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In SCSI, we get the sense data as part of the completion, for ATA however, we need to fetch the sense data as an extra step. For an aborted ATA command the sense data is fetched via libata's ->eh_strategy_handler(). For Command Duration Limits policy 0xD: The device shall complete the command without error with the additional sense code set to DATA CURRENTLY UNAVAILABLE. In order to handle this policy in libata, we intend to send a successful command via SCSI EH, and let libata's ->eh_strategy_handler() fetch the sense data for the good command. This is similar to how we handle an aborted ATA command, just that we need to read the Successful NCQ Commands log instead of the NCQ Command Error log. When we get a SATA completion with successful commands, ATA_SENSE will be set, indicating that some commands in the completion have sense data. The sense_valid bitmask in the Sense Data for Successful NCQ Commands log will inform exactly which commands that had sense data, which might be a subset of all the commands that was completed in the same completion. (Yet all will have ATA_SENSE set, since the status is per completion.) The successful commands that have e.g. a "DATA CURRENTLY UNAVAILABLE" sense data will have a SCSI ML byte set, so scsi_eh_flush_done_q() will not set the scmd->result to DID_TIME_OUT for these commands. However, the successful commands that did not have sense data, must not get their result marked as DID_TIME_OUT by SCSI EH. Add a new flag SCMD_FORCE_EH_SUCCESS, which tells SCSI EH to not mark a command as DID_TIME_OUT, even if it has scmd->result == SAM_STAT_GOOD. This will be used by libata in a subsequent commit. Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com> Link: https://lore.kernel.org/r/20230511011356.227789-5-nks@flawful.org Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.