Function raw_co_truncate does not check effective size for BLK device file,
and QEMU may notify guest without any size changing.
Two cases can be reproduced easily by qmp command:
CASE 1:
1, create a logical volume(12M) by LVM, and guest uses this volume as "vdb"
2, run qmp command : virsh qemu-monitor-command INSTANCE '{"execute":
"block_resize", "arguments":{"device":"drive-virtio-disk1","size":12582912}}'
The effective size(12M) is equal to the argument(12M) and the real device file
size(12M). QEMU should ignore this command and has no need to notify guest.
CASE 2:
1, create a logical volume(12M) by LVM, and guest uses this volume as "vdb"
2, resize LV to 16M by lvresize command
3, run qmp command : virsh qemu-monitor-command INSTANCE '{"execute":
"block_resize", "arguments":{"device":"drive-virtio-disk1","size":10485760}}'
The device file size actually grew, but the argument(10M) is less than the
effective size(12M). This command should fail, but QEMU still report success.
Signed-off-by: zhenwei pi <pizhen...@bytedance.com>
---
block/file-posix.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/block/file-posix.c b/block/file-posix.c
index 07bbdab953..951d910b0b 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -1991,6 +1991,7 @@ static int coroutine_fn raw_co_truncate(BlockDriverState
*bs, int64_t offset,
BDRVRawState *s = bs->opaque;
struct stat st;
int ret;
+ int64_t sectors;
if (fstat(s->fd, &st)) {
ret = -errno;
@@ -2013,6 +2014,20 @@ static int coroutine_fn raw_co_truncate(BlockDriverState
*bs, int64_t offset,
error_setg(errp, "Cannot grow device files");
return -EINVAL;
}
+
+ sectors = raw_getlength(bs) >> BDRV_SECTOR_BITS;
+ if (sectors > bs->total_sectors) {
+ /* device size actually grew */
+ if (offset <= bs->total_sectors * BDRV_SECTOR_SIZE) {
+ error_setg(errp, "The effective size of this device is "
+ "greater than or equal to the argument");
+ return -EINVAL;
+ }
+ } else if (sectors == bs->total_sectors) {
+ /* device size actually not changed */
+ error_setg(errp, "Detect device file size not changing");
+ return -EINVAL;
+ }
} else {
error_setg(errp, "Resizing this file is not supported");
return -ENOTSUP;
--
2.11.0
