[SCSI] libosd: OSD2r05: Prepare for rev5 attribute list changes

In OSD2r05 draft each attribute list element header was changed
so attribute-value would be 8 bytes aligned. In OSD2r01-r04
it was aligned on 2 bytes. (This is because in OSD2r01 the complete
element was 8 bytes padded at end but the header was not adjusted
and caused permanent miss-alignment.)

OSD1 elements are not padded and might be or might not be aligned.
OSD1 is still supported.

In this code we do all the code re-factoring to separate OSD1/OSD2
differences but do not change actual wire format. All wire format
changes will happen in one patch later, for bisect-ability.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

2 files changed, 83 insertions, 23 deletions

diff --git a/drivers/scsi/osd/osd_initiator.c b/drivers/scsi/osd/osd_initiator.c
index 76de88962237..e266f803aa96 100644
--- a/drivers/scsi/osd/osd_initiator.c
+++ b/drivers/scsi/osd/osd_initiator.c
@@ -205,6 +205,69 @@ static unsigned _osd_req_alist_elem_size(struct osd_request *or, unsigned len)
                 osdv2_attr_list_elem_size(len);
 }
 
+static void _osd_req_alist_elem_encode(struct osd_request *or,
+        void *attr_last, const struct osd_attr *oa)
+{
+        if (osd_req_is_ver1(or)) {
+                struct osdv1_attributes_list_element *attr = attr_last;
+
+                attr->attr_page = cpu_to_be32(oa->attr_page);
+                attr->attr_id = cpu_to_be32(oa->attr_id);
+                attr->attr_bytes = cpu_to_be16(oa->len);
+                memcpy(attr->attr_val, oa->val_ptr, oa->len);
+        } else {
+                struct osdv2_attributes_list_element *attr = attr_last;
+
+                attr->attr_page = cpu_to_be32(oa->attr_page);
+                attr->attr_id = cpu_to_be32(oa->attr_id);
+                attr->attr_bytes = cpu_to_be16(oa->len);
+                memcpy(attr->attr_val, oa->val_ptr, oa->len);
+        }
+}
+
+static int _osd_req_alist_elem_decode(struct osd_request *or,
+        void *cur_p, struct osd_attr *oa, unsigned max_bytes)
+{
+        unsigned inc;
+        if (osd_req_is_ver1(or)) {
+                struct osdv1_attributes_list_element *attr = cur_p;
+
+                if (max_bytes < sizeof(*attr))
+                        return -1;
+
+                oa->len = be16_to_cpu(attr->attr_bytes);
+                inc = _osd_req_alist_elem_size(or, oa->len);
+                if (inc > max_bytes)
+                        return -1;
+
+                oa->attr_page = be32_to_cpu(attr->attr_page);
+                oa->attr_id = be32_to_cpu(attr->attr_id);
+
+                /* OSD1: On empty attributes we return a pointer to 2 bytes
+                 * of zeros. This keeps similar behaviour with OSD2.
+                 * (See below)
+                 */
+                oa->val_ptr = likely(oa->len) ? attr->attr_val :
+                                                (u8 *)&attr->attr_bytes;
+        } else {
+                struct osdv2_attributes_list_element *attr = cur_p;
+
+                if (max_bytes < sizeof(*attr))
+                        return -1;
+
+                oa->len = be16_to_cpu(attr->attr_bytes);
+                inc = _osd_req_alist_elem_size(or, oa->len);
+                if (inc > max_bytes)
+                        return -1;
+
+                oa->attr_page = be32_to_cpu(attr->attr_page);
+                oa->attr_id = be32_to_cpu(attr->attr_id);
+
+                oa->val_ptr = attr->attr_val;
+        }
+        return inc;
+}
+
 static unsigned _osd_req_alist_size(struct osd_request *or, void *list_head)
 {
         return osd_req_is_ver1(or) ?
@@ -798,7 +861,6 @@ int osd_req_add_set_attr_list(struct osd_request *or,
         attr_last = or->set_attr.buff + total_bytes;
 
         for (; nelem; --nelem) {
-                struct osd_attributes_list_element *attr;
                 unsigned elem_size = _osd_req_alist_elem_size(or, oa->len);
 
                 total_bytes += elem_size;
@@ -811,11 +873,7 @@ int osd_req_add_set_attr_list(struct osd_request *or,
                                 or->set_attr.buff + or->set_attr.total_bytes;
                 }
 
