xfs: fix a double completion for buffers on in-memory targets

__xfs_buf_submit calls xfs_buf_ioend when b_io_remaining hits zero.  For
in-memory buftargs b_io_remaining is never incremented from it's initial
value of 1, so this always happens.  Thus the extra call to xfs_buf_ioend
in _xfs_buf_ioapply causes a double completion.  Fortunately
__xfs_buf_submit is only used for synchronous reads on in-memory buftargs
due to the peculiarities of how they work, so this is mostly harmless and
just causes a little extra work to be done.

Fixes: 5076a6040ca1 ("xfs: support in-memory buffer cache targets")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index dc219678003cfb7705e4a1952d9df10e529066dd..0e438c4267ef25f271ee16f19f783118b293a5ab 100644 (file)
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1658,10 +1658,8 @@ _xfs_buf_ioapply(
        op |= REQ_META;
 
        /* in-memory targets are directly mapped, no IO required. */
-       if (xfs_buftarg_is_mem(bp->b_target)) {
-               xfs_buf_ioend(bp);
+       if (xfs_buftarg_is_mem(bp->b_target))
                return;
-       }
 
        /*
         * Walk all the vectors issuing IO on them. Set up the initial offset