On Tue, Nov 27, 2018 at 08:49:48PM -0700, Allison Henderson wrote: > This patch adds a new field b_rw_hint to xfs_buf. We will > need this to properly initialize the new bio->bi_rw_hint when > submitting the read request. When the read completes, we > then store the returned mirror in the b_rw_hint. > > Signed-off-by: Allison Henderson <[email protected]> > --- > fs/xfs/xfs_buf.c | 5 ++++- > fs/xfs/xfs_buf.h | 7 +++++++ > 2 files changed, 11 insertions(+), 1 deletion(-) > > diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c > index b21ea2b..dd8ba59 100644 > --- a/fs/xfs/xfs_buf.c > +++ b/fs/xfs/xfs_buf.c > @@ -1322,8 +1322,10 @@ xfs_buf_bio_end_io( > if (!bp->b_error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ)) > invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp)); > > - if (atomic_dec_and_test(&bp->b_io_remaining) == 1) > + if (atomic_dec_and_test(&bp->b_io_remaining) == 1) { > + bp->b_rw_hint = bio->bi_rw_hint; > xfs_buf_ioend_async(bp); > + } > bio_put(bio); > } >
This will miss setting bp->b_rw_hint for IO that completes before submission returns to __xfs_buf_submit() (i.e. b_io_remaining is 2 at IO completion). So I suspect it won't do the right thing on fast or synchronous block devices like pmem. You should be able to tst this with a RAID1 made from two ramdisks... Cheers, Dave. -- Dave Chinner [email protected]
