It's pretty handy if we can get debug output for locking status of an
extent buffer, specially for race related debugging.
So add the following output for btrfs_print_tree() and
btrfs_print_leaf():
- refs
- write_locks (as w:%u)
- read_locks (as r:%u)
- blocking_writers (as bw:%u)
- blocking_readers (as br:%u)
- spinning_writers (as sw:%u)
- spinning_readers (as sr:%u)
- lock_owner
- current->pid
Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
---
fs/btrfs/print-tree.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/fs/btrfs/print-tree.c b/fs/btrfs/print-tree.c
index 9904cf741e1c..7f0ada51e5fe 100644
--- a/fs/btrfs/print-tree.c
+++ b/fs/btrfs/print-tree.c
@@ -179,6 +179,26 @@ static void print_uuid_item(struct extent_buffer *l, unsigned long offset,
}
}
+/*
+ * Helper to output refs and locking status.
+ *
+ * Useful to debug race related problem
+ */
+static void print_eb_refs_lock(struct extent_buffer *eb)
+{
+#ifdef CONFIG_BTRFS_DEBUG
+ btrfs_info(eb->fs_info,
+"refs %u lock(w:%u r:%u bw:%u br:%u sw:%u sr:%u) lock_owner %u current %u",
+ atomic_read(&eb->refs), atomic_read(&eb->write_locks),
+ atomic_read(&eb->read_locks),
+ atomic_read(&eb->blocking_writers),
+ atomic_read(&eb->blocking_readers),
+ atomic_read(&eb->spinning_writers),
+ atomic_read(&eb->spinning_readers),
+ eb->lock_owner, current->pid);
+#endif
+}
+
void btrfs_print_leaf(struct extent_buffer *l)
{
struct btrfs_fs_info *fs_info;
@@ -206,6 +226,7 @@ void btrfs_print_leaf(struct extent_buffer *l)
"leaf %llu gen %llu total ptrs %d free space %d owner %llu",
btrfs_header_bytenr(l), btrfs_header_generation(l), nr,
btrfs_leaf_free_space(fs_info, l), btrfs_header_owner(l));
+ print_eb_refs_lock(l);
for (i = 0 ; i < nr ; i++) {
item = btrfs_item_nr(i);
btrfs_item_key_to_cpu(l, &key, i);
@@ -360,6 +381,7 @@ void btrfs_print_tree(struct extent_buffer *c, bool follow)
btrfs_header_bytenr(c), level, btrfs_header_generation(c),
nr, (u32)BTRFS_NODEPTRS_PER_BLOCK(fs_info) - nr,
btrfs_header_owner(c));
+ print_eb_refs_lock(c);
for (i = 0; i < nr; i++) {
btrfs_node_key_to_cpu(c, &key, i);
pr_info("\tkey %d (%llu %u %llu) block %llu gen %llu\n",
--
2.17.0
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