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Date:   Tue, 8 Mar 2022 13:07:31 +0100
From:   Jan Kara <jack@suse.cz>
To:     Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Cc:     linux-ext4@vger.kernel.org, riteshh@linux.ibm.com, jack@suse.cz,
        tytso@mit.edu
Subject: Re: [PATCH 2/5] ext4: drop i_fc_updates from inode fc info
Message-ID: <20220308120731.rw525hbt2i7fl2lf@quack3.lan>
References: <20220308105112.404498-1-harshads@google.com>
 <20220308105112.404498-3-harshads@google.com>
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On Tue 08-03-22 02:51:09, Harshad Shirwadkar wrote:
> From: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
> 
> The new logic introduced in this series does not require tracking number
> of active handles open on an inode. So, drop it.
> 
> Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>

OK, but this patch needs to go towards the end of the series. Otherwise
fastcommit would be broken in the middle of the series which is nasty (e.g.
for bisection).

								Honza

> ---
>  fs/ext4/ext4.h        |  5 ----
>  fs/ext4/fast_commit.c | 58 +------------------------------------------
>  2 files changed, 1 insertion(+), 62 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index fb6d65f1176f..6861a3127a42 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1059,9 +1059,6 @@ struct ext4_inode_info {
>  	/* End of lblk range that needs to be committed in this fast commit */
>  	ext4_lblk_t i_fc_lblk_len;
>  
> -	/* Number of ongoing updates on this inode */
> -	atomic_t  i_fc_updates;
> -
>  	/* Fast commit wait queue for this inode */
>  	wait_queue_head_t i_fc_wait;
>  
> @@ -2930,8 +2927,6 @@ void __ext4_fc_track_create(handle_t *handle, struct inode *inode,
>  void ext4_fc_track_create(handle_t *handle, struct dentry *dentry);
>  void ext4_fc_track_inode(handle_t *handle, struct inode *inode);
>  void ext4_fc_mark_ineligible(struct super_block *sb, int reason, handle_t *handle);
> -void ext4_fc_start_update(struct inode *inode);
> -void ext4_fc_stop_update(struct inode *inode);
>  void ext4_fc_del(struct inode *inode);
>  bool ext4_fc_replay_check_excluded(struct super_block *sb, ext4_fsblk_t block);
>  void ext4_fc_replay_cleanup(struct super_block *sb);
> diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
> index 4f2caf6f987c..a589fc415dbe 100644
> --- a/fs/ext4/fast_commit.c
> +++ b/fs/ext4/fast_commit.c
> @@ -201,7 +201,6 @@ void ext4_fc_init_inode(struct inode *inode)
>  	INIT_LIST_HEAD(&ei->i_fc_list);
>  	INIT_LIST_HEAD(&ei->i_fc_dilist);
>  	init_waitqueue_head(&ei->i_fc_wait);
> -	atomic_set(&ei->i_fc_updates, 0);
>  }
>  
>  /* This function must be called with sbi->s_fc_lock held. */
> @@ -229,50 +228,6 @@ __releases(&EXT4_SB(inode->i_sb)->s_fc_lock)
>  	finish_wait(wq, &wait.wq_entry);
>  }
>  
> -/*
> - * Inform Ext4's fast about start of an inode update
> - *
> - * This function is called by the high level call VFS callbacks before
> - * performing any inode update. This function blocks if there's an ongoing
> - * fast commit on the inode in question.
> - */
> -void ext4_fc_start_update(struct inode *inode)
> -{
> -	struct ext4_inode_info *ei = EXT4_I(inode);
> -
> -	if (!test_opt2(inode->i_sb, JOURNAL_FAST_COMMIT) ||
> -	    (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY))
> -		return;
> -
> -restart:
> -	spin_lock(&EXT4_SB(inode->i_sb)->s_fc_lock);
> -	if (list_empty(&ei->i_fc_list))
> -		goto out;
> -
> -	if (ext4_test_inode_state(inode, EXT4_STATE_FC_COMMITTING)) {
> -		ext4_fc_wait_committing_inode(inode);
> -		goto restart;
> -	}
> -out:
> -	atomic_inc(&ei->i_fc_updates);
> -	spin_unlock(&EXT4_SB(inode->i_sb)->s_fc_lock);
> -}
> -
> -/*
> - * Stop inode update and wake up waiting fast commits if any.
> - */
> -void ext4_fc_stop_update(struct inode *inode)
> -{
> -	struct ext4_inode_info *ei = EXT4_I(inode);
> -
> -	if (!test_opt2(inode->i_sb, JOURNAL_FAST_COMMIT) ||
> -	    (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY))
> -		return;
> -
> -	if (atomic_dec_and_test(&ei->i_fc_updates))
> -		wake_up_all(&ei->i_fc_wait);
> -}
> -
>  /*
>   * Remove inode from fast commit list. If the inode is being committed
>   * we wait until inode commit is done.
> @@ -939,18 +894,7 @@ static int ext4_fc_submit_inode_data_all(journal_t *journal)
>  	spin_lock(&sbi->s_fc_lock);
>  	list_for_each_entry(ei, &sbi->s_fc_q[FC_Q_MAIN], i_fc_list) {
>  		ext4_set_inode_state(&ei->vfs_inode, EXT4_STATE_FC_COMMITTING);
> -		while (atomic_read(&ei->i_fc_updates)) {
> -			DEFINE_WAIT(wait);
> -
> -			prepare_to_wait(&ei->i_fc_wait, &wait,
> -						TASK_UNINTERRUPTIBLE);
> -			if (atomic_read(&ei->i_fc_updates)) {
> -				spin_unlock(&sbi->s_fc_lock);
> -				schedule();
> -				spin_lock(&sbi->s_fc_lock);
> -			}
> -			finish_wait(&ei->i_fc_wait, &wait);
> -		}
> +
>  		spin_unlock(&sbi->s_fc_lock);
>  		ret = jbd2_submit_inode_data(ei->jinode);
>  		if (ret)
> -- 
> 2.35.1.616.g0bdcbb4464-goog
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR