[PATCH 0/3] parted: add command to create partitions specifying the size

[PATCH 0/3] parted: add command to create partitions specifying the size

[Sascha Hauer]

So far to create partitions we have to specify both start and end of a
partition. Create a mkpart_size command to conveniently create a
partition by specifying only the size.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
Sascha Hauer (3):
      partitions: add function to find free space on partition table
      parted: align partitions to 1MiB
      parted: implement mkpart_size command

 commands/parted.c    | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 common/partitions.c  | 42 +++++++++++++++++++++++++++++++++
 include/partitions.h |  7 +++++-
 3 files changed, 111 insertions(+), 3 deletions(-)
---
base-commit: dbc28aa3aad573f6ed0199c4fb85295b95e3bd11
change-id: 20250522-parted-size-9dbf0ee60661

Best regards,
-- 
Sascha Hauer <s.hauer@pengutronix.de>

[PATCH 1/3] partitions: add function to find free space on partition table

[Sascha Hauer]

We currently only support creating partitions by specifying the exact
start and end position. Add some functions to find free space in a
partition table so that we can implement creating partitions with only
specifying the size.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 common/partitions.c  | 42 ++++++++++++++++++++++++++++++++++++++++++
 include/partitions.h |  3 ++-
 2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/common/partitions.c b/common/partitions.c
index bc90f51f611223a59a28812b0f9854b342b30ad3..25d5f15721fc5980c927863b2745c23d7149da92 100644
--- a/common/partitions.c
+++ b/common/partitions.c
@@ -163,6 +163,48 @@ int partition_table_write(struct partition_desc *pdesc)
 	return pdesc->parser->write(pdesc);
 }
 
+bool partition_is_free(struct partition_desc *pdesc, uint64_t start, uint64_t size)
+{
+	struct partition *p;
+
+	if (start < PARTITION_ALIGN_SECTORS)
+		return false;
+
+	if (start + size >= pdesc->blk->num_blocks)
+		return false;
+
+	list_for_each_entry(p, &pdesc->partitions, list) {
+		if (region_overlap_size(p->first_sec, p->size, start, size))
+			return false;
+	}
+
+	return true;
+}
+
+int partition_find_free_space(struct partition_desc *pdesc, uint64_t sectors, uint64_t *start)
+{
+	struct partition *p;
+	uint64_t min_sec = PARTITION_ALIGN_SECTORS;
+
+	min_sec = ALIGN(min_sec, PARTITION_ALIGN_SECTORS);
+
+	if (partition_is_free(pdesc, min_sec, sectors)) {
+		*start = min_sec;
+		return 0;
+	}
+
+	list_for_each_entry(p, &pdesc->partitions, list) {
+		uint64_t s = ALIGN(p->first_sec + p->size, PARTITION_ALIGN_SECTORS);
+
+		if (partition_is_free(pdesc, s, sectors)) {
+			*start = s;
+			return 0;
+		}
+	}
+
+	return -ENOSPC;
+}
+
 int partition_create(struct partition_desc *pdesc, const char *name,
 		     const char *fs_type, uint64_t lba_start, uint64_t lba_end)
 {
diff --git a/include/partitions.h b/include/partitions.h
index 785fb77ab1674d92fdbac5f5df03910b1e2196af..7fd6899bd3b88f691385c330bb7900d9ec1547ac 100644
--- a/include/partitions.h
+++ b/include/partitions.h
@@ -64,6 +64,7 @@ int partition_create(struct partition_desc *pdesc, const char *name,
 		     const char *fs_type, uint64_t lba_start, uint64_t lba_end);
 int partition_remove(struct partition_desc *pdesc, int num);
 void partition_table_free(struct partition_desc *pdesc);
-
+bool partition_is_free(struct partition_desc *pdesc, uint64_t start, uint64_t size);
+int partition_find_free_space(struct partition_desc *pdesc, uint64_t sectors, uint64_t *start);
 
 #endif /* __PARTITIONS_PARSER_H__ */

-- 
2.39.5

[PATCH 2/3] parted: align partitions to 1MiB

[Sascha Hauer]

Common partitioning tools align partition start offsets and sizes to
1MiB. Do likewise in barebox parted to avoid unnecessary write
amplification due to unaligned partition starts.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 commands/parted.c    | 10 ++++++++--
 include/partitions.h |  4 ++++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/commands/parted.c b/commands/parted.c
index 68b056a0758a14e597d72f76cdc4ba6781a06051..221c6fc98601f1532ea85e000d1e2147f7a5af63 100644
--- a/commands/parted.c
+++ b/commands/parted.c
@@ -8,6 +8,7 @@
 #include <linux/sizes.h>
 #include <partitions.h>
 #include <linux/math64.h>
+#include <range.h>
 
 static struct partition_desc *gpdesc;
 static bool table_needs_write;
@@ -160,13 +161,18 @@ static int do_mkpart(struct block_device *blk, int argc, char *argv[])
 	end *= mult;
 
 	/* If not on sector boundaries move start up and end down */
-	start = ALIGN(start, SECTOR_SIZE);
-	end = ALIGN_DOWN(end, SECTOR_SIZE);
+	start = ALIGN(start, SZ_1M);
+	end = ALIGN_DOWN(end, SZ_1M);
 
 	/* convert to LBA */
 	start >>= SECTOR_SHIFT;
 	end >>= SECTOR_SHIFT;
 
