Bug#934331: linux: backport "dm: disable DISCARD if the underlying storage no longer supports it"?
Package: linux
Version: 4.9.168-1+deb9u4
Severity: normal
Hi!
Today I ran into an issue that matches the description of upstream
commit bcb44433bba5eaff293888ef22ffa07f1f0347d6:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=bcb44433bba5eaff293888ef22ffa07f1f0347d6
> dm: disable DISCARD if the underlying storage no longer supports it
>
> Storage devices which report supporting discard commands like
> WRITE_SAME_16 with unmap, but reject discard commands sent to the
> storage device. This is a clear storage firmware bug but it doesn't
> change the fact that should a program cause discards to be sent to a
> multipath device layered on this buggy storage, all paths can end up
> failed at the same time from the discards, causing possible I/O loss.
>
> The first discard to a path will fail with Illegal Request, Invalid
> field in cdb, e.g.:
> kernel: sd 8:0:8:19: [sdfn] tag#0 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
> kernel: sd 8:0:8:19: [sdfn] tag#0 Sense Key : Illegal Request [current]
> kernel: sd 8:0:8:19: [sdfn] tag#0 Add. Sense: Invalid field in cdb
> kernel: sd 8:0:8:19: [sdfn] tag#0 CDB: Write same(16) 93 08 00 00 00 00 00 a0 08 00 00 00 80 00 00 00
> kernel: blk_update_request: critical target error, dev sdfn, sector 10487808
The patch was CC'ed to stable but doesn't seem to appear in 4.19.y.
Unfortunately this appears to be a transient bug in the storage
firmware, so I don't know how to reproduce it -- deleting and rescanning
the sdX device has cleared the repeated error condition for now.
However I'd really like to avoid corrupting the involved file systems,
so if bcb44433bba5eaff293888ef22ffa07f1f0347d6 could make it into either
the 4.9 branch or the 4.19 branch, that'd be lovely.
I've also asked the storage vendor what they think about this, but I'm
not going to hold my breath.
Many thanks in advance,
Chris
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