whether blocks should migrate to/from the cache. The bio-prison-v2
interface supports this improvement by enabling direct dispatch of
work to workqueues rather than having to delay the actual work
dispatch to the DM cache core. So the dm-cache policies are much more
nimble by being able to drive IO as they see fit. One immediate
benefit from the improved latency is a cache that should be much more
adaptive to changing workloads.
- Add a new DM integrity target that emulates a block device that has
additional per-sector tags that can be used for storing integrity
information.
- Add a new authenticated encryption feature to the DM crypt target that
builds on the capabilities provided by the DM integrity target.
- Add MD interface for switching the raid4/5/6 journal mode and update
the DM raid target to use it to enable aid4/5/6 journal write-back
support.
- Switch the DM verity target over to using the asynchronous hash crypto
API (this helps work better with architectures that have access to
off-CPU algorithm providers, which should reduce CPU utilization).
- Various request-based DM and DM multipath fixes and improvements from
Bart and Christoph.
- A DM thinp target fix for a bio structure leak that occurs for each
discard IFF discard passdown is enabled.
- A fix for a possible deadlock in DM bufio and a fix to re-check the
new buffer allocation watermark in the face of competing admin changes
to the 'max_cache_size_bytes' tunable.
- A couple DM core cleanups.
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Merge tag 'for-4.12/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm
Pull device mapper updates from Mike Snitzer:
- A major update for DM cache that reduces the latency for deciding
whether blocks should migrate to/from the cache. The bio-prison-v2
interface supports this improvement by enabling direct dispatch of
work to workqueues rather than having to delay the actual work
dispatch to the DM cache core. So the dm-cache policies are much more
nimble by being able to drive IO as they see fit. One immediate
benefit from the improved latency is a cache that should be much more
adaptive to changing workloads.
- Add a new DM integrity target that emulates a block device that has
additional per-sector tags that can be used for storing integrity
information.
- Add a new authenticated encryption feature to the DM crypt target
that builds on the capabilities provided by the DM integrity target.
- Add MD interface for switching the raid4/5/6 journal mode and update
the DM raid target to use it to enable aid4/5/6 journal write-back
support.
- Switch the DM verity target over to using the asynchronous hash
crypto API (this helps work better with architectures that have
access to off-CPU algorithm providers, which should reduce CPU
utilization).
- Various request-based DM and DM multipath fixes and improvements from
Bart and Christoph.
- A DM thinp target fix for a bio structure leak that occurs for each
discard IFF discard passdown is enabled.
- A fix for a possible deadlock in DM bufio and a fix to re-check the
new buffer allocation watermark in the face of competing admin
changes to the 'max_cache_size_bytes' tunable.
- A couple DM core cleanups.
* tag 'for-4.12/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (50 commits)
dm bufio: check new buffer allocation watermark every 30 seconds
dm bufio: avoid a possible ABBA deadlock
dm mpath: make it easier to detect unintended I/O request flushes
dm mpath: cleanup QUEUE_IF_NO_PATH bit manipulation by introducing assign_bit()
dm mpath: micro-optimize the hot path relative to MPATHF_QUEUE_IF_NO_PATH
dm: introduce enum dm_queue_mode to cleanup related code
dm mpath: verify __pg_init_all_paths locking assumptions at runtime
dm: verify suspend_locking assumptions at runtime
dm block manager: remove an unused argument from dm_block_manager_create()
dm rq: check blk_mq_register_dev() return value in dm_mq_init_request_queue()
dm mpath: delay requeuing while path initialization is in progress
dm mpath: avoid that path removal can trigger an infinite loop
dm mpath: split and rename activate_path() to prepare for its expanded use
dm ioctl: prevent stack leak in dm ioctl call
dm integrity: use previously calculated log2 of sectors_per_block
dm integrity: use hex2bin instead of open-coded variant
dm crypt: replace custom implementation of hex2bin()
dm crypt: remove obsolete references to per-CPU state
dm verity: switch to using asynchronous hash crypto API
dm crypt: use WQ_HIGHPRI for the IO and crypt workqueues
...