+	if (end == start) {
+		printf("Error: After alignment the partition has zero size\n");
+		return -EINVAL;
+	}
+
 	/*
 	 * When unit is >= KB then substract one sector for user convenience.
 	 * It allows to start the next partition where the previous ends
diff --git a/include/partitions.h b/include/partitions.h
index 7fd6899bd3b88f691385c330bb7900d9ec1547ac..dd3e631c5aa337d752312cd94be5e7dbb4f527a5 100644
--- a/include/partitions.h
+++ b/include/partitions.h
@@ -11,6 +11,7 @@
 #include <filetype.h>
 #include <linux/uuid.h>
 #include <linux/list.h>
+#include <linux/sizes.h>
 
 #define MAX_PARTITION		128
 #define MAX_PARTITION_NAME	38
@@ -55,6 +56,9 @@ struct partition_parser {
 	const char *name;
 };
 
+#define PARTITION_ALIGN_SIZE	SZ_1M
+#define PARTITION_ALIGN_SECTORS	(PARTITION_ALIGN_SIZE >> SECTOR_SHIFT)
+
 void partition_desc_init(struct partition_desc *pd, struct block_device *blk);
 int partition_parser_register(struct partition_parser *p);
 struct partition_desc *partition_table_read(struct block_device *blk);

-- 
2.39.5

[PATCH 3/3] parted: implement mkpart_size command

[Sascha Hauer]

This creates a command which creates a partition with specified size.
The command finds a suitable place for the partition itself.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 commands/parted.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/commands/parted.c b/commands/parted.c
index 221c6fc98601f1532ea85e000d1e2147f7a5af63..6872a8414c79e8e116c9ecce864888cec542ad18 100644
--- a/commands/parted.c
+++ b/commands/parted.c
@@ -192,6 +192,57 @@ static int do_mkpart(struct block_device *blk, int argc, char *argv[])
 	return ret < 0 ? ret : 5;
 }
 
+static int do_mkpart_size(struct block_device *blk, int argc, char *argv[])
+{
+	struct partition_desc *pdesc;
+	uint64_t size, start;
+	const char *name, *fs_type;
+	int ret;
+	uint64_t mult;
+
+	if (argc < 4) {
+		printf("Error: Missing required arguments\n");
+		return -EINVAL;
+	}
+
+	name = argv[1];
+	fs_type = argv[2];
+
+	ret = parted_strtoull(argv[3], &size, &mult);
+	if (ret)
+		return ret;
+
+	if (!mult)
+		mult = gunit;
+
+	size *= mult;
+
+	/* If not on sector boundaries move start up and end down */
+	size = ALIGN(size, PARTITION_ALIGN_SIZE);
+
+	/* convert to LBA */
+	size >>= SECTOR_SHIFT;
+
+	pdesc = pdesc_get(blk);
+	if (!pdesc)
+		return -EINVAL;
+
+	ret = partition_find_free_space(pdesc, size, &start);
+	if (ret) {
+		printf("No free space for %llu sectors found\n", size);
+		return ret;
+	}
+
+	printf("%s: creating partition with %llu blocks at %llu\n", __func__, size, start);
+
+	ret = partition_create(pdesc, name, fs_type, start, start + size - 1);
+
+	if (!ret)
+		table_needs_write = true;
+
+	return ret < 0 ? ret : 4;
+}
+
 static int do_rmpart(struct block_device *blk, int argc, char *argv[])
 {
 	struct partition_desc *pdesc;
@@ -267,6 +318,9 @@ struct parted_command parted_commands[] = {
 		.name = "mkpart",
 		.command = do_mkpart,
 	}, {
+		.name = "mkpart_size",
+		.command = do_mkpart_size,
+	},  {
 		.name = "print",
 		.command = do_print,
 	}, {
@@ -360,6 +414,7 @@ BAREBOX_CMD_HELP_OPT ("print", "print partitions")
 BAREBOX_CMD_HELP_OPT ("mklabel <type>", "create a new partition table")
 BAREBOX_CMD_HELP_OPT ("rm <num>", "remove a partition")
 BAREBOX_CMD_HELP_OPT ("mkpart <name> <fstype> <start> <end>", "create a new partition")
+BAREBOX_CMD_HELP_OPT ("mkpart_size <name> <fstype> <size>", "create a new partition")
 BAREBOX_CMD_HELP_OPT ("unit <unit>", "change display/input units")
 BAREBOX_CMD_HELP_OPT ("refresh", "refresh a partition table")
 BAREBOX_CMD_HELP_TEXT("")

-- 
2.39.5

Re: [PATCH 0/3] parted: add command to create partitions specifying the size

[Sascha Hauer]

On Thu, 22 May 2025 15:40:21 +0200, Sascha Hauer wrote:
> So far to create partitions we have to specify both start and end of a
> partition. Create a mkpart_size command to conveniently create a
> partition by specifying only the size.
> 
> 

Applied, thanks!

[1/3] partitions: add function to find free space on partition table
      https://git.pengutronix.de/cgit/barebox/commit/?id=f19d76f0dad8 (link may not be stable)
[2/3] parted: align partitions to 1MiB
      https://git.pengutronix.de/cgit/barebox/commit/?id=541a8f5c5e43 (link may not be stable)
[3/3] parted: implement mkpart_size command
      https://git.pengutronix.de/cgit/barebox/commit/?id=be5e1d5106a0 (link may not be stable)

Best regards,
-- 
Sascha Hauer <s.hauer@pengutronix.de>