2020-03-10 13:21:51

by Martijn Coenen

Subject: [PATCH] loop: Only freeze block queue when needed.

__loop_update_dio() can be called as a part of loop_set_fd(), when the
block queue is not yet up and running; avoid freezing the block queue in
that case, since that is an expensive operation.

Signed-off-by: Martijn Coenen <[email protected]>
---
drivers/block/loop.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 739b372a5112..c1c844ad6b1a 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -214,7 +214,8 @@ static void __loop_update_dio(struct loop_device *lo, bool dio)
* LO_FLAGS_READ_ONLY, both are set from kernel, and losetup
* will get updated by ioctl(LOOP_GET_STATUS)
*/
- blk_mq_freeze_queue(lo->lo_queue);
+ if (lo->lo_state == Lo_bound)
+ blk_mq_freeze_queue(lo->lo_queue);
lo->use_dio = use_dio;
if (use_dio) {
blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, lo->lo_queue);
@@ -223,7 +224,8 @@ static void __loop_update_dio(struct loop_device *lo, bool dio)
blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
lo->lo_flags &= ~LO_FLAGS_DIRECT_IO;
}
- blk_mq_unfreeze_queue(lo->lo_queue);
+ if (lo->lo_state == Lo_bound)
+ blk_mq_unfreeze_queue(lo->lo_queue);
}

static int
--
2.25.1.481.gfbce0eb801-goog

2020-03-10 17:49:48

by Christoph Hellwig

Subject: Re: [PATCH] loop: Only freeze block queue when needed.

On Tue, Mar 10, 2020 at 02:06:54PM +0100, Martijn Coenen wrote:
> __loop_update_dio() can be called as a part of loop_set_fd(), when the
> block queue is not yet up and running; avoid freezing the block queue in
> that case, since that is an expensive operation.
>
> Signed-off-by: Martijn Coenen <[email protected]>

Looks good,

Reviewed-by: Christoph Hellwig <[email protected]>

2020-03-10 20:06:50

by Chaitanya Kulkarni

Subject: Re: [PATCH] loop: Only freeze block queue when needed.

Looks good to me.

Reviewed-by: Chaitanya Kulkarni <[email protected]>

On 03/10/2020 06:07 AM, Martijn Coenen wrote:
> __loop_update_dio() can be called as a part of loop_set_fd(), when the
> block queue is not yet up and running; avoid freezing the block queue in
> that case, since that is an expensive operation.
>
> Signed-off-by: Martijn Coenen<[email protected]>

2020-03-10 20:12:45

by Jens Axboe

Subject: Re: [PATCH] loop: Only freeze block queue when needed.

On 3/10/20 7:06 AM, Martijn Coenen wrote:
> __loop_update_dio() can be called as a part of loop_set_fd(), when the
> block queue is not yet up and running; avoid freezing the block queue in
> that case, since that is an expensive operation.

Applied, thanks.

--
Jens Axboe