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[Dle-develop] [-v3 PATCH 1/3] block: add a new attribute "alias" in gendisk
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From: Nao N. <nao...@hi...> - 2011-08-25 09:10:22
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This patch allows the user to set an "alias" of the disk via sysfs interface.
This patch only adds a new attribute "alias" in gendisk structure.
To show the alias instead of the device name in kernel messages,
we need to revise printk messages and use alias_name() in them.
Example:
(current) printk("disk name is %s\n", disk->disk_name);
(new) printk("disk name is %s\n", alias_name(disk));
Users can use alphabets, numbers, '-' and '_' in "alias" attribute. A disk can
have an "alias" which length is up to 255 bytes. This attribute is write-once.
Suggested-by: James Bottomley <Jam...@Ha...>
Suggested-by: Jon Masters <jc...@re...>
Signed-off-by: Nao Nishijima <nao...@hi...>
---
Documentation/ABI/testing/sysfs-block | 13 ++++++
block/genhd.c | 71 +++++++++++++++++++++++++++++++++
include/linux/genhd.h | 4 ++
3 files changed, 88 insertions(+), 0 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-block b/Documentation/ABI/testing/sysfs-block
index c1eb41c..2b5d561 100644
--- a/Documentation/ABI/testing/sysfs-block
+++ b/Documentation/ABI/testing/sysfs-block
@@ -206,3 +206,16 @@ Description:
when a discarded area is read the discard_zeroes_data
parameter will be set to one. Otherwise it will be 0 and
the result of reading a discarded area is undefined.
+What: /sys/block/<disk>/alias
+Date: Aug 2011
+Contact: Nao Nishijima <nao...@hi...>
+Description:
+ A raw device name of a disk does not always point a same disk
+ each boot-up time. Therefore, users have to use persistent
+ device names, which udev creates when the kernel finds a disk,
+ instead of raw device name. However, kernel doesn't show those
+ persistent names on its messages (e.g. dmesg).
+ This file can store an alias of the disk and it would be
+ appeared in kernel messages if it is set. A disk can have an
+ alias which length is up to 255bytes. Users can use alphabets,
+ numbers, "-" and "_" in alias name. This file is writeonce.
diff --git a/block/genhd.c b/block/genhd.c
index e2f6790..94855a9 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -19,6 +19,7 @@
#include <linux/mutex.h>
#include <linux/idr.h>
#include <linux/log2.h>
+#include <linux/ctype.h>
#include "blk.h"
@@ -909,6 +910,74 @@ static int __init genhd_device_init(void)
subsys_initcall(genhd_device_init);
+static ssize_t alias_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct gendisk *disk = dev_to_disk(dev);
+ ssize_t ret = 0;
+
+ if (disk->alias)
+ ret = snprintf(buf, ALIAS_LEN, "%s\n", disk->alias);
+ return ret;
+}
+
+static ssize_t alias_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct gendisk *disk = dev_to_disk(dev);
+ char *alias;
+ char *envp[] = { NULL, NULL };
+ unsigned char c;
+ int i;
+ ssize_t ret = count;
+
+ if (!count)
+ return -EINVAL;
+
+ if (count >= ALIAS_LEN) {
+ printk(KERN_ERR "alias: alias is too long\n");
+ return -EINVAL;
+ }
+
+ /* Validation check */
+ for (i = 0; i < count; i++) {
+ c = buf[i];
+ if (i == count - 1 && c == '\n')
+ break;
+ if (!isalnum(c) && c != '_' && c != '-') {
+ printk(KERN_ERR "alias: invalid alias\n");
+ return -EINVAL;
+ }
+ }
+
+ if (disk->alias) {
+ printk(KERN_INFO "alias: %s is already assigned (%s)\n",
+ disk->disk_name, disk->alias);
+ return -EINVAL;
+ }
+
+ alias = kasprintf(GFP_KERNEL, "%s", buf);
+ if (!alias)
+ return -ENOMEM;
+
+ if (alias[count - 1] == '\n')
+ alias[count - 1] = '\0';
+
+ envp[0] = kasprintf(GFP_KERNEL, "ALIAS=%s", alias);
+ if (!envp[0]) {
+ kfree(alias);
+ return -ENOMEM;
+ }
+
+ disk->alias = alias;
+ printk(KERN_INFO "alias: assigned %s to %s\n", alias, disk->disk_name);
+
+ kobject_uevent_env(&dev->kobj, KOBJ_ADD, envp);
+
+ kfree(envp[0]);
+ return ret;
+}
+
static ssize_t disk_range_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
@@ -968,6 +1037,7 @@ static ssize_t disk_discard_alignment_show(struct device *dev,
return sprintf(buf, "%d\n", queue_discard_alignment(disk->queue));
}
+static DEVICE_ATTR(alias, S_IRUGO|S_IWUSR, alias_show, alias_store);
static DEVICE_ATTR(range, S_IRUGO, disk_range_show, NULL);
static DEVICE_ATTR(ext_range, S_IRUGO, disk_ext_range_show, NULL);
static DEVICE_ATTR(removable, S_IRUGO, disk_removable_show, NULL);
@@ -990,6 +1060,7 @@ static struct device_attribute dev_attr_fail_timeout =
#endif
static struct attribute *disk_attrs[] = {
+ &dev_attr_alias.attr,
&dev_attr_range.attr,
&dev_attr_ext_range.attr,
&dev_attr_removable.attr,
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 02fa469..6957350 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -21,6 +21,8 @@
#define dev_to_part(device) container_of((device), struct hd_struct, __dev)
#define disk_to_dev(disk) (&(disk)->part0.__dev)
#define part_to_dev(part) (&((part)->__dev))
+#define alias_name(disk) ((disk)->alias ? (disk)->alias : \
+ (disk)->disk_name)
extern struct device_type part_type;
extern struct kobject *block_depr;
@@ -58,6 +60,7 @@ enum {
#define DISK_MAX_PARTS 256
#define DISK_NAME_LEN 32
+#define ALIAS_LEN 256
#include <linux/major.h>
#include <linux/device.h>
@@ -162,6 +165,7 @@ struct gendisk {
* disks that can't be partitioned. */
char disk_name[DISK_NAME_LEN]; /* name of major driver */
+ char *alias; /* alias name of disk */
char *(*devnode)(struct gendisk *gd, mode_t *mode);
unsigned int events; /* supported events */
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