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    io_uring: fix manual setup of iov_iter for fixed buffers · 99c79f66
    Aleix Roca Nonell 提交于
    Commit bd11b3a3 ("io_uring: don't use iov_iter_advance() for fixed
    buffers") introduced an optimization to avoid using the slow
    iov_iter_advance by manually populating the iov_iter iterator in some
    cases.
    
    However, the computation of the iterator count field was erroneous: The
    first bvec was always accounted for an extent of page size even if the
    bvec length was smaller.
    
    In consequence, some I/O operations on fixed buffers were unable to
    operate on the full extent of the buffer, consistently skipping some
    bytes at the end of it.
    
    Fixes: bd11b3a3 ("io_uring: don't use iov_iter_advance() for fixed buffers")
    Cc: stable@vger.kernel.org
    Signed-off-by: NAleix Roca Nonell <aleix.rocanonell@bsc.es>
    Signed-off-by: NJens Axboe <axboe@kernel.dk>
    99c79f66
io_uring.c 83.0 KB