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    SubjectRe: [RFC] Generic deferred file writing


    On Sat, 30 Dec 2000, Alexander Viro wrote:
    >
    > Except that we've got file-expanding writes outside of ->i_sem. Thanks, but
    > no thanks.

    No, Al, the file size is still updated inside i_sem.

    Yes, it will do actual block allocation outside i_sem, but that is already
    true of any mmap'ed writes, and has been true for a long long time. So if
    we have a bug here (and I don't think we have one), it's not something
    new. But the inode semaphore doesn't protect the balloc() data structures
    anyway, as they are filesystem-global.

    If you're nervous about the effects of "truncate()", then that should be
    handled properly by truncate_inode_pages().

    In short, I don't see _those_ kinds of issues. I do see error reporting as
    a major issue, though. If we need to do proper low-level block allocation
    in order to get correct ENOSPC handling, then the win from doing deferred
    writes is not very big.

    Linus

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