linux-ext4 - Re: [RFC PATCH v2 3/7] jbd2: don't abort the journal when freeing buffers

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Date:   Wed, 21 Apr 2021 15:23:54 +0200
From:   Jan Kara <jack@...e.cz>
To:     Zhang Yi <yi.zhang@...wei.com>
Cc:     linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        tytso@....edu, adilger.kernel@...ger.ca, jack@...e.cz,
        yukuai3@...wei.com
Subject: Re: [RFC PATCH v2 3/7] jbd2: don't abort the journal when freeing
 buffers

On Wed 14-04-21 21:47:33, Zhang Yi wrote:
> Now, we can make sure to abort the journal once the original buffer was
  ^^ Now that we can be sure the journal is aborted once a buffer has
failed to be written back to disk, ...

> failed to write back to disk, we can remove the journal abort logic in
> jbd2_journal_try_to_free_buffers() which was introduced in
> <c044f3d8360d> ("jbd2: abort journal if free a async write error
> metadata buffer"), because it may costs and propably not safe.
				    ^^ cost	^^ probably is

> Signed-off-by: Zhang Yi <yi.zhang@...wei.com>

Looks good. You can add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/jbd2/transaction.c | 17 -----------------
>  1 file changed, 17 deletions(-)
> 
> diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
> index 9396666b7314..3e0db4953fe4 100644
> --- a/fs/jbd2/transaction.c
> +++ b/fs/jbd2/transaction.c
> @@ -2118,7 +2118,6 @@ int jbd2_journal_try_to_free_buffers(journal_t *journal, struct page *page)
>  {
>  	struct buffer_head *head;
>  	struct buffer_head *bh;
> -	bool has_write_io_error = false;
>  	int ret = 0;
>  
>  	J_ASSERT(PageLocked(page));
> @@ -2143,26 +2142,10 @@ int jbd2_journal_try_to_free_buffers(journal_t *journal, struct page *page)
>  		jbd2_journal_put_journal_head(jh);
>  		if (buffer_jbd(bh))
>  			goto busy;
> -
> -		/*
> -		 * If we free a metadata buffer which has been failed to
> -		 * write out, the jbd2 checkpoint procedure will not detect
> -		 * this failure and may lead to filesystem inconsistency
> -		 * after cleanup journal tail.
> -		 */
> -		if (buffer_write_io_error(bh)) {
> -			pr_err("JBD2: Error while async write back metadata bh %llu.",
> -			       (unsigned long long)bh->b_blocknr);
> -			has_write_io_error = true;
> -		}
>  	} while ((bh = bh->b_this_page) != head);
>  
>  	ret = try_to_free_buffers(page);
> -
>  busy:
> -	if (has_write_io_error)
> -		jbd2_journal_abort(journal, -EIO);
> -
>  	return ret;
>  }
>  
> -- 
> 2.25.4
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR