btrfs: backref, add tracepoints for prelim_ref insertion and merging

This patch adds a tracepoint event for prelim_ref insertion and
merging.  For each, the ref being inserted or merged and the count
of tree nodes is issued.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

4 files changed, 131 insertions, 58 deletions

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 297f33850425..4cda81964dd4 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -18,6 +18,7 @@
 
 #include <linux/mm.h>
 #include <linux/rbtree.h>
+#include <trace/events/btrfs.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "backref.h"
@@ -120,20 +121,6 @@ static int find_extent_in_eb(const struct extent_buffer *eb,
         return 0;
 }
 
-/*
- * this structure records all encountered refs on the way up to the root
- */
-struct prelim_ref {
-        struct rb_node rbnode;
-        u64 root_id;
-        struct btrfs_key key_for_search;
-        int level;
-        int count;
-        struct extent_inode_elem *inode_list;
-        u64 parent;
-        u64 wanted_disk_byte;
-};
-
 struct preftree {
         struct rb_root root;
         unsigned int count;
@@ -212,7 +199,8 @@ static int prelim_ref_compare(struct prelim_ref *ref1,
  *
  * Callers should assumed that newref has been freed after calling.
  */
-static void prelim_ref_insert(struct preftree *preftree,
+static void prelim_ref_insert(const struct btrfs_fs_info *fs_info,
+                              struct preftree *preftree,
                               struct prelim_ref *newref)
 {
         struct rb_root *root;
@@ -243,6 +231,8 @@ static void prelim_ref_insert(struct preftree *preftree,
                                 ref->inode_list = newref->inode_list;
                         else
                                 eie->next = newref->inode_list;
+                        trace_btrfs_prelim_ref_merge(fs_info, ref, newref,
+                                                     preftree->count);
                         ref->count += newref->count;
                         free_pref(newref);
                         return;
@@ -250,6 +240,7 @@ static void prelim_ref_insert(struct preftree *preftree,
         }
 
         preftree->count++;
+        trace_btrfs_prelim_ref_insert(fs_info, newref, NULL, preftree->count);
         rb_link_node(&newref->rbnode, parent, p);
         rb_insert_color(&newref->rbnode, root);
 }
@@ -308,7 +299,8 @@ static void prelim_release(struct preftree *preftree)
  * additional information that's available but not required to find the parent
  * block might help in merging entries to gain some speed.
  */
-static int add_prelim_ref(struct preftree *preftree, u64 root_id,
+static int add_prelim_ref(const struct btrfs_fs_info *fs_info,
+                          struct preftree *preftree, u64 root_id,
                           const struct btrfs_key *key, int level, u64 parent,
                           u64 wanted_disk_byte, int count, gfp_t gfp_mask)
 {
@@ -355,21 +347,23 @@ static int add_prelim_ref(struct preftree *preftree, u64 root_id,
         ref->count = count;
         ref->parent = parent;
         ref->wanted_disk_byte = wanted_disk_byte;
-        prelim_ref_insert(preftree, ref);
+        prelim_ref_insert(fs_info, preftree, ref);
 
         return 0;
 }
 
 /* direct refs use root == 0, key == NULL */
-static int add_direct_ref(struct preftrees *preftrees, int level, u64 parent,
+static int add_direct_ref(const struct btrfs_fs_info *fs_info,
+                          struct preftrees *preftrees, int level, u64 parent,
                           u64 wanted_disk_byte, int count, gfp_t gfp_mask)
 {
-        return add_prelim_ref(&preftrees->direct, 0, NULL, level, parent,
-                              wanted_disk_byte, count, gfp_mask);
+        return add_prelim_ref(fs_info, &preftrees->direct, 0, NULL, level,
+                              parent, wanted_disk_byte, count, gfp_mask);
 }
 
 /* indirect refs use parent == 0 */
-static int add_indirect_ref(struct preftrees *preftrees, u64 root_id,
+static int add_indirect_ref(const struct btrfs_fs_info *fs_info,
+                            struct preftrees *preftrees, u64 root_id,
                             const struct btrfs_key *key, int level,
                             u64 wanted_disk_byte, int count, gfp_t gfp_mask)
 {
@@ -377,7 +371,7 @@ static int add_indirect_ref(struct preftrees *preftrees, u64 root_id,
 
         if (!key)
                 tree = &preftrees->indirect_missing_keys;
-        return add_prelim_ref(tree, root_id, key, level, 0,
+        return add_prelim_ref(fs_info, tree, root_id, key, level, 0,
                               wanted_disk_byte, count, gfp_mask);
 }
 
