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path: root/drivers/md/dm.h
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* dm: retain table limits when swapping to new table with no devicesMike Snitzer2012-09-261-0/+1
| | | | | | | | | | | | | | | | | | | | | | Add a safety net that will re-use the DM device's existing limits in the event that DM device has a temporary table that doesn't have any component devices. This is to reduce the chance that requests not respecting the hardware limits will reach the device. DM recalculates queue limits based only on devices which currently exist in the table. This creates a problem in the event all devices are temporarily removed such as all paths being lost in multipath. DM will reset the limits to the maximum permissible, which can then assemble requests which exceed the limits of the paths when the paths are restored. The request will fail the blk_rq_check_limits() test when sent to a path with lower limits, and will be retried without end by multipath. This became a much bigger issue after v3.6 commit fe86cdcef ("block: do not artificially constrain max_sectors for stacking drivers"). Reported-by: David Jeffery <djeffery@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm thin: commit before gathering statusAlasdair G Kergon2012-07-271-0/+5
| | | | | | | | | | | | | | | | Commit outstanding metadata before returning the status for a dm thin pool so that the numbers reported are as up-to-date as possible. The commit is not performed if the device is suspended or if the DM_NOFLUSH_FLAG is supplied by userspace and passed to the target through a new 'status_flags' parameter in the target's dm_status_fn. The userspace dmsetup tool will support the --noflush flag with the 'dmsetup status' and 'dmsetup wait' commands from version 1.02.76 onwards. Tested-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm table: add immutable featureAlasdair G Kergon2011-10-311-0/+2
| | | | | | | | | | Introduce DM_TARGET_IMMUTABLE to indicate that the target type cannot be mixed with any other target type, and once loaded into a device, it cannot be replaced with a table containing a different type. The thin provisioning pool device will use this. Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: ignore merge_bvec for snapshots when safeMikulas Patocka2011-08-021-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add a new flag DMF_MERGE_IS_OPTIONAL to struct mapped_device to indicate whether the device can accept bios larger than the size its merge function returns. When set, use this to send large bios to snapshots which can split them if necessary. Snapshot I/O may be significantly fragmented and this approach seems to improve peformance. Before the patch, dm_set_device_limits restricted bio size to page size if the underlying device had a merge function and the target didn't provide a merge function. After the patch, dm_set_device_limits restricts bio size to page size if the underlying device has a merge function, doesn't have DMF_MERGE_IS_OPTIONAL flag and the target doesn't provide a merge function. The snapshot target can't provide a merge function because when the merge function is called, it is impossible to determine where the bio will be remapped. Previously this led us to impose a 4k limit, which we can now remove if the snapshot store is located on a device without a merge function. Together with another patch for optimizing full chunk writes, it improves performance from 29MB/s to 40MB/s when writing to the filesystem on snapshot store. If the snapshot store is placed on a non-dm device with a merge function (such as md-raid), device mapper still limits all bios to page size. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* block: Require subsystems to explicitly allocate bio_set integrity mempoolMartin K. Petersen2011-03-171-1/+1
| | | | | | | | | | | | | | | | | | MD and DM create a new bio_set for every metadevice. Each bio_set has an integrity mempool attached regardless of whether the metadevice is capable of passing integrity metadata. This is a waste of memory. Instead we defer the allocation decision to MD and DM since we know at metadevice creation time whether integrity passthrough is needed or not. Automatic integrity mempool allocation can then be removed from bioset_create() and we make an explicit integrity allocation for the fs_bio_set. Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Reported-by: Zdenek Kabelac <zkabelac@redhat.com> Acked-by: Mike Snitzer <snizer@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* dm: linear support discardMike Snitzer2010-08-121-0/+1
| | | | | | | | | | | | | | | | | Allow discards to be passed through to linear mappings if at least one underlying device supports it. Discards will be forwarded only to devices that support them. A target that supports discards should set num_discard_requests to indicate how many times each discard request must be submitted to it. Verify table's underlying devices support discards prior to setting the associated DM device as capable of discards (via QUEUE_FLAG_DISCARD). Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Joe Thornber <thornber@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm ioctl: refactor dm_table_completeWill Drewry2010-08-121-1/+0
