Re: [LTP] [linus:master] [iomap] 219580eea1: ltp.writev07.fail

[Cyril Hrubis <chrubis@xxxxxxx>]

Hi!
> I can't reproduce this on current mainline.  Is this a robust failure
> or flapping test?  Especiall as the FAIL conditions look rather
> unrelated.

Actually the test is spot on, the difference is that previously the
error was returned form the iomap_file_buffered_write() only if we
failed with the first buffer from the iov, now we always return the
error and we do not advance the offset.

The change that broke it:

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 063133ec77f4..550525a525c4 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -864,16 +864,19 @@ iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *i,
                .len            = iov_iter_count(i),
                .flags          = IOMAP_WRITE,
        };
-       int ret;
+       ssize_t ret;

        if (iocb->ki_flags & IOCB_NOWAIT)
                iter.flags |= IOMAP_NOWAIT;

        while ((ret = iomap_iter(&iter, ops)) > 0)
                iter.processed = iomap_write_iter(&iter, i);
-       if (iter.pos == iocb->ki_pos)
+
+       if (unlikely(ret < 0))
                return ret;
-       return iter.pos - iocb->ki_pos;
+       ret = iter.pos - iocb->ki_pos;
+       iocb->ki_pos += ret;
+       return ret;
 }

I suppose that we shoudl fix is with something as:

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index adb92cdb24b0..bfb39f7bc303 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -872,11 +872,12 @@ iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *i,
        while ((ret = iomap_iter(&iter, ops)) > 0)
                iter.processed = iomap_write_iter(&iter, i);

+       iocb->ki_pos += iter.pos - iocb->ki_pos;
+
        if (unlikely(ret < 0))
                return ret;
-       ret = iter.pos - iocb->ki_pos;
-       iocb->ki_pos += ret;
-       return ret;
+
+       return iter.pos - iocb->ki_pos;
 }
 EXPORT_SYMBOL_GPL(iomap_file_buffered_write);


-- 
Cyril Hrubis
chrubis@xxxxxxx