On 5/20/25 10:53 PM, Christoph Hellwig wrote:
On Tue, May 20, 2025 at 11:09:15AM -0700, Bart Van Assche wrote:
If the sequential write bios are split by the device mapper, sorting
bios in the block layer is not necessary. Christoph and Damien, do you
agree to replace the bio sorting code in my previous email with the
patch below?
No. First please create a reproducer for your issue using null_blk
or scsi_debug, otherwise we have no way to understand what is going
on here, and will regress in the future.
Second should very much be able to fix the splitting in dm to place
the bios in the right order. As mentioned before I have a theory
of how to do it, but we really need a proper reproducer to test this
and then to write it up to blktests first.
Hi Christoph,
The following pull request includes a test that triggers the deadlock
fixed by patch 2/2 reliably:
https://github.com/osandov/blktests/pull/171
I do not yet have a reproducer for the bio reordering but I'm still
working on this.
Bart.
