diff options
author | Mike Snitzer <snitzer@redhat.com> | 2017-12-07 22:42:27 -0500 |
---|---|---|
committer | Mike Snitzer <snitzer@redhat.com> | 2017-12-08 10:49:40 -0500 |
commit | c1fd0abee0d52eb7e2871194b6c79d54792f515f (patch) | |
tree | 682306b0ffb307ae6dbc465459ca3db400b1aea3 | |
parent | 7e6358d244e4706fe612a77b9c36519a33600ac0 (diff) |
dm mpath: fix bio-based multipath queue_if_no_path handling
Commit ca5beb76 ("dm mpath: micro-optimize the hot path relative to
MPATHF_QUEUE_IF_NO_PATH") caused bio-based DM-multipath to fail mptest's
"test_02_sdev_delete".
Restoring the logic that existed prior to commit ca5beb76 fixes this
bio-based DM-multipath regression. Also verified all mptest tests pass
with request-based DM-multipath.
This commit effectively reverts commit ca5beb76 -- but it does so
without reintroducing the need to take the m->lock spinlock in
must_push_back_{rq,bio}.
Fixes: ca5beb76 ("dm mpath: micro-optimize the hot path relative to MPATHF_QUEUE_IF_NO_PATH")
Cc: stable@vger.kernel.org # 4.12+
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
-rw-r--r-- | drivers/md/dm-mpath.c | 49 |
1 files changed, 42 insertions, 7 deletions
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index 35a2a2fa477f..f7810cc869ac 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -458,6 +458,38 @@ do { \ } while (0) /* + * Check whether bios must be queued in the device-mapper core rather + * than here in the target. + * + * If MPATHF_QUEUE_IF_NO_PATH and MPATHF_SAVED_QUEUE_IF_NO_PATH hold + * the same value then we are not between multipath_presuspend() + * and multipath_resume() calls and we have no need to check + * for the DMF_NOFLUSH_SUSPENDING flag. + */ +static bool __must_push_back(struct multipath *m, unsigned long flags) +{ + return ((test_bit(MPATHF_QUEUE_IF_NO_PATH, &flags) != + test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &flags)) && + dm_noflush_suspending(m->ti)); +} + +/* + * Following functions use READ_ONCE to get atomic access to + * all m->flags to avoid taking spinlock + */ +static bool must_push_back_rq(struct multipath *m) +{ + unsigned long flags = READ_ONCE(m->flags); + return test_bit(MPATHF_QUEUE_IF_NO_PATH, &flags) || __must_push_back(m, flags); +} + +static bool must_push_back_bio(struct multipath *m) +{ + unsigned long flags = READ_ONCE(m->flags); + return __must_push_back(m, flags); +} + +/* * Map cloned requests (request-based multipath) */ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq, @@ -478,7 +510,7 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq, pgpath = choose_pgpath(m, nr_bytes); if (!pgpath) { - if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) + if (must_push_back_rq(m)) return DM_MAPIO_DELAY_REQUEUE; dm_report_EIO(m); /* Failed */ return DM_MAPIO_KILL; @@ -553,7 +585,7 @@ static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_m } if (!pgpath) { - if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) + if (must_push_back_bio(m)) return DM_MAPIO_REQUEUE; dm_report_EIO(m); return DM_MAPIO_KILL; @@ -651,8 +683,7 @@ static int queue_if_no_path(struct multipath *m, bool queue_if_no_path, assign_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags, (save_old_value && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) || (!save_old_value && queue_if_no_path)); - assign_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags, - queue_if_no_path || dm_noflush_suspending(m->ti)); + assign_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags, queue_if_no_path); spin_unlock_irqrestore(&m->lock, flags); if (!queue_if_no_path) { @@ -1486,7 +1517,7 @@ static int multipath_end_io(struct dm_target *ti, struct request *clone, fail_path(pgpath); if (atomic_read(&m->nr_valid_paths) == 0 && - !test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) { + !must_push_back_rq(m)) { if (error == BLK_STS_IOERR) dm_report_EIO(m); /* complete with the original error */ @@ -1521,8 +1552,12 @@ static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone, if (atomic_read(&m->nr_valid_paths) == 0 && !test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) { - dm_report_EIO(m); - *error = BLK_STS_IOERR; + if (must_push_back_bio(m)) { + r = DM_ENDIO_REQUEUE; + } else { + dm_report_EIO(m); + *error = BLK_STS_IOERR; + } goto done; } |