[Unix-jun72] Anyone working on V1 mkfs?

Tim Newsham newsham at lava.net
Thu May 1 22:45:22 EDT 2008


>  a) the i-mode bitmap is missing bits 0 to 40, but

    The first bit is for i-number 41, yes.
    if(n >= 41) then to check if i-number n is allocated:
        map[(n-41)/8] & (1 << ((n-41)%8)

    if I read the bit ordering correctly.

>  b) the actual i-nodes 0 to 40 do exist, and

    Almost, there is no i-number 0.  The first one is i-number 1 which
    starts at byte zero of block 2.

       inode-block(n) = (n+31)/16
       inode-offset(n) = 32 * ((n+31)%16)

>  c) the system can still "read i-node 7", even if it can't allocate i-node 7.

    sounds like it.

> Let me know if that sounds right, or if I'm off-base somewhere.

Sounds like you got it, except for the i-numbering starting at 1.

> 	Warren

Tim Newsham
http://www.thenewsh.com/~newsham/



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