6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Christoph Hellwig <hch@xxxxxx>
[ Upstream commit 667ea36378cf7f669044b27871c496e1559c872a ]
QUEUE_FLAG_NOMERGES isn't really a driver interface, but a user tunable.
There also isn't any good reason to set it in the loop driver.
The original commit adding it (5b5e20f421c0b6d "block: loop: set
QUEUE_FLAG_NOMERGES for request queue of loop") claims that "It doesn't
make sense to enable merge because the I/O submitted to backing file is
handled page by page." which of course isn't true for multi-page bvec
now, and it never has been for direct I/O, for which commit 40326d8a33d
("block/loop: allow request merge for directio mode") alredy disabled
the nomerges flag.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
Link: https://lore.kernel.org/r/20240627124926.512662-2-hch@xxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/block/loop.c | 15 ++-------------
1 file changed, 2 insertions(+), 13 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 12ff6f58b8a90..041d307a2f280 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -211,13 +211,10 @@ static void __loop_update_dio(struct loop_device *lo, bool dio)
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);
+ if (use_dio)
lo->lo_flags |= LO_FLAGS_DIRECT_IO;
- } else {
- blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
+ else
lo->lo_flags &= ~LO_FLAGS_DIRECT_IO;
- }
if (lo->lo_state == Lo_bound)
blk_mq_unfreeze_queue(lo->lo_queue);
}
@@ -2034,14 +2031,6 @@ static int loop_add(int i)
blk_queue_max_hw_sectors(lo->lo_queue, BLK_DEF_MAX_SECTORS);
- /*
- * By default, we do buffer IO, so it doesn't make sense to enable
- * merge because the I/O submitted to backing file is handled page by
- * page. For directio mode, merge does help to dispatch bigger request
- * to underlayer disk. We will enable merge once directio is enabled.
- */
- blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
-
/*
* Disable partition scanning by default. The in-kernel partition
* scanning can be requested individually per-device during its
--
2.43.0
