On 3.12.18 г. 17:20 ч., Josef Bacik wrote:
> Any space used in the delayed_refs_rsv will be freed up by a transaction
> commit, so instead of just counting the pinned space we also need to
> account for any space in the delayed_refs_rsv when deciding if it will
> make a different to commit the transaction to satisfy our space
> reservation. If we have enough bytes to satisfy our reservation ticket
> then we are good to go, otherwise subtract out what space we would gain
> back by committing the transaction and compare that against the pinned
> space to make our decision.
>
> Signed-off-by: Josef Bacik <jo...@toxicpanda.com>
Reviewed-by: Nikolay Borisov <nbori...@suse.com>
However, look below for one suggestion:
> ---
> fs/btrfs/extent-tree.c | 24 +++++++++++++++---------
> 1 file changed, 15 insertions(+), 9 deletions(-)
>
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index aa0a638d0263..63ff9d832867 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -4843,8 +4843,10 @@ static int may_commit_transaction(struct btrfs_fs_info
> *fs_info,
> {
> struct reserve_ticket *ticket = NULL;
> struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_block_rsv;
> + struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv;
> struct btrfs_trans_handle *trans;
> - u64 bytes;
> + u64 bytes_needed;
> + u64 reclaim_bytes = 0;
>
> trans = (struct btrfs_trans_handle *)current->journal_info;
> if (trans)
> @@ -4857,15 +4859,15 @@ static int may_commit_transaction(struct
> btrfs_fs_info *fs_info,
> else if (!list_empty(&space_info->tickets))
> ticket = list_first_entry(&space_info->tickets,
> struct reserve_ticket, list);
> - bytes = (ticket) ? ticket->bytes : 0;
> + bytes_needed = (ticket) ? ticket->bytes : 0;
> spin_unlock(&space_info->lock);
>
> - if (!bytes)
> + if (!bytes_needed)
> return 0;
>
> /* See if there is enough pinned space to make this reservation */
> if (__percpu_counter_compare(&space_info->total_bytes_pinned,
> - bytes,
> + bytes_needed,
> BTRFS_TOTAL_BYTES_PINNED_BATCH) >= 0)
> goto commit;
>
> @@ -4877,14 +4879,18 @@ static int may_commit_transaction(struct
> btrfs_fs_info *fs_info,
> return -ENOSPC;
If we remove this :
if (space_info != delayed_rsv->space_info)
return -ENOSPC;
Check, can't we move the reclaim_bytes calc code above the
__percpu_counter_compare
and eventually be left with just a single invocation to percpu_compare.
The diff should looke something along the lines of:
@@ -4828,19 +4827,6 @@ static int may_commit_transaction(struct btrfs_fs_info
*fs_info,
if (!bytes)
return 0;
- /* See if there is enough pinned space to make this reservation */
- if (__percpu_counter_compare(&space_info->total_bytes_pinned,
- bytes,
- BTRFS_TOTAL_BYTES_PINNED_BATCH) >= 0)
- goto commit;
-
- /*
- * See if there is some space in the delayed insertion reservation for
- * this reservation.
- */
- if (space_info != delayed_rsv->space_info)
- return -ENOSPC;
-
spin_lock(&delayed_rsv->lock);
if (delayed_rsv->size > bytes)
bytes = 0;
@@ -4850,9 +4836,8 @@ static int may_commit_transaction(struct btrfs_fs_info
*fs_info,
if (__percpu_counter_compare(&space_info->total_bytes_pinned,
bytes,
- BTRFS_TOTAL_BYTES_PINNED_BATCH) < 0) {
+ BTRFS_TOTAL_BYTES_PINNED_BATCH) < 0)
return -ENOSPC;
- }
commit:
trans = btrfs_join_transaction(fs_info->extent_root);
>
> spin_lock(&delayed_rsv->lock);
> - if (delayed_rsv->size > bytes)
> - bytes = 0;
> - else
> - bytes -= delayed_rsv->size;
> + reclaim_bytes += delayed_rsv->reserved;
> spin_unlock(&delayed_rsv->lock);
>
> + spin_lock(&delayed_refs_rsv->lock);
> + reclaim_bytes += delayed_refs_rsv->reserved;
> + spin_unlock(&delayed_refs_rsv->lock);
> + if (reclaim_bytes >= bytes_needed)
> + goto commit;
> + bytes_needed -= reclaim_bytes;
> +
> if (__percpu_counter_compare(&space_info->total_bytes_pinned,
> - bytes,
> + bytes_needed,
> BTRFS_TOTAL_BYTES_PINNED_BATCH) < 0) {
> return -ENOSPC;
> }
>
