Commit Graph

29 Commits

Author SHA1 Message Date
Mikulas Patocka db2351eb22 dm kcopyd: avoid useless atomic operations
The functions set_bit and clear_bit are atomic. We don't need
atomicity when making flags for dm-kcopyd. So, change them to direct
manipulation of the flags.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2021-06-04 12:07:24 -04:00
Damien Le Moal 174364f6a8 dm zoned: Fix zone reclaim trigger
Only triggering reclaim based on the percentage of unmapped cache
zones can fail to detect cases where reclaim is needed, e.g. if the
target has only 2 or 3 cache zones and only one unmapped cache zone,
the percentage of free cache zones is higher than
DMZ_RECLAIM_LOW_UNMAP_ZONES (30%) and reclaim does not trigger.

This problem, combined with the fact that dmz_schedule_reclaim() is
called from dmz_handle_bio() without the map lock held, leads to a
race between zone allocation and dmz_should_reclaim() result.
Depending on the workload applied, this race can lead to the write
path waiting forever for a free zone without reclaim being triggered.

Fix this by moving dmz_schedule_reclaim() inside dmz_alloc_zone()
under the map lock. This results in checking the need for zone reclaim
whenever a new data or buffer zone needs to be allocated.

Also fix dmz_reclaim_percentage() to always return 0 if the number of
unmapped cache (or random) zones is less than or equal to 1.

Suggested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-07-08 12:21:53 -04:00
Wei Yongjun ce34c9b461 dm zoned: fix unused but set variable warnings
Fix unused but set variable warnings:

drivers/md/dm-zoned-reclaim.c:504:42: warning:
 variable nr_rnd set but not used [-Wunused-but-set-variable]
  504 |  unsigned int p_unmap, nr_unmap_rnd = 0, nr_rnd = 0;
      |                                          ^~~~~~
drivers/md/dm-zoned-reclaim.c:504:24: warning:
 variable nr_unmap_rnd set but not used [-Wunused-but-set-variable]
  504 |  unsigned int p_unmap, nr_unmap_rnd = 0, nr_rnd = 0;
      |                        ^~~~~~~~~~~~

Fixes: f97809aec5 ("dm zoned: per-device reclaim")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-07-08 11:11:21 -04:00
Damien Le Moal c69cb1d17b dm zoned: fix uninitialized pointer dereference
Make sure that the local variable rzone in dmz_do_reclaim() is always
initialized before being used for printing debug messages.

Fixes: f97809aec5 ("dm zoned: per-device reclaim")
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-06-17 12:13:08 -04:00
Hannes Reinecke 69875d443b dm zoned: select reclaim zone based on device index
per-device reclaim should select zones on that device only.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-06-05 14:59:53 -04:00
Hannes Reinecke 22c1ef66c4 dm zoned: allocate zone by device index
When allocating a zone, pass in an indicator on which device the zone
should be allocated; this increases performance for a multi-device
setup because reclaim will now allocate zones on the device for which
reclaim is running.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-06-05 14:59:52 -04:00
Hannes Reinecke bd82fdabf1 dm zoned: move random and sequential zones into struct dmz_dev
Random and sequential zones should be part of the respective
device structure to make arbitration between devices possible.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-06-05 14:59:50 -04:00
Hannes Reinecke f97809aec5 dm zoned: per-device reclaim
Instead of having one reclaim workqueue for the entire set we should
be allocating a reclaim workqueue per device; doing so will reduce
contention and should boost performance for a multi-device setup.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-06-05 14:59:50 -04:00
Hannes Reinecke 8f22272af7 dm zoned: add device pointer to struct dm_zone
Add a pointer, to the containing device, within struct dm_zone and
kill dmz_zone_to_dev().

