[PATCH] Fix qemu-img can't create qcow image based on read-only image

Sheng Yang
2010-01-28T05:23:48Z

Commit 03cbdac7 "Disable fall-back to read-only when cannot open drive's
file for read-write" result in read-only image can't be used as backed
image in qemu-img.

CC: Naphtali Sprei <nsprei@redhat.com>
Signed-off-by: Sheng Yang <sheng@linux.intel.com>
---

This issue blocked our QA's KVM nightly test. But in fact, I don't like this
patch, feeling uncomfortable to change long existed interface... Any
alternative? Add a readonly command line would change the default behavior(I
don't think fall back to readonly looks like a bug); or even revert the
commit? What's the story behind it?

qemu-img.c | 15 ++++++++++-----
1 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/qemu-img.c b/qemu-img.c
index 3cea8ce..f8be5cb 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -188,11 +188,13 @@ static int read_password(char *buf, int buf_size)
#endif

static BlockDriverState *bdrv_new_open(const char *filename,
- const char *fmt)
+ const char *fmt,
+ int readonly)
{
BlockDriverState *bs;
BlockDriver *drv;
char password[256];
+ int flags = BRDV_O_FLAGS;

bs = bdrv_new("");
if (!bs)
@@ -204,7 +206,10 @@ static BlockDriverState *bdrv_new_open(const char *filename,
} else {
drv = NULL;
}
- if (bdrv_open2(bs, filename, BRDV_O_FLAGS | BDRV_O_RDWR, drv) < 0) {
+ if (!readonly) {
+ flags |= BDRV_O_RDWR;
+ }
+ if (bdrv_open2(bs, filename, flags, drv) < 0) {
error("Could not open '%s'", filename);
}
if (bdrv_is_encrypted(bs)) {
@@ -343,7 +348,7 @@ static int img_create(int argc, char **argv)
}
}

- bs = bdrv_new_open(backing_file->value.s, fmt);
+ bs = bdrv_new_open(backing_file->value.s, fmt, 1);
bdrv_get_geometry(bs, &size);
size *= 512;
bdrv_delete(bs);
@@ -627,7 +632,7 @@ static int img_convert(int argc, char **argv)

total_sectors = 0;
for (bs_i = 0; bs_i < bs_n; bs_i++) {
- bs[bs_i] = bdrv_new_open(argv[optind + bs_i], fmt);
+ bs[bs_i] = bdrv_new_open(argv[optind + bs_i], fmt, 0);
if (!bs[bs_i])
error("Could not open '%s'", argv[optind + bs_i]);
bdrv_get_geometry(bs[bs_i], &bs_sectors);
@@ -685,7 +690,7 @@ static int img_convert(int argc, char **argv)
}
}

- out_bs = bdrv_new_open(out_filename, out_fmt);
+ out_bs = bdrv_new_open(out_filename, out_fmt, 0);

bs_i = 0;
bs_offset = 0;
--
1.5.4.5