block: Consolidate phys_segment and hw_segment limits

Except for SCSI no device drivers distinguish between physical and
hardware segment limits.  Consolidate the two into a single segment
limit.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

3 files changed, 16 insertions, 55 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 36c0deebc2dc..9fe174dc74d1 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1614,8 +1614,7 @@ int blk_rq_check_limits(struct request_queue *q, struct request *rq)
          * limitation.
          */
         blk_recalc_rq_segments(rq);
-        if (rq->nr_phys_segments > queue_max_phys_segments(q) ||
-            rq->nr_phys_segments > queue_max_hw_segments(q)) {
+        if (rq->nr_phys_segments > queue_max_segments(q)) {
                 printk(KERN_ERR "%s: over max segments limit.\n", __func__);
                 return -EIO;
         }
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 99cb5cf1f447..5e7dc9973458 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -206,8 +206,7 @@ static inline int ll_new_hw_segment(struct request_queue *q,
 {
         int nr_phys_segs = bio_phys_segments(q, bio);
 
-        if (req->nr_phys_segments + nr_phys_segs > queue_max_hw_segments(q) ||
-            req->nr_phys_segments + nr_phys_segs > queue_max_phys_segments(q)) {
+        if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q)) {
                 req->cmd_flags |= REQ_NOMERGE;
                 if (req == q->last_merge)
                         q->last_merge = NULL;
@@ -300,10 +299,7 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
                 total_phys_segments--;
         }
 
-        if (total_phys_segments > queue_max_phys_segments(q))
-                return 0;
-
-        if (total_phys_segments > queue_max_hw_segments(q))
+        if (total_phys_segments > queue_max_segments(q))
                 return 0;
 
         /* Merge is OK... */
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 61afae9dbc6d..31e7a9375c13 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -91,8 +91,7 @@ EXPORT_SYMBOL_GPL(blk_queue_lld_busy);
  */
 void blk_set_default_limits(struct queue_limits *lim)
 {
-        lim->max_phys_segments = MAX_PHYS_SEGMENTS;
-        lim->max_hw_segments = MAX_HW_SEGMENTS;
+        lim->max_segments = BLK_MAX_SEGMENTS;
         lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
         lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
         lim->max_sectors = BLK_DEF_MAX_SECTORS;
@@ -252,17 +251,15 @@ void blk_queue_max_discard_sectors(struct request_queue *q,
 EXPORT_SYMBOL(blk_queue_max_discard_sectors);
 
 /**
- * blk_queue_max_phys_segments - set max phys segments for a request for this queue
+ * blk_queue_max_segments - set max hw segments for a request for this queue
  * @q:  the request queue for the device
  * @max_segments:  max number of segments
  *
  * Description:
  *    Enables a low level driver to set an upper limit on the number of
- *    physical data segments in a request.  This would be the largest sized
- *    scatter list the driver could handle.
+ *    hw data segments in a request.
  **/
-void blk_queue_max_phys_segments(struct request_queue *q,
-                                 unsigned short max_segments)
+void blk_queue_max_segments(struct request_queue *q, unsigned short max_segments)
 {
         if (!max_segments) {
                 max_segments = 1;
@@ -270,33 +267,9 @@ void blk_queue_max_phys_segments(struct request_queue *q,
                        __func__, max_segments);
         }
 
-        q->limits.max_phys_segments = max_segments;
+        q->limits.max_segments = max_segments;
 }
-EXPORT_SYMBOL(blk_queue_max_phys_segments);
-
-/**
- * blk_queue_max_hw_segments - set max hw segments for a request for this queue
- * @q:  the request queue for the device
- * @max_segments:  max number of segments
- *
- * Description:
- *    Enables a low level driver to set an upper limit on the number of
- *    hw data segments in a request.  This would be the largest number of
- *    address/length pairs the host adapter can actually give at once
- *    to the device.
- **/
-void blk_queue_max_hw_segments(struct request_queue *q,
-                               unsigned short max_segments)
-{
-        if (!max_segments) {
-                max_segments = 1;
-                printk(KERN_INFO "%s: set to minimum %d\n",
-                       __func__, max_segments);
-        }
-
-        q->limits.max_hw_segments = max_segments;
-}
-EXPORT_SYMBOL(blk_queue_max_hw_segments);
+EXPORT_SYMBOL(blk_queue_max_segments);
 
 /**
  * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
@@ -531,11 +504,7 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
         t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask,
                                             b->seg_boundary_mask);
 
-        t->max_phys_segments = min_not_zero(t->max_phys_segments,
-                                            b->max_phys_segments);
-
-        t->max_hw_segments = min_not_zero(t->max_hw_segments,
-                                          b->max_hw_segments);
+        t->max_segments = min_not_zero(t->max_segments, b->max_segments);
 
         t->max_segment_size = min_not_zero(t->max_segment_size,
                                            b->max_segment_size);
@@ -739,22 +708,19 @@ EXPORT_SYMBOL(blk_queue_update_dma_pad);
  * does is adjust the queue so that the buf is always appended
  * silently to the scatterlist.
  *
- * Note: This routine adjusts max_hw_segments to make room for
- * appending the drain buffer.  If you call
- * blk_queue_max_hw_segments() or blk_queue_max_phys_segments() after
- * calling this routine, you must set the limit to one fewer than your
- * device can support otherwise there won't be room for the drain
- * buffer.
+ * Note: This routine adjusts max_hw_segments to make room for appending
+ * the drain buffer.  If you call blk_queue_max_segments() after calling
+ * this routine, you must set the limit to one fewer than your device
+ * can support otherwise there won't be room for the drain buffer.
  */
 int blk_queue_dma_drain(struct request_queue *q,
                                dma_drain_needed_fn *dma_drain_needed,
                                void *buf, unsigned int size)
 {
-        if (queue_max_hw_segments(q) < 2 || queue_max_phys_segments(q) < 2)
+        if (queue_max_segments(q) < 2)
                 return -EINVAL;
         /* make room for appending the drain */
-        blk_queue_max_hw_segments(q, queue_max_hw_segments(q) - 1);
-        blk_queue_max_phys_segments(q, queue_max_phys_segments(q) - 1);
+        blk_queue_max_segments(q, queue_max_segments(q) - 1);
         q->dma_drain_needed = dma_drain_needed;
         q->dma_drain_buffer = buf;
         q->dma_drain_size = size;