Re: [PATCH 25/28] xfs: remove unusued old inode reclaim code

[Brian Foster]

On Fri, Nov 01, 2019 at 10:46:15AM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
> 
> Now that the custom AG radix tree walker has been replaced and
> removed, we don't need the radix tree tags anymore, nor the reclaim
> cursors or the locks taht protect it. Remove all remaining traces of
> these things.
> 
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> ---

Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>

>  fs/xfs/xfs_icache.c | 82 +--------------------------------------------
>  fs/xfs/xfs_icache.h |  7 ++--
>  fs/xfs/xfs_mount.c  |  4 ---
>  fs/xfs/xfs_mount.h  |  3 --
>  fs/xfs/xfs_super.c  |  5 +--
>  5 files changed, 6 insertions(+), 95 deletions(-)
> 
> diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
> index 05dd292bfdb6..71a729e29260 100644
> --- a/fs/xfs/xfs_icache.c
> +++ b/fs/xfs/xfs_icache.c
> @@ -139,83 +139,6 @@ xfs_inode_free(
>  	__xfs_inode_free(ip);
>  }
>  
> -static void
> -xfs_perag_set_reclaim_tag(
> -	struct xfs_perag	*pag)
> -{
> -	struct xfs_mount	*mp = pag->pag_mount;
> -
> -	lockdep_assert_held(&pag->pag_ici_lock);
> -	if (pag->pag_ici_reclaimable++)
> -		return;
> -
> -	/* propagate the reclaim tag up into the perag radix tree */
> -	spin_lock(&mp->m_perag_lock);
> -	radix_tree_tag_set(&mp->m_perag_tree, pag->pag_agno,
> -			   XFS_ICI_RECLAIM_TAG);
> -	spin_unlock(&mp->m_perag_lock);
> -
> -	trace_xfs_perag_set_reclaim(mp, pag->pag_agno, -1, _RET_IP_);
> -}
> -
> -static void
> -xfs_perag_clear_reclaim_tag(
> -	struct xfs_perag	*pag)
> -{
> -	struct xfs_mount	*mp = pag->pag_mount;
> -
> -	lockdep_assert_held(&pag->pag_ici_lock);
> -	if (--pag->pag_ici_reclaimable)
> -		return;
> -
> -	/* clear the reclaim tag from the perag radix tree */
> -	spin_lock(&mp->m_perag_lock);
> -	radix_tree_tag_clear(&mp->m_perag_tree, pag->pag_agno,
> -			     XFS_ICI_RECLAIM_TAG);
> -	spin_unlock(&mp->m_perag_lock);
> -	trace_xfs_perag_clear_reclaim(mp, pag->pag_agno, -1, _RET_IP_);
> -}
> -
> -
> -/*
> - * We set the inode flag atomically with the radix tree tag.
> - * Once we get tag lookups on the radix tree, this inode flag
> - * can go away.
> - */
> -void
> -xfs_inode_set_reclaim_tag(
> -	struct xfs_inode	*ip)
> -{
> -	struct xfs_mount	*mp = ip->i_mount;
> -	struct xfs_perag	*pag;
> -
> -	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
> -	spin_lock(&pag->pag_ici_lock);
> -	spin_lock(&ip->i_flags_lock);
> -
> -	radix_tree_tag_set(&pag->pag_ici_root, XFS_INO_TO_AGINO(mp, ip->i_ino),
> -			   XFS_ICI_RECLAIM_TAG);
> -	xfs_perag_set_reclaim_tag(pag);
> -	__xfs_iflags_set(ip, XFS_IRECLAIMABLE);
> -
> -	list_lru_add(&mp->m_inode_lru, &VFS_I(ip)->i_lru);
> -
> -	spin_unlock(&ip->i_flags_lock);
> -	spin_unlock(&pag->pag_ici_lock);
> -	xfs_perag_put(pag);
> -}
> -
> -STATIC void
> -xfs_inode_clear_reclaim_tag(
> -	struct xfs_perag	*pag,
> -	xfs_ino_t		ino)
> -{
> -	radix_tree_tag_clear(&pag->pag_ici_root,
> -			     XFS_INO_TO_AGINO(pag->pag_mount, ino),
> -			     XFS_ICI_RECLAIM_TAG);
> -	xfs_perag_clear_reclaim_tag(pag);
> -}
> -
>  static void
>  xfs_inew_wait(
>  	struct xfs_inode	*ip)
> @@ -397,18 +320,16 @@ xfs_iget_cache_hit(
>  			goto out_error;
>  		}
>  
> -		spin_lock(&pag->pag_ici_lock);
> -		spin_lock(&ip->i_flags_lock);
>  
>  		/*
>  		 * Clear the per-lifetime state in the inode as we are now
>  		 * effectively a new inode and need to return to the initial
>  		 * state before reuse occurs.
>  		 */
> +		spin_lock(&ip->i_flags_lock);
>  		ip->i_flags &= ~XFS_IRECLAIM_RESET_FLAGS;
>  		ip->i_flags |= XFS_INEW;
>  		list_lru_del(&mp->m_inode_lru, &inode->i_lru);
> -		xfs_inode_clear_reclaim_tag(pag, ip->i_ino);
>  		inode->i_state = I_NEW;
>  		ip->i_sick = 0;
>  		ip->i_checked = 0;
> @@ -417,7 +338,6 @@ xfs_iget_cache_hit(
>  		init_rwsem(&inode->i_rwsem);
>  
>  		spin_unlock(&ip->i_flags_lock);
