[Ocfs2-tools-devel] [PATCH] adding code to mounted.c to translate /dev/dm-[N] names to /dev/mapper/xxx names.

[Tristan]

xiaowei hu wrote:
> thanks for your comments.
> answers inline.
>
> will resend a patch following your suggestions.:)
>
> On Thu, 2009-12-03 at 13:20 -0800, Sunil Mushran wrote:
>   
>> Please make the title (first line) shorter followed by a description of
>> what the patch does.
>>
>> Comments inline.
>>
>> XiaoweiHu wrote:
>>     
>>> Signed-off-by: XiaoweiHu <xiaowei.hu at oracle.com>
>>> ---
>>>  mounted.ocfs2/mounted.c |   76 +++++++++++++++++++++++++++++++++++++++++++++-
>>>  1 files changed, 74 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/mounted.ocfs2/mounted.c b/mounted.ocfs2/mounted.c
>>> index e4c5877..c691a3d 100644
>>> --- a/mounted.ocfs2/mounted.c
>>> +++ b/mounted.ocfs2/mounted.c
>>> @@ -33,6 +33,7 @@
>>>  #include <linux/fd.h>
>>>  #include <string.h>
>>>  #include <sys/stat.h>
>>> +#include <dirent.h>
>>>  
>>>  #include <uuid/uuid.h>
>>>  
>>> @@ -155,12 +156,70 @@ static void ocfs2_print_quick_detect(struct list_head *dev_list)
>>>  	}
>>>  }
>>>  
>>> +char *devname_strndup(const char *s, int length)
>>> +{
>>> +        char *ret;
>>> +
>>> +        if (!s)
>>> +                return NULL;
>>> +
>>> +        if (!length)
>>> +                length = strlen(s);
>>> +
>>> +        ret = malloc(length + 1);
>>> +        if (ret) {
>>> +                strncpy(ret, s, length);
>>> +                ret[length] = '\0';
>>> +        }
>>> +        return ret;
>>> +}
>>>       
>> Why not use strndup()?
>>     
> yes, use this lib function is better:).
>
>   
>>> +
>>> +char *devname_strdup(const char *s)
>>> +{
>>> +        return devname_strndup(s, 0);
>>> +}
>>>       
>> Please use tabs.
>> http://oss.oracle.com/osswiki/OCFS2/CodingStyle
>>
>> Easiest if you added the following at the top of the file.
>> /* -*- mode: c; c-basic-offset: 8; -*-
>> * vim: noexpandtab sw=8 ts=8 sts=0:
>> *
>>
>>     
>>> +
>>> +void scan_dir_for_dev(char *dirname, dev_t devno, char **devname)
>>> +{
>>> +        DIR     *dir;
>>> +        struct dirent *dp;
>>> +        char    path[1024];
>>>       
>> Use PATH_MAX.
>>     
>
>   
>>> +        int     dirlen;
>>> +        struct stat st;
>>> +
>>> +        if ((dir = opendir(dirname)) == NULL)
>>> +                return;
>>> +        dirlen = strlen(dirname) + 2;
>>> +        while ((dp = readdir(dir)) != 0) {
>>> +                if (dirlen + strlen(dp->d_name) >= sizeof(path))
>>> +                        continue;
>>> +
>>> +                if (dp->d_name[0] == '.' &&
>>> +                    ((dp->d_name[1] == 0) ||
>>> +                     ((dp->d_name[1] == '.') && (dp->d_name[2] == 0))))
>>> +                        continue;
>>>       
>> You will skip filename "A.". ;)
>>     
> actually this won't skip "A." if the dp-d_name[0] == '.' is fause it
> won't compare the following characters ,not matter what the following
> character is '.' or not.
>
>   
I saw you just want to skip the '.' and '..', why not use a separate 
func to clearly clarify this:

int is_dot_entry(const char *d_name)
{
if (!d_name)
return 0;

if (strlen(d_name) == 1 && d_name[0] = '.')
return 1;
if (strlen(d_name) == 2 && d_name[0] ='.' && d_name[1] == '.')
return 1;

return 0;
}

then,

if (is_dot_entry(dp->d_name))
contiune;
...

>> Why not strncmp "." and "..". Compare only if the strlen matches.
>>
>>     
>>> +
>>> +                sprintf(path, "%s/%s", dirname, dp->d_name);
>>> +                if (stat(path, &st) < 0)
>>> +                        continue;
>>> +
>>> +                if (S_ISBLK(st.st_mode) && st.st_rdev == devno) {
>>> +			*devname = devname_strdup(path);
>>> +                        break;
>>> +                }
>>>       
>> This may not work for multipath. In this case, you will find a mpath
>> for one dm device but not the other. Have you tested this on a multipath
>> setup?
>>     
>
> Yes ,I did this to solving a CT bug, and I tested this patch on a
> multipath setup,it works fine.
>   
>>> +        }
>>> +        closedir(dir);
>>> +        return;
>>> +}
>>> +
>>>  static errcode_t ocfs2_partition_list (struct list_head *dev_list)
>>>  {
>>>  	errcode_t ret = 0;
>>>  	FILE *proc;
>>>  	char line[256];
>>>  	char name[256];
>>> +	char *devname = NULL;
>>> +	int major,minor;
>>>  	ocfs2_devices *dev;
>>>  
>>>  	proc = fopen ("/proc/partitions", "r");
>>> @@ -170,14 +229,27 @@ static errcode_t ocfs2_partition_list (struct list_head *dev_list)
>>>  	}
>>>  
>>>  	while (fgets (line, sizeof(line), proc) != NULL) {
>>> -		if (sscanf(line, "%*d %*d %*d %99[^ \t\n]", name) != 1)
>>> +		if (sscanf(line, "%d %d %*d %99[^ \t\n]", &major, &minor, name) != 3)
>>>  			continue;
>>>  
>>>  		ret = ocfs2_malloc0(sizeof(ocfs2_devices), &dev);
>>>  		if (ret)
>>>  			goto bail;
>>>  
>>> -		snprintf(dev->dev_name, sizeof(dev->dev_name), "/dev/%s", name);
>>> +		/* Try to translate private device-mapper dm-<N> names
>>> +         	 * to standard /dev/mapper/<name>.
>>> +         	 */
>>> +        	if (!strncmp(name, "dm-", 3) && isdigit(name[3])) {
>>> +                        scan_dir_for_dev("/dev/mapper", makedev(major, minor), &devname);
>>> +                	if (devname)
>>> +				snprintf(dev->dev_name, sizeof(dev->dev_name), "%s", devname);
>>> +			else
>>> +				snprintf(dev->dev_name, sizeof(dev->dev_name), "/dev/%s", name);
>>> +
>>> +        	} else {
>>> +			snprintf(dev->dev_name, sizeof(dev->dev_name), "/dev/%s", name);
>>> +		}
>>> +
>>>  		list_add_tail(&(dev->list), dev_list);
>>>  	}
>>>  
>>>       
>
>
>
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