Introduce an enumeration type for the queue mode. This patch does
not change any functionality but makes the DM code easier to read.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Ensure that the assumptions about the caller holding suspend_lock
are checked at runtime if lockdep is enabled.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
A dm-crypt on dm-integrity device incorrectly advertises an integrity
profile on the DM crypt device. It can be seen in the files
"/sys/block/dm-*/integrity/*" that both dm-integrity and dm-crypt target
advertise the integrity profile. That is incorrect, only the
dm-integrity target should advertise the integrity profile.
A general problem in DM is that if we have a DM device that depends on
another device with an integrity profile, the upper device will always
advertise the integrity profile, even when the target driver doesn't
support handling integrity data.
Most targets don't support integrity data, so we provide a whitelist of
targets that support it (linear, delay and striped). The targets that
support passing integrity data to the lower device are marked with the
flag DM_TARGET_PASSES_INTEGRITY. The DM core will now advertise
integrity data on a DM device only if all the targets support the
integrity data.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Also remove some unnecessary use of uninitialized_var().
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Now that we use the proper REQ_OP_WRITE_ZEROES operation everywhere we can
kill this hack.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Copy & paste from the REQ_OP_WRITE_SAME code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Add DM_TARGET_INTEGRITY flag that specifies bio integrity metadata is
not inherited but implemented in the target itself.
Signed-off-by: Milan Broz <gmazyland@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
We will want to have struct backing_dev_info allocated separately from
struct request_queue. As the first step add pointer to backing_dev_info
to request_queue and convert all users touching it. No functional
changes in this patch.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
Use a single loop instead of two loops to determine whether or not
all_blk_mq has to be set.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
When dm_table_set_type() is used by a target to establish a DM table's
type (e.g. DM_TYPE_MQ_REQUEST_BASED in the case of DM multipath) the
DM core must go on to verify that the devices in the table are
compatible with the established type.
Fixes: e83068a5 ("dm mpath: add optional "queue_mode" feature")
Cc: stable@vger.kernel.org # 4.8+
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
An earlier DM multipath table could have been build ontop of underlying
devices that were all using blk-mq. In that case, if that active
multipath table is replaced with an empty DM multipath table (that
reflects all paths have failed) then it is important that the
'all_blk_mq' state of the active table is transfered to the new empty DM
table. Otherwise dm-rq.c:dm_old_prep_tio() will incorrectly clone a
request that isn't needed by the DM multipath target when it is to issue
IO to an underlying blk-mq device.
Fixes: e83068a5 ("dm mpath: add optional "queue_mode" feature")
Cc: stable@vger.kernel.org # 4.8+
Reported-by: Bart Van Assche <bart.vanassche@sandisk.com>
Tested-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
dm_get_target_type() was previously called so any error returned from
dm_table_add_target() must first call dm_put_target_type(). Otherwise
the DM target module's reference count will leak and the associated
kernel module will be unable to be removed.
Also, leverage the fact that r is already -EINVAL and remove an extra
newline.
Fixes: 36a0456 ("dm table: add immutable feature")
Fixes: cc6cbe1 ("dm table: add always writeable feature")
Fixes: 3791e2f ("dm table: add singleton feature")
Cc: stable@vger.kernel.org # 3.2+
Signed-off-by: tang.junhui <tang.junhui@zte.com.cn>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Change mapped device to implement direct_access function,
dm_blk_direct_access(), which calls a target direct_access function.
'struct target_type' is extended to have target direct_access interface.
This function limits direct accessible size to the dm_target's limit
with max_io_len().
Add dm_table_supports_dax() to iterate all targets and associated block
devices to check for DAX support. To add DAX support to a DM target the
target must only implement the direct_access function.
Add a new dm type, DM_TYPE_DAX_BIO_BASED, which indicates that mapped
device supports DAX and is bio based. This new type is used to assure
that all target devices have DAX support and remain that way after
QUEUE_FLAG_DAX is set in mapped device.
At initial table load, QUEUE_FLAG_DAX is set to mapped device when setting
DM_TYPE_DAX_BIO_BASED to the type. Any subsequent table load to the
mapped device must have the same type, or else it fails per the check in
table_load().
