Re: [PATCH v4 03/11] xfs: track allocation busy state in allocation cursor

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Mon, Sep 16, 2019 at 08:16:27AM -0400, Brian Foster wrote:
> Extend the allocation cursor to track extent busy state for an
> allocation attempt. No functional changes.
> 
> Signed-off-by: Brian Foster <bfoster@redhat.com>
> ---
>  fs/xfs/libxfs/xfs_alloc.c | 25 ++++++++++++++-----------
>  1 file changed, 14 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> index d159377ed603..5c34d4c41761 100644
> --- a/fs/xfs/libxfs/xfs_alloc.c
> +++ b/fs/xfs/libxfs/xfs_alloc.c
> @@ -716,6 +716,8 @@ struct xfs_alloc_cur {
>  	struct xfs_btree_cur		*cnt;	/* btree cursors */
>  	struct xfs_btree_cur		*bnolt;
>  	struct xfs_btree_cur		*bnogt;
> +	unsigned			busy_gen;/* busy state */

Nit: unsigned int here?

'unsigned' without the 'int' looks a little funny to me, but eh
whatever, I guess we do that in the iomap code so:

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> +	bool				busy;
>  };
>  
>  /*
> @@ -733,6 +735,9 @@ xfs_alloc_cur_setup(
>  
>  	ASSERT(args->alignment == 1 || args->type != XFS_ALLOCTYPE_THIS_BNO);
>  
> +	acur->busy = false;
> +	acur->busy_gen = 0;
> +
>  	/*
>  	 * Perform an initial cntbt lookup to check for availability of maxlen
>  	 * extents. If this fails, we'll return -ENOSPC to signal the caller to
> @@ -1185,8 +1190,6 @@ xfs_alloc_ag_vextent_near(
>  	xfs_extlen_t	ltlena;		/* aligned ... */
>  	xfs_agblock_t	ltnew;		/* useful start bno of left side */
>  	xfs_extlen_t	rlen;		/* length of returned extent */
> -	bool		busy;
> -	unsigned	busy_gen;
>  #ifdef DEBUG
>  	/*
>  	 * Randomly don't execute the first algorithm.
> @@ -1211,7 +1214,6 @@ xfs_alloc_ag_vextent_near(
>  	ltlen = 0;
>  	gtlena = 0;
>  	ltlena = 0;
> -	busy = false;
>  
>  	/*
>  	 * Set up cursors and see if there are any free extents as big as
> @@ -1290,8 +1292,8 @@ xfs_alloc_ag_vextent_near(
>  			if (error)
>  				goto out;
>  			XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, out);
> -			busy = xfs_alloc_compute_aligned(args, ltbno, ltlen,
> -					&ltbnoa, &ltlena, &busy_gen);
> +			acur.busy = xfs_alloc_compute_aligned(args, ltbno, ltlen,
> +					&ltbnoa, &ltlena, &acur.busy_gen);
>  			if (ltlena < args->minlen)
>  				continue;
>  			if (ltbnoa < args->min_agbno || ltbnoa > args->max_agbno)
> @@ -1373,8 +1375,8 @@ xfs_alloc_ag_vextent_near(
>  			if (error)
>  				goto out;
>  			XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, out);
> -			busy |= xfs_alloc_compute_aligned(args, ltbno, ltlen,
> -					&ltbnoa, &ltlena, &busy_gen);
> +			acur.busy |= xfs_alloc_compute_aligned(args, ltbno,
> +					ltlen, &ltbnoa, &ltlena, &acur.busy_gen);
>  			if (ltlena >= args->minlen && ltbnoa >= args->min_agbno)
>  				break;
>  			error = xfs_btree_decrement(acur.bnolt, 0, &i);
> @@ -1388,8 +1390,8 @@ xfs_alloc_ag_vextent_near(
>  			if (error)
>  				goto out;
>  			XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, out);
> -			busy |= xfs_alloc_compute_aligned(args, gtbno, gtlen,
> -					&gtbnoa, &gtlena, &busy_gen);
> +			acur.busy |= xfs_alloc_compute_aligned(args, gtbno,
> +					gtlen, &gtbnoa, &gtlena, &acur.busy_gen);
>  			if (gtlena >= args->minlen && gtbnoa <= args->max_agbno)
>  				break;
>  			error = xfs_btree_increment(acur.bnogt, 0, &i);
> @@ -1449,9 +1451,10 @@ xfs_alloc_ag_vextent_near(
>  	 */
>  	if (!xfs_alloc_cur_active(acur.bnolt) &&
>  	    !xfs_alloc_cur_active(acur.bnogt)) {
> -		if (busy) {
> +		if (acur.busy) {
>  			trace_xfs_alloc_near_busy(args);
> -			xfs_extent_busy_flush(args->mp, args->pag, busy_gen);
> +			xfs_extent_busy_flush(args->mp, args->pag,
> +					      acur.busy_gen);
>  			goto restart;
>  		}
>  		trace_xfs_alloc_size_neither(args);
> -- 
> 2.20.1
>