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dm mpath: take m->lock spinlock when testing QUEUE_IF_NO_PATH 

Fix multipath_end_io, multipath_end_io_bio and multipath_busy to take
m->lock while testing if MPATHF_QUEUE_IF_NO_PATH bit is set.  These are
all slow-path cases when no paths are available so extra locking isn't a
performance hit.  Correctness matters most.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mike Snitzer 2020-06-10 16:07:57 -04:00
parent 69cea0d45a
commit a271a89c6e
1 changed files with 34 additions and 18 deletions
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52
drivers/md/dm-mpath.c
View File

@ -1621,12 +1621,16 @@ static int multipath_end_io(struct dm_target *ti, struct request *clone,
if (pgpath)
fail_path(pgpath);
if (atomic_read(&m->nr_valid_paths) == 0 &&
!must_push_back_rq(m)) {
if (error == BLK_STS_IOERR)
dm_report_EIO(m);
/* complete with the original error */
r = DM_ENDIO_DONE;
if (!atomic_read(&m->nr_valid_paths)) {
unsigned long flags;
spin_lock_irqsave(&m->lock, flags);
if (!must_push_back_rq(m)) {
if (error == BLK_STS_IOERR)
dm_report_EIO(m);
/* complete with the original error */
r = DM_ENDIO_DONE;
}
spin_unlock_irqrestore(&m->lock, flags);
}
}
@ -1656,15 +1660,19 @@ static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone,
if (pgpath)
fail_path(pgpath);
if (atomic_read(&m->nr_valid_paths) == 0 &&
!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
if (__must_push_back(m)) {
r = DM_ENDIO_REQUEUE;
} else {
dm_report_EIO(m);
*error = BLK_STS_IOERR;
if (!atomic_read(&m->nr_valid_paths)) {
spin_lock_irqsave(&m->lock, flags);
if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
if (__must_push_back(m)) {
r = DM_ENDIO_REQUEUE;
} else {
dm_report_EIO(m);
*error = BLK_STS_IOERR;
}
spin_unlock_irqrestore(&m->lock, flags);
goto done;
}
goto done;
spin_unlock_irqrestore(&m->lock, flags);
}
spin_lock_irqsave(&m->lock, flags);
@ -1962,10 +1970,11 @@ static int multipath_prepare_ioctl(struct dm_target *ti,
}
} else {
/* No path is available */
r = -EIO;
spin_lock_irqsave(&m->lock, flags);
if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
r = -ENOTCONN;
else
r = -EIO;
spin_unlock_irqrestore(&m->lock, flags);
}
if (r == -ENOTCONN) {
@ -2036,8 +2045,15 @@ static int multipath_busy(struct dm_target *ti)
return true;
/* no paths available, for blk-mq: rely on IO mapping to delay requeue */
if (!atomic_read(&m->nr_valid_paths) && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
return (m->queue_mode != DM_TYPE_REQUEST_BASED);
if (!atomic_read(&m->nr_valid_paths)) {
unsigned long flags;
spin_lock_irqsave(&m->lock, flags);
if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
spin_unlock_irqrestore(&m->lock, flags);
return (m->queue_mode != DM_TYPE_REQUEST_BASED);
}
spin_unlock_irqrestore(&m->lock, flags);
}
/* Guess which priority_group will be used at next mapping time */
pg = READ_ONCE(m->current_pg);