Re: [PATCH 17/24] xfs: remove SYNC_TRYLOCK from inode reclaim

From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH 17/24] xfs: remove SYNC_TRYLOCK from inode reclaim
Date: Fri, 22 May 2020 16:14:35 -0700	[thread overview]
Message-ID: <20200522231435.GU8230@magnolia> (raw)
In-Reply-To: <20200522035029.3022405-18-david@fromorbit.com>

On Fri, May 22, 2020 at 01:50:22PM +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.

Random question: Does xfs_quiesce_attr need to call xfs_reclaim_inodes
twice now, or does the second SYNC_WAIT call suffice now?

> Signed-off-by: Dave Chinner <dchinner@redhat.com>

This patch itself looks fine though.
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
>  fs/xfs/xfs_icache.c | 27 +++++++++++----------------
>  1 file changed, 11 insertions(+), 16 deletions(-)
> 
> diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
> index c020d2379e12e..8b366bc7b53c9 100644
> --- a/fs/xfs/xfs_icache.c
> +++ b/fs/xfs/xfs_icache.c
> @@ -1049,10 +1049,9 @@ xfs_inode_ag_iterator_tag(
>   * 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());
>  
> @@ -1061,12 +1060,10 @@ 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;
>  
>  	/*
> @@ -1133,8 +1130,7 @@ 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 */
>  
> @@ -1224,7 +1220,6 @@ xfs_reclaim_inode(
>  static int
>  xfs_reclaim_inodes_ag(
>  	struct xfs_mount	*mp,
> -	int			flags,
>  	int			*nr_to_scan)
>  {
>  	struct xfs_perag	*pag;
> @@ -1262,7 +1257,7 @@ 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;
>  
>  				/*
> @@ -1293,7 +1288,7 @@ 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++;
>  			}
>  
> @@ -1319,13 +1314,13 @@ 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;
> @@ -1349,7 +1344,7 @@ 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
> 