block/scsi: Provide a limit on the number of integrity segments

Some controllers have a hardware limit on the number of protection
information scatter-gather list segments they can handle.

Introduce a max_integrity_segments limit in the block layer and provide
a new scsi_host_template setting that allows HBA drivers to provide a
value suitable for the hardware.

Add support for honoring the integrity segment limit when merging both
bios and requests.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@carl.home.kernel.dk>

4 files changed, 46 insertions, 4 deletions

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 5274103434a..2c3fd742160 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -496,6 +496,10 @@ static inline struct bio *bio_list_get(struct bio_list *bl)
 #define bip_for_each_vec(bvl, bip, i)                                   \
         __bip_for_each_vec(bvl, bip, i, (bip)->bip_idx)
 
+#define bio_for_each_integrity_vec(_bvl, _bio, _iter)                   \
+        for_each_bio(_bio)                                              \
+                bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)
+
 #define bio_integrity(bio) (bio->bi_integrity != NULL)
 
 extern struct bio_integrity_payload *bio_integrity_alloc_bioset(struct bio *, gfp_t, unsigned int, struct bio_set *);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 2c54906f678..7e661106270 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -124,6 +124,9 @@ struct request {
          * physical address coalescing is performed.
          */
         unsigned short nr_phys_segments;
+#if defined(CONFIG_BLK_DEV_INTEGRITY)
+        unsigned short nr_integrity_segments;
+#endif
 
         unsigned short ioprio;
 
@@ -243,6 +246,7 @@ struct queue_limits {
 
         unsigned short          logical_block_size;
         unsigned short          max_segments;
+        unsigned short          max_integrity_segments;
 
         unsigned char           misaligned;
         unsigned char           discard_misaligned;
@@ -1213,8 +1217,13 @@ struct blk_integrity {
 extern int blk_integrity_register(struct gendisk *, struct blk_integrity *);
 extern void blk_integrity_unregister(struct gendisk *);
 extern int blk_integrity_compare(struct gendisk *, struct gendisk *);
-extern int blk_rq_map_integrity_sg(struct request *, struct scatterlist *);
-extern int blk_rq_count_integrity_sg(struct request *);
+extern int blk_rq_map_integrity_sg(struct request_queue *, struct bio *,
+                                   struct scatterlist *);
+extern int blk_rq_count_integrity_sg(struct request_queue *, struct bio *);
+extern int blk_integrity_merge_rq(struct request_queue *, struct request *,
+                                  struct request *);
+extern int blk_integrity_merge_bio(struct request_queue *, struct request *,
+                                   struct bio *);
 
 static inline
 struct blk_integrity *bdev_get_integrity(struct block_device *bdev)
@@ -1235,16 +1244,32 @@ static inline int blk_integrity_rq(struct request *rq)
         return bio_integrity(rq->bio);
 }
 
+static inline void blk_queue_max_integrity_segments(struct request_queue *q,
+                                                    unsigned int segs)
+{
+        q->limits.max_integrity_segments = segs;
+}
+
+static inline unsigned short
+queue_max_integrity_segments(struct request_queue *q)
+{
+        return q->limits.max_integrity_segments;
+}
+
 #else /* CONFIG_BLK_DEV_INTEGRITY */
 
 #define blk_integrity_rq(rq)                    (0)
-#define blk_rq_count_integrity_sg(a)            (0)
-#define blk_rq_map_integrity_sg(a, b)           (0)
+#define blk_rq_count_integrity_sg(a, b)         (0)
+#define blk_rq_map_integrity_sg(a, b, c)        (0)
 #define bdev_get_integrity(a)                   (0)
 #define blk_get_integrity(a)                    (0)
 #define blk_integrity_compare(a, b)             (0)
 #define blk_integrity_register(a, b)            (0)
 #define blk_integrity_unregister(a)             do { } while (0);
+#define blk_queue_max_integrity_segments(a, b)  do { } while (0);
+#define queue_max_integrity_segments(a)         (0)
+#define blk_integrity_merge_rq(a, b, c)         (0)
+#define blk_integrity_merge_bio(a, b, c)        (0)
 
 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 
diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h
index 8fcb6e0e9e7..d63533a4a59 100644
--- a/include/scsi/scsi.h
+++ b/include/scsi/scsi.h
@@ -32,6 +32,12 @@ struct scsi_cmnd;
 #endif
 
 /*
+ * DIX-capable adapters effectively support infinite chaining for the
+ * protection information scatterlist
+ */
+#define SCSI_MAX_PROT_SG_SEGMENTS       0xFFFF
+
+/*
  * Special value for scanning to specify scanning or rescanning of all
  * possible channels, (target) ids, or luns on a given shost.
  */
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index b7bdecb7b76..d0a6a845f20 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -388,6 +388,7 @@ struct scsi_host_template {
          * of scatter-gather.
          */
         unsigned short sg_tablesize;
+        unsigned short sg_prot_tablesize;
 
         /*
          * Set this if the host adapter has limitations beside segment count.
@@ -599,6 +600,7 @@ struct Scsi_Host {
         int can_queue;
         short cmd_per_lun;
         short unsigned int sg_tablesize;
+        short unsigned int sg_prot_tablesize;
         short unsigned int max_sectors;
         unsigned long dma_boundary;
         /* 
@@ -823,6 +825,11 @@ static inline unsigned int scsi_host_get_prot(struct Scsi_Host *shost)
         return shost->prot_capabilities;
 }
 
+static inline int scsi_host_prot_dma(struct Scsi_Host *shost)
+{
+        return shost->prot_capabilities >= SHOST_DIX_TYPE0_PROTECTION;
+}
+
 static inline unsigned int scsi_host_dif_capable(struct Scsi_Host *shost, unsigned int target_type)
 {
         static unsigned char cap[] = { 0,