On 11/11/21 4:13 AM, Kent Overstreet wrote:
On Wed, Nov 10, 2021 at 11:14:41AM +0530, Nikhil Kshirsagar wrote:
Hello,
After a reboot of an Ubuntu server running 4.15.0-143-generic kernel,
the storage devices using bcache do not come back up and the following
stack traces are seen in kern.log. Please could someone help me
understand if this is due to a full bcache journal? Is there any
workaround, or fix?
Your journal is completely full, so persisting the new btree root while doing
journal replay is hanging.
There isn't a _good_ solution for this journal deadlock in bcache (it's fixed in
bcachefs), but there is a hack:
edit drivers/md/bcache/btree.c line 2493
delete the call to bch_journal_meta(), and build a new kernel. Once you've
gotten it to register, do a clean shutdown and then go back to a stock kernel.
Running the kernel with that call deleted won't be safe if you crash, but it'll
get you going again.
This happens eventually. I had a patch to reserve the last 2 blocks in
the last journal bucket, and only to use them during boot time. It seems
to be time to refine the patch.
(BTW, looking forward to see bcachefs in mainline kernel).
Coly Li