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Allow a user to specify an optional feature 'queue_mode <mode>' where
<mode> 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 <snitzer@redhat.com>
Add some seperation between bio-based and request-based DM core code.
'struct mapped_device' and other DM core only structures and functions
have been moved to dm-core.h and all relevant DM core .c files have been
updated to include dm-core.h rather than dm.h
DM targets should _never_ include dm-core.h!
[block core merge conflict resolution from Stephen Rothwell]
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Now that we converted everything to the newer block write cache
interface, kill off the queue flush_flags and queueable flush
entries.
Signed-off-by: Jens Axboe <axboe@fb.com>
DM multipath is the only dm-mq target. But that aside, request-based DM
only supports tables with a single target that is immutable. Leverage
this fact in dm_mq_queue_rq() by using the 'immutable_target' stored in
the mapped_device when the table was made active. This saves the need
to even take the read-side of the SRCU via dm_{get,put}_live_table.
If the active DM table does not have an immutable target (e.g. "error"
target was swapped in) then fallback to the slow-path where the target
is looked up from the live table.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
The DM_TARGET_WILDCARD feature indicates that the "error" target may
replace any target; even immutable targets. This feature will be useful
to preserve the ability to replace the "multipath" target even once it
is formally converted over to having the DM_TARGET_IMMUTABLE feature.
Also, implicit in the DM_TARGET_WILDCARD feature flag being set is that
.map, .map_rq, .clone_and_map_rq and .release_clone_rq are all defined
in the target_type.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Up until now the_integrity profile has been dynamically allocated and
attached to struct gendisk after the disk has been made active.
This causes problems because NVMe devices need to register the profile
prior to the partition table being read due to a mandatory metadata
buffer requirement. In addition, DM goes through hoops to deal with
preallocating, but not initializing integrity profiles.
Since the integrity profile is small (4 bytes + a pointer), Christoph
suggested moving it to struct gendisk proper. This requires several
changes:
- Moving the blk_integrity definition to genhd.h.
- Inlining blk_integrity in struct gendisk.
- Removing the dynamic allocation code.
- Adding helper functions which allow gendisk to set up and tear down
the integrity sysfs dir when a disk is added/deleted.
- Adding a blk_integrity_revalidate() callback for updating the stable
pages bdi setting.
- The calls that depend on whether a device has an integrity profile or
not now key off of the bi->profile pointer.
- Simplifying the integrity support routines in DM (Mike Snitzer).
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reported-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
The SG_GAPS queue flag caused checks for bio vector alignment against
PAGE_SIZE, but the device may have different constraints. This patch
adds a queue limits so a driver with such constraints can set to allow
requests that would have been unnecessarily split. The new gaps check
takes the request_queue as a parameter to simplify the logic around
invoking this function.
This new limit makes the queue flag redundant, so removing it and
all usage. Device-mappers will inherit the correct settings through
blk_stack_limits().
Signed-off-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
As generic_make_request() is now able to handle arbitrarily sized bios,
it's no longer necessary for each individual block driver to define its
own ->merge_bvec_fn() callback. Remove every invocation completely.
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lars Ellenberg <drbd-dev@lists.linbit.com>
Cc: drbd-user@lists.linbit.com
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Yehuda Sadeh <yehuda@inktank.com>
Cc: Sage Weil <sage@inktank.com>
Cc: Alex Elder <elder@kernel.org>
Cc: ceph-devel@vger.kernel.org
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: dm-devel@redhat.com
Cc: Neil Brown <neilb@suse.de>
Cc: linux-raid@vger.kernel.org
Cc: Christoph Hellwig <hch@infradead.org>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Acked-by: NeilBrown <neilb@suse.de> (for the 'md' bits)
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
[dpark: also remove ->merge_bvec_fn() in dm-thin as well as
dm-era-target, and resolve merge conflicts]
Signed-off-by: Dongsu Park <dpark@posteo.net>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This reverts commit 5f1b670d0b.
Justification for revert as reported in this dm-devel post:
https://www.redhat.com/archives/dm-devel/2015-June/msg00160.html
this change should not be pushed to mainline yet.
