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From:   Evan Green <evgreen@chromium.org>
To:     Jens Axboe <axboe@kernel.dk>,
        Martin K Petersen <martin.petersen@oracle.com>
Cc:     Gwendal Grignou <gwendal@chromium.org>,
        Christoph Hellwig <hch@infradead.org>,
        Ming Lei <ming.lei@redhat.com>,
        "Darrick J . Wong" <darrick.wong@oracle.com>,
        Alexis Savery <asavery@chromium.org>,
        Douglas Anderson <dianders@chromium.org>,
        Bart Van Assche <bvanassche@acm.org>,
        Evan Green <evgreen@chromium.org>, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH v7 1/2] loop: Report EOPNOTSUPP properly
Date:   Thu, 14 Nov 2019 15:50:07 -0800
Message-Id: <20191114154903.v7.1.I0b2734bafaa1bd6831dec49cdb4730d04be60fc8@changeid>
In-Reply-To: <20191114235008.185111-1-evgreen@chromium.org>
References: <20191114235008.185111-1-evgreen@chromium.org>
MIME-Version: 1.0
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Properly plumb out EOPNOTSUPP from loop driver operations, which may
get returned when for instance a discard operation is attempted but not
supported by the underlying block device. Before this change, everything
was reported in the log as an I/O error, which is scary and not
helpful in debugging.

Signed-off-by: Evan Green <evgreen@chromium.org>
---

Changes in v7:
- Use errno_to_blk_status() (Christoph)

Changes in v6:
- Updated tags

Changes in v5: None
Changes in v4: None
Changes in v3:
- Updated tags

Changes in v2:
- Unnested error if statement (Bart)

 drivers/block/loop.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index ef6e251857c8..6a9fe1f9fe84 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -461,7 +461,7 @@ static void lo_complete_rq(struct request *rq)
 	if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) ||
 	    req_op(rq) != REQ_OP_READ) {
 		if (cmd->ret < 0)
-			ret = BLK_STS_IOERR;
+			ret = errno_to_blk_status(cmd->ret);
 		goto end_io;
 	}
 
@@ -1950,7 +1950,10 @@ static void loop_handle_cmd(struct loop_cmd *cmd)
  failed:
 	/* complete non-aio request */
 	if (!cmd->use_aio || ret) {
-		cmd->ret = ret ? -EIO : 0;
+		if (ret == -EOPNOTSUPP)
+			cmd->ret = ret;
+		else
+			cmd->ret = ret ? -EIO : 0;
 		blk_mq_complete_request(rq);
 	}
 }
-- 
2.21.0