[PATCH][ioemu] strip tap subtype prefix from image name

[PATCH][ioemu] strip tap subtype prefix from image name

[Pat Campbell]

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Currently I am not able to mount or boot from an HVM CDROM when it is configured for 'tap:aio' instead of 'file'.

disk=[ 'tap:aio:/var/lib/xen/images/sles10-sp2-fv/disk0,hda,w', '
       tap:aio:/home/iso/sles/SLES10.iso,hdc:cdrom,r', ]

With the attached patch I am able to boot from the CDROM and or mount it.

Patch changes xenstore.c:xenstore_process_event() to strip the tap subtype prefix from the image name. 

Please apply to xen-unstable tip.

Signed-off-by: Pat Campbell <plc@novell.com>


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diff -r 1c826ea72a80 tools/ioemu/xenstore.c
--- a/tools/ioemu/xenstore.c	Wed Jan 23 15:42:52 2008 +0000
+++ b/tools/ioemu/xenstore.c	Wed Jan 30 05:36:18 2008 -0700
@@ -418,7 +418,7 @@ void xenstore_record_dm_state(char *stat
 
 void xenstore_process_event(void *opaque)
 {
-    char **vec, *image = NULL;
+    char **vec, *bpath, *buf, *image = NULL;
     unsigned int len, num, hd_index;
 
     vec = xs_read_watch(xsh, &num);
@@ -440,8 +440,33 @@ void xenstore_process_event(void *opaque
         goto out;
     hd_index = vec[XS_WATCH_TOKEN][2] - 'a';
     image = xs_read(xsh, XBT_NULL, vec[XS_WATCH_PATH], &len);
-    if (image == NULL || !strcmp(image, bs_table[hd_index]->filename))
-        goto out;  /* gone or identical */
+    if (image == NULL)
+        goto out;  /* gone */
+
+    /* Strip off blktap sub-type prefix */
+    bpath = strdup(vec[XS_WATCH_PATH]); 
+    if (bpath) {
+        char * offset = strrchr(bpath, '/');
+        if (offset) {
+            *offset = '\0';
+            if (pasprintf(&buf, "%s/type", bpath) == 0) {
+                char * drv = xs_read(xsh, XBT_NULL, buf, &len);
+                if (drv != NULL) {
+                    if (!strcmp(drv, "tap")) {
+                        offset = strchr(image, ':'); 
+                        if (offset) 
+                            memmove(image, offset+1, strlen(offset+1)+1 );
+                    }
+                    free(drv);
+                }
+                free(buf);
+            }
+        }
+        free(bpath);
+    }
+
+    if (!strcmp(image, bs_table[hd_index]->filename))
+        goto out;  /* identical */
 
     do_eject(0, vec[XS_WATCH_TOKEN]);
     bs_table[hd_index]->filename[0] = 0;

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Re: [PATCH][ioemu] strip tap subtype prefix from image name

[Christoph Egger]

On Wednesday 30 January 2008 13:57:24 Pat Campbell wrote:
> Currently I am not able to mount or boot from an HVM CDROM when it is
> configured for 'tap:aio' instead of 'file'.
>
> disk=[ 'tap:aio:/var/lib/xen/images/sles10-sp2-fv/disk0,hda,w', '
>        tap:aio:/home/iso/sles/SLES10.iso,hdc:cdrom,r', ]
>
> With the attached patch I am able to boot from the CDROM and or mount it.
>
> Patch changes xenstore.c:xenstore_process_event() to strip the tap subtype
> prefix from the image name.
>
> Please apply to xen-unstable tip.
>
> Signed-off-by: Pat Campbell <plc@novell.com>

Please use a more readable coding style.

What you did is this:

if (a) {
        if (b) {
                if (c) {
                        /* do it */
                } else {
                        /* Alternative C */
                } 
        } else {
                /* Alternative B */
        }
} else {
        /* Alternative A */
}
return;



I suggest you to use this style:

if (!a) {
    /* Alternative A */
    return;
}
if (!b) {
    /* Alternative B */
    return;
}
if (!c) {
    /* Alternative C */
    return;
}
/* do it */
return;



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Re: [PATCH][ioemu] strip tap subtype prefix from image name

[Keir Fraser]

On 30/1/08 13:07, "Christoph Egger" <Christoph.Egger@amd.com> wrote:

>> Please apply to xen-unstable tip.
>> 
>> Signed-off-by: Pat Campbell <plc@novell.com>
> 
> Please use a more readable coding style.

Seconded.

 -- Keir