Re: [QUESTION] xfs, iomap: Handle writeback errors to prevent silent data corruption

[Christoph Hellwig <hch@infradead.org>]

[taking this private to discuss the mpt drivers]

> Hmmm... DID_SOFT_ERROR... Normally, this is an immediate retry as this normally
> is used to indicate that a command is a collateral abort due to an NCQ error,
> and per ATA spec, that command should be retried. However, the *BAD* thing
> about Broadcom HBAs using this is that it increments the command retry counter,
> so if a command ends up being retried more than 5 times due to other commands
> failing, the command runs out of retries and is failed like this. The command
> retry counter should *not* be incremented for NCQ collateral aborts. I tried to
> fix this, but it is impossible as we actually do not know if this is a
> collateral abort or something else. The HBA events used to handle completion do
> not allow differentiation. Waiting on Broadcom to do something about this (the
> mpi3mr HBA driver has the same nasty issue).

Maybe we should just change the mpt3 sas/mr drivers to use
DID_SOFT_ERROR less?  In fact there's not really a whole lot of
DID_SOFT_ERROR users otherwise, and there's probably better status
codes whatever they are doing can be translated to that do not increment
the retry counter.