Re: [PATCH 1/5] Btrfs: wake up the tasks that wait for the io earlier

[Liu Bo <bo.li.liu@oracle.com>]

On Thu, Nov 21, 2013 at 09:43:14PM +0800, Miao Xie wrote:
> The tasks that wait for the IO_DONE flag just care about the io of the dirty
> pages, so it is better to wake up them immediately after all the pages are
> written, not the whole process of the io completes.

This doesn't seem to make sense, the waiters still go to wait and schedule since
IO_DONE is not set there yet.

-liubo

> 
> Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
> ---
>  fs/btrfs/ordered-data.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
> index eb5bac4..1bd7002 100644
> --- a/fs/btrfs/ordered-data.c
> +++ b/fs/btrfs/ordered-data.c
> @@ -348,10 +348,13 @@ int btrfs_dec_test_first_ordered_pending(struct inode *inode,
>  	if (!uptodate)
>  		set_bit(BTRFS_ORDERED_IOERR, &entry->flags);
>  
> -	if (entry->bytes_left == 0)
> +	if (entry->bytes_left == 0) {
>  		ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);
> -	else
> +		if (waitqueue_active(&entry->wait))
> +			wake_up(&entry->wait);
> +	} else {
>  		ret = 1;
> +	}
>  out:
>  	if (!ret && cached && entry) {
>  		*cached = entry;
> @@ -408,10 +411,13 @@ have_entry:
>  	if (!uptodate)
>  		set_bit(BTRFS_ORDERED_IOERR, &entry->flags);
>  
> -	if (entry->bytes_left == 0)
> +	if (entry->bytes_left == 0) {
>  		ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);
> -	else
> +		if (waitqueue_active(&entry->wait))
> +			wake_up(&entry->wait);
> +	} else {
>  		ret = 1;
> +	}
>  out:
>  	if (!ret && cached && entry) {
>  		*cached = entry;
> -- 
> 1.8.3.1
> 
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