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

[Andrey Wagin]

2014-04-18 13:03 GMT+04:00 Pavel Emelyanov <xemul at parallels.com>:
> 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()?

And for bind mounts of the root mount...

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