Messages in this thread | | | Date | Fri, 3 Nov 2006 15:39:24 +0100 (CET) | From | Mikulas Patocka <> | Subject | Re: New filesystem for Linux |
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On Fri, 3 Nov 2006, Nikita Danilov wrote:
> Mikulas Patocka writes: > > > Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz> writes: > > > > > >> new method to keep data consistent in case of crashes (instead > > >> of journaling), > > > > > > What is that method? > > > > Some tricks to avoid journal --- see > > http://artax.karlin.mff.cuni.cz/~mikulas/spadfs/download/INTERNALS > > > > --- unlike journaling it survives only 65536 crashes :) > > What happens when hard-linked file is accessed, and it is found that > last fnode (one in fixed_fnode_block), has wrong "crash count"? > > Nikita.
Fixed fnode block contains (txc,cc) pair describing which fnode and nlink count is valid. --- currently two fnodes are superflous (there could be just one), they are reserved for the possibility to atomically modify extended attributes --- but there is no code currently that does it.
The fnodes live on their own with their own (txc,cc) pair --- it is a bit confusing to have pair on both fixed_fnode_block and fnode --- the reason is that the code for handling fnodes in directories can be reused to handle fnodes in fixed_fnode_blocks and I can avoid many if (is_fnode_fixed()) branches.
If the fnode in fixed_fnode_block has invalid crash count, fixed_fnode_block's (cc,txc) pair should never point to it. Or did it happen to you?
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