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dm mpath: fix bio-based multipath queue_if_no_path handling

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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>
This commit is contained in:
Mike Snitzer 2017-12-07 22:42:27 -05:00
parent 7e6358d244
commit c1fd0abee0
1 changed files with 42 additions and 7 deletions
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49
drivers/md/dm-mpath.c
View File

@ -457,6 +457,38 @@ do { \
dm_noflush_suspending((m)->ti)); \
} 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)
*/
@ -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;
}