linux-toradex.git/drivers/md/dm-mpath.c, branch v4.9.123

dm mpath: cleanup -Wbool-operation warning in choose_pgpath()

2017-07-27T22:07:55+00:00

commit d19a55ccad15a486ffe03030570744e5d5bd9f8e upstream.

Reported-by: David Binderman 
Signed-off-by: Mike Snitzer 
Signed-off-by: Greg Kroah-Hartman

dm mpath: split and rename activate_path() to prepare for its expanded use

2017-05-25T13:44:33+00:00

commit 89bfce763e43fa4897e0d3af6b29ed909df64cfd upstream.

activate_path() is renamed to activate_path_work() which now calls
activate_or_offline_path().  activate_or_offline_path() will be used
by the next commit.

Signed-off-by: Bart Van Assche 
Cc: Hannes Reinecke 
Cc: Christoph Hellwig 
Signed-off-by: Mike Snitzer 
Signed-off-by: Greg Kroah-Hartman

dm mpath: always return reservation conflict without failing over

2016-09-29T14:57:07+00:00

If dm-mpath encounters an reservation conflict it should not fail the
path (as communication with the target is not affected) but should
rather retry on another path.  However, in doing so we might be inducing
a ping-pong between paths, with no guarantee of any forward progress.
And arguably a reservation conflict is an unexpected error, so we should
be passing it upwards to allow the application to take appropriate
steps.

This change resolves a show-stopper problem seen with the pNFS SCSI
layout because it is trivial to hit reservation conflict based failover
loops without it.

Doubts were raised about the implications of this change relative to
products like IBM's SVC.  But there is little point withholding a fix
for Linux because a proprietary product may or may not have some issues
in its implementation of how it interfaces with Linux.  In the future,
if there is glaring evidence that this change is certainly problematic
we can revisit it.

Signed-off-by: Hannes Reinecke 
Acked-by: Christoph Hellwig 
Tested-by: Christoph Hellwig 
Signed-off-by: Mike Snitzer  # tweaked header

dm mpath: delay the requeue of blk-mq requests while all paths down

2016-09-15T15:16:17+00:00

Return DM_MAPIO_DELAY_REQUEUE from .clone_and_map_rq.  Also, return
false from .busy, if all paths are down, so that blk-mq requests get
mapped via .clone_and_map_rq -- which results in DM_MAPIO_DELAY_REQUEUE
being returned to dm-rq.

This change allows for a noticeable reduction in cpu utilization
(reduced kworker load) while all paths are down, e.g.:

system CPU idleness (as measured by fio's --idle-prof=system):
before: system: 86.58%
after:  system: 98.60%

Signed-off-by: Mike Snitzer 
Reviewed-by: Hannes Reinecke

dm mpath: use dm_mq_kick_requeue_list()

2016-09-15T15:16:11+00:00

When reinstating a path the blk-mq request_queue's requeue_list should
get kicked.  It makes sense to kick the requeue_list as part of the
existing hook (previously only used by bio-based support).

Rename process_queued_bios_list to process_queued_io_list.

Signed-off-by: Mike Snitzer 
Reviewed-by: Hannes Reinecke

dm: convert wait loops to use autoremove_wake_function()

2016-09-14T17:56:38+00:00

Use autoremove_wake_function() instead of default_wake_function()
to make the dm wait loops more similar to other wait loops in the
kernel.  This patch does not change any functionality.

Signed-off-by: Bart Van Assche 
Signed-off-by: Mike Snitzer

dm mpath: check if path's request_queue is dying in activate_path()

2016-09-14T17:56:38+00:00

If pg_init_retries is set and a request is queued against a multipath
device with all underlying block device request_queues in the "dying"
state then an infinite loop is triggered because activate_path() never
succeeds and hence never calls pg_init_done().

This change avoids that device removal triggers an infinite loop by
failing the activate_path() which causes the "dying" path to be failed.

Reported-by: Bart Van Assche 
Signed-off-by: Mike Snitzer 
Cc: stable@vger.kernel.org

block: rename bio bi_rw to bi_opf

2016-08-07T20:41:02+00:00

Since commit 63a4cc24867d, bio->bi_rw contains flags in the lower
portion and the op code in the higher portions. This means that
old code that relies on manually setting bi_rw is most likely
going to be broken. Instead of letting that brokeness linger,
rename the member, to force old and out-of-tree code to break
at compile time instead of at runtime.

No intended functional changes in this commit.

Signed-off-by: Jens Axboe

dm mpath: add locking to multipath_resume and must_push_back

2016-08-02T20:21:34+00:00

Multiple flags were being tested without locking.  Protect against
non-atomic bit changes in m->flags by holding m->lock (while testing or
setting the queue_if_no_path related flags).

Signed-off-by: Mike Snitzer

dm mpath: add optional "queue_mode" feature

2016-06-10T19:16:02+00:00

Allow a user to specify an optional feature 'queue_mode ' where
 may be "bio", "rq" or "mq" -- which corresponds to bio-based,
request_fn rq-based, and blk-mq rq-based respectively.

If the queue_mode feature isn't specified the default for the
"multipath" target is still "rq" but if dm_mod.use_blk_mq is set to Y
it'll default to mode "mq".

This new queue_mode feature introduces the ability for each multipath
device to have its own queue_mode (whereas before this feature all
multipath devices effectively had to have the same queue_mode).

This commit also goes a long way to eliminate the awkward (ab)use of
DM_TYPE_*, the associated filter_md_type() and other relatively fragile
and difficult to maintain code.

Signed-off-by: Mike Snitzer