| | | | | | | | | This change unifies the various checks and finalization that occurs on a table prior to use. By doing so, it allows table construction without traversing the dm-ioctl interface. Signed-off-by: Will Drewry <wad@chromium.org> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: do not initialise full request queue when bio basedMike Snitzer2010-08-121-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Change bio-based mapped devices no longer to have a fully initialized request_queue (request_fn, elevator, etc). This means bio-based DM devices no longer register elevator sysfs attributes ('iosched/' tree or 'scheduler' other than "none"). In contrast, a request-based DM device will continue to have a full request_queue and will register elevator sysfs attributes. Therefore a user can determine a DM device's type by checking if elevator sysfs attributes exist. First allocate a minimalist request_queue structure for a DM device (needed for both bio and request-based DM). Initialization of a full request_queue is deferred until it is known that the DM device is request-based, at the end of the table load sequence. Factor DM device's request_queue initialization: - common to both request-based and bio-based into dm_init_md_queue(). - specific to request-based into dm_init_request_based_queue(). The md->type_lock mutex is used to protect md->queue, in addition to md->type, during table_load(). A DM device's first table_load will establish the immutable md->type. But md->queue initialization, based on md->type, may fail at that time (because blk_init_allocated_queue cannot allocate memory). Therefore any subsequent table_load must (re)try dm_setup_md_queue independently of establishing md->type. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Acked-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm ioctl: make bio or request based device type immutableMike Snitzer2010-08-121-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Determine whether a mapped device is bio-based or request-based when loading its first (inactive) table and don't allow that to be changed later. This patch performs different device initialisation in each of the two cases. (We don't think it's necessary to add code to support changing between the two types.) Allowed md->type transitions: DM_TYPE_NONE to DM_TYPE_BIO_BASED DM_TYPE_NONE to DM_TYPE_REQUEST_BASED We now prevent table_load from replacing the inactive table with a conflicting type of table even after an explicit table_clear. Introduce 'type_lock' into the struct mapped_device to protect md->type and to prepare for the next patch that will change the queue initialization and allocate memory while md->type_lock is held. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Acked-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> drivers/md/dm-ioctl.c | 15 +++++++++++++++ drivers/md/dm.c | 37 ++++++++++++++++++++++++++++++------- drivers/md/dm.h | 5 +++++ include/linux/dm-ioctl.h | 4 ++-- 4 files changed, 52 insertions(+), 9 deletions(-)
* dm: separate device deletion from dm_putKiyoshi Ueda2010-08-121-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch separates the device deletion code from dm_put() to make sure the deletion happens in the process context. By this patch, device deletion always occurs in an ioctl (process) context and dm_put() can be called in interrupt context. As a result, the request-based dm's bad dm_put() usage pointed out by Mikulas below disappears. http://marc.info/?l=dm-devel&m=126699981019735&w=2 Without this patch, I confirmed there is a case to crash the system: dm_put() => dm_table_destroy() => vfree() => BUG_ON(in_interrupt()) Some more backgrounds and details: In request-based dm, a device opener can remove a mapped_device while the last request is still completing, because bios in the last request complete first and then the device opener can close and remove the mapped_device before the last request completes: CPU0 CPU1 ================================================================= <<INTERRUPT>> blk_end_request_all(clone_rq) blk_update_request(clone_rq) bio_endio(clone_bio) == end_clone_bio blk_update_request(orig_rq) bio_endio(orig_bio) <<I/O completed>> dm_blk_close() dev_remove() dm_put(md) <<Free md>> blk_finish_request(clone_rq) .... dm_end_request(clone_rq) free_rq_clone(clone_rq) blk_end_request_all(orig_rq) rq_completed(md) So request-based dm used dm_get()/dm_put() to hold md for each I/O until its request completion handling is fully done. However, the final dm_put() can call the device deletion code which must not be run in interrupt context and may cause kernel panic. To solve the problem, this patch moves the device deletion code, dm_destroy(), to predetermined places that is actually deleting the mapped_device in ioctl (process) context, and changes dm_put() just to decrement the reference count of the mapped_device. By this change, dm_put() can be used in any context and the symmetric model below is introduced: dm_create(): create a mapped_device dm_destroy(): destroy a mapped_device dm_get(): increment the reference count of a mapped_device dm_put(): decrement the reference count of a mapped_device dm_destroy() waits for all references of the mapped_device to disappear, then deletes the mapped_device. dm_destroy() uses active waiting with msleep(1), since deleting the mapped_device isn't performance-critical task. And since at this point, nobody opens the mapped_device and no new reference will be taken, the pending counts are just for racing completing activity and will eventually decrease to zero. For the unlikely case of the forced module unload, dm_destroy_immediate(), which doesn't wait and forcibly deletes the mapped_device, is also introduced and used in dm_hash_remove_all(). Otherwise, "rmmod -f" may be stuck and never return. And now, because the mapped_device is deleted at this point, subsequent accesses to the mapped_device may cause NULL pointer references. Cc: stable@kernel.org Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm ioctl: introduce flag indicating uevent was generatedPeter Rajnoha2010-03-061-2/+2
