From af5e3e5ad9183d4a78bd4a2d287c872aabecbf8c Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Fri, 17 Feb 2012 14:20:00 +0100
Subject: [PATCH 2/4] qemu-img rebase: Fix for undersized backing files
RH-Author: Kevin Wolf <kwolf@redhat.com>
Message-id: <1329488400-14832-1-git-send-email-kwolf@redhat.com>
Patchwork-id: 37415
O-Subject: [RHEL-6.3 qemu-kvm PATCH] qemu-img rebase: Fix for undersized backing files
Bugzilla: 638055
RH-Acked-by: Markus Armbruster <armbru@redhat.com>
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
Bugzilla: 638055
Backing files may be smaller than the corresponding COW file. When
reading directly from the backing file, qemu-img rebase must consider
this and assume zero sectors after the end of backing files.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
(cherry picked from commit 87a1b3e381c282b143023c411df284175f0b656b)
Conflicts:
qemu-img.c
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
qemu-img.c | 42 +++++++++++++++++++++++++++++++++---------
1 files changed, 33 insertions(+), 9 deletions(-)
Signed-off-by: Michal Novotny <minovotn@redhat.com>
---
qemu-img.c | 42 +++++++++++++++++++++++++++++++++---------
1 files changed, 33 insertions(+), 9 deletions(-)
diff --git a/qemu-img.c b/qemu-img.c
index 94cd684..38de348 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1405,6 +1405,8 @@ static int img_rebase(int argc, char **argv)
*/
if (!unsafe) {
uint64_t num_sectors;
+ uint64_t old_backing_num_sectors;
+ uint64_t new_backing_num_sectors;
uint64_t sector;
int n;
uint8_t * buf_old;
@@ -1415,6 +1417,8 @@ static int img_rebase(int argc, char **argv)
buf_new = qemu_blockalign(bs, IO_BUF_SIZE);
bdrv_get_geometry(bs, &num_sectors);
+ bdrv_get_geometry(bs_old_backing, &old_backing_num_sectors);
+ bdrv_get_geometry(bs_new_backing, &new_backing_num_sectors);
local_progress = (float)100 /
(num_sectors / MIN(num_sectors, IO_BUF_SIZE / 512));
@@ -1433,16 +1437,36 @@ static int img_rebase(int argc, char **argv)
continue;
}
- /* Read old and new backing file */
- ret = bdrv_read(bs_old_backing, sector, buf_old, n);
- if (ret < 0) {
- error("error while reading from old backing file");
- goto out;
+ /*
+ * Read old and new backing file and take into consideration that
+ * backing files may be smaller than the COW image.
+ */
+ if (sector >= old_backing_num_sectors) {
+ memset(buf_old, 0, n * BDRV_SECTOR_SIZE);
+ } else {
+ if (sector + n > old_backing_num_sectors) {
+ n = old_backing_num_sectors - sector;
+ }
+
+ ret = bdrv_read(bs_old_backing, sector, buf_old, n);
+ if (ret < 0) {
+ error("error while reading from old backing file");
+ goto out;
+ }
}
- ret = bdrv_read(bs_new_backing, sector, buf_new, n);
- if (ret < 0) {
- error("error while reading from new backing file");
- goto out;
+
+ if (sector >= new_backing_num_sectors) {
+ memset(buf_new, 0, n * BDRV_SECTOR_SIZE);
+ } else {
+ if (sector + n > new_backing_num_sectors) {
+ n = new_backing_num_sectors - sector;
+ }
+
+ ret = bdrv_read(bs_new_backing, sector, buf_new, n);
+ if (ret < 0) {
+ error("error while reading from new backing file");
+ goto out;
+ }
}
/* If they differ, we need to write to the COW file */
--
1.7.7.6