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authorStefan Hajnoczi <stefanha@linux.vnet.ibm.com>2012-08-28 15:26:48 +0100
committerKevin Wolf <kwolf@redhat.com>2012-08-29 15:23:35 +0200
commit571cd9dcc7f2fee59e47913365ced7781f33c2d3 (patch)
tree525bfcaecefe0ff548ff8fd94ea1ad0ccdf5cc34
parentef72f76e58107bd4096018c3db2912d28249308e (diff)
downloadqemu-arm-571cd9dcc7f2fee59e47913365ced7781f33c2d3.tar.gz
stream: complete early if end of backing file is reached
It is possible to create an image that is larger than its backing file. Reading beyond the end of the backing file produces zeroes if no writes have been made to those sectors in the image file. This patch finishes streaming early when the end of the backing file is reached. Without this patch the block job hangs and continually tries to stream the first sectors beyond the end of the backing file. To reproduce the hung block job bug: $ qemu-img create -f qcow2 backing.qcow2 128M $ qemu-img create -f qcow2 -o backing_file=backing.qcow2 image.qcow2 6G $ qemu -drive if=virtio,cache=none,file=image.qcow2 (qemu) block_stream virtio0 (qemu) info block-jobs The qemu-iotests 030 streaming test still passes. Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
-rw-r--r--block/stream.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/block/stream.c b/block/stream.c
index 37c46525d2..c4f87dd5b6 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -122,6 +122,12 @@ wait:
* known-unallocated area [sector_num, sector_num+n). */
ret = bdrv_co_is_allocated_above(bs->backing_hd, base,
sector_num, n, &n);
+
+ /* Finish early if end of backing file has been reached */
+ if (ret == 0 && n == 0) {
+ n = end - sector_num;
+ }
+
copy = (ret == 1);
}
trace_stream_one_iteration(s, sector_num, n, ret);