linux-ext4 - Re: [PATCH] jbd2: stop waiting for space when jbd2_cleanup_journal

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Message-ID: <20240718135129.jzhxdh5ejtwkqehr@quack3>
Date: Thu, 18 Jul 2024 15:51:29 +0200
From: Jan Kara <jack@...e.cz>
To: libaokun@...weicloud.com
Cc: linux-ext4@...r.kernel.org, tytso@....edu, jack@...e.cz,
	linux-kernel@...r.kernel.org, yi.zhang@...wei.com,
	yangerkun@...wei.com, Baokun Li <libaokun1@...wei.com>,
	stable@...nel.org
Subject: Re: [PATCH] jbd2: stop waiting for space when
 jbd2_cleanup_journal_tail() returns error

On Thu 18-07-24 19:53:36, libaokun@...weicloud.com wrote:
> From: Baokun Li <libaokun1@...wei.com>
> 
> In __jbd2_log_wait_for_space(), we might call jbd2_cleanup_journal_tail()
> to recover some journal space. But if an error occurs while executing
> jbd2_cleanup_journal_tail() (e.g., an EIO), we don't stop waiting for free
> space right away, we try other branches, and if j_committing_transaction
> is NULL (i.e., the tid is 0), we will get the following complain:
> 
> ============================================
> JBD2: I/O error when updating journal superblock for sdd-8.
> __jbd2_log_wait_for_space: needed 256 blocks and only had 217 space available
> __jbd2_log_wait_for_space: no way to get more journal space in sdd-8
> ------------[ cut here ]------------
> WARNING: CPU: 2 PID: 139804 at fs/jbd2/checkpoint.c:109 __jbd2_log_wait_for_space+0x251/0x2e0
> Modules linked in:
> CPU: 2 PID: 139804 Comm: kworker/u8:3 Not tainted 6.6.0+ #1
> RIP: 0010:__jbd2_log_wait_for_space+0x251/0x2e0
> Call Trace:
>  <TASK>
>  add_transaction_credits+0x5d1/0x5e0
>  start_this_handle+0x1ef/0x6a0
>  jbd2__journal_start+0x18b/0x340
>  ext4_dirty_inode+0x5d/0xb0
>  __mark_inode_dirty+0xe4/0x5d0
>  generic_update_time+0x60/0x70
> [...]
> ============================================
> 
> So only if jbd2_cleanup_journal_tail() returns 1, i.e., there is nothing to
> clean up at the moment, continue to try to reclaim free space in other ways.
> 
> Note that this fix relies on commit 6f6a6fda2945 ("jbd2: fix ocfs2 corrupt
> when updating journal superblock fails") to make jbd2_cleanup_journal_tail
> return the correct error code.
> 
> Fixes: 8c3f25d8950c ("jbd2: don't give up looking for space so easily in __jbd2_log_wait_for_space")
> Cc: stable@...nel.org
> Signed-off-by: Baokun Li <libaokun1@...wei.com>

Looks good. Feel free to add:

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

								Honza

> ---
>  fs/jbd2/checkpoint.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
> index 951f78634adf..7b593591273a 100644
> --- a/fs/jbd2/checkpoint.c
> +++ b/fs/jbd2/checkpoint.c
> @@ -86,8 +86,11 @@ __releases(&journal->j_state_lock)
>  			write_unlock(&journal->j_state_lock);
>  			if (chkpt) {
>  				jbd2_log_do_checkpoint(journal);
> -			} else if (jbd2_cleanup_journal_tail(journal) == 0) {
> -				/* We were able to recover space; yay! */
> +			} else if (jbd2_cleanup_journal_tail(journal) <= 0) {
> +				/*
> +				 * We were able to recover space or the
> +				 * journal was aborted due to an error.
> +				 */
>  				;
>  			} else if (tid) {
>  				/*
> -- 
> 2.39.2
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR