linux-kernel - [PATCH 3.16 141/346] dm flakey: error READ bios during the down

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Message-ID: <lsq.1479082460.223051456@decadent.org.uk>
Date:   Mon, 14 Nov 2016 00:14:20 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Akira Hayakawa" <ruby.wktk@...il.com>,
        "Mike Snitzer" <snitzer@...hat.com>
Subject: [PATCH 3.16 141/346] dm flakey: error READ bios during the
 down_interval

3.16.39-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Mike Snitzer <snitzer@...hat.com>

commit 99f3c90d0d85708e7401a81ce3314e50bf7f2819 upstream.

When the corrupt_bio_byte feature was introduced it caused READ bios to
no longer be errored with -EIO during the down_interval.  This had to do
with the complexity of needing to submit READs if the corrupt_bio_byte
feature was used.

Fix it so READ bios are properly errored with -EIO; doing so early in
flakey_map() as long as there isn't a match for the corrupt_bio_byte
feature.

Fixes: a3998799fb4df ("dm flakey: add corrupt_bio_byte feature")
Reported-by: Akira Hayakawa <ruby.wktk@...il.com>
Signed-off-by: Mike Snitzer <snitzer@...hat.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/md/dm-flakey.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

--- a/drivers/md/dm-flakey.c
+++ b/drivers/md/dm-flakey.c
@@ -287,10 +287,16 @@ static int flakey_map(struct dm_target *
 		pb->bio_submitted = true;
 
 		/*
-		 * Map reads as normal.
+		 * Map reads as normal only if corrupt_bio_byte set.
 		 */
-		if (bio_data_dir(bio) == READ)
-			goto map_bio;
+		if (bio_data_dir(bio) == READ) {
+			/* If flags were specified, only corrupt those that match. */
+			if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) &&
+			    all_corrupt_bio_flags_match(bio, fc))
+				goto map_bio;
+			else
+				return -EIO;
+		}
 
 		/*
 		 * Drop writes?
@@ -328,12 +334,13 @@ static int flakey_end_io(struct dm_targe
 
 	/*
 	 * Corrupt successful READs while in down state.
-	 * If flags were specified, only corrupt those that match.
 	 */
-	if (fc->corrupt_bio_byte && !error && pb->bio_submitted &&
-	    (bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) &&
-	    all_corrupt_bio_flags_match(bio, fc))
-		corrupt_bio_data(bio, fc);
+	if (!error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
+		if (fc->corrupt_bio_byte)
+			corrupt_bio_data(bio, fc);
+		else
+			return -EIO;
+	}
 
 	return error;
 }