• Jeff Moyer's avatar
    O_DIRECT: fix the splitting up of contiguous I/O · 7a801ac6
    Jeff Moyer authored
    commit c2c6ca41 (direct-io: do not merge logically non-contiguous requests)
    introduced a bug whereby all O_DIRECT I/Os were submitted a page at a time
    to the block layer.  The problem is that the code expected
    dio->block_in_file to correspond to the current page in the dio.  In fact,
    it corresponds to the previous page submitted via submit_page_section.
    This was purely an oversight, as the dio->cur_page_fs_offset field was
    introduced for just this purpose.  This patch simply uses the correct
    variable when calculating whether there is a mismatch between contiguous
    logical blocks and contiguous physical blocks (as described in the
    I also switched the if conditional following this check to an else if, to
    ensure that we never call dio_bio_submit twice for the same dio (in
    theory, this should not happen, anyway).
    I've tested this by running blktrace and verifying that a 64KB I/O was
    submitted as a single I/O.  I also ran the patched kernel through
    xfstests' aio tests using xfs, ext4 (with 1k and 4k block sizes) and btrfs
    and verified that there were no regressions as compared to an unpatched
    Signed-off-by: default avatarJeff Moyer <jmoyer@redhat.com>
    Acked-by: default avatarJosef Bacik <jbacik@redhat.com>
    Cc: Christoph Hellwig <hch@infradead.org>
    Cc: Chris Mason <chris.mason@oracle.com>
    Cc: <stable@kernel.org>		[2.6.35.x]
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
direct-io.c 35 KB