@@ -631,7 +625,7 @@ static int resolve_indirect_refs(struct btrfs_fs_info *fs_info,
                  * and return directly.
                  */
                 if (err == -ENOENT) {
-                        prelim_ref_insert(&preftrees->direct, ref);
+                        prelim_ref_insert(fs_info, &preftrees->direct, ref);
                         continue;
                 } else if (err) {
                         free_pref(ref);
@@ -659,11 +653,11 @@ static int resolve_indirect_refs(struct btrfs_fs_info *fs_info,
                         memcpy(new_ref, ref, sizeof(*ref));
                         new_ref->parent = node->val;
                         new_ref->inode_list = unode_aux_to_inode_list(node);
-                        prelim_ref_insert(&preftrees->direct, new_ref);
+                        prelim_ref_insert(fs_info, &preftrees->direct, new_ref);
                 }
 
                 /* Now it's a direct ref, put it in the the direct tree */
-                prelim_ref_insert(&preftrees->direct, ref);
+                prelim_ref_insert(fs_info, &preftrees->direct, ref);
 
                 ulist_reinit(parents);
         }
@@ -707,7 +701,7 @@ static int add_missing_keys(struct btrfs_fs_info *fs_info,
                         btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
                 btrfs_tree_read_unlock(eb);
                 free_extent_buffer(eb);
-                prelim_ref_insert(&preftrees->indirect, ref);
+                prelim_ref_insert(fs_info, &preftrees->indirect, ref);
         }
         return 0;
 }
@@ -716,7 +710,8 @@ static int add_missing_keys(struct btrfs_fs_info *fs_info,
  * add all currently queued delayed refs from this head whose seq nr is
  * smaller or equal that seq to the list
  */
-static int add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
+static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
+                            struct btrfs_delayed_ref_head *head, u64 seq,
                             struct preftrees *preftrees, u64 *total_refs,
                             u64 inum)
 {
@@ -759,8 +754,9 @@ static int add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
                         struct btrfs_delayed_tree_ref *ref;
 
                         ref = btrfs_delayed_node_to_tree_ref(node);
-                        ret = add_indirect_ref(preftrees, ref->root, &tmp_op_key,
-                                               ref->level + 1, node->bytenr,
+                        ret = add_indirect_ref(fs_info, preftrees, ref->root,
+                                               &tmp_op_key, ref->level + 1,
+                                               node->bytenr,
                                                node->ref_mod * sgn,
                                                GFP_ATOMIC);
                         break;
@@ -771,9 +767,9 @@ static int add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
 
                         ref = btrfs_delayed_node_to_tree_ref(node);
 
-                        ret = add_direct_ref(preftrees, ref->level + 1,
-                                             ref->parent, node->bytenr,
-                                             node->ref_mod * sgn,
+                        ret = add_direct_ref(fs_info, preftrees,
+                                             ref->level + 1, ref->parent,
+                                             node->bytenr, node->ref_mod * sgn,
                                              GFP_ATOMIC);
                         break;
                 }
@@ -795,8 +791,8 @@ static int add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
                                 break;
                         }
 
-                        ret = add_indirect_ref(preftrees, ref->root, &key, 0,
-                                               node->bytenr,
+                        ret = add_indirect_ref(fs_info, preftrees, ref->root,
+                                               &key, 0, node->bytenr,
                                                node->ref_mod * sgn,
                                                GFP_ATOMIC);
                         break;
@@ -807,8 +803,8 @@ static int add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
 
                         ref = btrfs_delayed_node_to_data_ref(node);
 
-                        ret = add_direct_ref(preftrees, 0, ref->parent,
-                                             node->bytenr,
+                        ret = add_direct_ref(fs_info, preftrees, 0,
+                                             ref->parent, node->bytenr,
                                              node->ref_mod * sgn,
                                              GFP_ATOMIC);
                         break;
@@ -826,7 +822,8 @@ static int add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
 /*
  * add all inline backrefs for bytenr to the list
  */
-static int add_inline_refs(struct btrfs_path *path, u64 bytenr,
+static int add_inline_refs(const struct btrfs_fs_info *fs_info,
+                           struct btrfs_path *path, u64 bytenr,
                            int *info_level, struct preftrees *preftrees,
                            u64 *total_refs, u64 inum)
 {
@@ -883,7 +880,8 @@ static int add_inline_refs(struct btrfs_path *path, u64 bytenr,
 
                 switch (type) {
                 case BTRFS_SHARED_BLOCK_REF_KEY:
-                        ret = add_direct_ref(preftrees, *info_level + 1, offset,
+                        ret = add_direct_ref(fs_info, preftrees,
+                                             *info_level + 1, offset,
                                              bytenr, 1, GFP_NOFS);
                         break;
                 case BTRFS_SHARED_DATA_REF_KEY: {
@@ -893,14 +891,14 @@ static int add_inline_refs(struct btrfs_path *path, u64 bytenr,
                         sdref = (struct btrfs_shared_data_ref *)(iref + 1);
                         count = btrfs_shared_data_ref_count(leaf, sdref);
 