Firstly, Christoph has a newer version of the patch that fixes silent
data corruption problem:
https://www.redhat.com/archives/dm-devel/2015-May/msg00229.html
And the new version still depends on LLDDs to always complete requests
to the end when error happens, while block API doesn't enforce such a
requirement. If the assumption is ever broken, the inconsistency between
request and bio (e.g. rq->__sector and rq->bio) will cause silent data
corruption:
https://www.redhat.com/archives/dm-devel/2015-June/msg00022.html
Reported-by: Junichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Do not allocate the io_pool mempool for blk-mq request-based DM
(DM_TYPE_MQ_REQUEST_BASED) in dm_alloc_rq_mempools().
Also refine __bind_mempools() to have more precise awareness of which
mempools each type of DM device uses -- avoids mempool churn when
reloading DM tables (particularly for DM_TYPE_REQUEST_BASED).
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
dm-multipath accepts 0 path mapping.
# echo '0 2097152 multipath 0 0 0 0' | dmsetup create newdev
Such a mapping can be used to release underlying devices while still
holding requests in its queue until working paths come back.
However, once the multipath device is created over blk-mq devices,
it rejects reloading of 0 path mapping:
# echo '0 2097152 multipath 0 0 1 1 queue-length 0 1 1 /dev/sda 1' \
| dmsetup create mpath1
# echo '0 2097152 multipath 0 0 0 0' | dmsetup load mpath1
device-mapper: reload ioctl on mpath1 failed: Invalid argument
Command failed
With following kernel message:
device-mapper: ioctl: can't change device type after initial table load.
DM tries to inherit the current table type using dm_table_set_type()
but it doesn't work as expected because of unnecessary check about
whether the target type is hybrid or not.
Hybrid type is for targets that work as either request-based or bio-based
and not required for blk-mq or non blk-mq checking.
Fixes: 65803c2059 ("dm table: train hybrid target type detection to select blk-mq if appropriate")
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Currently dm-multipath has to clone the bios for every request sent
to the lower devices, which wastes cpu cycles and ties down memory.
This patch instead adds a new REQ_CLONE flag that instructs req_bio_endio
to not complete bios attached to a request, which we set on clone
requests similar to bios in a flush sequence. With this change I/O
errors on a path failure only get propagated to dm-multipath, which
can then either resubmit the I/O or complete the bios on the original
request.
I've done some basic testing of this on a Linux target with ALUA support,
and it survives path failures during I/O nicely.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
If a device is used as the root filesystem, it can't be built
off of devices which are within the root filesystem (just like
command line arguments to root=). For this reason, Linux has a
pseudo-filesystem for root= and MD initialization (based on the
function name_to_dev_t) which handles different ways of specifying
devices including PARTUUID and major:minor.
Switch to using name_to_dev_t() in dm_get_device(). Rather than
having DM assume that all things which are not major:minor are paths in
an already-mounted filesystem, change dm_get_device() to first attempt
to look up the device in the filesystem, and if not found it will fall
back to using name_to_dev_t().
In terms of backwards compatibility, there are some cases where
behavior will be different:
- If you have a file in the current working directory named 1:2 and
you initialze DM there, then it will try to use that file rather
than the disk with that major:minor pair as a backing device.
- Similarly for other bdev types which name_to_dev_t() knows how to
interpret, the previous behavior was to repeatedly check for the
existence of the file (e.g., while waiting for rootfs to come up)
but the new behavior is to use the name_to_dev_t() interpretation.
For example, if you have a file named /dev/ubiblock0_0 which is
a symlink to /dev/sda3, but it is not yet present when DM starts
to initialize, then the name_to_dev_t() interpretation will take
precedence.
These incompatibilities would only show up in really strange setups
with bad practices so we shouldn't have to worry about them.
Signed-off-by: Dan Ehrenberg <dehrenberg@chromium.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Request-based DM's blk-mq support defaults to off; but a user can easily
change the default using the dm_mod.use_blk_mq module/boot option.