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-06-05 14:59:48 -04:00
Hannes Reinecke c3ff479dde dm zoned: improve logging messages for reclaim
Instead of just reporting the errno, add some more verbose debugging
message in the reclaim path.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-06-05 14:59:45 -04:00
Hannes Reinecke a16b7dee30 dm zoned: terminate reclaim on congestion
When dmz_get_chunk_mapping() selects a zone which is under reclaim
we should terminate the reclaim copy process. Since we're changing
the zone itself, reclaim needs to run afterwards again anyway.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-05-20 17:09:52 -04:00
Hannes Reinecke c5c7885952 dm zoned: start reclaim with sequential zones
Sequential zones perform better for reclaim, so start off using
them and only use random zones as a fallback when cache zones are
present.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-05-20 17:09:51 -04:00
Hannes Reinecke 90a9b8693f dm zoned: reclaim random zones when idle
When the system is idle we should be starting reclaiming
random zones, too.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-05-20 17:09:50 -04:00
Hannes Reinecke 34f5affd04 dm zoned: separate random and cache zones
Instead of lumping emulated zones together with random zones we
should be handling them as separate 'cache' zones. This improves
code readability and allows an easier implementation of different
cache policies.

Also add additional allocation flags, to separate the type (cache,
random, or sequential) from the purpose (eg reclaim).

Also switch the allocation policy to not use random zones as buffer
zones if cache zones are present. This avoids a performance drop when
all cache zones are used.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-05-20 17:09:49 -04:00
Hannes Reinecke 489dc0f06a dm zoned: return NULL if dmz_get_zone_for_reclaim() fails to find a zone
The only case where dmz_get_zone_for_reclaim() cannot return a zone is
if the respective lists are empty. So we should just return a simple
NULL value here as we really don't have an error code which would make
sense.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-05-20 17:09:49 -04:00
Hannes Reinecke 49de3b7d21 dm zoned: remove spurious newlines from debugging messages
DMDEBUG will already add a newline to the logging messages, so we
shouldn't be adding it to the message itself.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-05-20 17:09:46 -04:00
Hannes Reinecke 6c805f77f1 dm zoned: remove 'dev' argument from reclaim
Use the dmz_zone_to_dev() mapping function to remove the
'dev' argument from reclaim.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-05-19 13:30:30 -04:00
Hannes Reinecke d0e21ce40c dm zoned: Introduce dmz_dev_is_dying() and dmz_check_dev()
Introduce accessors dmz_dev_is_dying() and dmz_check_dev() to
avoid having to reference the devices directly.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-05-15 10:29:37 -04:00
Hannes Reinecke 2234e7321d dm zoned: introduce dmz_metadata_label() to format device name
Introduce dmz_metadata_label() to format the device-mapper device
name and use it instead of the device name of the underlying device.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-05-15 10:29:37 -04:00
Hannes Reinecke 3682056013 dm zoned: move fields from struct dmz_dev to dmz_metadata
Move fields from the device structure into the metadata structure
and provide accessor functions.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-05-15 10:29:37 -04:00
Hannes Reinecke b712287398 dm zoned: store zone id within the zone structure and kill dmz_id()
Instead of calculating the zone index by the offset within the
zone array store the index within the structure itself. With that
the helper dmz_id() is pointless and can be replaced with accessing
the ->id value directly.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-05-15 10:29:36 -04:00
Dmitry Fomichev e7fad909b6 dm zoned: reduce overhead of backing device checks
Commit 75d66ffb48 added backing device health checks and as a part
of these checks, check_events() block ops template call is invoked in
dm-zoned mapping path as well as in reclaim and flush path. Calling
check_events() with ATA or SCSI backing devices introduces a blocking
scsi_test_unit_ready() call being made in sd_check_events(). Even though
the overhead of calling scsi_test_unit_ready() is small for ATA zoned
devices, it is much larger for SCSI and it affects performance in a very
negative way.

Fix this performance regression by executing check_events() only in case
of any I/O errors. The function dmz_bdev_is_dying() is modified to call
only blk_queue_dying(), while calls to check_events() are made in a new
helper function, dmz_check_bdev().

Reported-by: zhangxiaoxu <zhangxiaoxu5@huawei.com>
Fixes: 75d66ffb48 ("dm zoned: properly handle backing device failure")
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-11-07 10:08:36 -05:00
Dmitry Fomichev ad1bd578bd dm zoned: fix a few typos
Signed-off-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-08-15 15:57:43 -04:00
Dmitry Fomichev bae9a0aa33 dm zoned: add SPDX license identifiers
Signed-off-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-08-15 15:57:42 -04:00
Dmitry Fomichev 75d66ffb48 dm zoned: properly handle backing device failure
dm-zoned is observed to lock up or livelock in case of hardware
failure or some misconfiguration of the backing zoned device.

