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    SubjectRe: Boot failure with ext2 and initrds
    On Wed, 15 Nov 2006 22:55:43 -0800
    Mingming Cao <cmm@us.ibm.com> wrote:

    > Hmm, maxblocks, in bitmap_search_next_usable_block(), is the end block
    > number of the range to search, not the lengh of the range. maxblocks
    > get passed to ext2_find_next_zero_bit(), where it expecting to take the
    > _size_ of the range to search instead...
    >
    > Something like this: (this is not a patch)
    > @@ -524,7 +524,7 @@ bitmap_search_next_usable_block(ext2_grp
    > ext2_grpblk_t next;
    >
    > - next = ext2_find_next_zero_bit(bh->b_data, maxblocks, start);
    > + next = ext2_find_next_zero_bit(bh->b_data, maxblocks-start + 1, start);
    > if (next >= maxblocks)
    > return -1;
    > return next;
    > }

    yes, the `size' arg to find_next_zero_bit() represents the number of bits
    to scan at `offset'.

    So I think your change is correctish. But we don't want the "+ 1", do we?

    If we're right then this bug could cause the code to scan off the end of the
    bitmap. But it won't explain Hugh's bug, because of the if (next >= maxblocks).

    btw, how come try_to_extend_reservation() uses spin_trylock?
    -
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