[PATCH v4 2/2] ndctl/namespace: Implement write-infoblock for sector mode namespaces

[Tarun Sahu <tsahu@linux.ibm.com>]

While writing to the infoblock for sector mode, collected
namespace info in ns_info structure can be used to write the
original infoblock values except the ones that have been
provided by parameter arguments to write-infoblock command.

Currently, this patch allows only uuid and parent_uuid to be
changed. In future, support for other values can be implemented
easily by adding condition inside write_btt_sb() function, which
has been created to write BTT sector mode specific namespace.

$ ./ndctl read-infoblock namespace0.0 -j
[
  {
    "dev":"namespace0.0",
    "signature":"BTT_ARENA_INFO",
    "uuid":"7296ebd6-7039-4d02-9ed9-ac5f351ff0e4",
    "parent_uuid":"46850d31-8fb5-4492-b630-9f3cd7b77500",
    "flags":0,
    "version":"2.0",
    "external_lbasize":4096,
    "external_nlba":8380160,
    "internal_lbasize":4096,
    "internal_nlba":8380416,
    "nfree":256,
    "infosize":4096,
    "nextoff":0,
    "dataoff":4096,
    "mapoff":34326196224,
    "logoff":34359717888,
    "info2off":34359734272
  }
]
read 1 infoblock

$ ./ndctl write-infoblock namespace0.0 \
>	--uuid "d0b19883-0874-4847-8c71-71549590949c"
wrote 1 infoblock

$ ./ndctl read-infoblock namespace0.0 -j
[
  {
    "dev":"namespace0.0",
    "signature":"BTT_ARENA_INFO",
    "uuid":"d0b19883-0874-4847-8c71-71549590949c",
    "parent_uuid":"46850d31-8fb5-4492-b630-9f3cd7b77500",
    "flags":0,
    "version":"2.0",
    "external_lbasize":4096,
    "external_nlba":8380160,
    "internal_lbasize":4096,
    "internal_nlba":8380416,
    "nfree":256,
    "infosize":4096,
    "nextoff":0,
    "dataoff":4096,
    "mapoff":34326196224,
    "logoff":34359717888,
    "info2off":34359734272
  }
]
read 1 infoblock

Signed-off-by: Tarun Sahu <tsahu@linux.ibm.com>
---
 ndctl/namespace.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/ndctl/namespace.c b/ndctl/namespace.c
index e890fc2..2b0c821 100644
--- a/ndctl/namespace.c
+++ b/ndctl/namespace.c
@@ -253,6 +253,7 @@ static int set_defaults(enum device_action action)
 			break;
 		case NDCTL_NS_MODE_FSDAX:
 		case NDCTL_NS_MODE_DEVDAX:
+		case NDCTL_NS_MODE_SECTOR:
 			break;
 		default:
 			if (action == ACTION_WRITE_INFOBLOCK) {
@@ -2021,6 +2022,48 @@ static int write_pfn_sb(int fd, unsigned long long size, const char *sig,
 	return 0;
 }
 
+static int write_btt_sb(const int fd, unsigned long long size, struct ns_info *ns_info)
+{
+	int rc = 0;
+	uuid_t uuid, parent_uuid;
+
+	// updating the original values which are asked to change,
+	// rest will be unchanged
+	if (param.uuid) {
+		rc = uuid_parse(param.uuid, uuid);
+		if (rc) {
+			error("Failed to parse UUID");
+			return rc;
+		}
+		memcpy(((struct btt_sb *)(ns_info->ns_sb_buf + ns_info->offset))->uuid,
+				uuid, sizeof(uuid_t));
+	}
+	if (param.parent_uuid) {
+		rc = uuid_parse(param.parent_uuid, parent_uuid);
+		if (rc) {
+			error("Failed to parse UUID");
+			return rc;
+		}
+		memcpy(((struct btt_sb *)(ns_info->ns_sb_buf + ns_info->offset))->parent_uuid,
+				parent_uuid, sizeof(uuid_t));
+	}
+
+	if (pwrite(fd, ns_info->ns_sb_buf + ns_info->offset, sizeof(struct btt_sb),
+			       ns_info->offset) < 0) {
+		pr_verbose("Unable to write the info block: %s\n",
+				strerror(errno));
+		rc = -errno;
+	}
+
+	if (pwrite(fd, ns_info->ns_sb_buf + ns_info->offset, sizeof(struct btt_sb),
+				size - sizeof(struct btt_sb)) < 0) {
+		pr_verbose("Unable to write the info block: %s\n",
+			strerror(errno));
+		rc = -errno;
+	}
+	return rc;
+}
+
 static int file_write_infoblock(const char *path, struct ns_info *ns_info)
 {
 	unsigned long long size = parse_size64(param.size);
@@ -2068,6 +2111,14 @@ static int file_write_infoblock(const char *path, struct ns_info *ns_info)
 	case NDCTL_NS_MODE_DEVDAX:
 		rc = write_pfn_sb(fd, size, DAX_SIG, ns_info);
 		break;
+	case NDCTL_NS_MODE_SECTOR:
+		if (ns_info->mode == NDCTL_NS_MODE_SECTOR)
+			rc = write_btt_sb(fd, size, ns_info);
+		else {
+			pr_verbose("Conversion from non-sector to sector mode not allowed");
+			rc = -EPERM;
+		}
+		break;
 	case NDCTL_NS_MODE_UNKNOWN:
 		switch (ns_info->mode) {
 		case NDCTL_NS_MODE_FSDAX:
@@ -2076,6 +2127,9 @@ static int file_write_infoblock(const char *path, struct ns_info *ns_info)
 		case NDCTL_NS_MODE_DEVDAX:
 			rc = write_pfn_sb(fd, size, DAX_SIG, ns_info);
 			break;
+		case NDCTL_NS_MODE_SECTOR:
+			rc = write_btt_sb(fd, size, ns_info);
+			break;
 		default:
 			rc = -EINVAL;
 			break;
-- 
2.35.1