[PATCH v9 03/12] hw/block/nvme: Separate read and write handlers

[Dmitry Fomichev]

With ZNS support in place, the majority of code in nvme_rw() has
become read- or write-specific. Move these parts to two separate
handlers, nvme_read() and nvme_write() to make the code more
readable and to remove multiple is_write checks that so far existed
in the i/o path.

This is a refactoring patch, no change in functionality.

Signed-off-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
Reviewed-by: Niklas Cassel <Niklas.Cassel@wdc.com>
Acked-by: Klaus Jensen <its@irrelevant.dk>
---
 hw/block/nvme.c       | 91 ++++++++++++++++++++++++++++++-------------
 hw/block/trace-events |  3 +-
 2 files changed, 67 insertions(+), 27 deletions(-)

diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index ed3f38f01d..770e42a066 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -953,6 +953,54 @@ static uint16_t nvme_flush(NvmeCtrl *n, NvmeRequest *req)
     return NVME_NO_COMPLETE;
 }
 
+static uint16_t nvme_read(NvmeCtrl *n, NvmeRequest *req)
+{
+    NvmeRwCmd *rw = (NvmeRwCmd *)&req->cmd;
+    NvmeNamespace *ns = req->ns;
+    uint64_t slba = le64_to_cpu(rw->slba);
+    uint32_t nlb = (uint32_t)le16_to_cpu(rw->nlb) + 1;
+    uint64_t data_size = nvme_l2b(ns, nlb);
+    uint64_t data_offset;
+    BlockBackend *blk = ns->blkconf.blk;
+    uint16_t status;
+
+    trace_pci_nvme_read(nvme_cid(req), nvme_nsid(ns), nlb, data_size, slba);
+
+    status = nvme_check_mdts(n, data_size);
+    if (status) {
+        trace_pci_nvme_err_mdts(nvme_cid(req), data_size);
+        goto invalid;
+    }
+
+    status = nvme_check_bounds(n, ns, slba, nlb);
+    if (status) {
+        trace_pci_nvme_err_invalid_lba_range(slba, nlb, ns->id_ns.nsze);
+        goto invalid;
+    }
+
+    status = nvme_map_dptr(n, data_size, req);
+    if (status) {
+        goto invalid;
+    }
+
+    data_offset = nvme_l2b(ns, slba);
+
+    block_acct_start(blk_get_stats(blk), &req->acct, data_size,
+                     BLOCK_ACCT_READ);
+    if (req->qsg.sg) {
+        req->aiocb = dma_blk_read(blk, &req->qsg, data_offset,
+                                  BDRV_SECTOR_SIZE, nvme_rw_cb, req);
+    } else {
+        req->aiocb = blk_aio_preadv(blk, data_offset, &req->iov, 0,
+                                    nvme_rw_cb, req);
+    }
+    return NVME_NO_COMPLETE;
+
+invalid:
+    block_acct_invalid(blk_get_stats(blk), BLOCK_ACCT_READ);
+    return status | NVME_DNR;
+}
+
 static uint16_t nvme_write_zeroes(NvmeCtrl *n, NvmeRequest *req)
 {
     NvmeRwCmd *rw = (NvmeRwCmd *)&req->cmd;
@@ -978,22 +1026,19 @@ static uint16_t nvme_write_zeroes(NvmeCtrl *n, 
NvmeRequest *req)
     return NVME_NO_COMPLETE;
 }
 
-static uint16_t nvme_rw(NvmeCtrl *n, NvmeRequest *req)
+static uint16_t nvme_write(NvmeCtrl *n, NvmeRequest *req)
 {
     NvmeRwCmd *rw = (NvmeRwCmd *)&req->cmd;
     NvmeNamespace *ns = req->ns;
-    uint32_t nlb = (uint32_t)le16_to_cpu(rw->nlb) + 1;
     uint64_t slba = le64_to_cpu(rw->slba);
-
+    uint32_t nlb = (uint32_t)le16_to_cpu(rw->nlb) + 1;
     uint64_t data_size = nvme_l2b(ns, nlb);
-    uint64_t data_offset = nvme_l2b(ns, slba);
-    enum BlockAcctType acct = req->cmd.opcode == NVME_CMD_WRITE ?
-        BLOCK_ACCT_WRITE : BLOCK_ACCT_READ;
+    uint64_t data_offset;
     BlockBackend *blk = ns->blkconf.blk;
     uint16_t status;
 
-    trace_pci_nvme_rw(nvme_cid(req), nvme_io_opc_str(rw->opcode),
-                      nvme_nsid(ns), nlb, data_size, slba);
+    trace_pci_nvme_write(nvme_cid(req), nvme_io_opc_str(rw->opcode),
+                         nvme_nsid(ns), nlb, data_size, slba);
 
     status = nvme_check_mdts(n, data_size);
     if (status) {
@@ -1012,29 +1057,22 @@ static uint16_t nvme_rw(NvmeCtrl *n, NvmeRequest *req)
         goto invalid;
     }
 
