[PATCH 1/1] mtd: block2mtd: add support for an optional custom MTD label

Joachim Wiberg
2021-10-05T08:05:02Z

This patch adds support for an optional MTD label for mtd2block emulated
MTD devices. Useful when, e.g. testing device images using Qemu. The
following /etc/fstab line in can then be used to mount a file system
regardless of the actual MTD partition number:

mtd:Config /mnt jffs2 noatime,nodiratime 0 0

Kernel command line syntax:

block2mtd.block2mtd=/dev/sda,,Config

The ',,' is the optional erase_size, which like before this patch,
defaults to PAGE_SIZE when omitted.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
---
drivers/mtd/devices/block2mtd.c | 26 +++++++++++++++++---------
1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/drivers/mtd/devices/block2mtd.c b/drivers/mtd/devices/block2mtd.c
index c08721b11642..9465b8ff48f6 100644
--- a/drivers/mtd/devices/block2mtd.c
+++ b/drivers/mtd/devices/block2mtd.c
@@ -214,7 +214,7 @@ static void block2mtd_free_device(struct block2mtd_dev *dev)

static struct block2mtd_dev *add_device(char *devname, int erase_size,
- int timeout)
+ char *label, int timeout)
{
#ifndef MODULE
int i;
@@ -278,7 +278,10 @@ static struct block2mtd_dev *add_device(char *devname, int erase_size,

/* Setup the MTD structure */
/* make the name contain the block device in */
- name = kasprintf(GFP_KERNEL, "block2mtd: %s", devname);
+ if (!label)
+ name = kasprintf(GFP_KERNEL, "block2mtd: %s", devname);
+ else
+ name = kstrdup(label, GFP_KERNEL);
if (!name)
goto err_destroy_mutex;

@@ -304,7 +307,7 @@ static struct block2mtd_dev *add_device(char *devname, int erase_size,

list_add(&dev->list, &blkmtd_device_list);
pr_info("mtd%d: [%s] erase_size = %dKiB [%d]\n",
- dev->mtd.index,
+ dev->mtd.index, label ? label :
dev->mtd.name + strlen("block2mtd: "),
dev->mtd.erasesize >> 10, dev->mtd.erasesize);
return dev;
@@ -381,8 +384,8 @@ static int block2mtd_setup2(const char *val)
/* 80 for device, 12 for erase size, 80 for name, 8 for timeout */
char buf[80 + 12 + 80 + 8];
char *str = buf;
- char *token[2];
- char *name;
+ char *token[3];
+ char *name, *label = NULL;
size_t erase_size = PAGE_SIZE;
unsigned long timeout = MTD_DEFAULT_TIMEOUT;
int i, ret;
@@ -395,7 +398,7 @@ static int block2mtd_setup2(const char *val)
strcpy(str, val);
kill_final_newline(str);

- for (i = 0; i < 2; i++)
+ for (i = 0; i < 3; i++)
token[i] = strsep(&str, ",");

if (str) {
@@ -414,7 +417,7 @@ static int block2mtd_setup2(const char *val)
return 0;
}

- if (token[1]) {
+ if (token[1] && strlen(token[1])) {
ret = parse_num(&erase_size, token[1]);
if (ret) {
pr_err("illegal erase size\n");
@@ -422,7 +425,12 @@ static int block2mtd_setup2(const char *val)
}
}

- add_device(name, erase_size, timeout);
+ if (token[2]) {
+ label = token[2];
+ pr_info("Using custom MTD label '%s' for dev %s\n", label, name);
+ }
+
+ add_device(name, erase_size, label, timeout);

return 0;
}
@@ -456,7 +464,7 @@ static int block2mtd_setup(const char *val, const struct kernel_param *kp)

module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
-MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
+MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,[<erasesize>][, ]]\"");

static int __init block2mtd_init(void)
{
--
2.25.1