Re: Linux 2.6.29

Harald Arnesen
2009-04-01T22:00:34Z

david@lang.hm writes:

>> Understood that it's not deliberate just careless. The two behaviors
>> which are reported are (a) updating a record in an existing file and
>> having the entire file content vanish, and (b) finding some one
>> else's old data in my file - a serious security issue. I haven't
>> seen any report of the case where a process unlinks or truncates a
>> file, the disk space gets reused, and then the systems fails before
>> the metadata is updated, leaving the data written by some other
>> process in the file where it can be read - another possible security
>> issue.
>
> ext3 eliminates this security issue by writing the data before the
> metadata. ext4 (and I thing XFS) eliminate this security issue by not
> allocating the blocks until it goes to write the data out. I don't
> know how other filesystems deal with this.

I've been wondering about that during the last days. How abut JFS and
data loss (files containing zeroes after a crash), as compared to ext3,
ext4, ordered and writeback journal modes? Is is safe?
--
Hilsen Harald.