On Fri, Jul 29 2016 at 10:35am -0400, Mike Snitzer <[email protected]> wrote:
> On Fri, Jul 29 2016 at 10:31am -0400, > Lukas Herbolt <[email protected]> wrote: > > > - http://people.redhat.com/~lherbolt/dm-flakey/v4.7-dm_flakey.tar.gz > > > > Lukas > > Please post an incremental patch relative to 4.7 or latest Linus > kernel. Don't make people suffer with tarballs of whatever you've > packaged above. I pulled out your incremental diff. Your proposed fix isn't correct. It breaks the corrupt_bio_byte feature. We cannot blindly drop reads early in flakey_map(), like you've proposed, because the corrupt_bio_byte feature relies on corrupt data being returned on read during the down_interval. The issue reported is: reads aren't dropped during the "down_interval". I do agree that this needs fixing, and it was commit a3998799fb4df ("dm flakey: add corrupt_bio_byte feature") that caused this regression. But a fix must not break the corrupt_bio_byte feature. This fix should resolve the problem, I'll be staging it to go upstream during the 4.8-rc cycle (Akira, please test to verify your test fails as expected now): From: Mike Snitzer <[email protected]> Date: Fri, 29 Jul 2016 13:19:55 -0400 Subject: [PATCH] dm flakey: error READ bios during the down_interval 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 <[email protected]> Signed-off-by: Mike Snitzer <[email protected]> Cc: [email protected] --- drivers/md/dm-flakey.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c index 29b99fb..19db13e 100644 --- a/drivers/md/dm-flakey.c +++ b/drivers/md/dm-flakey.c @@ -289,10 +289,16 @@ static int flakey_map(struct dm_target *ti, struct bio *bio) 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? @@ -330,12 +336,13 @@ static int flakey_end_io(struct dm_target *ti, struct bio *bio, int error) /* * 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; } -- 2.7.4 (Apple Git-66) -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