-                attr = attr_last;
-                attr->attr_page = cpu_to_be32(oa->attr_page);
-                attr->attr_id = cpu_to_be32(oa->attr_id);
-                attr->attr_bytes = cpu_to_be16(oa->len);
-                memcpy(attr->attr_val, oa->val_ptr, oa->len);
+                _osd_req_alist_elem_encode(or, attr_last, oa);
 
                 attr_last += elem_size;
                 ++oa;
@@ -1070,15 +1128,10 @@ int osd_req_decode_get_attr_list(struct osd_request *or,
         }
 
         for (n = 0; (n < *nelem) && (cur_bytes < returned_bytes); ++n) {
-                struct osd_attributes_list_element *attr = cur_p;
-                unsigned inc;
+                int inc = _osd_req_alist_elem_decode(or, cur_p, oa,
+                                                 returned_bytes - cur_bytes);
 
-                oa->len = be16_to_cpu(attr->attr_bytes);
-                inc = _osd_req_alist_elem_size(or, oa->len);
-                OSD_DEBUG("oa->len=%d inc=%d cur_bytes=%d\n",
-                          oa->len, inc, cur_bytes);
-                cur_bytes += inc;
-                if (cur_bytes > returned_bytes) {
+                if (inc < 0) {
                         OSD_ERR("BAD FOOD from target. list not valid!"
                                 "c=%d r=%d n=%d\n",
                                 cur_bytes, returned_bytes, n);
@@ -1086,10 +1139,7 @@ int osd_req_decode_get_attr_list(struct osd_request *or,
                         break;
                 }
 
-                oa->attr_page = be32_to_cpu(attr->attr_page);
-                oa->attr_id = be32_to_cpu(attr->attr_id);
-                oa->val_ptr = attr->attr_val;
-
+                cur_bytes += inc;
                 cur_p += inc;
                 ++oa;
         }
diff --git a/include/scsi/osd_protocol.h b/include/scsi/osd_protocol.h
index cd3cbf764650..fa8343ce3ca2 100644
--- a/include/scsi/osd_protocol.h
+++ b/include/scsi/osd_protocol.h
@@ -301,14 +301,24 @@ struct osd_attributes_list_attrid {
 } __packed;
 
 /*
+ * NOTE: v1: is not aligned.
+ */
+struct osdv1_attributes_list_element {
+        __be32 attr_page;
+        __be32 attr_id;
+        __be16 attr_bytes; /* valid bytes at attr_val without padding */
+        u8 attr_val[0];
+} __packed;
+
+/*
  * osd2r03: 7.1.3.3 List entry format for retrieved attributes and
  *                  for setting attributes
- * NOTE: v2 is 8-bytes aligned, v1 is not aligned.
+ * NOTE: v2 is 8-bytes aligned
  */
-struct osd_attributes_list_element {
+struct osdv2_attributes_list_element {
         __be32 attr_page;
         __be32 attr_id;
-        __be16 attr_bytes;
+        __be16 attr_bytes; /* valid bytes at attr_val without padding */
         u8 attr_val[0];
 } __packed;
 
@@ -324,13 +334,13 @@ enum {
 
 static inline unsigned osdv1_attr_list_elem_size(unsigned len)
 {
-        return ALIGN(len + sizeof(struct osd_attributes_list_element),
+        return ALIGN(len + sizeof(struct osdv1_attributes_list_element),
                      OSDv1_ATTRIBUTES_ELEM_ALIGN);
 }
 
 static inline unsigned osdv2_attr_list_elem_size(unsigned len)
 {
-        return ALIGN(len + sizeof(struct osd_attributes_list_element),
+        return ALIGN(len + sizeof(struct osdv2_attributes_list_element),
                      OSD_ATTRIBUTES_ELEM_ALIGN);
 }