[dm-devel] [RFC Patch 2/3] libmultipath: make sysfs_is_multipathed able to return wwid

[Martin Wilck]

On Mon, 2020-03-30 at 21:00 -0500, Benjamin Marzinski wrote:
> sysfs_is_multipathed reads the wwid of the dm device holding a path
> to
> check if its a multipath device.  Add code to optinally set pp->wwid
> to
> that wwid.  This will be used by a future patch.
> 
> Signed-off-by: Benjamin Marzinski <bmarzins at redhat.com>
> ---
>  libmultipath/sysfs.c | 22 +++++++++++++++++++---
>  libmultipath/sysfs.h |  2 +-
>  multipath/main.c     |  7 ++++---
>  3 files changed, 24 insertions(+), 7 deletions(-)
> 
> diff --git a/libmultipath/sysfs.c b/libmultipath/sysfs.c
> index 62ec2ed7..034f082f 100644
> --- a/libmultipath/sysfs.c
> +++ b/libmultipath/sysfs.c
> @@ -295,7 +295,7 @@ static int select_dm_devs(const struct dirent
> *di)
>  	return fnmatch("dm-*", di->d_name, FNM_FILE_NAME) == 0;
>  }
>  
> -bool sysfs_is_multipathed(const struct path *pp)
> +bool sysfs_is_multipathed(struct path *pp, bool set_wwid)
>  {
>  	char pathbuf[PATH_MAX];
>  	struct scandir_result sr;
> @@ -342,9 +342,25 @@ bool sysfs_is_multipathed(const struct path *pp)
>  		if (nr == sizeof(uuid) && !memcmp(uuid, "mpath-",
> sizeof(uuid)))
>  			found = true;
>  		else if (nr < 0) {
> -			condlog(1, "%s: error reading from %s: %s",
> -				__func__, pathbuf, strerror(errno));
> +			condlog(1, "%s: error reading from %s: %m",
> +				__func__, pathbuf);
>  		}
> +		if (found && set_wwid) {
> +			nr = read(fd, pp->wwid, WWID_SIZE);

I'd rather read the whole UUID in a single syscall (i.e. merge this
with the previous read() that fetched the first 6 chars).

Regards,
Martin


-- 
Dr. Martin Wilck <mwilck at suse.com>, Tel. +49 (0)911 74053 2107
SUSE  Software Solutions Germany GmbH
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