Re: [RFC] TileFS - a proposal for scalable integrity checking

[Nikita Danilov <nikita@clusterfs.com>]

Valerie Henson writes:

[...]

 > 
 > Hm, I'm not sure that everyone understands, a particular subtlety of
 > how the fsck algorithm works in chunkfs.  A lot of people seem to
 > think that you need to check *all* cross-chunk links, every time an
 > individual chunk is checked.  That's not the case; you only need to
 > check the links that go into and out of the dirty chunk.  You also
 > don't need to check the other parts of the file outside the chunk,
 > except for perhaps reading the byte range info for each continuation
 > node and making sure no two continuation inodes think they both have
 > the same range, but you don't check the indirect blocks, block
 > bitmaps, etc.

I guess I miss something. If chunkfs maintains "at most one continuation
per chunk" invariant, then continuation inode might end up with multiple
byte ranges, and to check that they do not overlap one has to read
indirect blocks (or some equivalent data-structure).

Nikita.