Re: [f2fs-dev] [PATCH v2] f2fs: call __add_ino_entry out of the eviction path

[Chao Yu <chao@kernel.org>]

On 8/5/26 09:28, Jaegeuk Kim via Linux-f2fs-devel wrote:
> The f2fs_evict_inode() can be called during the direct reclaim path, but
> __add_ino_entry requires allocating some memory. Since we don't need to
> do that in that context, let's migrate it in other workqueue context.
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> ---
>  Change log from v1:
>   - fix a bug on the wait logic
> 
>  fs/f2fs/checkpoint.c | 11 ++++++
>  fs/f2fs/data.c       | 13 ++++++-
>  fs/f2fs/f2fs.h       |  4 ++
>  fs/f2fs/inode.c      | 91 +++++++++++++++++++++++++++++++++++++++++---
>  fs/f2fs/super.c      |  9 ++++-
>  5 files changed, 121 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index 064f5b537423..4413eccb5ecb 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -766,6 +766,15 @@ static void __remove_ino_entry(struct f2fs_sb_info *sbi, nid_t ino, int type)
>  	spin_unlock(&im->ino_lock);
>  }
>  
> +static void f2fs_wait_for_inode_record(struct f2fs_sb_info *sbi, int mode)
> +{
> +	if (mode != APPEND_INO && mode != UPDATE_INO)
> +		return;
> +
> +	/* Let's wait for some pending updates for APPEND_INO and UPDATE_INO. */
> +	flush_workqueue(sbi->evict_wq);
> +}
> +
>  void f2fs_add_ino_entry(struct f2fs_sb_info *sbi, nid_t ino, int type)
>  {
>  	/* add new dirty ino entry into list */
> @@ -798,6 +807,8 @@ void f2fs_release_ino_entry(struct f2fs_sb_info *sbi, bool all)
>  	for (i = all ? ORPHAN_INO : APPEND_INO; i < MAX_INO_ENTRY; i++) {
>  		struct inode_management *im = &sbi->im[i];
>  
> +		f2fs_wait_for_inode_record(sbi, i);
> +
>  		spin_lock(&im->ino_lock);
>  		list_for_each_entry_safe(e, tmp, &im->ino_list, list) {
>  			list_del(&e->list);
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index c219ea76a3a7..6ae0eb37d20f 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -4558,13 +4558,24 @@ int f2fs_init_wq(struct f2fs_sb_info *sbi)
>  {
>  	sbi->wq = alloc_workqueue("f2fs_wq", WQ_UNBOUND | WQ_HIGHPRI,
>  				  num_online_cpus());
> -	return sbi->wq ? 0 : -ENOMEM;
> +	if (!sbi->wq)
> +		return -ENOMEM;
> +
> +	sbi->evict_wq = alloc_workqueue("f2fs_evict_wq",
> +			WQ_UNBOUND | WQ_HIGHPRI, num_online_cpus());
> +	if (!sbi->evict_wq) {
> +		destroy_workqueue(sbi->wq);
> +		return -ENOMEM;
> +	}
> +	return 0;
>  }
>  
>  void f2fs_destroy_wq(struct f2fs_sb_info *sbi)
>  {
>  	if (sbi->wq)
>  		destroy_workqueue(sbi->wq);
> +	if (sbi->evict_wq)
> +		destroy_workqueue(sbi->evict_wq);
>  }
>  
>  int __init f2fs_init_bio_entry_cache(void)
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index c44908258dc1..54f9d3856b5c 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -2016,6 +2016,8 @@ struct f2fs_sb_info {
>  
>  	struct workqueue_struct *wq;		/* bio completion workqueue */
>  
> +	struct workqueue_struct *evict_wq;	/* inode eviction workqueue */
> +
>  	/*
>  	 * If we are in irq context, let's update error information into
>  	 * on-disk superblock in the work.
> @@ -3875,6 +3877,8 @@ int f2fs_write_inode(struct inode *inode, struct writeback_control *wbc);
>  void f2fs_remove_donate_inode(struct inode *inode);
>  void f2fs_evict_inode(struct inode *inode);
>  void f2fs_handle_failed_inode(struct inode *inode, struct f2fs_lock_context *lc);
> +int f2fs_init_evict_inode_work(void);