> -		spin_unlock(&pag->pag_ici_lock);
>  	} else {
>  		/* If the VFS inode is being torn down, pause and try again. */
>  		if (!igrab(inode)) {
> diff --git a/fs/xfs/xfs_icache.h b/fs/xfs/xfs_icache.h
> index 86e858e4a281..ec646b9e88b7 100644
> --- a/fs/xfs/xfs_icache.h
> +++ b/fs/xfs/xfs_icache.h
> @@ -25,9 +25,8 @@ struct xfs_eofblocks {
>   */
>  #define XFS_ICI_NO_TAG		(-1)	/* special flag for an untagged lookup
>  					   in xfs_inode_ag_iterator */
> -#define XFS_ICI_RECLAIM_TAG	0	/* inode is to be reclaimed */
> -#define XFS_ICI_EOFBLOCKS_TAG	1	/* inode has blocks beyond EOF */
> -#define XFS_ICI_COWBLOCKS_TAG	2	/* inode can have cow blocks to gc */
> +#define XFS_ICI_EOFBLOCKS_TAG	0	/* inode has blocks beyond EOF */
> +#define XFS_ICI_COWBLOCKS_TAG	1	/* inode can have cow blocks to gc */
>  
>  /*
>   * Flags for xfs_iget()
> @@ -68,8 +67,6 @@ enum lru_status xfs_inode_reclaim_isolate(struct list_head *item,
>  void xfs_dispose_inodes(struct list_head *freeable);
>  void xfs_reclaim_all_inodes(struct xfs_mount *mp);
>  
> -void xfs_inode_set_reclaim_tag(struct xfs_inode *ip);
> -
>  void xfs_inode_set_eofblocks_tag(struct xfs_inode *ip);
>  void xfs_inode_clear_eofblocks_tag(struct xfs_inode *ip);
>  int xfs_icache_free_eofblocks(struct xfs_mount *, struct xfs_eofblocks *);
> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> index 5f3fd1d8f63f..9d60a4e033a0 100644
> --- a/fs/xfs/xfs_mount.c
> +++ b/fs/xfs/xfs_mount.c
> @@ -148,7 +148,6 @@ xfs_free_perag(
>  		ASSERT(atomic_read(&pag->pag_ref) == 0);
>  		xfs_iunlink_destroy(pag);
>  		xfs_buf_hash_destroy(pag);
> -		mutex_destroy(&pag->pag_ici_reclaim_lock);
>  		call_rcu(&pag->rcu_head, __xfs_free_perag);
>  	}
>  }
> @@ -200,7 +199,6 @@ xfs_initialize_perag(
>  		pag->pag_agno = index;
>  		pag->pag_mount = mp;
>  		spin_lock_init(&pag->pag_ici_lock);
> -		mutex_init(&pag->pag_ici_reclaim_lock);
>  		INIT_RADIX_TREE(&pag->pag_ici_root, GFP_ATOMIC);
>  		if (xfs_buf_hash_init(pag))
>  			goto out_free_pag;
> @@ -242,7 +240,6 @@ xfs_initialize_perag(
>  out_hash_destroy:
>  	xfs_buf_hash_destroy(pag);
>  out_free_pag:
> -	mutex_destroy(&pag->pag_ici_reclaim_lock);
>  	kmem_free(pag);
>  out_unwind_new_pags:
>  	/* unwind any prior newly initialized pags */
> @@ -252,7 +249,6 @@ xfs_initialize_perag(
>  			break;
>  		xfs_buf_hash_destroy(pag);
>  		xfs_iunlink_destroy(pag);
> -		mutex_destroy(&pag->pag_ici_reclaim_lock);
>  		kmem_free(pag);
>  	}
>  	return error;
> diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
> index 4f153ee17e18..dea05cd867bf 100644
> --- a/fs/xfs/xfs_mount.h
> +++ b/fs/xfs/xfs_mount.h
> @@ -343,9 +343,6 @@ typedef struct xfs_perag {
>  
>  	spinlock_t	pag_ici_lock;	/* incore inode cache lock */
>  	struct radix_tree_root pag_ici_root;	/* incore inode cache root */
> -	int		pag_ici_reclaimable;	/* reclaimable inodes */
> -	struct mutex	pag_ici_reclaim_lock;	/* serialisation point */
> -	unsigned long	pag_ici_reclaim_cursor;	/* reclaim restart point */
>  
>  	/* buffer cache index */
>  	spinlock_t	pag_buf_lock;	/* lock for pag_buf_hash */
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 096ae31b5436..d2200fbce139 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -916,7 +916,6 @@ xfs_fs_destroy_inode(
>  	spin_lock(&ip->i_flags_lock);
>  	ASSERT_ALWAYS(!__xfs_iflags_test(ip, XFS_IRECLAIMABLE));
>  	ASSERT_ALWAYS(!__xfs_iflags_test(ip, XFS_IRECLAIM));
> -	spin_unlock(&ip->i_flags_lock);
>  
>  	/*
>  	 * We always use background reclaim here because even if the
> @@ -925,7 +924,9 @@ xfs_fs_destroy_inode(
>  	 * this more efficiently than we can here, so simply let background
>  	 * reclaim tear down all inodes.
>  	 */
> -	xfs_inode_set_reclaim_tag(ip);
> +	__xfs_iflags_set(ip, XFS_IRECLAIMABLE);
> +	list_lru_add(&mp->m_inode_lru, &VFS_I(ip)->i_lru);
> +	spin_unlock(&ip->i_flags_lock);
>  }
>  
>  static void
> -- 
> 2.24.0.rc0
>