-                        ret = add_direct_ref(preftrees, 0, offset,
+                        ret = add_direct_ref(fs_info, preftrees, 0, offset,
                                              bytenr, count, GFP_NOFS);
                         break;
                 }
                 case BTRFS_TREE_BLOCK_REF_KEY:
-                        ret = add_indirect_ref(preftrees, offset, NULL,
-                                               *info_level + 1, bytenr, 1,
-                                               GFP_NOFS);
+                        ret = add_indirect_ref(fs_info, preftrees, offset,
+                                               NULL, *info_level + 1,
+                                               bytenr, 1, GFP_NOFS);
                         break;
                 case BTRFS_EXTENT_DATA_REF_KEY: {
                         struct btrfs_extent_data_ref *dref;
@@ -921,8 +919,9 @@ static int add_inline_refs(struct btrfs_path *path, u64 bytenr,
 
                         root = btrfs_extent_data_ref_root(leaf, dref);
 
-                        ret = add_indirect_ref(preftrees, root, &key, 0, bytenr,
-                                               count, GFP_NOFS);
+                        ret = add_indirect_ref(fs_info, preftrees, root,
+                                               &key, 0, bytenr, count,
+                                               GFP_NOFS);
                         break;
                 }
                 default:
@@ -973,9 +972,9 @@ static int add_keyed_refs(struct btrfs_fs_info *fs_info,
                 switch (key.type) {
                 case BTRFS_SHARED_BLOCK_REF_KEY:
                         /* SHARED DIRECT METADATA backref */
-                        ret = add_direct_ref(preftrees, info_level + 1,
-                                             key.offset, bytenr, 1,
-                                             GFP_NOFS);
+                        ret = add_direct_ref(fs_info, preftrees,
+                                             info_level + 1, key.offset,
+                                             bytenr, 1, GFP_NOFS);
                         break;
                 case BTRFS_SHARED_DATA_REF_KEY: {
                         /* SHARED DIRECT FULL backref */
@@ -985,15 +984,16 @@ static int add_keyed_refs(struct btrfs_fs_info *fs_info,
                         sdref = btrfs_item_ptr(leaf, slot,
                                               struct btrfs_shared_data_ref);
                         count = btrfs_shared_data_ref_count(leaf, sdref);
-                        ret = add_direct_ref(preftrees, 0, key.offset, bytenr,
-                                             count, GFP_NOFS);
+                        ret = add_direct_ref(fs_info, preftrees, 0,
+                                             key.offset, bytenr, count,
+                                             GFP_NOFS);
                         break;
                 }
                 case BTRFS_TREE_BLOCK_REF_KEY:
                         /* NORMAL INDIRECT METADATA backref */
-                        ret = add_indirect_ref(preftrees, key.offset, NULL,
-                                               info_level + 1, bytenr, 1,
-                                               GFP_NOFS);
+                        ret = add_indirect_ref(fs_info, preftrees, key.offset,
+                                               NULL, info_level + 1, bytenr,
+                                               1, GFP_NOFS);
                         break;
                 case BTRFS_EXTENT_DATA_REF_KEY: {
                         /* NORMAL INDIRECT DATA backref */
@@ -1015,8 +1015,9 @@ static int add_keyed_refs(struct btrfs_fs_info *fs_info,
                         }
 
                         root = btrfs_extent_data_ref_root(leaf, dref);
-                        ret = add_indirect_ref(preftrees, root, &key, 0, bytenr,
-                                               count, GFP_NOFS);
+                        ret = add_indirect_ref(fs_info, preftrees, root,
+                                               &key, 0, bytenr, count,
+                                               GFP_NOFS);
                         break;
                 }
                 default:
@@ -1129,8 +1130,8 @@ again:
                                 goto again;
                         }
                         spin_unlock(&delayed_refs->lock);
-                        ret = add_delayed_refs(head, time_seq, &preftrees,
-                                               &total_refs, inum);
+                        ret = add_delayed_refs(fs_info, head, time_seq,
+                                               &preftrees, &total_refs, inum);
                         mutex_unlock(&head->mutex);
                         if (ret)
                                 goto out;
@@ -1150,8 +1151,9 @@ again:
                 if (key.objectid == bytenr &&
                     (key.type == BTRFS_EXTENT_ITEM_KEY ||
                      key.type == BTRFS_METADATA_ITEM_KEY)) {
-                        ret = add_inline_refs(path, bytenr, &info_level,
-                                              &preftrees, &total_refs, inum);
+                        ret = add_inline_refs(fs_info, path, bytenr,
+                                              &info_level, &preftrees,
+                                              &total_refs, inum);
                         if (ret)
                                 goto out;
                         ret = add_keyed_refs(fs_info, path, bytenr, info_level,
diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
index f9428aaaa77a..e410335841aa 100644
--- a/fs/btrfs/backref.h
+++ b/fs/btrfs/backref.h
@@ -72,4 +72,16 @@ int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr);
 
