On fri, 22 Jun 2012 11:26:01 -0400, Josef Bacik wrote:
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index 4b5a1e1..4053e3e 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -3727,6 +3727,62 @@ commit:
> return btrfs_commit_transaction(trans, root);
> }
>
> +enum flush_state {
> + FLUSH_DELALLOC = 1,
> + FLUSH_DELALLOC_WAIT = 2,
> + FLUSH_DELAYED_ITEMS_NR = 3,
> + FLUSH_DELAYED_ITEMS = 4,
> + COMMIT_TRANS = 5,
> +};
> +
> +static int flush_space(struct btrfs_root *root,
> + struct btrfs_space_info *space_info, u64 num_bytes,
> + u64 orig_bytes, int *state)
> +{
> + struct btrfs_trans_handle *trans;
> + int nr;
> + int ret;
> +
> + switch (*state) {
> + case FLUSH_DELALLOC:
> + case FLUSH_DELALLOC_WAIT:
> + ret = shrink_delalloc(root, num_bytes,
> + *state == FLUSH_DELALLOC_WAIT);
> + if (ret > 0)
> + ret = 0;
> + break;
> + case FLUSH_DELAYED_ITEMS_NR:
> + case FLUSH_DELAYED_ITEMS:
> + if (*state == FLUSH_DELAYED_ITEMS_NR) {
> + u64 bytes = btrfs_calc_trans_metadata_size(root, 1);
> +
> + nr = (int)div64_u64(num_bytes, bytes);
> + if (!nr)
> + nr = 1;
> + nr *= 2;
> + } else {
> + nr = -1;
> + }
> + trans = btrfs_join_transaction(root);
> + if (IS_ERR(trans)) {
> + ret = PTR_ERR(trans);
> + break;
> + }
> + ret = btrfs_run_delayed_items_nr(trans, root, nr);
why not use btrfs_wq_run_delayed_node() ?
> + btrfs_end_transaction(trans, root);
> + break;
> + case COMMIT_TRANS:
> + ret = may_commit_transaction(root, space_info, orig_bytes, 0);
> + break;
> + default:
> + ret = -ENOSPC;
> + break;
> + }
> +
> + if (!ret)
> + (*state)++;
It is better that this function just do flush, and do not update state. and the
caller
decides to do the higher level flush or just go back. I think.
> + return ret;
> +}
> /**
> * reserve_metadata_bytes - try to reserve bytes from the block_rsv's space
> * @root - the root we're allocating for
> @@ -3748,11 +3804,10 @@ static int reserve_metadata_bytes(struct btrfs_root
> *root,
> struct btrfs_space_info *space_info = block_rsv->space_info;
> u64 used;
> u64 num_bytes = orig_bytes;
> - int retries = 0;
> + int flush_state = FLUSH_DELALLOC;
> int ret = 0;
> - bool committed = false;
> bool flushing = false;
> - bool wait_ordered = false;
> + bool committed = false;
>
> again:
> ret = 0;
> @@ -3811,9 +3866,8 @@ again:
> * amount plus the amount of bytes that we need for this
> * reservation.
> */
> - wait_ordered = true;
> num_bytes = used - space_info->total_bytes +
> - (orig_bytes * (retries + 1));
> + (orig_bytes * 2);
> }
>
> if (ret) {
> @@ -3866,8 +3920,6 @@ again:
> trace_btrfs_space_reservation(root->fs_info,
> "space_info", space_info->flags, orig_bytes, 1);
> ret = 0;
> - } else {
> - wait_ordered = true;
> }
> }
>
> @@ -3886,36 +3938,10 @@ again:
> if (!ret || !flush)
> goto out;
>
> - /*
> - * We do synchronous shrinking since we don't actually unreserve
> - * metadata until after the IO is completed.
> - */
> - ret = shrink_delalloc(root, num_bytes, wait_ordered);
> - if (ret < 0)
> - goto out;
> -
> - ret = 0;
> -
> - /*
> - * So if we were overcommitted it's possible that somebody else flushed
> - * out enough space and we simply didn't have enough space to reclaim,
> - * so go back around and try again.
> - */
> - if (retries < 2) {
> - wait_ordered = true;
> - retries++;
> - goto again;
> - }
> -
> - ret = -ENOSPC;
> - if (committed)
> - goto out;
> -
> - ret = may_commit_transaction(root, space_info, orig_bytes, 0);
> - if (!ret) {
> - committed = true;
> + ret = flush_space(root, space_info, num_bytes, orig_bytes,
> + &flush_state);
> + if (!ret)
> goto again;
> - }
It is better to try do the higher level flush if flush_space() fails. I think.
Thanks
Miao
>
> out:
> if (flushing) {
--
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