Re: [PATCH 1/9] btrfs: qgroup: Add trace point for qgroup reserved space

[Qu Wenruo]

At 03/08/2017 12:30 AM, Jeff Mahoney wrote:
On 2/27/17 2:10 AM, Qu Wenruo wrote:
Introduce the following trace points:
qgroup_update_reserve
qgroup_meta_reserve

These trace points are handy to trace qgroup reserve space related
problems.

Signed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com>
---
 fs/btrfs/qgroup.c            | 15 +++++++++++++++
 include/trace/events/btrfs.h | 43 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index a5da750c1087..b303d4794026 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -1075,6 +1075,8 @@ static int __qgroup_excl_accounting(struct btrfs_fs_info 
*fs_info,
        qgroup->excl += sign * num_bytes;
        qgroup->excl_cmpr += sign * num_bytes;
        if (sign > 0) {
+               trace_qgroup_update_reserve(fs_info, qgroup->qgroupid,
+                                           qgroup->reserved, -(s64)num_bytes);
                if (WARN_ON(qgroup->reserved < num_bytes))
                        report_reserved_underflow(fs_info, qgroup, num_bytes);
                else
@@ -1100,6 +1102,9 @@ static int __qgroup_excl_accounting(struct btrfs_fs_info 
*fs_info,
                WARN_ON(sign < 0 && qgroup->excl < num_bytes);
                qgroup->excl += sign * num_bytes;
                if (sign > 0) {
+                       trace_qgroup_update_reserve(fs_info, qgroup->qgroupid,
+                                                   qgroup->reserved,
+                                                   -(s64)num_bytes);
                        if (WARN_ON(qgroup->reserved < num_bytes))
                                report_reserved_underflow(fs_info, qgroup,
                                                          num_bytes);
@@ -2424,6 +2429,8 @@ static int qgroup_reserve(struct btrfs_root *root, u64 
num_bytes, bool enforce)

                qg = unode_aux_to_qgroup(unode);

+               trace_qgroup_update_reserve(fs_info, qg->qgroupid,
+                                           qg->reserved, num_bytes);
                qg->reserved += num_bytes;
        }

@@ -2469,6 +2476,8 @@ void btrfs_qgroup_free_refroot(struct btrfs_fs_info 
*fs_info,

                qg = unode_aux_to_qgroup(unode);

+               trace_qgroup_update_reserve(fs_info, qg->qgroupid,
+                                           qg->reserved, -(s64)num_bytes);
                if (WARN_ON(qg->reserved < num_bytes))
                        report_reserved_underflow(fs_info, qg, num_bytes);
                else
@@ -2945,6 +2954,8 @@ int btrfs_qgroup_reserve_meta(struct btrfs_root *root, 
int num_bytes,
                return 0;

        BUG_ON(num_bytes != round_down(num_bytes, fs_info->nodesize));
+       trace_qgroup_meta_reserve(fs_info, root->objectid,
+                                 (s64)num_bytes);
        ret = qgroup_reserve(root, num_bytes, enforce);
        if (ret < 0)
                return ret;
@@ -2964,6 +2975,8 @@ void btrfs_qgroup_free_meta_all(struct btrfs_root *root)
        reserved = atomic_xchg(&root->qgroup_meta_rsv, 0);
        if (reserved == 0)
                return;
+       trace_qgroup_meta_reserve(root->fs_info, root->objectid,
+                                 -(s64)reserved);
        btrfs_qgroup_free_refroot(fs_info, root->objectid, reserved);
 }

@@ -2978,6 +2991,8 @@ void btrfs_qgroup_free_meta(struct btrfs_root *root, int 
num_bytes)
        BUG_ON(num_bytes != round_down(num_bytes, fs_info->nodesize));
        WARN_ON(atomic_read(&root->qgroup_meta_rsv) < num_bytes);
        atomic_sub(num_bytes, &root->qgroup_meta_rsv);
+       trace_qgroup_meta_reserve(root->fs_info, root->objectid,
+                                 -(s64)num_bytes);
        btrfs_qgroup_free_refroot(fs_info, root->objectid, num_bytes);
 }

diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h
index a3c3cab643a9..2d5799d8a4a2 100644
--- a/include/trace/events/btrfs.h
+++ b/include/trace/events/btrfs.h
@@ -1475,6 +1475,49 @@ TRACE_EVENT(qgroup_update_counters,
                  __entry->cur_new_count)
 );

+TRACE_EVENT(qgroup_update_reserve,
+
+       TP_PROTO(struct btrfs_fs_info *fs_info, u64 qgid, u64 cur_reserved,
+                s64 diff),
+
+       TP_ARGS(fs_info, qgid, cur_reserved, diff),
+
+       TP_STRUCT__entry_btrfs(
+               __field(        u64,    qgid                    )
+               __field(        u64,    cur_reserved            )
+               __field(        s64,    diff                    )
+       ),
+
+       TP_fast_assign_btrfs(fs_info,
+               __entry->qgid                = qgid;
+               __entry->cur_reserved        = cur_reserved;
+               __entry->diff                = diff;
+       ),
+
+       TP_printk_btrfs("qgid = %llu, cur_reserved = %llu, diff = %lld",
+               __entry->qgid, __entry->cur_reserved, __entry->diff)
+);
+

This is always called using a qgroup pointer.  Why not just pass it and
let the the assignment clause grab the values?

Nice idea, I'll update the parameters along with the output format to 
match the latest standard.

Thanks for the review,
Qu

+TRACE_EVENT(qgroup_meta_reserve,
+
+       TP_PROTO(struct btrfs_fs_info *fs_info, u64 refroot, s64 diff),
+
+       TP_ARGS(fs_info, refroot, diff),
+
+       TP_STRUCT__entry_btrfs(
+               __field(        u64,    refroot                 )
+               __field(        s64,    diff                    )
+       ),
+
+       TP_fast_assign_btrfs(fs_info,
+               __entry->refroot     = refroot;
+               __entry->diff                = diff;
+       ),
+
+       TP_printk_btrfs("refroot = %llu, diff = %lld",
+               __entry->refroot, __entry->diff)
+);

Same here, but with btrfs_root * instead.

-Jeff

+
 #endif /* _TRACE_BTRFS_H */

 /* This part must be outside protection */





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