[stgt] RFC [patch] Search /sys/class/bsg/<ctl>/dev for bsg major number.

[Nicholas A. Bellinger]

On Sat, 2010-08-21 at 16:07 +1000, Mark Harvey wrote:
> >From a90611630879205ef497821552474e894d463c94 Mon Sep 17 00:00:00 2001
> From: Mark Harvey <markh794 at gmail.com>
> Date: Sat, 21 Aug 2010 15:22:48 +1000
> Subject: Check bsg major number from /sys/class/bsg/<c:t:l>/dev
> 
> Signed-off-by: Mark Harvey <markh794 at gmail.com>
> ---
>  usr/bs_sg.c |   35 ++++++++++++++++++++++++++++++++---
>  1 files changed, 32 insertions(+), 3 deletions(-)
> 
> diff --git a/usr/bs_sg.c b/usr/bs_sg.c
> index dfd49c3..7fc9787 100644
> --- a/usr/bs_sg.c
> +++ b/usr/bs_sg.c
> @@ -269,6 +269,34 @@ static void bs_sg_cmd_complete(int fd, int
> events, void *data)
>  	cmd->scsi_cmd_done(cmd, io_hdr.status);
>  }
> 
> +static int get_bsg_major(char *path)
> +{
> +	FILE *devfd;
> +	char majorno[8];
> +	char dev[128];
> +	int ch;
> +	int i;
> +
> +	dev[0] = '\0';
> +	strncat(dev, "/sys/class/bsg/", 16);
> +	strncat(dev, &path[9], 64);
> +	strncat(dev, "/dev", 5);
> +	devfd = fopen(dev, "r");
> +	if (!devfd)
> +		return -1;
> +	ch = fgetc(devfd);
> +	for (i = 0; i < 7; i++) {
> +		if (ch == ':') {
> +			majorno[i] = '\0';
> +			break;
> +		}
> +		majorno[i] = ch;
> +		ch = fgetc(devfd);
> +	}
> +	fclose(devfd);
> +	return atoi(majorno);
> +}
> +
>  static int chk_sg_device(char *path)
>  {
>  	struct stat st;
> @@ -287,9 +315,10 @@ static int chk_sg_device(char *path)
>  	if (major(st.st_rdev) == SCSI_GENERIC_MAJOR)
>  		return 0;
> 
> -	/* This is not yet defined in include/linux/major.h.. */
> -	if (major(st.st_rdev) == 254)
> -		return 1;
> +	if (!strncmp("/dev/bsg", path, 8)) {
> +		if (major(st.st_rdev) == get_bsg_major(path))
> +			return 0;
> +	}
> 
>  	return -1;
>  }

Acked-by: Nicholas A. Bellinger <nab at linux-iscsi.org>

Hi Mark,

This looks perfectly sane to me, and many thanks for taking the time to
code this patch up!  Tomo, please add this to tgt.git, and I will add
something similar into the SGL passthrough qemu-kvm.git:hw/scsi-bsg.c
code shortly..

Thanks again!

--nab

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