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Kent Overstreet
b1c71cb492
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>
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.