Add a metadata pointer within struct dmz_dev and use it as argument
for blkdev_report_zones() instead of the metadata 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>

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>

Checking the tertiary superblock just consists of validating UUIDs,
crcs, and the generation number; it doesn't have contents which would
be required during the actual operation.

So allocate a temporary superblock when checking tertiary devices to
avoid having to store it together with the 'real' superblocks.
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>

The zones array is getting really large, and large arrays tend to
wreak havoc with the CPU caches.  So convert it to xarray to become
more cache friendly.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com> # fix leak in dmz_insert
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Instead of counting the number of reserved zones in dmz_free_zone(),
mark the zone as 'reserved' during allocation and simplify
dmz_free_zone().
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>

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>

The secondary superblock must reside on the same device as the primary
superblock, so there is no need to re-calculate the device.
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>

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>

Use dm_bufio_forget_buffers instead of a block-by-block loop that
calls dm_bufio_forget. dm_bufio_forget_buffers is faster than the loop
because it searches for used buffers using rb-tree.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Introduce a function forget_buffer_locked that forgets a range of
buffers. It is more efficient than calling forget_buffer in a loop.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

dm-bufio uses unnatural ordering in the rb-tree - blocks with smaller
numbers were put to the right node and blocks with bigger numbers were
put to the left node.

Reverse that logic so that it's natural.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

There is no user for this interface.  If in future it is needed it can
be reimplemented to walk the rbtree of buffers instead of doing
block-by-block lookups.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Remove a leftover hunk to switch from random zones to sequential
zones when selecting a reclaim zone; the logic has moved into the
caller and this hunk is now pointless.

Fixes: 34f5affd ("dm zoned: separate random and cache zones")
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>

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>

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>

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>

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>

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>

When building arm32 allyesconfig:

ld.lld: error: undefined symbol: __aeabi_uldivmod
>>> referenced by dm-zoned-target.c
>>>               md/dm-zoned-target.o:(dmz_ctr) in archive drivers/built-in.a

dmz_fixup_devices uses DIV_ROUND_UP with variables of type sector_t. As
such, it should be using DIV_ROUND_UP_SECTOR_T, which handles this
automatically.

Fixes: 70978208ec91 ("dm zoned: metadata version 2")
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Now that DMDEBUG uses pr_debug and DMDEBUG_LIMIT uses
pr_debug_ratelimited cleanup DM's 2 direct pr_debug callers to use
them to get the benefit of consistent DM_FMT formatting of debugging
messages.

While doing so, dm-mpath.c:dm_report_EIO() was switched over to using
DMDEBUG_LIMIT due to the potential for error handling floods in the IO
completion path.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

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>

Switch to use dynamic debug to avoid having recompile the kernel
just to enable debugging messages.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Implement handling for metadata version 2. The new metadata adds a
label and UUID for the device mapper device, and additional UUID for
the underlying block devices.

It also allows for an additional regular drive to be used for
emulating random access zones. The emulated zones will be placed
logically in front of the zones from the zoned block device, causing
the superblocks and metadata to be stored on that device.

The first zone of the original zoned device will be used to hold
another, tertiary copy of the metadata; this copy carries a generation
number of 0 and is never updated; it's just used for identification.
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>

When looking up zones in dmz_alloc_zone() we need to ignore
metadata zones so as not to accidentally overwrite metadata.
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>

dm-zoned is becoming quite chatty during startup; reduce the noise
by moving some information to 'debug' level.
Suggested-by: Mike Snitzer <snitzer@redhat.com>
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>

Use the metadata label for logging and not 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>

Use accessors to retrieve the device pointer in preparation
for adding an additional block 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>

Replace the 'target' pointer in the bio context with the
device pointer as this is what's actually used.
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>

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>

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>

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>

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>

Store the device together with the superblock so that
we don't have to recur to the metadata to find it.
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>

Instead of storing just the first superblock zone and calculate
the secondary relative to that we should be using an array for
holding the superblock zones.
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>

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>

Add callback for 'dmsetup message' to allow the reclaim process
to be triggered manually.
Eg.

	dmsetup message /dev/dm-X 0 message

will start the reclaim process even if the default threshold
of 50 percent of free random zones is not reached.
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>

Add callback to supply information for 'dmsetup status'
and 'dmsetup table'. The output for 'dmsetup status' is

0 <size> zoned <nr_zones> zones <nr_unmap_rnd>/<nr_rnd> random <nr_unmap_seq>/<nr_seq> sequential

where <nr_unmap_rnd> is the number of unmapped (ie free) random zones,
<nr_rnd> the total number of random zones, <nr_unmap_seq> the number
of unmapped sequential zones, and <nr_seq> the total number of
sequential zones.
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>

This new selector keeps an exponential moving average of the service
time for each path (losely defined as delta between start_io and
end_io), and uses this along with the number of inflight requests to
estimate future service time for a path.  Since we don't have a prober
to account for temporally slow paths, re-try "slow" paths every once in
a while (num_paths * historical_service_time). To account for fast paths
transitioning to slow, if a path has not completed any request within
(num_paths * historical_service_time), limit the number of outstanding
requests.  To account for low volume situations where number of
inflight IOs would be zero, the last finish time of each path is
factored in.
Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
Co-developed-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>