JFFS2: truncated files after power loss scenario

Sven svenjaborek at gmx.de
Sun Feb 6 10:47:27 EST 2011


> > I took a look at this, because we have seen a truncated configuration file once. I'm not sure what caused this. Perhaps a power loss during write.
> How big was this file?

9445 bytes.

> > I wonder about the Inode #42 Version 5 to 9 and about why two Dirent exist(ed) for #ino 42.
> > Do you think this was caused by a power loss scenario?

> Please, give more information:
> 1. Your flash type, if NAND - page size.

Need to check this. Page size is 128k i think.

> 2. What do you do to the file in your test - how exactly you change it.

I did two tests.
First one is a bash script running an endless loop. It creates new files
over and over by copying the 9445 bytes size file every time with a new
A power loss with this script running always produced the truncated last
file. It had the size of 4k or 8k then.

The second test reflects more our simple use case. A C-program which
uses fopen with "w+", and then uses GLib GKeyFile operations to modify a
key and then store the file again. An fclose follows of course.

> 3. How big is the file?
9445 bytes

Please, could you say something general about what the journaling in
jffs2+nand should be able to do about power loss scenarios? I could not
find specs about that.

br, Sven

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