On 16.08.19 г. 18:05 ч., Josef Bacik wrote:
> Historically we reserved worst case for every btree operation, and
> generally speaking we want to do that in cases where it could be the
> worst case. However for updating inodes we know the inode items are
> already in the tree, so it will only be an update operation and never an
> insert operation. This allows us to always reserve only the
> metadata_size amount for inode updates rather than the
> insert_metadata_size amount.
>
> Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
This alleviates some of the reservation pressure so :
Reviewed-by: Nikolay Borisov <nborisov@xxxxxxxx>, however one small nit
below.
> ---
> fs/btrfs/delalloc-space.c | 15 ++++++++++++---
> fs/btrfs/delayed-inode.c | 2 +-
> 2 files changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/fs/btrfs/delalloc-space.c b/fs/btrfs/delalloc-space.c
> index 2412be4a3de2..b8111ebdc92a 100644
> --- a/fs/btrfs/delalloc-space.c
> +++ b/fs/btrfs/delalloc-space.c
> @@ -251,9 +251,16 @@ static void btrfs_calculate_inode_block_rsv_size(struct btrfs_fs_info *fs_info,
>
> lockdep_assert_held(&inode->lock);
> outstanding_extents = inode->outstanding_extents;
> - if (outstanding_extents)
> +
> + /*
> + * Insert size for the number of outstanding extents, 1 normal size for
> + * updating the inode.
> + */
> + if (outstanding_extents) {
> reserve_size = btrfs_calc_insert_metadata_size(fs_info,
> - outstanding_extents + 1);
> + outstanding_extents);
> + reserve_size += btrfs_calc_metadata_size(fs_info, 1);
> + }
> csum_leaves = btrfs_csum_bytes_to_leaves(fs_info,
> inode->csum_bytes);
> reserve_size += btrfs_calc_insert_metadata_size(fs_info,
> @@ -278,10 +285,12 @@ static void calc_inode_reservations(struct btrfs_fs_info *fs_info,
> {
> u64 nr_extents = count_max_extents(num_bytes);
> u64 csum_leaves = btrfs_csum_bytes_to_leaves(fs_info, num_bytes);
> + u64 inode_update = btrfs_calc_metadata_size(fs_info, 1);
>
> /* We add one for the inode update at finish ordered time */
This comment becomes somewhat outdated and should be removed/reworded.
Perhaps put above *meta_reserve += inode_update.
> *meta_reserve = btrfs_calc_insert_metadata_size(fs_info,
> - nr_extents + csum_leaves + 1);
> + nr_extents + csum_leaves);
> + *meta_reserve += inode_update;
> *qgroup_reserve = nr_extents * fs_info->nodesize;
> }
>
> diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
> index de87ea7ce84d..9318cf761a07 100644
> --- a/fs/btrfs/delayed-inode.c
> +++ b/fs/btrfs/delayed-inode.c
> @@ -612,7 +612,7 @@ static int btrfs_delayed_inode_reserve_metadata(
> src_rsv = trans->block_rsv;
> dst_rsv = &fs_info->delayed_block_rsv;
>
> - num_bytes = btrfs_calc_insert_metadata_size(fs_info, 1);
> + num_bytes = btrfs_calc_metadata_size(fs_info, 1);
>
> /*
> * btrfs_dirty_inode will update the inode under btrfs_join_transaction
>
