linux-ext4 - Re: [PATCH] ext4: release discard bio after sending discard commands

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Message-ID: <20170801090909.GB4215@quack2.suse.cz>
Date:   Tue, 1 Aug 2017 11:09:09 +0200
From:   Jan Kara <jack@...e.cz>
To:     Daeho Jeong <daeho.jeong@...sung.com>
Cc:     jack@...e.com, tytso@....edu, linux-ext4@...r.kernel.org
Subject: Re: [PATCH] ext4: release discard bio after sending discard commands

On Tue 01-08-17 11:29:28, Daeho Jeong wrote:
> We've changed the discard command handling into parallel manner.
> But, in this change, I forgot decreasing the usage count of the bio
> which was used to send discard request. I'm sorry about that.
> 
> Signed-off-by: Daeho Jeong <daeho.jeong@...sung.com>
> Fixes: a015434480dc ("ext4: send parallel discards on commit
> completions")

Why do you think this is needed? submit_bio_wait() consumes the reference
that you've got from __blkdev_issue_discard()...

								Honza
> ---
>  fs/ext4/mballoc.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index ab70b69e644c..88317b0cf7b8 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -2892,8 +2892,10 @@ void ext4_process_freed_data(struct super_block *sb, tid_t commit_tid)
>  				break;
>  		}
>  
> -		if (discard_bio)
> +		if (discard_bio) {
>  			submit_bio_wait(discard_bio);
> +			bio_put(discard_bio);
> +		}
>  	}
>  
>  	list_for_each_entry_safe(entry, tmp, &freed_data_list, efd_list)
> -- 
> 2.13.0
> 
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR