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The ACS specification does not allow a non-NCQ command to be issued while an NCQ command is outstanding. Commit0ea84089db("ata: libata-scsi: avoid Non-NCQ command starvation") introduced a feature where a deferred non-NCQ command gets issued from a workqueue. The design stores a single non-NCQ command per port. However, when using Port Multipliers (PMPs), specifically PMPs that support FIS-Based Switching (FBS), non-NCQ and NCQ commands can be mixed on the same port, just not for the same link, see e.g. ata_std_qc_defer() which is, and always has operated on a per-link basis. Therefore, move the deferred_qc from struct ata_port to struct ata_link. This way, when using a PMP with FBS, we will not needlessly defer commands to all other links, just because one link issued a non-NCQ command while having an NCQ command outstanding. Only commands for that specific link will be deferred. This is in line with how PMPs with FBS worked before commit0ea84089db("ata: libata-scsi: avoid Non-NCQ command starvation"). Fixes:0ea84089db("ata: libata-scsi: avoid Non-NCQ command starvation") Tested-by: Tommy Kelly <linux@tkel.ly> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Signed-off-by: Niklas Cassel <cassel@kernel.org>