linux-ext4 - Re: [PATCH v2 1/5] ext4: convert i_fc

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Message-ID: <20220309101057.3uuix2gvjinobt3i@quack3.lan>
Date:   Wed, 9 Mar 2022 11:10:57 +0100
From:   Jan Kara <jack@...e.cz>
To:     Harshad Shirwadkar <harshadshirwadkar@...il.com>
Cc:     linux-ext4@...r.kernel.org, riteshh@...ux.ibm.com, jack@...e.cz,
        tytso@....edu
Subject: Re: [PATCH v2 1/5] ext4: convert i_fc_lock to spinlock

On Tue 08-03-22 08:33:15, Harshad Shirwadkar wrote:
> From: Harshad Shirwadkar <harshadshirwadkar@...il.com>
> 
> Convert ext4_inode_info->i_fc_lock to spinlock to avoid sleeping
> in invalid contexts.
> 
> Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@...il.com>

One comment below...

> @@ -972,9 +970,13 @@ static int ext4_fc_wait_inode_data_all(journal_t *journal)
>  
>  	spin_lock(&sbi->s_fc_lock);
>  	list_for_each_entry_safe(pos, n, &sbi->s_fc_q[FC_Q_MAIN], i_fc_list) {
> +		spin_lock(&pos->i_fc_lock);
>  		if (!ext4_test_inode_state(&pos->vfs_inode,
> -					   EXT4_STATE_FC_COMMITTING))
> +					   EXT4_STATE_FC_COMMITTING)) {
> +			spin_unlock(&pos->i_fc_lock);
>  			continue;
> +		}
> +		spin_unlock(&pos->i_fc_lock);
>  		spin_unlock(&sbi->s_fc_lock);

Why do you add a lock here in a pure lock-conversion patch? Furthermore I
don't think the lock is needed...

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR