Just as Filipe pointed out, the most time consuming part of qgroup is
btrfs_qgroup_account_extents() and
btrfs_qgroup_prepare_account_extents().
Which both call btrfs_find_all_roots() to get old_roots and new_roots
ulist.
However for old_roots, we don't really need to calculate it at transaction
commit time.
This patch moves the old_roots accounting part out of
commit_transaction(), so at least we won't block transaction too long.
But please note that, this won't speedup qgroup overall, it just moves
half of the cost out of commit_transaction().
Cc: Filipe Manana <fdmanana@xxxxxxxx>
Signed-off-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
---
fs/btrfs/delayed-ref.c | 20 ++++++++++++++++----
fs/btrfs/qgroup.c | 33 ++++++++++++++++++++++++++++++---
fs/btrfs/qgroup.h | 14 ++++++++++++++
3 files changed, 60 insertions(+), 7 deletions(-)
diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
index ef724a5..0ee927e 100644
--- a/fs/btrfs/delayed-ref.c
+++ b/fs/btrfs/delayed-ref.c
@@ -550,13 +550,14 @@ add_delayed_ref_head(struct btrfs_fs_info *fs_info,
struct btrfs_delayed_ref_node *ref,
struct btrfs_qgroup_extent_record *qrecord,
u64 bytenr, u64 num_bytes, u64 ref_root, u64 reserved,
- int action, int is_data)
+ int action, int is_data, int *qrecord_inserted_ret)
{
struct btrfs_delayed_ref_head *existing;
struct btrfs_delayed_ref_head *head_ref = NULL;
struct btrfs_delayed_ref_root *delayed_refs;
int count_mod = 1;
int must_insert_reserved = 0;
+ int qrecord_inserted = 0;
/* If reserved is provided, it must be a data extent. */
BUG_ON(!is_data && reserved);
@@ -623,6 +624,8 @@ add_delayed_ref_head(struct btrfs_fs_info *fs_info,
if(btrfs_qgroup_trace_extent_nolock(fs_info,
delayed_refs, qrecord))
kfree(qrecord);
+ else
+ qrecord_inserted = 1;
}
spin_lock_init(&head_ref->lock);
@@ -650,6 +653,8 @@ add_delayed_ref_head(struct btrfs_fs_info *fs_info,
atomic_inc(&delayed_refs->num_entries);
trans->delayed_ref_updates++;
}
+ if (qrecord_inserted_ret)
+ *qrecord_inserted_ret = qrecord_inserted;
return head_ref;
}
@@ -779,6 +784,7 @@ int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
struct btrfs_delayed_ref_head *head_ref;
struct btrfs_delayed_ref_root *delayed_refs;
struct btrfs_qgroup_extent_record *record = NULL;
+ int qrecord_inserted;
BUG_ON(extent_op && extent_op->is_data);
ref = kmem_cache_alloc(btrfs_delayed_tree_ref_cachep, GFP_NOFS);
@@ -806,12 +812,15 @@ int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
* the spin lock
*/
head_ref = add_delayed_ref_head(fs_info, trans, &head_ref->node, record,
- bytenr, num_bytes, 0, 0, action, 0);
+ bytenr, num_bytes, 0, 0, action, 0,
+ &qrecord_inserted);
add_delayed_tree_ref(fs_info, trans, head_ref, &ref->node, bytenr,
num_bytes, parent, ref_root, level, action);
spin_unlock(&delayed_refs->lock);
+ if (qrecord_inserted)
+ return btrfs_qgroup_trace_extent_post(fs_info, record);
return 0;
free_head_ref:
@@ -836,6 +845,7 @@ int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
struct btrfs_delayed_ref_head *head_ref;
struct btrfs_delayed_ref_root *delayed_refs;
struct btrfs_qgroup_extent_record *record = NULL;
+ int qrecord_inserted;
BUG_ON(extent_op && !extent_op->is_data);
ref = kmem_cache_alloc(btrfs_delayed_data_ref_cachep, GFP_NOFS);
@@ -870,13 +880,15 @@ int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
*/
head_ref = add_delayed_ref_head(fs_info, trans, &head_ref->node, record,
bytenr, num_bytes, ref_root, reserved,
- action, 1);
+ action, 1, &qrecord_inserted);
add_delayed_data_ref(fs_info, trans, head_ref, &ref->node, bytenr,
num_bytes, parent, ref_root, owner, offset,
action);
spin_unlock(&delayed_refs->lock);
+ if (qrecord_inserted)
+ return btrfs_qgroup_trace_extent_post(fs_info, record);
return 0;
}
@@ -899,7 +911,7 @@ int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
add_delayed_ref_head(fs_info, trans, &head_ref->node, NULL, bytenr,
num_bytes, 0, 0, BTRFS_UPDATE_DELAYED_HEAD,
- extent_op->is_data);
+ extent_op->is_data, NULL);
spin_unlock(&delayed_refs->lock);
return 0;
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 662821f..971cce15 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -1446,8 +1446,9 @@ int btrfs_qgroup_prepare_account_extents(struct btrfs_trans_handle *trans,
while (node) {
record = rb_entry(node, struct btrfs_qgroup_extent_record,
node);
- ret = btrfs_find_all_roots(NULL, fs_info, record->bytenr, 0,
- &record->old_roots);
+ if (WARN_ON(!record->old_roots))
+ ret = btrfs_find_all_roots(NULL, fs_info,
+ record->bytenr, 0, &record->old_roots);
if (ret < 0)
break;
if (qgroup_to_skip)
@@ -1486,6 +1487,28 @@ int btrfs_qgroup_trace_extent_nolock(struct btrfs_fs_info *fs_info,
return 0;
}
+int btrfs_qgroup_trace_extent_post(struct btrfs_fs_info *fs_info,
+ struct btrfs_qgroup_extent_record *qrecord)
+{
+ struct ulist *old_root;
+ u64 bytenr = qrecord->bytenr;
+ int ret;
+
+ ret = btrfs_find_all_roots(NULL, fs_info, bytenr, 0, &old_root);
+ if (ret < 0)
+ return ret;
+
+ /*
+ * Here we don't need to get the lock of
+ * trans->transcation->delayed_refs, since inserted qrecord won't
+ * be deleted, only qrecord->node may be modified (new qrecord insert)
+ *
+ * So modifying qrecord->old_roots is safe here
+ */
+ qrecord->old_roots = old_root;
+ return 0;
+}
+
int btrfs_qgroup_trace_extent(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info, u64 bytenr, u64 num_bytes,
gfp_t gfp_flag)
@@ -1506,7 +1529,11 @@ int btrfs_qgroup_trace_extent(struct btrfs_trans_handle *trans,
delayed_refs = &trans->transaction->delayed_refs;
record->bytenr = bytenr;
record->num_bytes = num_bytes;
- record->old_roots = NULL;
+ ret = btrfs_find_all_roots(NULL, fs_info, bytenr, 0, &record->old_roots);
+ if (ret < 0) {
+ kfree(record);
+ return ret;
+ }
spin_lock(&delayed_refs->lock);
ret = btrfs_qgroup_trace_extent_nolock(fs_info, delayed_refs, record);
diff --git a/fs/btrfs/qgroup.h b/fs/btrfs/qgroup.h
index 416ae8e..f7086a3 100644
--- a/fs/btrfs/qgroup.h
+++ b/fs/btrfs/qgroup.h
@@ -98,6 +98,10 @@ int btrfs_qgroup_prepare_account_extents(struct btrfs_trans_handle *trans,
*
* No lock version, caller must acquire delayed ref lock and allocate memory.
*
+ * NOTE: To reduce time consumed at commit_trans time, we must call
+ * btrfs_qgroup_trace_extent_post() to balance half of the account time
+ * if record is inserted successfully.
+ *
* Return 0 for success insert
* Return >0 for existing record, caller can free @record safely.
* Error is not possible
@@ -108,6 +112,16 @@ int btrfs_qgroup_trace_extent_nolock(
struct btrfs_qgroup_extent_record *record);
/*
+ * Post handler after qgroup_trace_extent_nolock().
+ *
+ * To balance half of the accounting out of commit_trans().
+ * Can sleep. So can't be called at the same context of
+ * qgroup_trace_extent_nolock()
+ */
+int btrfs_qgroup_trace_extent_post(struct btrfs_fs_info *fs_info,
+ struct btrfs_qgroup_extent_record *qrecord);
+
+/*
* Inform qgroup to trace one dirty extent, specified by @bytenr and
* @num_bytes.
* So qgroup can account it at commit trans time.
--
2.9.3
--
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