> +void f2fs_destroy_evict_inode_work(void);
>  
>  /*
>   * namei.c
> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
> index c95e0b126da4..0d30489cf083 100644
> --- a/fs/f2fs/inode.c
> +++ b/fs/f2fs/inode.c
> @@ -24,6 +24,18 @@
>  extern const struct address_space_operations f2fs_compress_aops;
>  #endif
>  
> +#define NUM_PREALLOC_EVICT_INODE_WORK 8
> +
> +static struct kmem_cache *evict_inode_work_cache;
> +static mempool_t *evict_inode_work_pool;
> +
> +struct evict_inode_work {
> +	struct work_struct work;
> +	struct f2fs_sb_info *sbi;
> +	nid_t ino;
> +	unsigned int add_ino_entry_bits;
> +};
> +
>  void f2fs_mark_inode_dirty_sync(struct inode *inode, bool sync)
>  {
>  	if (is_inode_flag_set(inode, FI_NEW_INODE))
> @@ -637,6 +649,9 @@ struct inode *f2fs_iget(struct super_block *sb, unsigned long ino)
>  		inode->i_fop = &f2fs_dir_operations;
>  		inode->i_mapping->a_ops = &f2fs_dblock_aops;
>  		mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
> +
> +		/* Let's prepare APPEND/UPDATE_INO before future access. */
> +		flush_workqueue(sbi->evict_wq);
>  	} else if (S_ISLNK(inode->i_mode)) {
>  		if (file_is_encrypt(inode))
>  			inode->i_op = &f2fs_encrypted_symlink_inode_operations;
> @@ -854,6 +869,25 @@ void f2fs_remove_donate_inode(struct inode *inode)
>  	spin_unlock(&sbi->inode_lock[DONATE_INODE]);
>  }
>  
> +static void f2fs_record_inode_state(struct f2fs_sb_info *sbi, nid_t ino,
> +				    unsigned int bits)
> +{
> +	if (bits & BIT(APPEND_INO))
> +		f2fs_add_ino_entry(sbi, ino, APPEND_INO);
> +	if (bits & BIT(UPDATE_INO))
> +		f2fs_add_ino_entry(sbi, ino, UPDATE_INO);
> +}
> +
> +static void f2fs_evict_inode_work(struct work_struct *work)
> +{
> +	struct evict_inode_work *ew =
> +		container_of(work, struct evict_inode_work, work);
> +
> +	f2fs_record_inode_state(ew->sbi, ew->ino, ew->add_ino_entry_bits);
> +
> +	mempool_free(ew, evict_inode_work_pool);
> +}
> +
>  /*
>   * Called at the last iput() if i_nlink is zero
>   */
> @@ -864,6 +898,7 @@ void f2fs_evict_inode(struct inode *inode)
>  	nid_t xnid = fi->i_xattr_nid;
>  	int err = 0;
>  	bool freeze_protected = false;
> +	unsigned int record_bits = 0;
>  
>  	f2fs_abort_atomic_write(inode, true);
>  
> @@ -1003,12 +1038,32 @@ void f2fs_evict_inode(struct inode *inode)
>  							inode->i_ino);
>  	if (xnid)
>  		invalidate_mapping_pages(NODE_MAPPING(sbi), xnid, xnid);
> -	if (inode->i_nlink) {
> -		if (is_inode_flag_set(inode, FI_APPEND_WRITE))
> -			f2fs_add_ino_entry(sbi, inode->i_ino, APPEND_INO);
> -		if (is_inode_flag_set(inode, FI_UPDATE_WRITE))
> -			f2fs_add_ino_entry(sbi, inode->i_ino, UPDATE_INO);
> +
> +	if (!inode->i_nlink)
> +		goto skip_record;
> +
> +	if (is_inode_flag_set(inode, FI_APPEND_WRITE))
> +		record_bits = BIT(APPEND_INO);
> +	if (is_inode_flag_set(inode, FI_UPDATE_WRITE))
> +		record_bits = BIT(UPDATE_INO);
> +
> +	if (!record_bits)
> +		goto skip_record;
> +
> +	/* Let's do this in workqueue out of the direct reclaim path. */
> +	if (current_is_kswapd()) {
> +		f2fs_record_inode_state(sbi, inode->i_ino, record_bits);
> +	} else {
> +		struct evict_inode_work *ew =
> +			mempool_alloc(evict_inode_work_pool, GFP_NOFS);
> +
> +		ew->sbi = sbi;
> +		ew->ino = inode->i_ino;
> +		ew->add_ino_entry_bits = record_bits;
> +		INIT_WORK(&ew->work, f2fs_evict_inode_work);
> +		queue_work(sbi->evict_wq, &ew->work);
>  	}
> +skip_record:

What do you think of wrapping above codes into a static function for cleanup?

Thanks,

>  	if (is_inode_flag_set(inode, FI_FREE_NID)) {
>  		f2fs_alloc_nid_failed(sbi, inode->i_ino);
>  		clear_inode_flag(inode, FI_FREE_NID);
> @@ -1079,3 +1134,29 @@ void f2fs_handle_failed_inode(struct inode *inode, struct f2fs_lock_context *lc)
>  	/* iput will drop the inode object */
>  	iput(inode);
>  }
> +
> +int __init f2fs_init_evict_inode_work(void)
> +{
> +	evict_inode_work_cache =
> +		kmem_cache_create("f2fs_evict_inode_work",
> +				  sizeof(struct evict_inode_work), 0, 0, NULL);
> +	if (!evict_inode_work_cache)
> +		goto fail;
> +	evict_inode_work_pool =
> +		mempool_create_slab_pool(NUM_PREALLOC_EVICT_INODE_WORK,
> +					 evict_inode_work_cache);
> +	if (!evict_inode_work_pool)
> +		goto fail_free_cache;
> +	return 0;
> +
> +fail_free_cache:
> +	kmem_cache_destroy(evict_inode_work_cache);
> +fail:
> +	return -ENOMEM;
> +}
> +
> +void f2fs_destroy_evict_inode_work(void)
> +{
> +	mempool_destroy(evict_inode_work_pool);
> +	kmem_cache_destroy(evict_inode_work_cache);
> +}
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 67abbf7ab477..6b55c30f0daa 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -5763,10 +5763,16 @@ static int __init init_f2fs_fs(void)
>  	err = f2fs_init_xattr_cache();
>  	if (err)
>  		goto free_casefold_cache;
> -	err = register_filesystem(&f2fs_fs_type);
> +	err = f2fs_init_evict_inode_work();
>  	if (err)
>  		goto free_xattr_cache;
> +	err = register_filesystem(&f2fs_fs_type);
> +	if (err)
> +		goto free_evict_inode_cache;
>  	return 0;
> +
> +free_evict_inode_cache:
> +	f2fs_destroy_evict_inode_work();
>  free_xattr_cache:
>  	f2fs_destroy_xattr_cache();
>  free_casefold_cache:
> @@ -5809,6 +5815,7 @@ static int __init init_f2fs_fs(void)
>  static void __exit exit_f2fs_fs(void)
>  {
>  	unregister_filesystem(&f2fs_fs_type);
> +	f2fs_destroy_evict_inode_work();
>  	f2fs_destroy_xattr_cache();
>  	f2fs_destroy_casefold_cache();
>  	f2fs_destroy_compress_cache();