-    block_acct_start(blk_get_stats(blk), &req->acct, data_size, acct);
+    data_offset = nvme_l2b(ns, slba);
+
+    block_acct_start(blk_get_stats(blk), &req->acct, data_size,
+                     BLOCK_ACCT_WRITE);
     if (req->qsg.sg) {
-        if (acct == BLOCK_ACCT_WRITE) {
-            req->aiocb = dma_blk_write(blk, &req->qsg, data_offset,
-                                       BDRV_SECTOR_SIZE, nvme_rw_cb, req);
-        } else {
-            req->aiocb = dma_blk_read(blk, &req->qsg, data_offset,
-                                      BDRV_SECTOR_SIZE, nvme_rw_cb, req);
-        }
+        req->aiocb = dma_blk_write(blk, &req->qsg, data_offset,
+                                   BDRV_SECTOR_SIZE, nvme_rw_cb, req);
     } else {
-        if (acct == BLOCK_ACCT_WRITE) {
-            req->aiocb = blk_aio_pwritev(blk, data_offset, &req->iov, 0,
-                                         nvme_rw_cb, req);
-        } else {
-            req->aiocb = blk_aio_preadv(blk, data_offset, &req->iov, 0,
-                                        nvme_rw_cb, req);
-        }
+        req->aiocb = blk_aio_pwritev(blk, data_offset, &req->iov, 0,
+                                     nvme_rw_cb, req);
     }
     return NVME_NO_COMPLETE;
 
 invalid:
-    block_acct_invalid(blk_get_stats(ns->blkconf.blk), acct);
-    return status;
+    block_acct_invalid(blk_get_stats(blk), BLOCK_ACCT_WRITE);
+    return status | NVME_DNR;
 }
 
 static uint16_t nvme_io_cmd(NvmeCtrl *n, NvmeRequest *req)
@@ -1064,8 +1102,9 @@ static uint16_t nvme_io_cmd(NvmeCtrl *n, NvmeRequest *req)
     case NVME_CMD_WRITE_ZEROES:
         return nvme_write_zeroes(n, req);
     case NVME_CMD_WRITE:
+        return nvme_write(n, req);
     case NVME_CMD_READ:
-        return nvme_rw(n, req);
+        return nvme_read(n, req);
     default:
         assert(false);
     }
diff --git a/hw/block/trace-events b/hw/block/trace-events
index 33832a2021..540c600931 100644
--- a/hw/block/trace-events
+++ b/hw/block/trace-events
@@ -40,7 +40,8 @@ pci_nvme_map_prp(uint64_t trans_len, uint32_t len, uint64_t 
prp1, uint64_t prp2,
 pci_nvme_map_sgl(uint16_t cid, uint8_t typ, uint64_t len) "cid %"PRIu16" type 
0x%"PRIx8" len %"PRIu64""
 pci_nvme_io_cmd(uint16_t cid, uint32_t nsid, uint16_t sqid, uint8_t opcode, 
const char *opname) "cid %"PRIu16" nsid %"PRIu32" sqid %"PRIu16" opc 0x%"PRIx8" 
opname '%s'"
 pci_nvme_admin_cmd(uint16_t cid, uint16_t sqid, uint8_t opcode, const char 
*opname) "cid %"PRIu16" sqid %"PRIu16" opc 0x%"PRIx8" opname '%s'"
-pci_nvme_rw(uint16_t cid, const char *verb, uint32_t nsid, uint32_t nlb, 
uint64_t count, uint64_t lba) "cid %"PRIu16" opname '%s' nsid %"PRIu32" nlb 
%"PRIu32" count %"PRIu64" lba 0x%"PRIx64""
+pci_nvme_read(uint16_t cid, uint32_t nsid, uint32_t nlb, uint64_t count, 
uint64_t lba) "cid %"PRIu16" nsid %"PRIu32" nlb %"PRIu32" count %"PRIu64" lba 
0x%"PRIx64""
+pci_nvme_write(uint16_t cid, const char *verb, uint32_t nsid, uint32_t nlb, 
uint64_t count, uint64_t lba) "cid %"PRIu16" opname '%s' nsid %"PRIu32" nlb 
%"PRIu32" count %"PRIu64" lba 0x%"PRIx64""
 pci_nvme_rw_cb(uint16_t cid, const char *blkname) "cid %"PRIu16" blk '%s'"
 pci_nvme_write_zeroes(uint16_t cid, uint32_t nsid, uint64_t slba, uint32_t 
nlb) "cid %"PRIu16" nsid %"PRIu32" slba %"PRIu64" nlb %"PRIu32""
 pci_nvme_create_sq(uint64_t addr, uint16_t sqid, uint16_t cqid, uint16_t 
qsize, uint16_t qflags) "create submission queue, addr=0x%"PRIx64", 
sqid=%"PRIu16", cqid=%"PRIu16", qsize=%"PRIu16", qflags=%"PRIu16""
-- 
2.21.0