Re: [PATCH 2/2] xfs: account for log space when formatting new AGs

[Allison Collins <allison.henderson@oracle.com>]

On 6/20/19 11:43 AM, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> When we're writing out a fresh new AG, make sure that we don't list an
> internal log as free and that we create the rmap for the region.  growfs
> never does this, but we will need it when we hook up mkfs.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Looks ok to me.  Thanks for the comments they help!
Reviewed-by: Allison Collins <allison.henderson@oracle.com>

> ---
>   fs/xfs/libxfs/xfs_ag.c |   66 ++++++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 66 insertions(+)
> 
> 
> diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
> index 80a3df7ccab3..57aa85d8e3aa 100644
> --- a/fs/xfs/libxfs/xfs_ag.c
> +++ b/fs/xfs/libxfs/xfs_ag.c
> @@ -10,6 +10,7 @@
>   #include "xfs_shared.h"
>   #include "xfs_format.h"
>   #include "xfs_trans_resv.h"
> +#include "xfs_bit.h"
>   #include "xfs_sb.h"
>   #include "xfs_mount.h"
>   #include "xfs_btree.h"
> @@ -44,6 +45,12 @@ xfs_get_aghdr_buf(
>   	return bp;
>   }
>   
> +static inline bool is_log_ag(struct xfs_mount *mp, struct aghdr_init_data *id)
> +{
> +	return mp->m_sb.sb_logstart > 0 &&
> +	       id->agno == XFS_FSB_TO_AGNO(mp, mp->m_sb.sb_logstart);
> +}
> +
>   /*
>    * Generic btree root block init function
>    */
> @@ -64,11 +71,50 @@ xfs_freesp_init_recs(
>   	struct aghdr_init_data	*id)
>   {
>   	struct xfs_alloc_rec	*arec;
> +	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
>   
>   	arec = XFS_ALLOC_REC_ADDR(mp, XFS_BUF_TO_BLOCK(bp), 1);
>   	arec->ar_startblock = cpu_to_be32(mp->m_ag_prealloc_blocks);
> +
> +	if (is_log_ag(mp, id)) {
> +		struct xfs_alloc_rec	*nrec;
> +		xfs_agblock_t		start = XFS_FSB_TO_AGBNO(mp,
> +							mp->m_sb.sb_logstart);
> +
> +		ASSERT(start >= mp->m_ag_prealloc_blocks);
> +		if (start != mp->m_ag_prealloc_blocks) {
> +			/*
> +			 * Modify first record to pad stripe align of log
> +			 */
> +			arec->ar_blockcount = cpu_to_be32(start -
> +						mp->m_ag_prealloc_blocks);
> +			nrec = arec + 1;
> +			/*
> +			 * Insert second record at start of internal log
> +			 * which then gets trimmed.
> +			 */
> +			nrec->ar_startblock = cpu_to_be32(
> +					be32_to_cpu(arec->ar_startblock) +
> +					be32_to_cpu(arec->ar_blockcount));
> +			arec = nrec;
> +			be16_add_cpu(&block->bb_numrecs, 1);
> +		}
> +		/*
> +		 * Change record start to after the internal log
> +		 */
> +		be32_add_cpu(&arec->ar_startblock, mp->m_sb.sb_logblocks);
> +	}
> +
> +	/*
> +	 * Calculate the record block count and check for the case where
> +	 * the log might have consumed all available space in the AG. If
> +	 * so, reset the record count to 0 to avoid exposure of an invalid
> +	 * record start block.
> +	 */
>   	arec->ar_blockcount = cpu_to_be32(id->agsize -
>   					  be32_to_cpu(arec->ar_startblock));
> +	if (!arec->ar_blockcount)
> +		block->bb_numrecs = 0;
>   }
>   
>   /*
> @@ -154,6 +200,18 @@ xfs_rmaproot_init(
>   		rrec->rm_offset = 0;
>   		be16_add_cpu(&block->bb_numrecs, 1);
>   	}
> +
> +	/* account for the log space */
> +	if (is_log_ag(mp, id)) {
> +		rrec = XFS_RMAP_REC_ADDR(block,
> +				be16_to_cpu(block->bb_numrecs) + 1);
> +		rrec->rm_startblock = cpu_to_be32(
> +				XFS_FSB_TO_AGBNO(mp, mp->m_sb.sb_logstart));
> +		rrec->rm_blockcount = cpu_to_be32(mp->m_sb.sb_logblocks);
> +		rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_LOG);
> +		rrec->rm_offset = 0;
> +		be16_add_cpu(&block->bb_numrecs, 1);
> +	}
>   }
>   
>   /*
> @@ -214,6 +272,14 @@ xfs_agfblock_init(
>   		agf->agf_refcount_level = cpu_to_be32(1);
>   		agf->agf_refcount_blocks = cpu_to_be32(1);
>   	}
> +
> +	if (is_log_ag(mp, id)) {
> +		int64_t	logblocks = mp->m_sb.sb_logblocks;
> +
> +		be32_add_cpu(&agf->agf_freeblks, -logblocks);
> +		agf->agf_longest = cpu_to_be32(id->agsize -
> +			XFS_FSB_TO_AGBNO(mp, mp->m_sb.sb_logstart) - logblocks);
> +	}
>   }
>   
>   static void
>