2 files changed, 14 insertions, 8 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index f2a6020366e1..73c5d0410d47 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4794,21 +4794,26 @@ void swap_buf_le16(u16 *buf, unsigned int buf_words)
 static struct ata_queued_cmd *ata_qc_new(struct ata_port *ap)
 {
         struct ata_queued_cmd *qc = NULL;
-        unsigned int i;
+        unsigned int i, tag;
 
         /* no command while frozen */
         if (unlikely(ap->pflags & ATA_PFLAG_FROZEN))
                 return NULL;
 
-        /* the last tag is reserved for internal command. */
-        for (i = 0; i < ATA_MAX_QUEUE - 1; i++)
-                if (!test_and_set_bit(i, &ap->qc_allocated)) {
-                        qc = __ata_qc_from_tag(ap, i);
+        for (i = 0; i < ATA_MAX_QUEUE; i++) {
+                tag = (i + ap->last_tag + 1) % ATA_MAX_QUEUE;
+
+                /* the last tag is reserved for internal command. */
+                if (tag == ATA_TAG_INTERNAL)
+                        continue;
+
+                if (!test_and_set_bit(tag, &ap->qc_allocated)) {
+                        qc = __ata_qc_from_tag(ap, tag);
+                        qc->tag = tag;
+                        ap->last_tag = tag;
                         break;
                 }
-
-        if (qc)
-                qc->tag = i;
+        }
 
         return qc;
 }
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 1de36be64df4..5ab4e3a76721 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -822,6 +822,7 @@ struct ata_port {
         unsigned long           qc_allocated;
         unsigned int            qc_active;
         int                     nr_active_links; /* #links with active qcs */
+        unsigned int            last_tag;       /* track next tag hw expects */
 
         struct ata_link         link;           /* host default link */
         struct ata_link         *slave_link;    /* see ata_slave_link_init() */