From: Filipe Manana <fdman...@suse.com>

If a bio for a direct IO request fails, we were not setting the error in
the parent bio (the main DIO bio), making us not return the error to
user space in btrfs_direct_IO(), that is, it made __blockdev_direct_IO()
return the number of bytes issued for IO and not the error a bio created
and submitted by btrfs_submit_direct() got from the block layer.
This essentially happens because when we call:

   dio_end_io(dio_bio, bio->bi_error);

It does not set dio_bio->bi_error to the value of the second argument.
So just add this missing assignment in endio callbacks, just as we do in
the error path at btrfs_submit_direct() when we fail to clone the dio bio
or allocate its private object.

This was detected by the new generic test cases in xfstests: 271, 272,
276 and 278. Which essentially setup a dm error target, then load the
error table, do a direct IO write and unload the error table. They
expect the write to fail with -EIO, which was not getting reported
when testing against btrfs.

Cc: sta...@vger.kernel.org
Signed-off-by: Filipe Manana <fdman...@suse.com>
---
 fs/btrfs/inode.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 600bf0d..e0ad8b2 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -7985,6 +7985,7 @@ static void btrfs_endio_direct_read(struct bio *bio)
 
        kfree(dip);
 
+       dio_bio->bi_error = bio->bi_error;
        dio_end_io(dio_bio, bio->bi_error);
 
        if (io_bio->end_io)
@@ -8039,6 +8040,7 @@ static void btrfs_endio_direct_write(struct bio *bio)
 
        kfree(dip);
 
+       dio_bio->bi_error = bio->bi_error;
        dio_end_io(dio_bio, bio->bi_error);
        bio_put(bio);
 }
-- 
2.7.0.rc3

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