[U-Boot] [RFC] fs: make it possible to read the filesystem UUID

[Christian Gmeiner]

Some filesystems have a UUID stored in its superblock. To
allow using root=UUID=... for the kernel command line we
need a way to read-out the filesystem UUID. This is what this
patch tries to do.

Keep in mind that this patch is an RFC and I hope to get some
feedback on this patch.

This is what blkid under linux gives me:
/dev/sdh1: LABEL="data" UUID="b6995cec-97e2-48b8-94dc-8ba7afc92bac" TYPE="ext4" PARTUUID="43f21f0e-01"
/dev/sdh2: LABEL="rfs" UUID="8d020de7-c75e-4674-948e-f7838a931b02" TYPE="ext4" PARTUUID="43f21f0e-02"

And here is the output from u-boot:
=> sata init
AHCI 0001.0300 32 slots 1 ports 3 Gbps 0x1 impl SATA mode
flags: ncq stag pm led clo only pmp pio slum part
SATA Device Info:
S/N: 000060059798A1000014
Product model number: SFCA4096H1BR4TO-I-MS-236-STD
Firmware version: 20111021
Capacity: 7793856 sectors
=> fs_uuid sata 0:1 ; print fs_uuid; fs_uuid sata 0:2 ; print fs_uuid
fs_uuid=b6995cec-97e2-48b8-94dc-8ba7afc92bac
fs_uuid=8d020de7-c75e-4674-948e-f7838a931b02

Signed-off-by: Christian Gmeiner <christian.gmeiner at gmail.com>
---
 common/Makefile       |  1 +
 common/cmd_fs_uuid.c  | 23 +++++++++++++++++++++++
 fs/ext4/ext4_common.c |  9 +++++++++
 fs/fs.c               | 28 ++++++++++++++++++++++++++++
 include/ext4fs.h      |  1 +
 include/fs.h          |  2 ++
 6 files changed, 64 insertions(+)
 create mode 100644 common/cmd_fs_uuid.c

diff --git a/common/Makefile b/common/Makefile
index b19d379..d5d3315 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -188,6 +188,7 @@ obj-y += usb.o usb_hub.o
 obj-$(CONFIG_USB_STORAGE) += usb_storage.o
 endif
 obj-$(CONFIG_CMD_FASTBOOT) += cmd_fastboot.o
+obj-$(CONFIG_CMD_FS_UUID) += cmd_fs_uuid.o
 
 obj-$(CONFIG_CMD_USB_MASS_STORAGE) += cmd_usb_mass_storage.o
 obj-$(CONFIG_CMD_THOR_DOWNLOAD) += cmd_thordown.o
diff --git a/common/cmd_fs_uuid.c b/common/cmd_fs_uuid.c
new file mode 100644
index 0000000..3af9518
--- /dev/null
+++ b/common/cmd_fs_uuid.c
@@ -0,0 +1,23 @@
+/*
+ * cmd_fs_uuid.c -- fs_uuid command
+ *
+ * Copyright (C) 2014, Bachmann electronic GmbH
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <command.h>
+#include <fs.h>
+
+static int do_fs_uuid_wrapper(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	return do_fs_uuid(cmdtp, flag, argc, argv, FS_TYPE_ANY);
+}
+
+U_BOOT_CMD(
+	fs_uuid,	3,	0,	do_fs_uuid_wrapper,
+	"filesystem UUDI related commands",
+	"<interface> <dev>:<part>\n"
+	"    - print filesystem UUID\n"
+);
diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
index 33d69c9..926b6c6 100644
--- a/fs/ext4/ext4_common.c
+++ b/fs/ext4/ext4_common.c
@@ -2246,3 +2246,12 @@ fail:
 
 	return 0;
 }
+
+void ext4fs_uuid(char *uuid_str)
+{
+	if (ext4fs_root == NULL)
+		return;
+
+	uuid_bin_to_str((unsigned char *)ext4fs_root->sblock.unique_id, uuid_str,
+			UUID_STR_FORMAT_STD);
+}
diff --git a/fs/fs.c b/fs/fs.c
index dd680f3..f8c6d64 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -85,6 +85,7 @@ struct fstype_info {
 	int (*size)(const char *filename);
 	int (*read)(const char *filename, void *buf, int offset, int len);
 	int (*write)(const char *filename, void *buf, int offset, int len);
+	void (*uuid)(char *uuid_str);
 	void (*close)(void);
 };
 
@@ -113,6 +114,7 @@ static struct fstype_info fstypes[] = {
 		.size = ext4fs_size,
 		.read = ext4_read_file,
 		.write = fs_write_unsupported,
+		.uuid = ext4fs_uuid,
 	},
 #endif
 #ifdef CONFIG_SANDBOX
@@ -206,6 +208,14 @@ static void fs_close(void)
 	fs_type = FS_TYPE_ANY;
 }
 
+void fs_uuid(char *uuid_str)
+{
+	struct fstype_info *info = fs_get_info(fs_type);
+
+	if (info->uuid)
+		info->uuid(uuid_str);
+}
+
 int fs_ls(const char *dirname)
 {
 	int ret;
@@ -289,6 +299,24 @@ int fs_write(const char *filename, ulong addr, int offset, int len)
 	return ret;
 }
 
+int do_fs_uuid(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
+		int fstype)
+{
+	char uuid[37];
+	memset(uuid, 0, sizeof(uuid));
+
+	if (argc != 3)
+		return CMD_RET_USAGE;
+
+	if (fs_set_blk_dev(argv[1], argv[2], fstype))
+		return 1;
+
+	fs_uuid(uuid);
+	setenv("fs_uuid", uuid);
+
+	return 0;
+}
+
 int do_size(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
 		int fstype)
 {
diff --git a/include/ext4fs.h b/include/ext4fs.h
index 6c419f3..4011370 100644
--- a/include/ext4fs.h
+++ b/include/ext4fs.h
@@ -132,6 +132,7 @@ struct ext_filesystem *get_fs(void);
 int ext4fs_open(const char *filename);
 int ext4fs_read(char *buf, unsigned len);
 int ext4fs_mount(unsigned part_length);
+void ext4fs_uuid(char *uuid_str);
 void ext4fs_close(void);
 void ext4fs_reinit_global(void);
 int ext4fs_ls(const char *dirname);
diff --git a/include/fs.h b/include/fs.h
index 06a45f2..1956b67 100644
--- a/include/fs.h
+++ b/include/fs.h
@@ -82,6 +82,8 @@ int fs_write(const char *filename, ulong addr, int offset, int len);
  * Common implementation for various filesystem commands, optionally limited
  * to a specific filesystem type via the fstype parameter.
  */
+int do_fs_uuid(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
+		int fstype);
 int do_size(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
 		int fstype);
 int do_load(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
-- 
1.9.3