On Thu, Feb 01, 2018 at 05:41:57PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> We currently write all new AG headers synchronously, which can be
> slow for large grow operations. All we really need to do is ensure
> all the headers are on disk before we run the growfs transaction, so
> convert this to a buffer list and a delayed write operation. We
> block waiting for the delayed write buffer submission to complete,
> so this will fulfill the requirement to have all the buffers written
> correctly before proceeding.
>
> Signed-Off-By: Dave Chinner <dchinner@xxxxxxxxxx>
> ---
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
> fs/xfs/xfs_fsops.c | 74 ++++++++++++++++++++++++------------------------------
> 1 file changed, 33 insertions(+), 41 deletions(-)
>
> diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
> index cd5196bf8756..d9e08d8cf9ac 100644
> --- a/fs/xfs/xfs_fsops.c
> +++ b/fs/xfs/xfs_fsops.c
> @@ -81,7 +81,8 @@ xfs_grow_ag_headers(
> struct xfs_mount *mp,
> xfs_agnumber_t agno,
> xfs_extlen_t agsize,
> - xfs_rfsblock_t *nfree)
> + xfs_rfsblock_t *nfree,
> + struct list_head *buffer_list)
> {
> struct xfs_agf *agf;
> struct xfs_agi *agi;
> @@ -135,11 +136,8 @@ xfs_grow_ag_headers(
> agf->agf_refcount_level = cpu_to_be32(1);
> agf->agf_refcount_blocks = cpu_to_be32(1);
> }
> -
> - error = xfs_bwrite(bp);
> + xfs_buf_delwri_queue(bp, buffer_list);
> xfs_buf_relse(bp);
> - if (error)
> - goto out_error;
>
> /*
> * AG freelist header block
> @@ -164,10 +162,8 @@ xfs_grow_ag_headers(
> for (bucket = 0; bucket < XFS_AGFL_SIZE(mp); bucket++)
> agfl_bno[bucket] = cpu_to_be32(NULLAGBLOCK);
>
> - error = xfs_bwrite(bp);
> + xfs_buf_delwri_queue(bp, buffer_list);
> xfs_buf_relse(bp);
> - if (error)
> - goto out_error;
>
> /*
> * AG inode header block
> @@ -201,10 +197,8 @@ xfs_grow_ag_headers(
> for (bucket = 0; bucket < XFS_AGI_UNLINKED_BUCKETS; bucket++)
> agi->agi_unlinked[bucket] = cpu_to_be32(NULLAGINO);
>
> - error = xfs_bwrite(bp);
> + xfs_buf_delwri_queue(bp, buffer_list);
> xfs_buf_relse(bp);
> - if (error)
> - goto out_error;
>
> /*
> * BNO btree root block
> @@ -226,10 +220,8 @@ xfs_grow_ag_headers(
> arec->ar_blockcount = cpu_to_be32(
> agsize - be32_to_cpu(arec->ar_startblock));
>
> - error = xfs_bwrite(bp);
> + xfs_buf_delwri_queue(bp, buffer_list);
> xfs_buf_relse(bp);
> - if (error)
> - goto out_error;
>
> /*
> * CNT btree root block
> @@ -251,10 +243,8 @@ xfs_grow_ag_headers(
> agsize - be32_to_cpu(arec->ar_startblock));
> *nfree += be32_to_cpu(arec->ar_blockcount);
>
> - error = xfs_bwrite(bp);
> + xfs_buf_delwri_queue(bp, buffer_list);
> xfs_buf_relse(bp);
> - if (error)
> - goto out_error;
>
> /* RMAP btree root block */
> if (xfs_sb_version_hasrmapbt(&mp->m_sb)) {
> @@ -326,10 +316,8 @@ xfs_grow_ag_headers(
> be16_add_cpu(&block->bb_numrecs, 1);
> }
>
> - error = xfs_bwrite(bp);
> + xfs_buf_delwri_queue(bp, buffer_list);
> xfs_buf_relse(bp);
> - if (error)
> - goto out_error;
> }
>
> /*
> @@ -345,11 +333,8 @@ xfs_grow_ag_headers(
> }
>
> xfs_btree_init_block(mp, bp, XFS_BTNUM_INO , 0, 0, agno, 0);
> -
> - error = xfs_bwrite(bp);
> + xfs_buf_delwri_queue(bp, buffer_list);
> xfs_buf_relse(bp);
> - if (error)
> - goto out_error;
>
> /*
> * FINO btree root block
> @@ -364,13 +349,9 @@ xfs_grow_ag_headers(
> goto out_error;
> }
>
> - xfs_btree_init_block(mp, bp, XFS_BTNUM_FINO,
> - 0, 0, agno, 0);
> -
> - error = xfs_bwrite(bp);
> + xfs_btree_init_block(mp, bp, XFS_BTNUM_FINO, 0, 0, agno, 0);
> + xfs_buf_delwri_queue(bp, buffer_list);
> xfs_buf_relse(bp);
> - if (error)
> - goto out_error;
> }
>
> /*
> @@ -386,13 +367,9 @@ xfs_grow_ag_headers(
> goto out_error;
> }
>
> - xfs_btree_init_block(mp, bp, XFS_BTNUM_REFC,
> - 0, 0, agno, 0);
> -
> - error = xfs_bwrite(bp);
> + xfs_btree_init_block(mp, bp, XFS_BTNUM_REFC, 0, 0, agno, 0);
> + xfs_buf_delwri_queue(bp, buffer_list);
> xfs_buf_relse(bp);
> - if (error)
> - goto out_error;
> }
>
> out_error:
> @@ -419,6 +396,7 @@ xfs_growfs_data_private(
> xfs_agnumber_t oagcount;
> int pct;
> xfs_trans_t *tp;
> + LIST_HEAD (buffer_list);
>
> nb = in->newblocks;
> pct = in->imaxpct;
> @@ -459,9 +437,16 @@ xfs_growfs_data_private(
> return error;
>
> /*
> - * Write new AG headers to disk. Non-transactional, but written
> - * synchronously so they are completed prior to the growfs transaction
> - * being logged.
> + * Write new AG headers to disk. Non-transactional, but need to be
> + * written and completed prior to the growfs transaction being logged.
> + * To do this, we use a delayed write buffer list and wait for
> + * submission and IO completion of the list as a whole. This allows the
> + * IO subsystem to merge all the AG headers in a single AG into a single
> + * IO and hide most of the latency of the IO from us.
> + *
> + * This also means that if we get an error whilst building the buffer
> + * list to write, we can cancel the entire list without having written
> + * anything.
> */
> nfree = 0;
> for (agno = nagcount - 1; agno >= oagcount; agno--, new -= agsize) {
> @@ -472,10 +457,17 @@ xfs_growfs_data_private(
> else
> agsize = mp->m_sb.sb_agblocks;
>
> - error = xfs_grow_ag_headers(mp, agno, agsize, &nfree);
> - if (error)
> + error = xfs_grow_ag_headers(mp, agno, agsize, &nfree,
> + &buffer_list);
> + if (error) {
> + xfs_buf_delwri_cancel(&buffer_list);
> goto error0;
> + }
> }
> + error = xfs_buf_delwri_submit(&buffer_list);
> + if (error)
> + goto error0;
> +
> xfs_trans_agblocks_delta(tp, nfree);
>
> /*
> --
> 2.15.1
>
> --
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