On Wed, Dec 07, 2016 at 02:46:34PM -0500, Brian Foster wrote: > Only for end_fsb... xfs_bmap_btalloc() calls xfs_bmap_extsize_align() > with the alignment, which rounds out the start and end offsets. ... and corrupts data in the direct I/O case. The problem is that the down-alignment in xfs_bmap_extsize_align will now create a real extent that spans before the extent that we have to COW in this write_begin call. But the area before might have been a hole before the dio write that had just before been filled with an allocation in the data fork. And due to the direct I/O end_io interface that only covers the range of the whole write we don't know at that point where exactly the COW operation started and will happily splice back our front pad into the data fork, replacing the just written data with garbage. xfs/228 and sometimes generic/199 reproduce this nicely. -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