This patch adds a new dm-zoned target function that checks the status of
the backing device. If the request queue of the backing device is found
to be in dying state or the SCSI backing device enters offline state,
the health check code sets a dm-zoned target flag prompting all further
incoming I/O to be rejected. In order to detect backing device failures
timely, this new function is called in the request mapping path, at the
beginning of every reclaim run and before performing any metadata I/O.

The proper way out of this situation is to do

dmsetup remove <dm-zoned target>

and recreate the target when the problem with the backing device
is resolved.

Fixes: 3b1a94c88b ("dm zoned: drive-managed zoned block device target")
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-08-15 15:57:42 -04:00
Dmitry Fomichev b234c6d7a7 dm zoned: improve error handling in reclaim
There are several places in reclaim code where errors are not
propagated to the main function, dmz_reclaim(). This function
is responsible for unlocking zones that might be still locked
at the end of any failed reclaim iterations. As the result,
some device zones may be left permanently locked for reclaim,
degrading target's capability to reclaim zones.

This patch fixes these issues as follows -

Make sure that dmz_reclaim_buf(), dmz_reclaim_seq_data() and
dmz_reclaim_rnd_data() return error codes to the caller.

dmz_reclaim() function is renamed to dmz_do_reclaim() to avoid
clashing with "struct dmz_reclaim" and is modified to return the
error to the caller.

dmz_get_zone_for_reclaim() now returns an error instead of NULL
pointer and reclaim code checks for that error.

Error logging/debug messages are added where necessary.

Fixes: 3b1a94c88b ("dm zoned: drive-managed zoned block device target")
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-08-15 15:57:40 -04:00
Mike Snitzer 7209049d40 dm kcopyd: return void from dm_kcopyd_copy()
dm_kcopyd_copy() only ever returns 0 so there is no need for callers to
account for possible failure.  Same goes for dm_kcopyd_zero().

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-07-31 17:33:21 -04:00
Damien Le Moal 4218a95546 dm zoned: use GFP_NOIO in I/O path
Use GFP_NOIO for memory allocations in the I/O path.  Other memory
allocations in the initialization path can use GFP_KERNEL.

Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-07-26 15:55:43 -04:00
Damien Le Moal 3b1a94c88b dm zoned: drive-managed zoned block device target
The dm-zoned device mapper target provides transparent write access
to zoned block devices (ZBC and ZAC compliant block devices).
dm-zoned hides to the device user (a file system or an application
doing raw block device accesses) any constraint imposed on write
requests by the device, equivalent to a drive-managed zoned block
device model.

Write requests are processed using a combination of on-disk buffering
using the device conventional zones and direct in-place processing for
requests aligned to a zone sequential write pointer position.
A background reclaim process implemented using dm_kcopyd_copy ensures
that conventional zones are always available for executing unaligned
write requests. The reclaim process overhead is minimized by managing
buffer zones in a least-recently-written order and first targeting the
oldest buffer zones. Doing so, blocks under regular write access (such
as metadata blocks of a file system) remain stored in conventional
zones, resulting in no apparent overhead.

dm-zoned implementation focus on simplicity and on minimizing overhead
(CPU, memory and storage overhead). For a 14TB host-managed disk with
256 MB zones, dm-zoned memory usage per disk instance is at most about
3 MB and as little as 5 zones will be used internally for storing metadata
and performing buffer zone reclaim operations. This is achieved using
zone level indirection rather than a full block indirection system for
managing block movement between zones.

dm-zoned primary target is host-managed zoned block devices but it can
also be used with host-aware device models to mitigate potential
device-side performance degradation due to excessive random writing.

Zoned block devices can be formatted and checked for use with the dm-zoned
target using the dmzadm utility available at:

https://github.com/hgst/dm-zoned-tools

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
[Mike Snitzer partly refactored Damien's original work to cleanup the code]
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-06-19 11:05:20 -04:00