|
 |
45e84a0 |
From 5bb37d151b026759ee35f04212b11b4d625c7431 Mon Sep 17 00:00:00 2001
|
|
|
45e84a0 |
From: Kevin Wolf <kwolf@redhat.com>
|
|
|
45e84a0 |
Date: Wed, 7 Dec 2011 12:42:10 +0100
|
|
|
45e84a0 |
Subject: [PATCH 23/25] qemu-img rebase: Fix for undersized backing files
|
|
|
45e84a0 |
|
|
|
45e84a0 |
Backing files may be smaller than the corresponding COW file. When
|
|
|
45e84a0 |
reading directly from the backing file, qemu-img rebase must consider
|
|
|
45e84a0 |
this and assume zero sectors after the end of backing files.
|
|
|
45e84a0 |
|
|
|
45e84a0 |
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
|
|
|
45e84a0 |
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
|
|
|
45e84a0 |
---
|
|
|
45e84a0 |
qemu-img.c | 42 +++++++++++++++++++++++++++++++++---------
|
|
|
45e84a0 |
1 files changed, 33 insertions(+), 9 deletions(-)
|
|
|
45e84a0 |
|
|
|
45e84a0 |
diff --git a/qemu-img.c b/qemu-img.c
|
|
|
45e84a0 |
index 8bdae66..01cc0d3 100644
|
|
|
45e84a0 |
--- a/qemu-img.c
|
|
|
45e84a0 |
+++ b/qemu-img.c
|
|
|
45e84a0 |
@@ -1420,6 +1420,8 @@ static int img_rebase(int argc, char **argv)
|
|
|
45e84a0 |
*/
|
|
|
45e84a0 |
if (!unsafe) {
|
|
|
45e84a0 |
uint64_t num_sectors;
|
|
|
45e84a0 |
+ uint64_t old_backing_num_sectors;
|
|
|
45e84a0 |
+ uint64_t new_backing_num_sectors;
|
|
|
45e84a0 |
uint64_t sector;
|
|
|
45e84a0 |
int n;
|
|
|
45e84a0 |
uint8_t * buf_old;
|
|
|
45e84a0 |
@@ -1430,6 +1432,8 @@ static int img_rebase(int argc, char **argv)
|
|
|
45e84a0 |
buf_new = qemu_blockalign(bs, IO_BUF_SIZE);
|
|
|
45e84a0 |
|
|
|
45e84a0 |
bdrv_get_geometry(bs, &num_sectors);
|
|
|
45e84a0 |
+ bdrv_get_geometry(bs_old_backing, &old_backing_num_sectors);
|
|
|
45e84a0 |
+ bdrv_get_geometry(bs_new_backing, &new_backing_num_sectors);
|
|
|
45e84a0 |
|
|
|
45e84a0 |
local_progress = (float)100 /
|
|
|
45e84a0 |
(num_sectors / MIN(num_sectors, IO_BUF_SIZE / 512));
|
|
|
45e84a0 |
@@ -1448,16 +1452,36 @@ static int img_rebase(int argc, char **argv)
|
|
|
45e84a0 |
continue;
|
|
|
45e84a0 |
}
|
|
|
45e84a0 |
|
|
|
45e84a0 |
- /* Read old and new backing file */
|
|
|
45e84a0 |
- ret = bdrv_read(bs_old_backing, sector, buf_old, n);
|
|
|
45e84a0 |
- if (ret < 0) {
|
|
|
45e84a0 |
- error_report("error while reading from old backing file");
|
|
|
45e84a0 |
- goto out;
|
|
|
45e84a0 |
+ /*
|
|
|
45e84a0 |
+ * Read old and new backing file and take into consideration that
|
|
|
45e84a0 |
+ * backing files may be smaller than the COW image.
|
|
|
45e84a0 |
+ */
|
|
|
45e84a0 |
+ if (sector >= old_backing_num_sectors) {
|
|
|
45e84a0 |
+ memset(buf_old, 0, n * BDRV_SECTOR_SIZE);
|
|
|
45e84a0 |
+ } else {
|
|
|
45e84a0 |
+ if (sector + n > old_backing_num_sectors) {
|
|
|
45e84a0 |
+ n = old_backing_num_sectors - sector;
|
|
|
45e84a0 |
+ }
|
|
|
45e84a0 |
+
|
|
|
45e84a0 |
+ ret = bdrv_read(bs_old_backing, sector, buf_old, n);
|
|
|
45e84a0 |
+ if (ret < 0) {
|
|
|
45e84a0 |
+ error_report("error while reading from old backing file");
|
|
|
45e84a0 |
+ goto out;
|
|
|
45e84a0 |
+ }
|
|
|
45e84a0 |
}
|
|
|
45e84a0 |
- ret = bdrv_read(bs_new_backing, sector, buf_new, n);
|
|
|
45e84a0 |
- if (ret < 0) {
|
|
|
45e84a0 |
- error_report("error while reading from new backing file");
|
|
|
45e84a0 |
- goto out;
|
|
|
45e84a0 |
+
|
|
|
45e84a0 |
+ if (sector >= new_backing_num_sectors) {
|
|
|
45e84a0 |
+ memset(buf_new, 0, n * BDRV_SECTOR_SIZE);
|
|
|
45e84a0 |
+ } else {
|
|
|
45e84a0 |
+ if (sector + n > new_backing_num_sectors) {
|
|
|
45e84a0 |
+ n = new_backing_num_sectors - sector;
|
|
|
45e84a0 |
+ }
|
|
|
45e84a0 |
+
|
|
|
45e84a0 |
+ ret = bdrv_read(bs_new_backing, sector, buf_new, n);
|
|
|
45e84a0 |
+ if (ret < 0) {
|
|
|
45e84a0 |
+ error_report("error while reading from new backing file");
|
|
|
45e84a0 |
+ goto out;
|
|
|
45e84a0 |
+ }
|
|
|
45e84a0 |
}
|
|
|
45e84a0 |
|
|
|
45e84a0 |
/* If they differ, we need to write to the COW file */
|
|
|
45e84a0 |
--
|
|
|
45e84a0 |
1.7.7.5
|
|
|
45e84a0 |
|