Re: df command reports incorrect usage

[Fariya F]

Hi,

The version of df command is 1.85.
Kernel version 4.9.31

The fsck check on that partition succeeds. I am able to use the partition,
create files etc. However df reports incorrectly the size and used
percentage.

Output from strace command is as follows;

statfs64("/data", 88, {f_type="EXT2_SUPER_MAGIC",
f_bsize=1024, f_blocks=18446744073659310077, f_bfree=87628, f_bavail=80460,
f_files=25688, f_ffree=25189, f_fsid={-1446355608, 1063639410},
f_namelen=255, f_frsize=1024, f_flags=4128}) = 0

As can be seen, value of f_blocks is a huge one. How can we get this
corrected and where is the corruption because of which this value goes
wrong?

I am badly stuck up on this! Help is greatly appreciated.

Regards

On Tue, 22 Mar, 2022, 2:52 am Bob Proulx, <bob@proulx.com> wrote:

> Fariya F wrote:
> > My eMMC device has a partition which reports the below output from df -h
> > command:
> >
> > Filesystem       Size  Used Avail Use% Mounted on
> > /dev/mmcblk2p3    16Z   16Z   84M 100% /data
>
> Since the df command is simply reporting back on what the Linux kernel
> reports, and the kernel is reporting data from the file system, this
> looks to be a problem with the file system.  Since this looks like an
> SD card it seems likely that the SD card is not happy.  It would be a
> good idea to test the SD card to see if it has failed.
>
> It would be useful to know at least some information in addition to
> this output.  What is the specific version of df?
>
>     df --version
>
> What kernel version are you using.
>
>     uname -a
>
> Since df is asking for the file system information from the kernel it
> would be useful to know what answer the kernel provided.
>
>     strace -v -e statfs /bin/df -h /data
>
> On my system I see the following from a couple of different examples.
> Just to provide something to show what would be useful.
>
>     rwp@angst:/tmp$ strace -v -e statfs /bin/df -hT /data
>     statfs("/data", {f_type=MSDOS_SUPER_MAGIC, f_bsize=16384,
> f_blocks=2044, f_bfree=857, f_bavail=857, f_files=0, f_ffree=0,
> f_fsid={val=[45826, 0]}, f_namelen=1530, f_frsize=16384,
> f_flags=ST_VALID|ST_RDONLY|ST_RELATIME}) = 0
>     Filesystem     Type  Size  Used Avail Use% Mounted on
>     /dev/mmcblk0p2 vfat   32M   19M   14M  59% /data
>     +++ exited with 0 +++
>
>     root@angst:~# strace -v -e statfs /bin/df -hT /data
>     statfs("/data", {f_type=EXT2_SUPER_MAGIC, f_bsize=4096,
> f_blocks=1924651, f_bfree=673176, f_bavail=579409, f_files=496784,
> f_ffree=417167, f_fsid={val=[961623697, 1875516586]}, f_namelen=255,
> f_frsize=4096, f_flags=ST_VALID|ST_RELATIME}) = 0
>     Filesystem         Type  Size  Used Avail Use% Mounted on
>     /dev/mapper/v1-var ext3  7.4G  4.8G  2.3G  69% /data
>     +++ exited with 0 +++
>
> I looked specifically at the statfs(2) system call here as it provides
> the majority of the information.  This is for a Linux kernel system.
> However if your system is much different then different information
> might be displayed or might be needed.
>
> Bob
>