int needed);
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 32b997dfe6f4..179eabd6e038 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1050,6 +1050,7 @@ void md_super_write(struct mddev *mddev, struct
md_rdev *rdev,
__bio_add_page(bio, page, size, 0);
bio->bi_private = rdev;
bio->bi_end_io = super_written;
+ bio_set_flag(bio, BIO_STACKED_META);
if (test_bit(MD_FAILFAST_SUPPORTED, &mddev->flags) &&
test_bit(FailFast, &rdev->flags) &&
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index f38425338c3f..88164cdae6aa 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -300,6 +300,7 @@ enum {
BIO_REMAPPED,
BIO_ZONE_WRITE_PLUGGING, /* bio handled through zone write
plugging */
BIO_EMULATES_ZONE_APPEND, /* bio emulates a zone append
operation */
+ BIO_STACKED_META, /* bio is metadata from stacked device */
BIO_FLAG_LAST
};
Thanks,
Kuai
.
.
