RE: [PATCH v7 01/12] mtd: core: always create master device

[Usyskin, Alexander]

> Subject: RE: [PATCH v7 01/12] mtd: core: always create master device
> 
> Hi
> 
> > Hello,
> >
> > > The mtd_master is completely different class to avoid mtd tree
> disturbances.
> > > It is real kernel device object, I'm not sure how we can do 'link to'
> > > magic here.
> >
> > Maybe we can add that later if someone needs.
> >
> > > About MTD_PARTITIONED_MASTER - we can treat it as another partition
> > and
> > > create master device plus whole device partition as it's child with all other
> > > partitions as children of master device.
> > > For unpartitioned device this mean that we create master device and
> > partition
> > > regardless of MTD_PARTITIONED_MASTER flag.
> >
> > I am not sure I follow you. I am proposing to create the mtd_master
> > device in all cases. I believe this is the future-proof approach. Can
> > you make this change?
> >
> > Regarding the hierarchy, I indeed agree with what you propose:
> > mtd_master parent of whole partition device (if any) parent of
> > partitions.
> >
> 
> To be sure:
> 
> You want to have this hierarchy without MTD_PARTITIONED_MASTER:
> mtd_master
> \/
> |->partition1
> |->partition2
> 
> With MTD_PARTITIONED_MASTER flag:
> 
> mtd_master
> \/
> |->master_partition
>    \/
>    |->partition1
>    |->partition2
> 

Like this?

diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index 8dc4f5c493fc..391d81ad960c 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -559,7 +559,7 @@ static int mtdchar_blkpg_ioctl(struct mtd_info *mtd,
 		/* Sanitize user input */
 		p.devname[BLKPG_DEVNAMELTH - 1] = '\0';
 
-		return mtd_add_partition(mtd, p.devname, p.start, p.length);
+		return mtd_add_partition(mtd, p.devname, p.start, p.length, NULL);
 
 	case BLKPG_DEL_PARTITION:
 
diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index ee46766d74f1..a32cea0ba535 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -1108,6 +1108,7 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
 			      const struct mtd_partition *parts,
 			      int nr_parts)
 {
+	struct mtd_info *parent;
 	int ret, err;
 
 	mtd_set_dev_defaults(mtd);
@@ -1116,17 +1117,31 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
 	if (ret)
 		goto out;
 
+	ret = add_mtd_device(mtd, false);
+	if (ret)
+		goto out;
+
+	if (IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER))
+	{
+		ret = mtd_add_partition(mtd, dev_name(&mtd->dev), 0, MTDPART_SIZ_FULL, &parent);
+		if (ret)
+			goto out;
+
+	} else {
+		parent = mtd;
+	}
+
 	/* Prefer parsed partitions over driver-provided fallback */
-	ret = parse_mtd_partitions(mtd, types, parser_data);
+	ret = parse_mtd_partitions(parent, types, parser_data);
 	if (ret == -EPROBE_DEFER)
 		goto out;
 
 	if (ret > 0)
 		ret = 0;
 	else if (nr_parts)
-		ret = add_mtd_partitions(mtd, parts, nr_parts);
-	else
-		ret = add_mtd_device(mtd, true);
+		ret = add_mtd_partitions(parent, parts, nr_parts);
+	else if (!IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER))
+		ret = mtd_add_partition(parent, dev_name(&mtd->dev), 0, MTDPART_SIZ_FULL, NULL);
 
 	if (ret)
 		goto out;
diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index 8a019cf0360d..cd5ae919b80c 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -242,7 +242,7 @@ static int mtd_add_partition_attrs(struct mtd_info *new)
 }
 
 int mtd_add_partition(struct mtd_info *parent, const char *name,
-		      long long offset, long long length)
+		      long long offset, long long length, struct mtd_info **out)
 {
 	struct mtd_info *master = mtd_get_master(parent);
 	u64 parent_size = mtd_is_partition(parent) ?
@@ -281,6 +281,9 @@ int mtd_add_partition(struct mtd_info *parent, const char *name,
 
 	mtd_add_partition_attrs(child);
 
+	if (*out)
+		*out = child;
+
 	return 0;
 
 err_remove_part:
@@ -401,12 +404,6 @@ int add_mtd_partitions(struct mtd_info *parent,
 	printk(KERN_NOTICE "Creating %d MTD partitions on \"%s\":\n",
 	       nbparts, parent->name);
 
-	if (!mtd_is_partition(parent)) {
-		ret = add_mtd_device(parent, IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER));
-		if (ret)
-			return ret;
-	}
-
 	for (i = 0; i < nbparts; i++) {
 		child = allocate_partition(parent, parts + i, i, cur_offset);
 		if (IS_ERR(child)) {
diff --git a/include/linux/mtd/partitions.h b/include/linux/mtd/partitions.h
index b74a539ec581..5daf80df9e89 100644
--- a/include/linux/mtd/partitions.h
+++ b/include/linux/mtd/partitions.h
@@ -108,7 +108,7 @@ extern void deregister_mtd_parser(struct mtd_part_parser *parser);
 		      deregister_mtd_parser)
 
 int mtd_add_partition(struct mtd_info *master, const char *name,
-		      long long offset, long long length);
+		      long long offset, long long length, struct mtd_info **part);
 int mtd_del_partition(struct mtd_info *master, int partno);
 uint64_t mtd_get_device_size(const struct mtd_info *mtd);