libata: Improve ATA queued command allocation

Improve ATA queued command allocation as follows:

- For attaining a qc tag for a SAS host we need to allocate a bit in
  ata_port.sas_tag_allocated bitmap.

  However we already have a unique tag per device in range
  [0, ATA_MAX_QUEUE -1] in the scsi cmnd budget token, so just use that
  instead.

- It is a bit pointless to have ata_qc_new_init() in libata-core.c since it
  pokes scsi internals, so inline it in ata_scsi_qc_new() (in
  libata-scsi.c). Also update Doc accordingly.

- Use standard SCSI helpers set_host_byte() and set_status_byte() in
  ata_scsi_qc_new().

Christoph Hellwig originally contributed the change to inline
ata_qc_new_init().

Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>

1 files changed, 0 insertions, 13 deletions

diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index c9c2496d91ea..926a7f41303d 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -44,7 +44,6 @@ static inline void ata_force_cbl(struct ata_port *ap) { }
 #endif
 extern u64 ata_tf_to_lba(const struct ata_taskfile *tf);
 extern u64 ata_tf_to_lba48(const struct ata_taskfile *tf);
-extern struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, int tag);
 extern int ata_build_rw_tf(struct ata_taskfile *tf, struct ata_device *dev,
 			   u64 block, u32 n_block, unsigned int tf_flags,
 			   unsigned int tag, int class);
@@ -91,18 +90,6 @@ extern unsigned int ata_read_log_page(struct ata_device *dev, u8 log,
 
 #define to_ata_port(d) container_of(d, struct ata_port, tdev)
 
-/* libata-sata.c */
-#ifdef CONFIG_SATA_HOST
-int ata_sas_allocate_tag(struct ata_port *ap);
-void ata_sas_free_tag(unsigned int tag, struct ata_port *ap);
-#else
-static inline int ata_sas_allocate_tag(struct ata_port *ap)
-{
-	return -EOPNOTSUPP;
-}
-static inline void ata_sas_free_tag(unsigned int tag, struct ata_port *ap) { }
-#endif
-
 /* libata-acpi.c */
 #ifdef CONFIG_ATA_ACPI
 extern unsigned int ata_acpi_gtf_filter;