Hi,
There seems to be a bug in sector calculation which may trigger with
e.g. corrupted fs. I just made a PR for this,
https://github.com/apache/incubator-nuttx/pull/3740
But I really don't know if this is related to your issues, this is just
something that suddenly popped up elsewhere.
-Jukka
On 18.5.2021 16.10, Reto Gähwiler wrote:
Dear All,
First of all, in case a similar thread pops-up authored by myself, please
ignore.
Recently we discovered some issues with the FAT32 partition on the SD-Card
used in our device running on nuttx. There are actually a bunch of issues
we are strugle to understand related to the filesystem.
The issue discovered recently is, that a statfs call won't return the true
number of free clusters. It rather returns what ever is in the FS INFO
section of the FAT32 partition. Inserting such a "corrupted" card into an
SD-Card reader and mounting it to Windows shows following:
#1 Windows file explorer reports the correct free space.
#2 Comparing the free space in file explorer and looging at FS INFO section
with "Active - Disk Editor" doesn't line up. Windows wouldn't write any
longer the FS INFO section on that card. Even if all the files/dires are
wiped from the card.
#3 Whenever files are added / removed under nuttx the FS INFO section would
be updated by nuttx, but to the wrong number since the base is wrong.
#4 Mounting the card to linux and properly unmount it might actually fix
the issue. But not always!
#5 Quick format the card resolved the issue too. Windows would once again
write the FS INFO section and nuttx would shows the correct free space.
#5 Running a "chkdsk /f" under windows on that broken SD-Card fixes the
issue too. Reporting a broken file in a root folder on that card.
We indeed had issues with corrupted files in the past. Usually in the
logging directory, which is accessed most. How they corrupt we do not know.
The corruption is recognised in the following ways:
#A cryptic and too long file names, we only make use of short file names
(8.3)
#B files whcih became folders
#C sizes which are not possible
#D combinations of the above
Our application supervises the SD-Card with statfs and removes files once
we hit a quota of 0.85. Therefore, the card is not filling up. However, the
most recent recognition of this behvaiour was due to an application bug
which allowed the card to fill up under some circumstances.
Playing around with a quickformated SD-Card, filled up with data and trying
to retrigger the issue revealed that I never get the ENOSPC but only EIO
once the card is full! But never managed to get the statfs issue.
For the logging we use the fstream family (fopen, fwrite, fread, fflush,
fsync) commands. For config files and other things also the low level
read/write are used.
One more thing, among all the logging files we once in a while have
corrupted file content. Typically that is a skipped byte or doubled byte
(we use protobuf and can see that encoding the binary). This seems to
happen during reading but also writing the file.
At the moment we didn't investigate the fat driver of nuttx but rather
tried to analyse the problem. And now we have a bunch of question marks.
#1 Has anyone recongised similar issues?
#2 Does anyone know a tool which can be used in nuttx equivalent to chkdsk
under windows? Or do quick format?
#3 Why is there no ENOSPC but EIO once the card is full?
#4 What triggers the corrupted files? How robust is the nuttx FAT32
considering stackdumps and powerlosses?
For the purpose of investigation, I have an image of the SD-Card when it
was in the state of reporting wrong sizes in nuttx.
Looking forward to your answers and ideas. Appreciate your help,
Reto
