[CRIU] [PATCH 1/2] mount: fill fstypes for btrfs mounts on restore

[Pavel Emelyanov]

On 04/18/2014 11:16 AM, Andrew Vagin wrote:
> On Thu, Apr 17, 2014 at 05:34:43PM +0400, Pavel Emelyanov wrote:
>> On 04/17/2014 03:04 PM, Andrew Vagin wrote:
>>> BTRFS returns subvolume dev-id instead of superblock dev-id,
>>> so we need to know which mounts are btrfs.
>>>
>>> Signed-off-by: Andrew Vagin <avagin at openvz.org>
>>> ---
>>>  include/fs-magic.h |  4 ++++
>>>  mount.c            | 13 +++++++++++++
>>>  2 files changed, 17 insertions(+)
>>>
>>> diff --git a/include/fs-magic.h b/include/fs-magic.h
>>> index 9db3ee9..12bb982 100644
>>> --- a/include/fs-magic.h
>>> +++ b/include/fs-magic.h
>>> @@ -33,4 +33,8 @@
>>>  #define DEVPTS_SUPER_MAGIC	0x1cd1
>>>  #endif
>>>  
>>> +#ifndef BTRFS_SUPER_MAGIC
>>> +#define BTRFS_SUPER_MAGIC	0x9123683E
>>> +#endif
>>> +
>>>  #endif /* __CR_FS_MAGIC_H__ */
>>> diff --git a/mount.c b/mount.c
>>> index 043b2c3..cddaf7f 100644
>>> --- a/mount.c
>>> +++ b/mount.c
>>> @@ -25,6 +25,8 @@
>>>  #include "namespaces.h"
>>>  #include "protobuf.h"
>>>  #include "kerndat.h"
>>> +#include "fs-magic.h"
>>> +
>>>  #include "protobuf/mnt.pb-c.h"
>>>  
>>>  /*
>>> @@ -1230,6 +1232,17 @@ static int do_mount_one(struct mount_info *mi)
>>>  	if (ret == 0 && propagate_mount(mi))
>>>  		return -1;
>>>  
>>> +	if (mi->fstype->code == FSTYPE__UNSUPPORTED) {
>>> +		struct statfs st;
>>> +
>>> +		if (statfs(mi->mountpoint, &st)) {
>>> +			pr_perror("Unable to statfs %s", mi->mountpoint);
>>> +			return -1;
>>> +		}
>>> +		if (st.f_type == BTRFS_SUPER_MAGIC)
>>> +			mi->fstype = find_fstype_by_name("btrfs");
>>
>> mi->fstype = find_fstype_by_name(mi->fstype->name)?
> 
> mi->fstype->name is "unsuppoerted" here, because fstype->code is saved in an image
> {
> .name = "unsupported",
> .code = FSTYPE__UNSUPPORTED,
> }, 
> {
> .name = "btrfs",
> .code = FSTYPE__UNSUPPORTED,
> }
> 
> An a second reason is that pocesses can be migrated from smth to btrfs.

That's all nice, but this can happen _only_ for the root mount.
Can we move this check int do_mount_root()?

>>
>>> +	}
>>> +
>>>  	return ret;
>>>  }
>>>  
>>>
>>
>>
> .
>