libata: add extra internal command

Bump the internal tag to 32, instead of stealing the last tag in
our regular command space. This works just fine, since we don't
actually need a separate hardware tag for this. Internal commands
cannot coexist with NCQ commands.

As a bonus, we get rid of the special casing of what tag to use
for the internal command.

This is in preparation for utilizing all 32 commands for normal IO.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 7 insertions, 8 deletions

diff --git a/include/linux/libata.h b/include/linux/libata.h
index 60ce1ba26fdd..1d026719461b 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -125,9 +125,8 @@ enum {
         LIBATA_MAX_PRD          = ATA_MAX_PRD / 2,
         LIBATA_DUMB_MAX_PRD     = ATA_MAX_PRD / 4,      /* Worst case */
         ATA_DEF_QUEUE           = 1,
-        /* tag ATA_MAX_QUEUE - 1 is reserved for internal commands */
         ATA_MAX_QUEUE           = 32,
-        ATA_TAG_INTERNAL        = ATA_MAX_QUEUE - 1,
+        ATA_TAG_INTERNAL        = ATA_MAX_QUEUE,
         ATA_SHORT_PAUSE         = 16,
 
         ATAPI_MAX_DRAIN         = 16 << 10,
@@ -850,7 +849,7 @@ struct ata_port {
         unsigned int            udma_mask;
         unsigned int            cbl;    /* cable type; ATA_CBL_xxx */
 
-        struct ata_queued_cmd   qcmd[ATA_MAX_QUEUE];
+        struct ata_queued_cmd   qcmd[ATA_MAX_QUEUE + 1];
         unsigned long           sas_tag_allocated; /* for sas tag allocation only */
         u64                     qc_active;
         int                     nr_active_links; /* #links with active qcs */
@@ -1486,14 +1485,14 @@ extern void ata_port_pbar_desc(struct ata_port *ap, int bar, ssize_t offset,
                                const char *name);
 #endif
 
-static inline unsigned int ata_tag_valid(unsigned int tag)
+static inline bool ata_tag_internal(unsigned int tag)
 {
-        return (tag < ATA_MAX_QUEUE) ? 1 : 0;
+        return tag == ATA_TAG_INTERNAL;
 }
 
-static inline bool ata_tag_internal(unsigned int tag)
+static inline bool ata_tag_valid(unsigned int tag)
 {
-        return tag == ATA_TAG_INTERNAL;
+        return tag < ATA_MAX_QUEUE || ata_tag_internal(tag);
 }
 
 /*
@@ -1656,7 +1655,7 @@ static inline void ata_qc_set_polling(struct ata_queued_cmd *qc)
 static inline struct ata_queued_cmd *__ata_qc_from_tag(struct ata_port *ap,
                                                        unsigned int tag)
 {
-        if (likely(ata_tag_valid(tag)))
+        if (ata_tag_valid(tag))
                 return &ap->qcmd[tag];
         return NULL;
 }