The meaning of first_logical_block in do_mpage_readpage - Kernel

This is a discussion on The meaning of first_logical_block in do_mpage_readpage - Kernel ; hi, it may be a stupid question, but I am not quite clear about what "first_logical_block" is used for as one of parameters of "do_mpage_readpage". I searched all the source code and I found that "first_logical_block" always equals zero when ...

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Thread: The meaning of first_logical_block in do_mpage_readpage

  1. The meaning of first_logical_block in do_mpage_readpage

    hi, it may be a stupid question, but I am not quite clear about what
    "first_logical_block" is used for as one of parameters of
    "do_mpage_readpage".

    I searched all the source code and I found that "first_logical_block"
    always equals zero when passed to "do_mpage_readpage" and is used
    only in scope of "do_mpage_readpage".

    This makes me wonder about:
    1. when should "first_logical_block" passed as non-zero values ?
    2. why "first_logical_block" is one of args of "do_mpage_readpage"
    instead of being a local variable of it ? ( it seems that no one uses
    "first_logical_block" outside "do_mpage_readpage")

    Anyone can help me out .
    Thanks in advance!
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  2. Re: The meaning of first_logical_block in do_mpage_readpage

    sorry, I think I've found the point.
    first_logical_block is passed out in a "for" loop in "mpage_readpages"
    and passed again to the next "do_mpage_readpage".

    Sorry for the haste asking.


    On 10/21/07, Nai XIA wrote:
    > hi, it may be a stupid question, but I am not quite clear about what
    > "first_logical_block" is used for as one of parameters of
    > "do_mpage_readpage".
    >
    > I searched all the source code and I found that "first_logical_block"
    > always equals zero when passed to "do_mpage_readpage" and is used
    > only in scope of "do_mpage_readpage".
    >
    > This makes me wonder about:
    > 1. when should "first_logical_block" passed as non-zero values ?
    > 2. why "first_logical_block" is one of args of "do_mpage_readpage"
    > instead of being a local variable of it ? ( it seems that no one uses
    > "first_logical_block" outside "do_mpage_readpage")
    >
    > Anyone can help me out .
    > Thanks in advance!
    >

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