Re: [Qemu-devel] [PATCH] block/raw-posix: get right size of partition size

[Christoph Egger]

On 05/23/11 13:06, Christoph Hellwig wrote:
On Mon, May 23, 2011 at 12:34:39PM +0200, Christoph Egger wrote:

This does 2 things:
- use the correct way to get the size of a disk device or partition
     (from h...@netbsd.org)
- if given a block device, use the character device instead.
     (from bou...@netbsd.org)

Please split that into two independent patches.

ok.


+    if (S_ISLNK(sb.st_mode)) {
+        fprintf(stderr, "%s: symbolic link not supported\n", filename);
+        return -EINVAL;
+    }

Why not, it's a pretty clear regression from current code, and will
break various Linux setups where there are lots of symlinks under /dev,
as well as users using symlinks for their image files.

there's no easy way to find the real target of a symlink, to find the 
corresponding character device (this could be refinded, because this 
restriction only applies if the target is a block device).


+#if defined(__NetBSD__)
+    if (S_ISBLK(sb.st_mode)) {
+        static char namebuf[PATH_MAX];
+        const char *dp = strrchr(filename, '/');
+
+        if (dp == NULL) {
+            snprintf(namebuf, PATH_MAX, "r%s", filename);
+        } else {
+            snprintf(namebuf, PATH_MAX, "%.*s/r%s",
+                (int)(dp - filename), filename, dp + 1);
+        }
+        fprintf(stderr, "%s is a block device", filename);
+        filename = namebuf;
+        fprintf(stderr, ", using %s\n", filename);
+    }
+#endif

Please split this out into a helper, which has a no-op version
for other operating systems.  It probably should also be enabled
for other operating systems having char and block nodes for disk
devices.  That's at least OpenBSD and Solaris, not sure about
Darwin.

Yes, but don't have a test machine right now.

-#ifdef __OpenBSD__
+#if defined(__OpenBSD__) || defined(__NetBSD__)
  static int64_t raw_getlength(BlockDriverState *bs)
  {
      BDRVRawState *s = bs->opaque;
@@ -613,12 +645,22 @@ static int64_t raw_getlength(BlockDriverState *bs)
      if (fstat(fd,&st))
          return -1;
      if (S_ISCHR(st.st_mode) || S_ISBLK(st.st_mode)) {
-        struct disklabel dl;
+#if defined(__NetBSD__)
+        struct dkwedge_info dkw;

-        if (ioctl(fd, DIOCGDINFO,&dl))
-            return -1;
-        return (uint64_t)dl.d_secsize *
-            dl.d_partitions[DISKPART(st.st_rdev)].p_size;
+        if (ioctl(fd, DIOCGWEDGEINFO,&dkw) != -1) {
+            return dkw.dkw_size * 512;
+        } else {
+#endif

Please provide a completely separate raw_getlength for NetBSD instead
of creating this ifdef mess for almost no shared code.

Ok.


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