Re: [PATCH 21/30] xfs: remove SYNC_TRYLOCK from inode reclaim

[Brian Foster <bfoster@redhat.com>]

On Thu, Jun 04, 2020 at 05:45:57PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> All background reclaim is SYNC_TRYLOCK already, and even blocking
> reclaim (SYNC_WAIT) can use trylock mechanisms as
> xfs_reclaim_inodes_ag() will keep cycling until there are no more
> reclaimable inodes. Hence we can kill SYNC_TRYLOCK from inode
> reclaim and make everything unconditionally non-blocking.
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/xfs/xfs_icache.c | 29 ++++++++++++-----------------
>  1 file changed, 12 insertions(+), 17 deletions(-)
> 
> diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
> index d1c47a0e0b0ec..ebe55124d6cb8 100644
> --- a/fs/xfs/xfs_icache.c
> +++ b/fs/xfs/xfs_icache.c
> @@ -174,7 +174,7 @@ xfs_reclaim_worker(
>  	struct xfs_mount *mp = container_of(to_delayed_work(work),
>  					struct xfs_mount, m_reclaim_work);
>  
> -	xfs_reclaim_inodes(mp, SYNC_TRYLOCK);
> +	xfs_reclaim_inodes(mp, 0);
>  	xfs_reclaim_work_queue(mp);
>  }
>  
> @@ -1030,10 +1030,9 @@ xfs_cowblocks_worker(
>   * Grab the inode for reclaim exclusively.
>   * Return 0 if we grabbed it, non-zero otherwise.
>   */
> -STATIC int
> +static int
>  xfs_reclaim_inode_grab(
> -	struct xfs_inode	*ip,
> -	int			flags)
> +	struct xfs_inode	*ip)
>  {
>  	ASSERT(rcu_read_lock_held());
>  
> @@ -1042,12 +1041,10 @@ xfs_reclaim_inode_grab(
>  		return 1;
>  
>  	/*
> -	 * If we are asked for non-blocking operation, do unlocked checks to
> -	 * see if the inode already is being flushed or in reclaim to avoid
> -	 * lock traffic.
> +	 * Do unlocked checks to see if the inode already is being flushed or in
> +	 * reclaim to avoid lock traffic.
>  	 */
> -	if ((flags & SYNC_TRYLOCK) &&
> -	    __xfs_iflags_test(ip, XFS_IFLOCK | XFS_IRECLAIM))
> +	if (__xfs_iflags_test(ip, XFS_IFLOCK | XFS_IRECLAIM))
>  		return 1;
>  
>  	/*
> @@ -1114,8 +1111,7 @@ xfs_reclaim_inode_grab(
>  static bool
>  xfs_reclaim_inode(
>  	struct xfs_inode	*ip,
> -	struct xfs_perag	*pag,
> -	int			sync_mode)
> +	struct xfs_perag	*pag)
>  {
>  	xfs_ino_t		ino = ip->i_ino; /* for radix_tree_delete */
>  
> @@ -1209,7 +1205,6 @@ xfs_reclaim_inode(
>  static int
>  xfs_reclaim_inodes_ag(
>  	struct xfs_mount	*mp,
> -	int			flags,
>  	int			*nr_to_scan)
>  {
>  	struct xfs_perag	*pag;
> @@ -1254,7 +1249,7 @@ xfs_reclaim_inodes_ag(
>  			for (i = 0; i < nr_found; i++) {
>  				struct xfs_inode *ip = batch[i];
>  
> -				if (done || xfs_reclaim_inode_grab(ip, flags))
> +				if (done || xfs_reclaim_inode_grab(ip))
>  					batch[i] = NULL;
>  
>  				/*
> @@ -1285,7 +1280,7 @@ xfs_reclaim_inodes_ag(
>  			for (i = 0; i < nr_found; i++) {
>  				if (!batch[i])
>  					continue;
> -				if (!xfs_reclaim_inode(batch[i], pag, flags))
> +				if (!xfs_reclaim_inode(batch[i], pag))
>  					skipped++;
>  			}
>  
> @@ -1311,13 +1306,13 @@ xfs_reclaim_inodes(
>  	int		nr_to_scan = INT_MAX;
>  	int		skipped;
>  
> -	xfs_reclaim_inodes_ag(mp, mode, &nr_to_scan);
> +	xfs_reclaim_inodes_ag(mp, &nr_to_scan);
>  	if (!(mode & SYNC_WAIT))
>  		return 0;
>  
>  	do {
>  		xfs_ail_push_all_sync(mp->m_ail);
> -		skipped = xfs_reclaim_inodes_ag(mp, mode, &nr_to_scan);
> +		skipped = xfs_reclaim_inodes_ag(mp, &nr_to_scan);
>  	} while (skipped > 0);
>  
>  	return 0;
> @@ -1341,7 +1336,7 @@ xfs_reclaim_inodes_nr(
>  	xfs_reclaim_work_queue(mp);
>  	xfs_ail_push_all(mp->m_ail);
>  
> -	xfs_reclaim_inodes_ag(mp, SYNC_TRYLOCK, &nr_to_scan);
> +	xfs_reclaim_inodes_ag(mp, &nr_to_scan);
>  	return 0;
>  }
>  
> -- 
> 2.26.2.761.g0e0b3e54be
>