[Toybox] Stat, wrong blockcount for F2FS filesystems?

[enh]

thanks. replied on the list, s/i/drosen/ :-)

On Fri, Apr 7, 2017 at 6:55 PM, enh <enh at google.com> wrote:

> yeah, there was a stat bug that was fixed. some filesystems modify the
> block value before passing it back. drosen fixed sdcardfs to look at this
> in "ANDROID: sdcardfs: Get the blocksize from the lower fs":
>
> int f2fs_getattr(struct vfsmount *mnt,
> struct dentry *dentry, struct kstat *stat)
> {
> struct inode *inode = dentry->d_inode;
> generic_fillattr(inode, stat);
> stat->blocks <<= 3;
> return 0;
> }
>
> so that's where the factor of 8 would come from.
>
>
> On Fri, Apr 7, 2017 at 11:31 AM, darken <darken at darken.eu> wrote:
>
>> Wrong train of thought, toybox stat doesn't do any blockcount
>> calculation, but just gets the value from `st_blocks`.
>>
>> We are getting bad values from `/storage/emulated/0` which is FUSE
>> mounted from `/data/media/0` and the blockcount values from `/data/media/0`
>> are sane.
>>
>> So this seems to be FUSE related...
>>
>> ~Matthias
>>
>> 2017-04-07 18:10 GMT+02:00 darken <darken at darken.eu>:
>>
>>> I'm using stat to display filesize and allocated size in my Android app.
>>>
>>> I calculate the allocated size by multiplying the block count (%b) with
>>> 512 Byte.
>>>
>>> I found out in https://github.com/landley/toybox/issues/41 that the
>>> blocksize for the blockcount calculation is hardcoded to 512. So this
>>> should work well (and has so far).
>>>
>>> Now a user of my app noticed that on their F2FS filesystem the allocated
>>> size is suspiciously small:
>>> https://github.com/d4rken/sdmaid-public/issues/830
>>>
>>> Specifically too small by a factor of 8, as if the blocksize used for
>>> blockcount calculation is 4096 (4096/512).
>>>
>>> Could stat have a problem with calculating the blockcount on F2FS
>>> filesystems or am I overlooking something else?
>>>
>>> ~Matthias
>>>
>>
>>
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>>
>
>
> --
> Elliott Hughes - http://who/enh - http://jessies.org/~enh/
> Android native code/tools questions? Mail me/drop by/add me as a reviewer.
>



-- 
Elliott Hughes - http://who/enh - http://jessies.org/~enh/
Android native code/tools questions? Mail me/drop by/add me as a reviewer.
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