linux-kernel - Re: [PATCH] jbd: don't abort if flushing file data failed

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Date:	Thu, 19 Jun 2008 10:01:08 +0200
From:	Jan Kara <jack@...e.cz>
To:	Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, sct@...hat.com,
	adilger@...sterfs.com, linux-kernel@...r.kernel.org,
	linux-ext4@...r.kernel.org, Jan Kara <jack@...e.cz>,
	Josef Bacik <jbacik@...hat.com>, Mingming Cao <cmm@...ibm.com>,
	Theodore Ts'o <tytso@....edu>,
	sugita <yumiko.sugita.yf@...achi.com>,
	Satoshi OSHIMA <satoshi.oshima.fk@...achi.com>
Subject: Re: [PATCH] jbd: don't abort if flushing file data failed

On Thu 19-06-08 15:32:34, Hidehiro Kawai wrote:
> In ordered mode, the current jbd aborts the journal if a file data
> buffer has an error.  But this behavior is unintended, and we found
> that it has been adopted accidentally.
> 
> This patch undoes it and just calls printk() instead of aborting
> the journal.  Additionally, set AS_EIO into the address_space
> object of the failed buffer which is submitted by
> journal_do_submit_data() so that fsync() can get -EIO.
> 
> Missing error checkings are also added to inform errors on file
> data buffers to the user.  The following buffers are targeted.
> 
>   (a) the buffer which has already been written out by pdflush
>   (b) the buffer which has been unlocked before scanned in the
>       t_locked_list loop
> 
> Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>
  You can add Acked-by: Jan Kara <jack@...e.cz>

  I have just one minor comment: Could you add device on which an error
happened to the error message in journal_commit_transaction()? It could
help the user in some cases...
  Thanks for fixing this.

									Honza
> ---
>  fs/jbd/commit.c |   32 +++++++++++++++++++++++++-------
>  1 file changed, 25 insertions(+), 7 deletions(-)
> 
> Index: linux-2.6.26-rc5-mm3/fs/jbd/commit.c
> ===================================================================
> --- linux-2.6.26-rc5-mm3.orig/fs/jbd/commit.c
> +++ linux-2.6.26-rc5-mm3/fs/jbd/commit.c
> @@ -172,7 +172,7 @@ static void journal_do_submit_data(struc
>  /*
>   *  Submit all the data buffers to disk
>   */
> -static void journal_submit_data_buffers(journal_t *journal,
> +static int journal_submit_data_buffers(journal_t *journal,
>  				transaction_t *commit_transaction)
>  {
>  	struct journal_head *jh;
> @@ -180,6 +180,7 @@ static void journal_submit_data_buffers(
>  	int locked;
>  	int bufs = 0;
>  	struct buffer_head **wbuf = journal->j_wbuf;
> +	int err = 0;
>  
>  	/*
>  	 * Whenever we unlock the journal and sleep, things can get added
> @@ -253,6 +254,8 @@ write_out_data:
>  			put_bh(bh);
>  		} else {
>  			BUFFER_TRACE(bh, "writeout complete: unfile");
> +			if (unlikely(!buffer_uptodate(bh)))
> +				err = -EIO;
>  			__journal_unfile_buffer(jh);
>  			jbd_unlock_bh_state(bh);
>  			if (locked)
> @@ -271,6 +274,8 @@ write_out_data:
>  	}
>  	spin_unlock(&journal->j_list_lock);
>  	journal_do_submit_data(wbuf, bufs);
> +
> +	return err;
>  }
>  
>  /*
> @@ -410,8 +415,7 @@ void journal_commit_transaction(journal_
>  	 * Now start flushing things to disk, in the order they appear
>  	 * on the transaction lists.  Data blocks go first.
>  	 */
> -	err = 0;
> -	journal_submit_data_buffers(journal, commit_transaction);
> +	err = journal_submit_data_buffers(journal, commit_transaction);
>  
>  	/*
>  	 * Wait for all previously submitted IO to complete.
> @@ -426,10 +430,21 @@ void journal_commit_transaction(journal_
>  		if (buffer_locked(bh)) {
>  			spin_unlock(&journal->j_list_lock);
>  			wait_on_buffer(bh);
> -			if (unlikely(!buffer_uptodate(bh)))
> -				err = -EIO;
>  			spin_lock(&journal->j_list_lock);
>  		}
> +		if (unlikely(!buffer_uptodate(bh))) {
> +			if (TestSetPageLocked(bh->b_page)) {
> +				spin_unlock(&journal->j_list_lock);
> +				lock_page(bh->b_page);
> +				spin_lock(&journal->j_list_lock);
> +			}
> +			if (bh->b_page->mapping)
> +				set_bit(AS_EIO, &bh->b_page->mapping->flags);
> +
> +			unlock_page(bh->b_page);
> +			SetPageError(bh->b_page);
> +			err = -EIO;
> +		}
>  		if (!inverted_lock(journal, bh)) {
>  			put_bh(bh);
>  			spin_lock(&journal->j_list_lock);
> @@ -448,8 +463,11 @@ void journal_commit_transaction(journal_
>  	}
>  	spin_unlock(&journal->j_list_lock);
>  
> -	if (err)
> -		journal_abort(journal, err);
> +	if (err) {
> +		printk(KERN_WARNING
> +		       "JBD: Detected IO errors during flushing file data\n");
> +		err = 0;
> +	}
>  
>  	journal_write_revoke_records(journal, commit_transaction);
>  
> 
> 
> 
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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