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block/backup: Fix hang for unaligned image size

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When doing a block backup of an image with an unaligned size (with
respect to the BACKUP_CLUSTER_SIZE), qemu would check the allocation
status of sectors after the end of the image. bdrv_is_allocated()
returns a result that is valid for 0 sectors in this case, so the backup
job ran into an endless loop.

Stop looping when seeing a result valid for 0 sectors, we're at EOF then.

The test case looks somewhat unrelated at first sight because I
originally tried to reproduce a different suspected bug that turned out
to not exist. Still a good test case and it accidentally found this one.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Kevin Wolf 2014-07-07 16:38:58 +02:00
parent 675879f6f3
commit d40593dd90
3 changed files with 296 additions and 2 deletions
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2
block/backup.c
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@ -307,7 +307,7 @@ static void coroutine_fn backup_run(void *opaque)
BACKUP_SECTORS_PER_CLUSTER - i, &n); BACKUP_SECTORS_PER_CLUSTER - i, &n);
i += n; i += n;
if (alloced == 1) { if (alloced == 1 || n == 0) {
break; break;
} }
} }

25
tests/qemu-iotests/028
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@ -33,6 +33,7 @@ status=1 # failure is the default!
_cleanup() _cleanup()
{ {
rm -f "${TEST_IMG}.copy"
_cleanup_test_img _cleanup_test_img
} }
trap "_cleanup; exit \$status" 0 1 2 3 15 trap "_cleanup; exit \$status" 0 1 2 3 15
@ -41,6 +42,7 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
. ./common.rc . ./common.rc
. ./common.filter . ./common.filter
. ./common.pattern . ./common.pattern
. ./common.qemu
# Any format supporting backing files except vmdk and qcow which do not support # Any format supporting backing files except vmdk and qcow which do not support
# smaller backing files. # smaller backing files.
@ -99,6 +101,29 @@ _check_test_img
# Rebase it on top of its base image # Rebase it on top of its base image
$QEMU_IMG rebase -b "$TEST_IMG.base" "$TEST_IMG" $QEMU_IMG rebase -b "$TEST_IMG.base" "$TEST_IMG"
echo
echo block-backup
echo
qemu_comm_method="monitor"
_launch_qemu -drive file="${TEST_IMG}",cache=${CACHEMODE},id=disk
h=$QEMU_HANDLE
QEMU_COMM_TIMEOUT=1
_send_qemu_cmd $h "drive_backup disk ${TEST_IMG}.copy" "(qemu)"
qemu_cmd_repeat=20 _send_qemu_cmd $h "info block-jobs" "No active jobs"
_send_qemu_cmd $h 'quit' ""
# Base image sectors
TEST_IMG="${TEST_IMG}.copy" io readv $(( offset )) 512 1024 32
# Image sectors
TEST_IMG="${TEST_IMG}.copy" io readv $(( offset + 512 )) 512 1024 64
# Zero sectors beyond end of base image
TEST_IMG="${TEST_IMG}.copy" io_zero readv $(( offset + 32 * 1024 )) 512 1024 32
_check_test_img _check_test_img
# success, all done # success, all done

269
tests/qemu-iotests/028.out
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