On 21.11.18 г. 21:03 ч., Josef Bacik wrote:
> For FLUSH_LIMIT flushers we really can only allocate chunks and flush
> delayed inode items, everything else is problematic. I added a bunch of
> new states and it lead to weirdness in the FLUSH_LIMIT case because I
> forgot about how it worked. So instead explicitly declare the states
> that are ok for flushing with FLUSH_LIMIT and use that for our state
> machine. Then as we add new things that are safe we can just add them
> to this list.
Code-wise it's ok but the changelog needs rewording. At the very least
explain the weirdness. Also in the last sentence the word 'thing' is
better substituted with "flush states".
>
> Signed-off-by: Josef Bacik <jo...@toxicpanda.com>
> ---
> fs/btrfs/extent-tree.c | 21 ++++++++++-----------
> 1 file changed, 10 insertions(+), 11 deletions(-)
>
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index 0e9ba77e5316..e31980d451c2 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -5112,12 +5112,18 @@ void btrfs_init_async_reclaim_work(struct work_struct
> *work)
> INIT_WORK(work, btrfs_async_reclaim_metadata_space);
> }
>
> +static const enum btrfs_flush_state priority_flush_states[] = {
> + FLUSH_DELAYED_ITEMS_NR,
> + FLUSH_DELAYED_ITEMS,
> + ALLOC_CHUNK,
> +};
> +
> static void priority_reclaim_metadata_space(struct btrfs_fs_info *fs_info,
> struct btrfs_space_info *space_info,
> struct reserve_ticket *ticket)
> {
> u64 to_reclaim;
> - int flush_state = FLUSH_DELAYED_ITEMS_NR;
> + int flush_state = 0;
>
> spin_lock(&space_info->lock);
> to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info,
> @@ -5129,7 +5135,8 @@ static void priority_reclaim_metadata_space(struct
> btrfs_fs_info *fs_info,
> spin_unlock(&space_info->lock);
>
> do {
> - flush_space(fs_info, space_info, to_reclaim, flush_state);
> + flush_space(fs_info, space_info, to_reclaim,
> + priority_flush_states[flush_state]);
> flush_state++;
> spin_lock(&space_info->lock);
> if (ticket->bytes == 0) {
> @@ -5137,15 +5144,7 @@ static void priority_reclaim_metadata_space(struct
> btrfs_fs_info *fs_info,
> return;
> }
> spin_unlock(&space_info->lock);
> -
> - /*
> - * Priority flushers can't wait on delalloc without
> - * deadlocking.
> - */
> - if (flush_state == FLUSH_DELALLOC ||
> - flush_state == FLUSH_DELALLOC_WAIT)
> - flush_state = ALLOC_CHUNK;
> - } while (flush_state < COMMIT_TRANS);
> + } while (flush_state < ARRAY_SIZE(priority_flush_states));
> }
>
> static int wait_reserve_ticket(struct btrfs_fs_info *fs_info,
>