Also, you can check what mode a given request-based DM device is using
with: cat /sys/block/dm-X/dm/use_blk_mq
This change enabled further cleanup and reduced work (e.g. the
md->io_pool and md->rq_pool isn't created if using blk-mq).
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Commit e5863d9ad ("dm: allocate requests in target when stacking on
blk-mq devices") served as the first step toward fully utilizing blk-mq
in request-based DM -- it enabled stacking an old-style (request_fn)
request_queue ontop of the underlying blk-mq device(s). That first step
didn't improve performance of DM multipath ontop of fast blk-mq devices
(e.g. NVMe) because the top-level old-style request_queue was severely
limited by the queue_lock.
The second step offered here enables stacking a blk-mq request_queue
ontop of the underlying blk-mq device(s). This unlocks significant
performance gains on fast blk-mq devices, Keith Busch tested on his NVMe
testbed and offered this really positive news:
"Just providing a performance update. All my fio tests are getting
roughly equal performance whether accessed through the raw block
device or the multipath device mapper (~470k IOPS). I could only push
~20% of the raw iops through dm before this conversion, so this latest
tree is looking really solid from a performance standpoint."
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Tested-by: Keith Busch <keith.busch@intel.com>
DM multipath is the only caller of blk_lld_busy() -- which calls a
queue's lld_busy_fn hook. Request-based DM doesn't support stacking
multipath devices so there is no reason to register the lld_busy_fn hook
on a multipath device's queue using blk_queue_lld_busy().
As such, remove functions dm_lld_busy and dm_table_any_busy_target.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
A DM device must inherit the QUEUE_FLAG_SG_GAPS flags from its
underlying block devices' request queues.
This fixes problems when submitting cloned requests to multipathed
devices requiring virtually contiguous buffers.
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Otherwise replacing the multipath target with the error target fails:
device-mapper: ioctl: can't change device type after initial table load.
The error target was mistakenly considered to be target type
DM_TYPE_REQUEST_BASED rather than DM_TYPE_MQ_REQUEST_BASED even if the
target it was to replace was of type DM_TYPE_MQ_REQUEST_BASED.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
For blk-mq request-based DM the responsibility of allocating a cloned
request is transfered from DM core to the target type. Doing so
enables the cloned request to be allocated from the appropriate
blk-mq request_queue's pool (only the DM target, e.g. multipath, can
know which block device to send a given cloned request to).
Care was taken to preserve compatibility with old-style block request
completion that requires request-based DM _not_ acquire the clone
request's queue lock in the completion path. As such, there are now 2
different request-based DM target_type interfaces:
1) the original .map_rq() interface will continue to be used for
non-blk-mq devices -- the preallocated clone request is passed in
from DM core.
2) a new .clone_and_map_rq() and .release_clone_rq() will be used for
blk-mq devices -- blk_get_request() and blk_put_request() are used
respectively from these hooks.
dm_table_set_type() was updated to detect if the request-based target is
being stacked on blk-mq devices, if so DM_TYPE_MQ_REQUEST_BASED is set.
DM core disallows switching the DM table's type after it is set. This
means that there is no mixing of non-blk-mq and blk-mq devices within
the same request-based DM table.
[This patch was started by Keith and later heavily modified by Mike]
Tested-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
The DM thin-pool target now must undo the changes performed during
pool_presuspend() so introduce presuspend_undo hook in target_type.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>
Until this change, when loading a new DM table, DM core would re-open
all of the devices in the DM table. Now, DM core will avoid redundant
device opens (and closes when destroying the old table) if the old
table already has a device open using the same mode. This is achieved
by managing reference counts on the table_devices that DM core now
stores in the mapped_device structure (rather than in the dm_table
structure). So a mapped_device's active and inactive dm_tables' dm_dev
lists now just point to the dm_devs stored in the mapped_device's
table_devices list.
This improvement in DM core's device reference counting has the
side-effect of fixing a long-standing limitation of the multipath
target: a DM multipath table couldn't include any paths that were unusable
(failed). For example: if all paths have failed and you add a new,
working, path to the table; you can't use it since the table load would
fail due to it still containing failed paths. Now a re-load of a
multipath table can include failed devices and when those devices become
active again they can be used instantly.
