[PATCH 3.16 058/245] dm flakey: fix reads to be issued if drop_writes configured

Ben Hutchings
2020-04-23T23:22:05Z

From: Mike Snitzer <snitzer@redhat.com>

commit 299f6230bc6d0ccd5f95bb0fb865d80a9c7d5ccc upstream.

v4.8-rc3 commit 99f3c90d0d ("dm flakey: error READ bios during the
down_interval") overlooked the 'drop_writes' feature, which is meant to
allow reads to be issued rather than errored, during the down_interval.

Fixes: 99f3c90d0d ("dm flakey: error READ bios during the down_interval")
Reported-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/md/dm-flakey.c | 27 ++++++++++++++++-----------
1 file changed, 16 insertions(+), 11 deletions(-)

--- a/drivers/md/dm-flakey.c
+++ b/drivers/md/dm-flakey.c
@@ -291,15 +291,13 @@ static int flakey_map(struct dm_target *
pb->bio_submitted = true;

/*
- * Map reads as normal only if corrupt_bio_byte set.
+ * Error reads if neither corrupt_bio_byte or drop_writes are set.
+ * Otherwise, flakey_end_io() will decide if the reads should be modified.
*/
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
+ if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags))
return -EIO;
+ goto map_bio;
}

/*
@@ -336,14 +334,21 @@ static int flakey_end_io(struct dm_targe
struct flakey_c *fc = ti->private;
struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));

- /*
- * Corrupt successful READs while in down state.
- */
if (!error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
- if (fc->corrupt_bio_byte)
+ if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) &&
+ all_corrupt_bio_flags_match(bio, fc)) {
+ /*
+ * Corrupt successful matching READs while in down state.
+ */
corrupt_bio_data(bio, fc);
- else
+
+ } else if (!test_bit(DROP_WRITES, &fc->flags)) {
+ /*
+ * Error read during the down_interval if drop_writes
+ * wasn't configured.
+ */
return -EIO;
+ }
}

return error;