No description
  • C 96.8%
  • Assembly 0.9%
  • Rust 0.7%
  • Shell 0.6%
  • Python 0.5%
  • Other 0.3%
Find a file
Kent Overstreet b1c71cb492 bcachefs: Fix broken btree_path lock invariants in next_node()
This fixes btree locking assert pops users were seeing during evacuate:

https://github.com/koverstreet/bcachefs/issues/878

May 09 22:45:02 sharon kernel: bcachefs (68116e25-fa2d-4c6f-86c7-e8b431d792ae):   bch2_btree_insert_node(): node not locked at level 1
May 09 22:45:02 sharon kernel:   bch2_btree_node_rewrite [bcachefs]: watermark=btree no_check_rw alloc l=0-1 mode=none nodes_written=0 cl.remaining=2 journal_seq=0
May 09 22:45:02 sharon kernel:   path: idx   1 ref 1:0   S B btree=alloc level=0 pos 0:3699637:0 0:3698012:1-0:3699637:0 bch2_move_btree.isra.0+0x1db/0x490 [bcachefs] uptodate 0 locks_want 2
May 09 22:45:02 sharon kernel:     l=0 locks intent seq 4 node ffff8bd700c93600
May 09 22:45:02 sharon kernel:     l=1 locks unlocked seq 1712 node ffff8bd6fd5e7a00
May 09 22:45:02 sharon kernel:     l=2 locks unlocked seq 2295 node ffff8bd6cc725400
May 09 22:45:02 sharon kernel:     l=3 locks unlocked seq 0 node 0000000000000000

Evacuate walks btree nodes with bch2_btree_iter_next_node() and rewrites
them, bch2_btree_update_start() upgrades the path to take intent locks
as far as it needs to.

But next_node() does low level unlock/relock calls on individual nodes,
and didn't handle the case where a path is supposed to be holding
multiple intent locks. If a path has locks_want > 1, it needs to be
either holding locks on all the btree nodes (at each level) requested,
or none of them.

Fix this with a bch2_btree_path_downgrade().

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
History 2025-05-14 17:05:19 -04:00
arch
block
certs
crypto
Documentation
drivers
fs
include
init
io_uring
ipc
kernel
lib
LICENSES
mm
net
rust
samples
scripts
security
sound
tools
usr
virt
.clang-format
.clippy.toml
.cocciconfig
.editorconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
.rustfmt.toml
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.