The device list code in dm.c isn't a straight copy/paste from the code in
dm-table.c, but it's very close (aside from some variable renames). One
subtle difference is that find_table_device for the tables_devices list
will only match devices with the same name and mode. This is because we
don't want to upgrade a device's mode in the active table when an
inactive table is loaded.
Access to the mapped_device structure's tables_devices list requires a
mutex (tables_devices_lock), so that tables cannot be created and
destroyed concurrently.
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Commit 05f1dd5 ("block: add queue flag for disabling SG merging")
introduced a new queue flag: QUEUE_FLAG_NO_SG_MERGE. This gets set by
default in blk_mq_init_queue for mq-enabled devices. The effect of
the flag is to bypass the SG segment merging. Instead, the
bio->bi_vcnt is used as the number of hardware segments.
With a device mapper target on top of a device with
QUEUE_FLAG_NO_SG_MERGE set, we can end up sending down more segments
than a driver is prepared to handle. I ran into this when backporting
the virtio_blk mq support. It triggerred this BUG_ON, in
virtio_queue_rq:
BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
The queue's max is set here:
blk_queue_max_segments(q, vblk->sg_elems-2);
Basically, what happens is that a bio is built up for the dm device
(which does not have the QUEUE_FLAG_NO_SG_MERGE flag set) using
bio_add_page. That path will call into __blk_recalc_rq_segments, so
what you end up with is bi_phys_segments being much smaller than bi_vcnt
(and bi_vcnt grows beyond the maximum sg elements). Then, when the bio
is submitted, it gets cloned. When the cloned bio is submitted, it will
end up in blk_recount_segments, here:
if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags))
bio->bi_phys_segments = bio->bi_vcnt;
and now we've set bio->bi_phys_segments to a number that is beyond what
was registered as queue_max_segments by the driver.
The right way to fix this is to propagate the queue flag up the stack.
The rules for propagating the flag are simple:
- if the flag is set for any underlying device, it must be set for the
upper device
- consequently, if the flag is not set for any underlying device, it
should not be set for the upper device.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # 3.16+
The function dm_table_supports_discards is only called from
dm-table.c:dm_table_set_restrictions(). So move it above
dm_table_set_restrictions and make it static.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
There is no need for code other than DM core to use dm_set_device_limits
so remove its EXPORT_SYMBOL_GPL. Also, cleanup a couple whitespace nits.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Introduce dm_table_run_md_queue_async() to run the request_queue of the
mapped_device associated with a request-based DM table.
Also add dm_md_get_queue() wrapper to extract the request_queue from a
mapped_device.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Make the function dm_table_alloc_md_mempools static because it is not
called from another file.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
A device mapper table is allocated in the following way:
* The function dm_table_create is called, it gets the number of targets
as an argument -- it allocates a targets array accordingly.
* For each target, we call dm_table_add_target.
If we add more targets than were specified in dm_table_create, the
function dm_table_add_target reallocates the targets array. However,
this reallocation code is wrong - it moves the targets array to a new
location, while some target constructors hold pointers to the array in
the old location.
The following DM target drivers save the pointer to the target
structure, so they corrupt memory if the target array is moved:
multipath, raid, mirror, snapshot, stripe, switch, thin, verity.
Under normal circumstances, the reallocation function is not called
(because dm_table_create is called with the correct number of targets),
so the buggy reallocation code is not used.
Prior to the fix "dm table: fail dm_table_create on dm_round_up
overflow", the reallocation code could only be used in case the user
specifies too large a value in param->target_count, such as 0xffffffff.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
The dm_round_up function may overflow to zero. In this case,
dm_table_create() must fail rather than go on to allocate an empty array
with alloc_targets().
This fixes a possible memory corruption that could be caused by passing
too large a number in "param->target_count".
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
If preresume fails it is worth logging an error given that a device is
left suspended due to the failure.
This change was motivated by local preresume error logging that was
added to the cache target ("preresume failed"). Elevating this
target-agnostic context for the where the target-specific error occurred
relative to the DM core's callouts makes sense.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Joe Thornber <ejt@redhat.com>
