[PATCH for-5.0?] qemu-img: Report convert errors by bytes, not sectors

[Eric Blake <eblake@redhat.com>]

Various qemu-img commands are inconsistent on whether they report
status/errors in terms of bytes or sector offsets.  The latter is
confusing (especially as more places move to 4k block sizes), so let's
switch everything to just use bytes everywhere.

Signed-off-by: Eric Blake <eblake@redhat.com>
---

Noticed while investigating https://bugzilla.redhat.com/1819240

By the way, I found it odd that even without --salvage, qemu-img
convert will process up to 8 EIO failures (based on its default
coroutine depth of 8) before finally exiting, rather than quitting
immediately on the first EIO failure.

 qemu-img.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/qemu-img.c b/qemu-img.c
index b167376bd72e..77219e25b33b 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1924,8 +1924,9 @@ retry:
         if (status == BLK_DATA && !copy_range) {
             ret = convert_co_read(s, sector_num, n, buf);
             if (ret < 0) {
-                error_report("error while reading sector %" PRId64
-                             ": %s", sector_num, strerror(-ret));
+                error_report("error while reading at byte %" PRId64
+                             ": %s", sector_num * BDRV_SECTOR_SIZE,
+                             strerror(-ret));
                 s->ret = ret;
             }
         } else if (!s->min_sparse && status == BLK_ZERO) {
@@ -1953,8 +1954,9 @@ retry:
                 ret = convert_co_write(s, sector_num, n, buf, status);
             }
             if (ret < 0) {
-                error_report("error while writing sector %" PRId64
-                             ": %s", sector_num, strerror(-ret));
+                error_report("error while writing at byte %" PRId64
+                             ": %s", sector_num * BDRV_SECTOR_SIZE,
+                             strerror(-ret));
                 s->ret = ret;
             }
         }
-- 
2.26.0.rc2