Re: Bug 1227257

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王松波你好,

Thanks a lot for reporting a bug and providing a patch for it. However,
you will need to send the patch using git send-email to this mailing
list: it will ease the review and integration in master.

Thanks a lot for your help,

--
Cedric

On Tue, 2015-06-02 at 20:27 +0800, 王松波 wrote:
> I report a bug [Bug 1227257] . In the environment
>  libvirt-1.2.16.tar.gz + qemu-img version 2.1.2 + ceph version 0.94.1.
> libvirt pool will become inactive after one client does vol.delete and
> the other does pool.refresh in the same pool simultaneously.
> 
> 
> The reason is that rbd_list and  rbd_open are not wrapped in an atomic
> operation, but two seperate operations.
> For example, two clients are operating in the same pool at the same
> time. One client does rbd_list, and got 10 rbd images, meanwhile, the
> other client deletes one of the rbd image. In this situation, when the
> first client does next operation, such as rbd_open , the command may
> fail, because the rbd image has been removed.
> 
> 
> I write a testcase in python to reproduce this problem as follow(also
> have put it in the attachment):
> ##################################
> import libvirt
> import sys
> import time
> import sys
> #coding:utf-8
> 
> 
> QEMU_URL = 'qemu:///system'
> 
> 
> VOL_TEMPLATE='''
> <volume>
>     <name>{vol}</name>
>     <key>{pool}/{vol}</key>
>     <source>
>     </source>
>     <capacity unit='MB'>{cap_size}</capacity>
>     <allocation unit='MB'>{alloc_size}</allocation>
>     <target>
>         <path>rbd:{pool}/{vol}</path>
>         <format type='unknown'/>
>         <permissions>
>             <mode>00</mode>
>             <owner>0</owner>
>             <group>0</group>
>         </permissions>
>     </target>
> </volume>'''
> 
> 
> def create_vol(pool_name, vol_name, cap_size, alloc_size):
>     conn = libvirt.open(QEMU_URL)
>     if conn == None:
>         print 'Failed to open connection to the hypervisor'
>         sys.exit(1)
> 
> 
>     try:
>         pool = conn.storagePoolLookupByName(pool_name)
>         pool.refresh()
>         template = VOL_TEMPLATE.format(pool=pool_name, vol=vol_name,
> cap_size=cap_size, alloc_size=alloc_size)
>         pool.createXML(template, 0)
>     except:
>         print 'Failed to open pool'
>         sys.exit(1)
>     finally:
> if conn is not None:
>             conn.close()
> 
> 
> def destroy_vol(pool_name, vol_name):
>     conn = libvirt.open(QEMU_URL)
>     if conn == None:
>         sys.exit(1)
>     pool = conn.storagePoolLookupByName(pool_name)
>     pool.refresh(0) 
>     vol = pool.storageVolLookupByName(vol_name)
>     if vol is not None:
>         vol.delete(0)
>     if conn is not None:
>          conn.close()
> 
> 
> if  sys.argv[2] == 'create':
>     for i in range(1, 20):
> volname = 'pool-down-test-%s-%d' % (sys.argv[1], i)
>         print 'create %s' % volname
>         create_vol('capacity', volname, '500', '500')
> elif sys.argv[2] == 'destroy':
>     for i in range(1, 20):
> volname = 'pool-down-test-%s-%d' % (sys.argv[1], i)
>         print 'destroy %s' % volname
>         destroy_vol('capacity', volname)
> else:
>     print 'Usage: python vol-test.py clientId OPER'
>     print '  '
>     print 'where  clientId : a num/string used to distinguish
> different client'
>     print '       OPER     : create/destroy'
> 
> 
> 
> 
> 
> 
> 
> 
> Patch for this is as fllow:
> 
> 
> diff --git a/src/storage/storage_backend_rbd.c
> b/src/storage/storage_backend_rbd.c
> index ae4bcb3..24fbc84 100644
> --- a/src/storage/storage_backend_rbd.c
> +++ b/src/storage/storage_backend_rbd.c
> @@ -266,6 +266,46 @@ static int
> virStorageBackendRBDCloseRADOSConn(virStorageBackendRBDStatePtr ptr)
>      return ret;
>  }
> 
> 
> +static int volStorageBackendRBDVolIsExist(char *volname,
> virStorageBackendRBDStatePtr ptr)
> +{
> +    int ret = -1;
> +    char *name, *names = NULL;
> +    size_t max_size = 1024;
> +    int len = -1;
> +
> +    while (true) {
> +        if (VIR_ALLOC_N(names, max_size) < 0)
> +            goto cleanup;
> +
> +        len = rbd_list(ptr->ioctx, names, &max_size);
> +        if (len >= 0)
> +            break;
> +        if (len != -ERANGE) {
> +            VIR_WARN("%s", _("A problem occurred while listing RBD
> images"));
> +            goto cleanup;
> +        }
> +        VIR_FREE(names);
> +    }
> +
> +    for (name = names; name < names + max_size;) {
> +
> +        if (STREQ(name, ""))
> +            break;
> +
> +        name += strlen(name) + 1;
> +        if (STREQ(volname, name)) {
> +            VIR_ERROR("RBD images '%s' is exist, but cannot open it",
> volname);
> +            ret = -2;
> +            break;
> +        }
> +    }
> +    ret = 0;
> +
> +cleanup:
> +    VIR_FREE(names);
> +    return ret;
> +}
> +
>  static int volStorageBackendRBDRefreshVolInfo(virStorageVolDefPtr
> vol,
>                                                virStoragePoolObjPtr
> pool,
> 
>  virStorageBackendRBDStatePtr ptr)
> @@ -276,8 +316,15 @@ static int
> volStorageBackendRBDRefreshVolInfo(virStorageVolDefPtr vol,
> 
> 
>      r = rbd_open(ptr->ioctx, vol->name, &image, NULL);
>      if (r < 0) {
> -        virReportSystemError(-r, _("failed to open the RBD image '%
> s'"),
> -                             vol->name);
> +        VIR_DEBUG("failed to open RBD image '%s', check if it was
> still exist in its pool",\
> +                  vol->name);
> +        if (volStorageBackendRBDVolIsExist(vol->name, ptr) == 0) {
> +            VIR_DEBUG("vol '%s' may be removed by the other rbd
> client", vol->name);
> +            ret = 0;
> +        } else {
> +            virReportSystemError(-r, _("failed to open the RBD image
> '%s'"),
> +                    vol->name);
> +        }
>          return ret;
>      }
> --
> libvir-list mailing list
> libvir-list@xxxxxxxxxx
> https://www.redhat.com/mailman/listinfo/libvir-list


--
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