 int __init btrfs_prelim_ref_init(void);
 void btrfs_prelim_ref_exit(void);
+
+struct prelim_ref {
+        struct rb_node rbnode;
+        u64 root_id;
+        struct btrfs_key key_for_search;
+        int level;
+        int count;
+        struct extent_inode_elem *inode_list;
+        u64 parent;
+        u64 wanted_disk_byte;
+};
+
 #endif
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 12540b6104b5..58650f2e0f17 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -61,6 +61,7 @@
 #include "tests/btrfs-tests.h"
 
 #include "qgroup.h"
+#include "backref.h"
 #define CREATE_TRACE_POINTS
 #include <trace/events/btrfs.h>
 
diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h
index 42560feb9920..90d25085762f 100644
--- a/include/trace/events/btrfs.h
+++ b/include/trace/events/btrfs.h
@@ -26,6 +26,7 @@ struct btrfs_work;
 struct __btrfs_workqueue;
 struct btrfs_qgroup_extent_record;
 struct btrfs_qgroup;
+struct prelim_ref;
 
 #define show_ref_type(type)                                             \
         __print_symbolic(type,                                          \
@@ -1636,6 +1637,63 @@ TRACE_EVENT(qgroup_meta_reserve,
                 show_root_type(__entry->refroot), __entry->diff)
 );
 
+DECLARE_EVENT_CLASS(btrfs__prelim_ref,
+        TP_PROTO(const struct btrfs_fs_info *fs_info,
+                 const struct prelim_ref *oldref,
+                 const struct prelim_ref *newref, u64 tree_size),
+        TP_ARGS(fs_info, newref, oldref, tree_size),
+
+        TP_STRUCT__entry_btrfs(
+                __field(        u64,  root_id           )
+                __field(        u64,  objectid          )
+                __field(         u8,  type              )
+                __field(        u64,  offset            )
+                __field(        int,  level             )
+                __field(        int,  old_count         )
+                __field(        u64,  parent            )
+                __field(        u64,  bytenr            )
+                __field(        int,  mod_count         )
+                __field(        u64,  tree_size         )
+        ),
+
+        TP_fast_assign_btrfs(fs_info,
+                __entry->root_id        = oldref->root_id;
+                __entry->objectid       = oldref->key_for_search.objectid;
+                __entry->type           = oldref->key_for_search.type;
+                __entry->offset         = oldref->key_for_search.offset;
+                __entry->level          = oldref->level;
+                __entry->old_count      = oldref->count;
+                __entry->parent         = oldref->parent;
+                __entry->bytenr         = oldref->wanted_disk_byte;
+                __entry->mod_count      = newref ? newref->count : 0;
+                __entry->tree_size      = tree_size;
+        ),
+
+        TP_printk_btrfs("root_id=%llu key=[%llu,%u,%llu] level=%d count=[%d+%d=%d] parent=%llu wanted_disk_byte=%llu nodes=%llu",
+                        (unsigned long long)__entry->root_id,
+                        (unsigned long long)__entry->objectid, __entry->type,
+                        (unsigned long long)__entry->offset, __entry->level,
+                        __entry->old_count, __entry->mod_count,
+                        __entry->old_count + __entry->mod_count,
+                        (unsigned long long)__entry->parent,
+                        (unsigned long long)__entry->bytenr,
+                        (unsigned long long)__entry->tree_size)
+);
+
+DEFINE_EVENT(btrfs__prelim_ref, btrfs_prelim_ref_merge,
+        TP_PROTO(const struct btrfs_fs_info *fs_info,
+                 const struct prelim_ref *oldref,
+                 const struct prelim_ref *newref, u64 tree_size),
+        TP_ARGS(fs_info, oldref, newref, tree_size)
+);
+
+DEFINE_EVENT(btrfs__prelim_ref, btrfs_prelim_ref_insert,
+        TP_PROTO(const struct btrfs_fs_info *fs_info,
+                 const struct prelim_ref *oldref,
+                 const struct prelim_ref *newref, u64 tree_size),
+        TP_ARGS(fs_info, oldref, newref, tree_size)
+);
+
 #endif /* _TRACE_BTRFS_H */
 
 /* This part must be outside protection */