Hi Josef,
are you fine with V2?
On Thu, Oct 13, 2016 at 05:31:25PM +0800, Wang Xiaoguang wrote:
> Since commit b02441999efcc6152b87cd58e7970bb7843f76cf, we don't wait all
> ordered extents, but I run into some enospc errors when doing large file
> create and delete tests, it's because shrink_delalloc() does not write
> enough delalloc bytes and wait them finished:
> From: Miao Xie <mi...@cn.fujitsu.com>
> Date: Mon, 4 Nov 2013 23:13:25 +0800
> Subject: [PATCH] Btrfs: don't wait for the completion of all the ordered
> extents
>
> It is very likely that there are lots of ordered extents in the filesytem,
> if we wait for the completion of all of them when we want to reclaim some
> space for the metadata space reservation, we would be blocked for a long
> time. The performance would drop down suddenly for a long time.
>
> Here we introduce a simple reclaim_priority variable, the lower the
> value, the higher the priority, 0 is the maximum priority. The core
> idea is:
> delalloc_bytes =
> percpu_counter_sum_positive(&root->fs_info->delalloc_bytes);
> if (reclaim_priority)
> to_reclaim = orig * (2 << (BTRFS_DEFAULT_FLUSH_PRIORITY -
> reclaim_priority));
> else
> to_reclaim = delalloc_bytes;
>
> Here 'orig' is the number of metadata we want to reserve, and as the priority
> increases, we will try wo write more delalloc bytes, meanwhile if
> "reclaim_priority == 0" returns true, we'll also wait all current ordered
> extents to finish.
>
> Signed-off-by: Wang Xiaoguang <wangxg.f...@cn.fujitsu.com>
> ---
> fs/btrfs/extent-tree.c | 63
> ++++++++++++++++++++++++++------------------
> include/trace/events/btrfs.h | 11 +++-----
> 2 files changed, 42 insertions(+), 32 deletions(-)
>
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index e08791d..7477c25 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -4686,16 +4686,18 @@ static inline int calc_reclaim_items_nr(struct
> btrfs_root *root, u64 to_reclaim)
> }
>
> #define EXTENT_SIZE_PER_ITEM SZ_256K
> +#define BTRFS_DEFAULT_FLUSH_PRIORITY 3
>
> /*
> * shrink metadata reservation for delalloc
> */
> -static void shrink_delalloc(struct btrfs_root *root, u64 to_reclaim, u64
> orig,
> - bool wait_ordered)
> +static void shrink_delalloc(struct btrfs_root *root, u64 orig,
> + bool wait_ordered, int reclaim_priority)
> {
> struct btrfs_block_rsv *block_rsv;
> struct btrfs_space_info *space_info;
> struct btrfs_trans_handle *trans;
> + u64 to_reclaim;
> u64 delalloc_bytes;
> u64 max_reclaim;
> long time_left;
> @@ -4703,22 +4705,36 @@ static void shrink_delalloc(struct btrfs_root *root,
> u64 to_reclaim, u64 orig,
> int loops;
> int items;
> enum btrfs_reserve_flush_enum flush;
> + int items_to_wait;
> +
> + delalloc_bytes = percpu_counter_sum_positive(
> + &root->fs_info->delalloc_bytes);
> + if (reclaim_priority < 0)
> + reclaim_priority = 0;
> +
> + if (reclaim_priority)
> + to_reclaim = orig * (2 << (BTRFS_DEFAULT_FLUSH_PRIORITY -
> + reclaim_priority));
> + else
> + to_reclaim = delalloc_bytes;
>
> /* Calc the number of the pages we need flush for space reservation */
> items = calc_reclaim_items_nr(root, to_reclaim);
> to_reclaim = (u64)items * EXTENT_SIZE_PER_ITEM;
> + if (reclaim_priority)
> + items_to_wait = items;
> + else
> + items_to_wait = -1;
>
> trans = (struct btrfs_trans_handle *)current->journal_info;
> block_rsv = &root->fs_info->delalloc_block_rsv;
> space_info = block_rsv->space_info;
>
> - delalloc_bytes = percpu_counter_sum_positive(
> - &root->fs_info->delalloc_bytes);
> if (delalloc_bytes == 0) {
> if (trans)
> return;
> if (wait_ordered)
> - btrfs_wait_ordered_roots(root->fs_info, items,
> + btrfs_wait_ordered_roots(root->fs_info, items_to_wait,
> 0, (u64)-1);
> return;
> }
> @@ -4763,7 +4779,7 @@ static void shrink_delalloc(struct btrfs_root *root,
> u64 to_reclaim, u64 orig,
>
> loops++;
> if (wait_ordered && !trans) {
> - btrfs_wait_ordered_roots(root->fs_info, items,
> + btrfs_wait_ordered_roots(root->fs_info, items_to_wait,
> 0, (u64)-1);
> } else {
> time_left = schedule_timeout_killable(1);
> @@ -4836,7 +4852,7 @@ struct reserve_ticket {
>
> static int flush_space(struct btrfs_root *root,
> struct btrfs_space_info *space_info, u64 num_bytes,
> - u64 orig_bytes, int state)
> + int state, int reclaim_priority)
> {
> struct btrfs_trans_handle *trans;
> int nr;
> @@ -4860,8 +4876,8 @@ static int flush_space(struct btrfs_root *root,
> break;
> case FLUSH_DELALLOC:
> case FLUSH_DELALLOC_WAIT:
> - shrink_delalloc(root, num_bytes * 2, orig_bytes,
> - state == FLUSH_DELALLOC_WAIT);
> + shrink_delalloc(root, num_bytes, state == FLUSH_DELALLOC_WAIT,
> + reclaim_priority);
> break;
> case ALLOC_CHUNK:
> trans = btrfs_join_transaction(root);
> @@ -4877,7 +4893,7 @@ static int flush_space(struct btrfs_root *root,
> ret = 0;
> break;
> case COMMIT_TRANS:
> - ret = may_commit_transaction(root, space_info, orig_bytes, 0);
> + ret = may_commit_transaction(root, space_info, num_bytes, 0);
> break;
> default:
> ret = -ENOSPC;
> @@ -4885,7 +4901,7 @@ static int flush_space(struct btrfs_root *root,
> }
>
> trace_btrfs_flush_space(root->fs_info, space_info->flags, num_bytes,
> - orig_bytes, state, ret);
> + state, ret);
> return ret;
> }
>
> @@ -5008,8 +5024,8 @@ static void btrfs_async_reclaim_metadata_space(struct
> work_struct *work)
> struct btrfs_space_info *space_info;
> u64 to_reclaim;
> int flush_state;
> - int commit_cycles = 0;
> u64 last_tickets_id;
> + int reclaim_priority = BTRFS_DEFAULT_FLUSH_PRIORITY;
>
> fs_info = container_of(work, struct btrfs_fs_info, async_reclaim_work);
> space_info = __find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
> @@ -5030,8 +5046,11 @@ static void btrfs_async_reclaim_metadata_space(struct
> work_struct *work)
> struct reserve_ticket *ticket;
> int ret;
>
> + if (flush_state > COMMIT_TRANS)
> + flush_state = FLUSH_DELAYED_ITEMS_NR;
> ret = flush_space(fs_info->fs_root, space_info, to_reclaim,
> - to_reclaim, flush_state);
> + flush_state, reclaim_priority);
> +
> spin_lock(&space_info->lock);
> if (!ret)
> try_to_wake_tickets(fs_info->fs_root, space_info);
> @@ -5049,21 +5068,15 @@ static void btrfs_async_reclaim_metadata_space(struct
> work_struct *work)
> } else {
> last_tickets_id = space_info->tickets_id;
> flush_state = FLUSH_DELAYED_ITEMS_NR;
> - if (commit_cycles)
> - commit_cycles--;
> + reclaim_priority = BTRFS_DEFAULT_FLUSH_PRIORITY;
> }
>
> - if (flush_state > COMMIT_TRANS) {
> - commit_cycles++;
> - if (commit_cycles > 2) {
> - wake_all_tickets(&space_info->tickets);
> - space_info->flush = 0;
> - } else {
> - flush_state = FLUSH_DELAYED_ITEMS_NR;
> - }
> + if (flush_state > COMMIT_TRANS && reclaim_priority == 0) {
> + wake_all_tickets(&space_info->tickets);
> + space_info->flush = 0;
> }
> spin_unlock(&space_info->lock);
> - } while (flush_state <= COMMIT_TRANS);
> + } while ((flush_state <= COMMIT_TRANS) || (--reclaim_priority >= 0));
> }
>
> void btrfs_init_async_reclaim_work(struct work_struct *work)
> @@ -5089,7 +5102,7 @@ static void priority_reclaim_metadata_space(struct
> btrfs_fs_info *fs_info,
>
> do {
> flush_space(fs_info->fs_root, space_info, to_reclaim,
> - to_reclaim, flush_state);
> + flush_state, 1);
> flush_state++;
> spin_lock(&space_info->lock);
> if (ticket->bytes == 0) {
> diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h
> index e030d6f..7d953a6 100644
> --- a/include/trace/events/btrfs.h
> +++ b/include/trace/events/btrfs.h
> @@ -857,15 +857,14 @@ TRACE_EVENT(btrfs_trigger_flush,
> TRACE_EVENT(btrfs_flush_space,
>
> TP_PROTO(struct btrfs_fs_info *fs_info, u64 flags, u64 num_bytes,
> - u64 orig_bytes, int state, int ret),
> + int state, int ret),
>
> - TP_ARGS(fs_info, flags, num_bytes, orig_bytes, state, ret),
> + TP_ARGS(fs_info, flags, num_bytes, state, ret),
>
> TP_STRUCT__entry(
> __array( u8, fsid, BTRFS_UUID_SIZE )
> __field( u64, flags )
> __field( u64, num_bytes )
> - __field( u64, orig_bytes )
> __field( int, state )
> __field( int, ret )
> ),
> @@ -874,19 +873,17 @@ TRACE_EVENT(btrfs_flush_space,
> memcpy(__entry->fsid, fs_info->fsid, BTRFS_UUID_SIZE);
> __entry->flags = flags;
> __entry->num_bytes = num_bytes;
> - __entry->orig_bytes = orig_bytes;
> __entry->state = state;
> __entry->ret = ret;
> ),
>
> TP_printk("%pU: state = %d(%s), flags = %llu(%s), num_bytes = %llu, "
> - "orig_bytes = %llu, ret = %d", __entry->fsid, __entry->state,
> + "ret = %d", __entry->fsid, __entry->state,
> show_flush_state(__entry->state),
> (unsigned long long)__entry->flags,
> __print_flags((unsigned long)__entry->flags, "|",
> BTRFS_GROUP_FLAGS),
> - (unsigned long long)__entry->num_bytes,
> - (unsigned long long)__entry->orig_bytes, __entry->ret)
> + (unsigned long long)__entry->num_bytes, __entry->ret)
> );
>
> DECLARE_EVENT_CLASS(btrfs__reserved_extent,
> --
> 2.7.4
>
>
>
> --
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