[lkml]   [1999]   [Dec]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [CFT][PATCH] block_write_*_buffer rewrite

    On Wed, 1 Dec 1999, Ingo Molnar wrote:

    > the problem is generic_file_write() locking the page while generating a
    > page fault (to the same page).

    OK, folks. Proposed fix:
    a) new function: pin_user_page(address); finds a page, faults it
    in, does get_page() and returns the struct page *.
    b) generic_file_write() doing it on consequent pages of user data
    _before_ calling write_one_page() and releasing them once they are not
    needed (we can have at most 2 at any moment).
    c) block_write_partial_page() and friends use memcpy() instead of
    copy_from_user(). verify_area() is done by generic_file_write().

    Comments? The new rule being that we should never do
    copy_from_user() while holding lock on any page and should pin the source
    while we don't hold any locks.

    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    Please read the FAQ at

     \ /
      Last update: 2005-03-22 13:55    [W:0.021 / U:0.344 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site