The use of protocols in backing_files is currently broken because of some
checks for adjusting relative pathnames.
Additionally, there's a spurious read when using an nbd protocol that can be
quite destructive when using copy-on-read. Potentially, this can lead to
probing an image file over top of NBD but this is completely wrong as NBD
devices are not growable.
Signed-off-by: Anthony Liguori <aligu...@us.ibm.com>
---
NB: this is absolutely not ideal. A more elegant suggestion would be
appreciated. I don't think NBD cleanly fits the model of a protocol as it
stands today.
diff --git a/block.c b/block.c
index cd2ee31..a32d5dd 100644
--- a/block.c
+++ b/block.c
@@ -344,6 +344,12 @@ static int find_image_format(const char *filename,
BlockDriver **pdrv)
return ret;
}
+ if (strcmp(bs->drv->protocol_name, "nbd") == 0) {
+ drv = bs->drv;
+ bdrv_delete(bs);
+ goto out;
+ }
+
/* Return the raw BlockDriver * to scsi-generic devices or empty drives */
if (bs->sg || !bdrv_is_inserted(bs)) {
bdrv_delete(bs);
@@ -373,6 +379,7 @@ static int find_image_format(const char *filename,
BlockDriver **pdrv)
}
}
}
+out:
if (!drv) {
ret = -ENOENT;
}
@@ -603,10 +610,16 @@ int bdrv_open(BlockDriverState *bs, const char *filename,
int flags,
BlockDriver *back_drv = NULL;
bs->backing_hd = bdrv_new("");
- path_combine(backing_filename, sizeof(backing_filename),
- filename, bs->backing_file);
- if (bs->backing_format[0] != '\0')
- back_drv = bdrv_find_format(bs->backing_format);
+ back_drv = bdrv_find_protocol(bs->backing_file);
+ if (!back_drv) {
+ path_combine(backing_filename, sizeof(backing_filename),
+ filename, bs->backing_file);
+ if (bs->backing_format[0] != '\0')
+ back_drv = bdrv_find_format(bs->backing_format);
+ } else {
+ pstrcpy(backing_filename, sizeof(backing_filename),
+ bs->backing_file);
+ }
/* backing files always opened read-only */
back_flags =
--
1.7.0.4
