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* [PATCH v2 1/1] mtd: block2mtd: add support for an optional custom MTD label
@ 2021-10-08 14:08 Joachim Wiberg
  2021-10-08 14:44 ` Miquel Raynal
  0 siblings, 1 reply; 2+ messages in thread
From: Joachim Wiberg @ 2021-10-08 14:08 UTC (permalink / raw)
  To: linux-mtd; +Cc: Joern Engel, Miquel Raynal, Joachim Wiberg

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 line in /etc/fstab can then be used to mount a file system
regardless if running on an embedded system, or emulated with block2mtd:

    mtd:Config  /mnt    jffs2   noatime,nodiratime      0    0

Kernel command line syntax in the emulated case:

    block2mtd.block2mtd=/dev/sda,,Config

Notioce the ',,', it is the optional erase_size, which like before this
patch, defaults to PAGE_SIZE when omitted.  Hence the strlen() check.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
Reviewed-by: Miquèl Raynal <miquel.raynal@bootlin.com>
---
v2:
  * Variables and arguments on their own lines
  * Add comment to explain why we need strlen()
  * Refactor hard coded constants with a define
  * Spell and grammar check commit message
---
 drivers/mtd/devices/block2mtd.c | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/drivers/mtd/devices/block2mtd.c b/drivers/mtd/devices/block2mtd.c
index c08721b11642..40d7211485da 100644
--- a/drivers/mtd/devices/block2mtd.c
+++ b/drivers/mtd/devices/block2mtd.c
@@ -31,6 +31,9 @@
 #include <linux/slab.h>
 #include <linux/major.h>
 
+/* Maximum number of comma-separated items in the 'block2mtd=' parameter */
+#define BLOCK2MTD_PARAM_MAX_COUNT 3
+
 /* Info for the block device */
 struct block2mtd_dev {
 	struct list_head list;
@@ -214,7 +217,7 @@ 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 +281,10 @@ 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;
 
@@ -305,7 +311,7 @@ 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.name + strlen("block2mtd: "),
+		label ? label : dev->mtd.name + strlen("block2mtd: "),
 		dev->mtd.erasesize >> 10, dev->mtd.erasesize);
 	return dev;
 
@@ -381,8 +387,9 @@ 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 *token[BLOCK2MTD_PARAM_MAX_COUNT];
 	char *name;
+	char *label = NULL;
 	size_t erase_size = PAGE_SIZE;
 	unsigned long timeout = MTD_DEFAULT_TIMEOUT;
 	int i, ret;
@@ -395,7 +402,7 @@ static int block2mtd_setup2(const char *val)
 	strcpy(str, val);
 	kill_final_newline(str);
 
-	for (i = 0; i < 2; i++)
+	for (i = 0; i < BLOCK2MTD_PARAM_MAX_COUNT; i++)
 		token[i] = strsep(&str, ",");
 
 	if (str) {
@@ -414,7 +421,8 @@ static int block2mtd_setup2(const char *val)
 		return 0;
 	}
 
-	if (token[1]) {
+	/* Optional argument when custom label is used */
+	if (token[1] && strlen(token[1])) {
 		ret = parse_num(&erase_size, token[1]);
 		if (ret) {
 			pr_err("illegal erase size\n");
@@ -422,7 +430,12 @@ 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 +469,7 @@ 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>][,<label>]]\"");
 
 static int __init block2mtd_init(void)
 {
-- 
2.25.1


______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/

^ permalink raw reply related	[flat|nested] 2+ messages in thread
* Re: [PATCH v2 1/1] mtd: block2mtd: add support for an optional custom MTD label
  2021-10-08 14:08 [PATCH v2 1/1] mtd: block2mtd: add support for an optional custom MTD label Joachim Wiberg
@ 2021-10-08 14:44 ` Miquel Raynal
  0 siblings, 0 replies; 2+ messages in thread
From: Miquel Raynal @ 2021-10-08 14:44 UTC (permalink / raw)
  To: Joachim Wiberg; +Cc: linux-mtd, Joern Engel

Hi Joachim,

troglobit@gmail.com wrote on Fri,  8 Oct 2021 16:08:35 +0200:

> 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 line in /etc/fstab can then be used to mount a file system
> regardless if running on an embedded system, or emulated with block2mtd:
> 
>     mtd:Config  /mnt    jffs2   noatime,nodiratime      0    0
> 
> Kernel command line syntax in the emulated case:
> 
>     block2mtd.block2mtd=/dev/sda,,Config
> 
> Notioce the ',,', it is the optional erase_size, which like before this
> patch, defaults to PAGE_SIZE when omitted.  Hence the strlen() check.
> 
> Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
> Reviewed-by: Miquèl Raynal <miquel.raynal@bootlin.com>
> ---
> v2:
>   * Variables and arguments on their own lines
>   * Add comment to explain why we need strlen()
>   * Refactor hard coded constants with a define
>   * Spell and grammar check commit message
> ---
>  drivers/mtd/devices/block2mtd.c | 29 +++++++++++++++++++++--------
>  1 file changed, 21 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/mtd/devices/block2mtd.c b/drivers/mtd/devices/block2mtd.c
> index c08721b11642..40d7211485da 100644
> --- a/drivers/mtd/devices/block2mtd.c
> +++ b/drivers/mtd/devices/block2mtd.c
> @@ -31,6 +31,9 @@
>  #include <linux/slab.h>
>  #include <linux/major.h>
>  
> +/* Maximum number of comma-separated items in the 'block2mtd=' parameter */
> +#define BLOCK2MTD_PARAM_MAX_COUNT 3
> +
>  /* Info for the block device */
>  struct block2mtd_dev {
>  	struct list_head list;
> @@ -214,7 +217,7 @@ 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 +281,10 @@ 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;
>  
> @@ -305,7 +311,7 @@ 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.name + strlen("block2mtd: "),
> +		label ? label : dev->mtd.name + strlen("block2mtd: "),
>  		dev->mtd.erasesize >> 10, dev->mtd.erasesize);
>  	return dev;
>  
> @@ -381,8 +387,9 @@ 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 *token[BLOCK2MTD_PARAM_MAX_COUNT];

I believe this change should still be kept in a separate patch.
Otherwise looks fine.

>  	char *name;
> +	char *label = NULL;
>  	size_t erase_size = PAGE_SIZE;
>  	unsigned long timeout = MTD_DEFAULT_TIMEOUT;
>  	int i, ret;
> @@ -395,7 +402,7 @@ static int block2mtd_setup2(const char *val)
>  	strcpy(str, val);
>  	kill_final_newline(str);
>  
> -	for (i = 0; i < 2; i++)
> +	for (i = 0; i < BLOCK2MTD_PARAM_MAX_COUNT; i++)
>  		token[i] = strsep(&str, ",");
>  
>  	if (str) {
> @@ -414,7 +421,8 @@ static int block2mtd_setup2(const char *val)
>  		return 0;
>  	}
>  
> -	if (token[1]) {
> +	/* Optional argument when custom label is used */
> +	if (token[1] && strlen(token[1])) {
>  		ret = parse_num(&erase_size, token[1]);
>  		if (ret) {
>  			pr_err("illegal erase size\n");
> @@ -422,7 +430,12 @@ 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 +469,7 @@ 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>][,<label>]]\"");
>  
>  static int __init block2mtd_init(void)
>  {


Thanks,
Miquèl

______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/

^ permalink raw reply	[flat|nested] 2+ messages in thread
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