Re: [PATCH 1/2] block: use DEFINE_WAIT_BIT instead of DEFINE_WAIT for bit wait queue

[Jacob Wen]

Can I have a review?

On 8/13/20 1:05 PM, Jacob Wen wrote:

DEFINE_WAIT_BIT uses wake_bit_function() which is able to avoid
false-wakeups due to possible hash collisions in the bit wait table.

Signed-off-by: Jacob Wen <jian.w....@oracle.com>
---
  fs/block_dev.c | 6 +++---
  1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 0ae656e022fd..ba4fad08cdaf 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1062,12 +1062,12 @@ static int bd_prepare_to_claim(struct block_device 
*bdev,
        /* if claiming is already in progress, wait for it to finish */
        if (whole->bd_claiming) {
                wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
-               DEFINE_WAIT(wait);
+               DEFINE_WAIT_BIT(wait, &whole->bd_claiming, 0);

- prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);

+               prepare_to_wait(wq, &wait.wq_entry, TASK_UNINTERRUPTIBLE);
                spin_unlock(&bdev_lock);
                schedule();
-               finish_wait(wq, &wait);
+               finish_wait(wq, &wait.wq_entry);
                spin_lock(&bdev_lock);
                goto retry;
        }