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    Subject[RFC PATCH 31/37] iterate_xarray(): only of the first iteration we might get offset != 0
    Date
    recalculating offset on each iteration is pointless - on all subsequent
    passes through the loop it will be zero anyway.

    Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
    ---
    lib/iov_iter.c | 6 +++---
    1 file changed, 3 insertions(+), 3 deletions(-)

    diff --git a/lib/iov_iter.c b/lib/iov_iter.c
    index c1580e574d76..9ecbf59c3378 100644
    --- a/lib/iov_iter.c
    +++ b/lib/iov_iter.c
    @@ -70,9 +70,9 @@
    __label__ __out; \
    size_t __off = 0; \
    struct page *head = NULL; \
    - size_t offset; \
    loff_t start = i->xarray_start + i->iov_offset; \
    - pgoff_t index = start >> PAGE_SHIFT; \
    + unsigned offset = start % PAGE_SIZE; \
    + pgoff_t index = start / PAGE_SIZE; \
    int j; \
    \
    XA_STATE(xas, i->xarray, index); \
    @@ -89,7 +89,6 @@
    for (j = (head->index < index) ? index - head->index : 0; \
    j < thp_nr_pages(head); j++) { \
    void *kaddr = kmap_local_page(head + j); \
    - offset = (start + __off) % PAGE_SIZE; \
    base = kaddr + offset; \
    len = PAGE_SIZE - offset; \
    len = min(n, len); \
    @@ -100,6 +99,7 @@
    n -= len; \
    if (left || n == 0) \
    goto __out; \
    + offset = 0; \
    } \
    } \
    __out: \
    --
    2.11.0
    \
     
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