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    btrfs: properly access unaligned checksum buffer · 7e75bf3f
    David Sterba 提交于
    On Fri, Mar 18, 2011 at 11:56:53AM -0400, Chris Mason wrote:
    > Thanks for fielding this one.  Does put_unaligned_le32 optimize away on
    > platforms with efficient access?  It would be great if we didn't need
    > the #ifdef.
    
    (quicktest: assembly output is same for put_unaligned_le32 and direct
    assignment on my x86_64)
    I was originally following examples in
    Documentation/unaligned-memory-access.txt. From other code it seems to me that
    the define CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS is intended for larger
    portions of code. Macros/wrappers for {put,get}_unaligned* are chosen via
    arch/<arch>/include/asm/unaligned.h accordingly, therefore it's safe to use
    put_unaligned_le32 without the ifdef.
    
    dave
    Signed-off-by: NChris Mason <chris.mason@oracle.com>
    7e75bf3f
disk-io.c 82.7 KB