Re: [PATCH v6 01/10] ext4: convert i_fc_lock to spinlock

[Jan Kara <jack@suse.cz>]

On Wed 29-05-24 01:19:54, Harshad Shirwadkar wrote:
> Convert ext4_inode_info->i_fc_lock to spinlock to avoid sleeping
> in invalid contexts.
> 
> Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>

Looks good. Feel free to add:

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

							Honza

> ---
>  fs/ext4/ext4.h        |  7 +++++--
>  fs/ext4/fast_commit.c | 24 +++++++++++-------------
>  fs/ext4/super.c       |  2 +-
>  3 files changed, 17 insertions(+), 16 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 983dad8c07ec..611b8c80d99c 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1062,8 +1062,11 @@ struct ext4_inode_info {
>  	/* Fast commit wait queue for this inode */
>  	wait_queue_head_t i_fc_wait;
>  
> -	/* Protect concurrent accesses on i_fc_lblk_start, i_fc_lblk_len */
> -	struct mutex i_fc_lock;
> +	/*
> +	 * Protect concurrent accesses on i_fc_lblk_start, i_fc_lblk_len
> +	 * and inode's EXT4_FC_STATE_COMMITTING state bit.
> +	 */
> +	spinlock_t i_fc_lock;
>  
>  	/*
>  	 * i_disksize keeps track of what the inode size is ON DISK, not
> diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
> index 87c009e0c59a..a1aadebfcd66 100644
> --- a/fs/ext4/fast_commit.c
> +++ b/fs/ext4/fast_commit.c
> @@ -382,7 +382,7 @@ static int ext4_fc_track_template(
>  	int ret;
>  
>  	tid = handle->h_transaction->t_tid;
> -	mutex_lock(&ei->i_fc_lock);
> +	spin_lock(&ei->i_fc_lock);
>  	if (tid == ei->i_sync_tid) {
>  		update = true;
>  	} else {
> @@ -390,7 +390,7 @@ static int ext4_fc_track_template(
>  		ei->i_sync_tid = tid;
>  	}
>  	ret = __fc_track_fn(inode, args, update);
> -	mutex_unlock(&ei->i_fc_lock);
> +	spin_unlock(&ei->i_fc_lock);
>  
>  	if (!enqueue)
>  		return ret;
> @@ -424,19 +424,19 @@ static int __track_dentry_update(struct inode *inode, void *arg, bool update)
>  	struct super_block *sb = inode->i_sb;
>  	struct ext4_sb_info *sbi = EXT4_SB(sb);
>  
> -	mutex_unlock(&ei->i_fc_lock);
> +	spin_unlock(&ei->i_fc_lock);
>  
>  	if (IS_ENCRYPTED(dir)) {
>  		ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_ENCRYPTED_FILENAME,
>  					NULL);
> -		mutex_lock(&ei->i_fc_lock);
> +		spin_lock(&ei->i_fc_lock);
>  		return -EOPNOTSUPP;
>  	}
>  
>  	node = kmem_cache_alloc(ext4_fc_dentry_cachep, GFP_NOFS);
>  	if (!node) {
>  		ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_NOMEM, NULL);
> -		mutex_lock(&ei->i_fc_lock);
> +		spin_lock(&ei->i_fc_lock);
>  		return -ENOMEM;
>  	}
>  
> @@ -448,7 +448,7 @@ static int __track_dentry_update(struct inode *inode, void *arg, bool update)
>  		if (!node->fcd_name.name) {
>  			kmem_cache_free(ext4_fc_dentry_cachep, node);
>  			ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_NOMEM, NULL);
> -			mutex_lock(&ei->i_fc_lock);
> +			spin_lock(&ei->i_fc_lock);
>  			return -ENOMEM;
>  		}
>  		memcpy((u8 *)node->fcd_name.name, dentry->d_name.name,
> @@ -482,7 +482,7 @@ static int __track_dentry_update(struct inode *inode, void *arg, bool update)
>  		list_add_tail(&node->fcd_dilist, &ei->i_fc_dilist);
>  	}
>  	spin_unlock(&sbi->s_fc_lock);
> -	mutex_lock(&ei->i_fc_lock);
> +	spin_lock(&ei->i_fc_lock);
>  
>  	return 0;
>  }
> @@ -614,10 +614,8 @@ static int __track_range(struct inode *inode, void *arg, bool update)
>  	struct __track_range_args *__arg =
>  		(struct __track_range_args *)arg;
>  
> -	if (inode->i_ino < EXT4_FIRST_INO(inode->i_sb)) {
> -		ext4_debug("Special inode %ld being modified\n", inode->i_ino);
> +	if (inode->i_ino < EXT4_FIRST_INO(inode->i_sb))
>  		return -ECANCELED;
> -	}
>  
>  	oldstart = ei->i_fc_lblk_start;
>  
> @@ -896,15 +894,15 @@ static int ext4_fc_write_inode_data(struct inode *inode, u32 *crc)
>  	struct ext4_extent *ex;
>  	int ret;
>  
> -	mutex_lock(&ei->i_fc_lock);
> +	spin_lock(&ei->i_fc_lock);
>  	if (ei->i_fc_lblk_len == 0) {
> -		mutex_unlock(&ei->i_fc_lock);
> +		spin_unlock(&ei->i_fc_lock);
>  		return 0;
>  	}
>  	old_blk_size = ei->i_fc_lblk_start;
>  	new_blk_size = ei->i_fc_lblk_start + ei->i_fc_lblk_len - 1;
>  	ei->i_fc_lblk_len = 0;
> -	mutex_unlock(&ei->i_fc_lock);
> +	spin_unlock(&ei->i_fc_lock);
>  
>  	cur_lblk_off = old_blk_size;
>  	ext4_debug("will try writing %d to %d for inode %ld\n",
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index f9a4a4e89dac..77173ec91e49 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1436,7 +1436,7 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
>  	atomic_set(&ei->i_unwritten, 0);
>  	INIT_WORK(&ei->i_rsv_conversion_work, ext4_end_io_rsv_work);
>  	ext4_fc_init_inode(&ei->vfs_inode);
> -	mutex_init(&ei->i_fc_lock);
> +	spin_lock_init(&ei->i_fc_lock);
>  	return &ei->vfs_inode;
>  }
>  
> -- 
> 2.45.1.288.g0e0cd299f1-goog
> 
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR