linux-kernel - Re: [f2fs-dev] [PATCH v2 1/2] f2fs: avoid redundant clean nat entry move in lru list

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Message-ID: <b17f5401-0462-42c7-8fef-0875814d1064@kernel.org>
Date: Thu, 24 Jul 2025 14:00:33 +0800
From: Chao Yu <chao@...nel.org>
To: wangzijie <wangzijie1@...or.com>, jaegeuk@...nel.org
Cc: chao@...nel.org, linux-f2fs-devel@...ts.sourceforge.net,
 linux-kernel@...r.kernel.org, bintian.wang@...or.com, feng.han@...or.com
Subject: Re: [f2fs-dev] [PATCH v2 1/2] f2fs: avoid redundant clean nat entry
 move in lru list

On 7/22/25 22:36, wangzijie wrote:
> __lookup_nat_cache follows LRU manner to move clean nat entry, when nat
> entries are going to be dirty, no need to move them to tail of lru list.
> Introduce a parameter 'for_dirty' to avoid it.
> 
> Signed-off-by: wangzijie <wangzijie1@...or.com>
> ---
> v2:
> - followed by Jaegeuk's suggestion to add a parameter in __lookup_nat_cache
> ---
>  fs/f2fs/node.c | 24 ++++++++++++------------
>  1 file changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index 76aba1961..a23db6238 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -204,14 +204,14 @@ static struct nat_entry *__init_nat_entry(struct f2fs_nm_info *nm_i,
>  	return ne;
>  }
>  
> -static struct nat_entry *__lookup_nat_cache(struct f2fs_nm_info *nm_i, nid_t n)
> +static struct nat_entry *__lookup_nat_cache(struct f2fs_nm_info *nm_i, nid_t n, bool for_dirty)
>  {
>  	struct nat_entry *ne;
>  
>  	ne = radix_tree_lookup(&nm_i->nat_root, n);
>  
> -	/* for recent accessed nat entry, move it to tail of lru list */
> -	if (ne && !get_nat_flag(ne, IS_DIRTY)) {
> +	/* for recent accessed(not used to set dirty) nat entry, move it to tail of lru list */

What do you think of this?

	/*
	 * for recent accessed nat entry which will not be dirtied soon
	 * later, move it to tail of lru list.
	 */

Thanks,

> +	if (ne && !get_nat_flag(ne, IS_DIRTY) && !for_dirty) {
>  		spin_lock(&nm_i->nat_list_lock);
>  		if (!list_empty(&ne->list))
>  			list_move_tail(&ne->list, &nm_i->nat_entries);
> @@ -383,7 +383,7 @@ int f2fs_need_dentry_mark(struct f2fs_sb_info *sbi, nid_t nid)
>  	bool need = false;
>  
>  	f2fs_down_read(&nm_i->nat_tree_lock);
> -	e = __lookup_nat_cache(nm_i, nid);
> +	e = __lookup_nat_cache(nm_i, nid, false);
>  	if (e) {
>  		if (!get_nat_flag(e, IS_CHECKPOINTED) &&
>  				!get_nat_flag(e, HAS_FSYNCED_INODE))
> @@ -400,7 +400,7 @@ bool f2fs_is_checkpointed_node(struct f2fs_sb_info *sbi, nid_t nid)
>  	bool is_cp = true;
>  
>  	f2fs_down_read(&nm_i->nat_tree_lock);
> -	e = __lookup_nat_cache(nm_i, nid);
> +	e = __lookup_nat_cache(nm_i, nid, false);
>  	if (e && !get_nat_flag(e, IS_CHECKPOINTED))
>  		is_cp = false;
>  	f2fs_up_read(&nm_i->nat_tree_lock);
> @@ -414,7 +414,7 @@ bool f2fs_need_inode_block_update(struct f2fs_sb_info *sbi, nid_t ino)
>  	bool need_update = true;
>  
>  	f2fs_down_read(&nm_i->nat_tree_lock);
> -	e = __lookup_nat_cache(nm_i, ino);
> +	e = __lookup_nat_cache(nm_i, ino, false);
>  	if (e && get_nat_flag(e, HAS_LAST_FSYNC) &&
>  			(get_nat_flag(e, IS_CHECKPOINTED) ||
>  			 get_nat_flag(e, HAS_FSYNCED_INODE)))
> @@ -439,7 +439,7 @@ static void cache_nat_entry(struct f2fs_sb_info *sbi, nid_t nid,
>  		return;
>  
>  	f2fs_down_write(&nm_i->nat_tree_lock);
> -	e = __lookup_nat_cache(nm_i, nid);
> +	e = __lookup_nat_cache(nm_i, nid, false);
>  	if (!e)
>  		e = __init_nat_entry(nm_i, new, ne, false);
>  	else
> @@ -460,7 +460,7 @@ static void set_node_addr(struct f2fs_sb_info *sbi, struct node_info *ni,
>  	struct nat_entry *new = __alloc_nat_entry(sbi, ni->nid, true);
>  
>  	f2fs_down_write(&nm_i->nat_tree_lock);
> -	e = __lookup_nat_cache(nm_i, ni->nid);
> +	e = __lookup_nat_cache(nm_i, ni->nid, true);
>  	if (!e) {
>  		e = __init_nat_entry(nm_i, new, NULL, true);
>  		copy_node_info(&e->ni, ni);
> @@ -502,7 +502,7 @@ static void set_node_addr(struct f2fs_sb_info *sbi, struct node_info *ni,
>  
>  	/* update fsync_mark if its inode nat entry is still alive */
>  	if (ni->nid != ni->ino)
> -		e = __lookup_nat_cache(nm_i, ni->ino);
> +		e = __lookup_nat_cache(nm_i, ni->ino, false);
>  	if (e) {
>  		if (fsync_done && ni->nid == ni->ino)
>  			set_nat_flag(e, HAS_FSYNCED_INODE, true);
> @@ -562,7 +562,7 @@ int f2fs_get_node_info(struct f2fs_sb_info *sbi, nid_t nid,
>  retry:
>  	/* Check nat cache */
>  	f2fs_down_read(&nm_i->nat_tree_lock);
> -	e = __lookup_nat_cache(nm_i, nid);
> +	e = __lookup_nat_cache(nm_i, nid, false);
>  	if (e) {
>  		ni->ino = nat_get_ino(e);
>  		ni->blk_addr = nat_get_blkaddr(e);
> @@ -2371,7 +2371,7 @@ static bool add_free_nid(struct f2fs_sb_info *sbi,
>  		 *   - __remove_nid_from_list(PREALLOC_NID)
>  		 *                         - __insert_nid_to_list(FREE_NID)
>  		 */
> -		ne = __lookup_nat_cache(nm_i, nid);
> +		ne = __lookup_nat_cache(nm_i, nid, false);
>  		if (ne && (!get_nat_flag(ne, IS_CHECKPOINTED) ||
>  				nat_get_blkaddr(ne) != NULL_ADDR))
>  			goto err_out;
> @@ -2936,7 +2936,7 @@ static void remove_nats_in_journal(struct f2fs_sb_info *sbi)
>  
>  		raw_ne = nat_in_journal(journal, i);
>  
> -		ne = __lookup_nat_cache(nm_i, nid);
> +		ne = __lookup_nat_cache(nm_i, nid, true);
>  		if (!ne) {
>  			ne = __alloc_nat_entry(sbi, nid, true);
>  			__init_nat_entry(nm_i, ne, &raw_ne, true);