More debugging infrastructure that might perhaps be of wider interest. Currently, when an asynchronous op gets stuck and never completes, it's a real problem to debug: all our normal introspection (e.g. /proc/pid/stack) doesn't work. e.g. if a bio doesn't (seem to) complete - what happened to it? Difficult question to answer. We have giant state machines, and debugging issues where we stop making forward progress requires visibility into the whole thing. (basic question: did the bio complete and the endio not funtion not flip the correct state bit, or did it get lost?) In the reports/test failures I look at, I've been seeing these the most in or at the boundary of mm - compaction/migration, writeback... This series introduces infrastructure that'll allow us to debug these kinds of issues in production: - fast_list, which is a high-enough performance "list" to track these kinds of objects (radix tree + percpu buffer) - infrastructure for making them visible in debugfs, hooking them up to pretty printers - and the last patch hooks into just some of the bcachefs paths where we we need this Kent Overstreet (5): bcachefs: bch2_bio_to_text() bcachefs: bch2_read_bio_to_text bcachefs: fast_list bcachefs: Async object debugging bcachefs: Make various async objs visible in debugfs fs/bcachefs/Kconfig | 5 ++ fs/bcachefs/Makefile | 3 + fs/bcachefs/async_objs.c | 126 +++++++++++++++++++++++++++++ fs/bcachefs/async_objs.h | 39 +++++++++ fs/bcachefs/async_objs_types.h | 24 ++++++ fs/bcachefs/bcachefs.h | 7 ++ fs/bcachefs/btree_io.c | 12 +++ fs/bcachefs/btree_io.h | 8 ++ fs/bcachefs/data_update.c | 18 ++++- fs/bcachefs/data_update.h | 15 ++++ fs/bcachefs/debug.c | 52 +++++------- fs/bcachefs/debug.h | 18 +++++ fs/bcachefs/errcode.h | 1 + fs/bcachefs/fast_list.c | 140 +++++++++++++++++++++++++++++++++ fs/bcachefs/fast_list.h | 41 ++++++++++ fs/bcachefs/io_read.c | 76 +++++++++++++++--- fs/bcachefs/io_read.h | 14 ++++ fs/bcachefs/super.c | 3 + fs/bcachefs/util.c | 10 +++ fs/bcachefs/util.h | 2 + 20 files changed, 566 insertions(+), 48 deletions(-) create mode 100644 fs/bcachefs/async_objs.c create mode 100644 fs/bcachefs/async_objs.h create mode 100644 fs/bcachefs/async_objs_types.h create mode 100644 fs/bcachefs/fast_list.c create mode 100644 fs/bcachefs/fast_list.h -- 2.49.0
