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Re: puzzling error message



On Wed, 9 Jan 2002, Stephen C. Tweedie wrote:
> On Tue, Jan 08, 2002 at 03:27:19PM -0800, Andrew Morton wrote:
> 
>> > What is weird is that in this recent case, and the one before, the
>> > corruption has been in partitions that I would have thought
>> > wouldn't be written too, e.g. I could understand if, while writing
>> > to /home I got trashed data, but I didn't expect /usr to be
>> > corrupted simply by reading it? Unless the head in the HDD had
>> > crashed but I would have expected the Win2000 partion to be
>> > affected as well and it doesn't seem upset at the moment.
>> 
>> The journal contains, basically, a list of block numbers (4-byte
>> integers) and then the block contents themselves.  On recovery,
>> we read the block numbers, save them in memory, then read that
>> many blocks and write them out into the fs.
>> 
>> So if the "list of block numbers" gets corrupted, the recovery
>> data will be sprayed all over the disk :(
> 
> No, we should be safe from that.  The recovery is done on the
> partition's own minor device, not on the whole-disk device, and the
> block layer does bounds checking on that.

Well, that's kind of nice to know. Is it possible for corruption of that
list to cause blocks to be written to the wrong place within the single
partition?

        Daniel

-- 
`geek' --- a carnival performer often billed as a wild man whose act usually
includes biting the head off a live chicken or snake.
        -- Webster's New Collegiate Dictionary, edition 1977





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