The Linux 6.14 stable kernel is likely to be released in just over one week and thus leading to Bcachefs file-system developers racing to track down a new bug that’s been reported by a user on upgrading to the new kernel.
Bcachefs on Thursday landed a few fixes for the in-development Linux 6.14 kernel as just some routine code churn ahead of the next stable kernel release later in the month. But then another one came in on Friday that was a bit more alarming. Bcachefs lead developer Kent Overstreet explained in Friday’s pull request:
“This one is high priority: a user hit an assertion in the upgrade to 6.14, and we don’t have a reproducer, so this changes the assertion to an emergency read-only with more info so we can debug it.”
The actual patch goes on to explain the situation further:
“We just had a report of the assert for “btree in write buffer for non-write buffer btree” popping during the 6.14 upgrade.
– 150TB filesystem, after a reboot the upgrade was able to continue from where it left off, so no major damage.
But with 6.14 about to come out we want to get this tracked down asap, and need more data if other users hit this.
Convert the BUG_ON() to an emergency read-only, and print out btree, the key itself, and stack trace from the original write buffer update (which did not have this check before).”
The good news is no data loss observed from the user reporting the assert, but the bad news is that it’s likely a little more than a week to go until the Linux 6.14 stable release and this pressing issue hasn’t been tracked down yet. Thus the high priority pull request to hopefully obtain some more information from any other affected users in the coming days.
There ended up being a third Bcachefs pull request for the week that was also merged yesterday to fix breaking 32-bit builds with the Bcachefs code.
