Re: btrfs fi du -s gives Inappropriate ioctl for device

[Nikolay Borisov <nborisov@suse.com>]

On 17.08.2017 23:59, Goffredo Baroncelli wrote:
> Hi,
> 
> On 08/17/2017 08:43 PM, Chris Murphy wrote:
>> # btrfs sub create test1
>> Create subvolume './test1'
>> # btrfs sub create test1/test2
>> Create subvolume 'test1/test2'
>> # btrfs sub snap test1 test1.snap
>> Create a snapshot of 'test1' in './test1.snap'
>> # btrfs fi du -s test1
>>      Total   Exclusive  Set shared  Filename
>>      0.00B       0.00B       0.00B  test1
>> # btrfs fi du -s test1.snap
>>      Total   Exclusive  Set shared  Filename
>> ERROR: cannot check space of 'test1.snap': Inappropriate ioctl for device
>> #
>>
> 
> tanks for the test case. Now I was able to reproduce the problem. The bug(s) are two:
> 
> 1) to get the treeid of the files/directory, the function lookup_path_rootid() is used, which behaves strangely when it is called on a directory that is BTRFS_EMPTY_SUBVOL_DIR_OBJECTID. In fact this function is commented as following:
> [....]
> /*
>  * For a given:
>  * - file or directory return the containing tree root id
>  * - subvolume return its own tree id
>  * - BTRFS_EMPTY_SUBVOL_DIR_OBJECTID (directory with ino == 2) the result is
>  *   undefined and function returns -1
>  */
> int lookup_path_rootid(int fd, u64 *rootid)
> {
> [....]
> 
> The caller (du_add_file()) doesn't consider this case.
> 
> 2) in the function du_walk_dir(), an error returned by du_add_file() is ignored, but the return value is not reset. So if the last entry has ino BTRFS_EMPTY_SUBVOL_DIR_OBJECTID (directory with ino == 2) an error is returned. But if there is another directory item no error is returned !
> 
> See the following tests cases:
> 
> # btrfs sub create test1
> # btrfs sub create test1/test2
> # btrfs sub snap test1 test1.snap
> # btrfs fi du -s test1
>      Total   Exclusive  Set shared  Filename
>      0.00B       0.00B       0.00B  test1
> # btrfs fi du -s test1.snap
>      Total   Exclusive  Set shared  Filename
> ERROR: cannot check space of 'test1.snap': Inappropriate ioctl for device
> 
> But if you add *another* file/dir in test1.snap you got:
> 
> # mkdir test1.snap/dir
> # btrfs fi du -s test1.snap
>      Total   Exclusive  Set shared  Filename
>      0.00B       0.00B       0.00B  test1.snap
> 
> The error disappea> Patches will follow shortly

It would be awesome if you manage to introduce xfstests for this case

> 
>>
>> # uname -r
>> 4.13.0-0.rc4.git1.1.fc27.x86_64
>> # rpm -q btrfs-progs
>> btrfs-progs-4.12-1.fc27.x86_64
>>
>>
>> ----
>> Chris Murphy
>>
> 
>