[Qemu-devel] snapshot：create snapshot for rbd disk failed.

[Zhangzijian]

Hello,

In 'bdrv_all_create_snapshot', each block will create snapshot in a for loop. 
If a domain configured disk mixed with qcow2 and rbd.
In 'qcow2_snapshot_create', sn_info->id_str will be set. But in 
'qemu_rbd_snap_create' the 'id_str' is checked. 
On this condition, 'id_str' check will be failed. Since 'id_str' is useless for 
rbd, why this check is needed, Can it be removed?

#0  qemu_rbd_snap_create (bs=0x55596a51eba0, sn_info=0x7fff4b0a0d60) at 
/root/code/qemu_201801/block/rbd.c:982
#1  0x0000555967fca15e in bdrv_snapshot_create (bs=0x55596a51eba0, 
sn_info=0x7fff4b0a0d60) at /root/code/qemu_201801/block/snapshot.c:171
#2  0x0000555967fca18d in bdrv_snapshot_create (bs=0x55596a518890, 
sn_info=0x7fff4b0a0d60) at /root/code/qemu_201801/block/snapshot.c:174
#3  0x0000555967fcaf43 in bdrv_all_create_snapshot (sn=0x7fff4b0a0d60, 
vm_state_bs=0x55596a509750, vm_state_size=0, first_bad_bs=0x7fff4b0a0d10)
    at /root/code/qemu_201801/block/snapshot.c:531
#4  0x0000555967ed9362 in save_snapshot (name=0x55596bc37bf0 "snap1", 
nostate=true, errp=0x7fff4b0a10c0) at 
/root/code/qemu_201801/migration/savevm.c:2256
#5  0x0000555967ca9ad7 in hmp_savevm (mon=0x7fff4b0a1180, qdict=0x55596af40d60) 
at /root/code/qemu_201801/hmp.c:1334
#6  0x0000555967b0f034 in handle_hmp_command (mon=0x7fff4b0a1180, 
cmdline=0x55596b4741e7 "-n snap1") at /root/code/qemu_201801/monitor.c:3110
#7  0x0000555967b0872b in qmp_human_monitor_command 
(command_line=0x55596b4741e0 "savevm -n snap1", has_cpu_index=false, 
cpu_index=0, errp=0x7fff4b0a12f0)
    at /root/code/qemu_201801/monitor.c:614