[Ocfs2-devel] [PATCH 2/3] ocfs2: implement discontiguous localalloc bitmap
Srinivas Eeda
srinivas.eeda at oracle.com
Mon May 7 19:10:32 PDT 2012
Joel Becker wrote:
> On Mon, May 07, 2012 at 04:21:29PM -0700, Srinivas Eeda wrote:
>
>
> OH MY DOG NO. NEVER EVER DO THIS. You cannot update an old
> filesystem on the fly! What about other nodes that are running older
> versions of the software? They will crash or corrupt data! The entire
> point of feature bits is to make sure all nodes are speaking the same
> code.
>
> NAK NAK NAK
>
> This explains why you trusted la_rec_count earlier. But that is
> broken. When your patches are done, the code should use la_bm_off and
> la_bitmap when !DISCONTIG_LA and then use la_rec_count, etc when
> DISCONTIG_LA. The only way to transition between them is a tunefs.ocfs2
> operation that walks the filesystem, flushes the bitmap, and then
> sets/clears la_rec_count appropriately depending on the direction..
>
Please please don't hate me :( ... the changes takes care of old formats
as well ... I used the reserved space in the structure so that the code
changes will be minimal and still compatible with old file system
formats. I agree that we need to have some reserved space still
available. So as discussed I'll redo the changes accordingly. Please
ignore all the patches.
Thanks,
--Srini
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