Commit d40593dd authored by Kevin Wolf's avatar Kevin Wolf
Browse files

block/backup: Fix hang for unaligned image size 



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: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
parent 675879f6

block/backup.c

+1 −1
Original line number Diff line number Diff line
@@ -307,7 +307,7 @@ static void coroutine_fn backup_run(void *opaque) 
                                BACKUP_SECTORS_PER_CLUSTER - i, &n);

                    i += n;



                    if (alloced == 1) {

                    if (alloced == 1 || n == 0) {

                        break;

                    }

                }

tests/qemu-iotests/028

+26 −1
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ status=1 # failure is the default! 


_cleanup()

{

    rm -f "${TEST_IMG}.copy"

    _cleanup_test_img

}

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.filter

. ./common.pattern

. ./common.qemu



# Any format supporting backing files except vmdk and qcow which do not support

# smaller backing files.
@@ -99,6 +101,29 @@ _check_test_img 
# Rebase it on top of its base image

$QEMU_IMG rebase -b "$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



# success, all done

tests/qemu-iotests/028.out

+269 −0

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