| | | | | | | | | Set a new DM_UEVENT_GENERATED_FLAG when returning from ioctls to indicate that a uevent was actually generated. This tells the userspace caller that it may need to wait for the event to be processed. Signed-off-by: Peter Rajnoha <prajnoha@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: rename dm_suspended to dm_suspended_mdKiyoshi Ueda2009-12-101-0/+5
| | | | | | | | | | | This patch renames dm_suspended() to dm_suspended_md() and keeps it internal to dm. No functional change. Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Cc: Mike Anderson <andmike@linux.vnet.ibm.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: add dm_deleting_md functionMike Anderson2009-12-101-0/+5
| | | | | | | | Add dm_deleting_md to check whether or not a given mapped device is currently being deleted. Signed-off-by: Mike Anderson <andmike@linux.vnet.ibm.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm io: use slab for struct ioMikulas Patocka2009-12-101-0/+3
| | | | | | | | | | | | Allocate "struct io" from a slab. This patch changes dm-io, so that "struct io" is allocated from a slab cache. It used to be allocated with kmalloc. Allocating from a slab will be needed for the next patch, because it requires a special alignment of "struct io" and kmalloc cannot meet this alignment. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: remove queue next_ordered workaround for barriersMike Snitzer2009-07-231-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | This patch removes DM's bio-based vs request-based conditional setting of next_ordered. For bio-based DM the next_ordered check is no longer a concern (as that check is now in the __make_request path). For request-based DM the default of QUEUE_ORDERED_NONE is now appropriate. bio-based DM was changed to work-around the previously misplaced next_ordered check with this commit: 99360b4c18f7675b50d283301d46d755affe75fd request-based DM does not yet support barriers but reacted to the above bio-based DM change with this commit: 5d67aa2366ccb8257d103d0b43df855605c3c086 The above changes are no longer needed given Neil Brown's recent fix to put the next_ordered check in the __make_request path: db64f680ba4b5c56c4be59f0698000df89ff0281 Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Cc: NeilBrown <neilb@suse.de> Acked-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Acked-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: do not set QUEUE_ORDERED_DRAIN if request basedKiyoshi Ueda2009-06-221-0/+1
| | | | | | | | | | | | Request-based dm doesn't have barrier support yet. So we need to set QUEUE_ORDERED_DRAIN only for bio-based dm. Since the device type is decided at the first table loading time, the flag set is deferred until then. Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Acked-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: enable request based optionKiyoshi Ueda2009-06-221-0/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch enables request-based dm. o Request-based dm and bio-based dm coexist, since there are some target drivers which are more fitting to bio-based dm. Also, there are other bio-based devices in the kernel (e.g. md, loop). Since bio-based device can't receive struct request, there are some limitations on device stacking between bio-based and request-based. type of underlying device bio-based request-based ---------------------------------------------- bio-based OK OK request-based -- OK The device type is recognized by the queue flag in the kernel, so dm follows that. o The type of a dm device is decided at the first table binding time. Once the type of a dm device is decided, the type can't be changed. o Mempool allocations are deferred to at the table loading time, since mempools for request-based dm are different from those for bio-based dm and needed mempool type is fixed by the type of table. o Currently, request-based dm supports only tables that have a single target. To support multiple targets, we need to support request splitting or prevent bio/request from spanning multiple targets. The former needs lots of changes in the block layer, and the latter needs that all target drivers support merge() function. Both will take a time. Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: prepare for request based optionKiyoshi Ueda2009-06-221-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds core functions for request-based dm. When struct mapped device (md) is initialized, md->queue has an I/O scheduler and the following functions are used for request-based dm as the queue functions: make_request_fn: dm_make_request() pref_fn: dm_prep_fn() request_fn: dm_request_fn() softirq_done_fn: dm_softirq_done() lld_busy_fn: dm_lld_busy() Actual initializations are done in another patch (PATCH 2). Below is a brief summary of how request-based dm behaves, including: - making request from bio - cloning, mapping and dispatching request - completing request and bio - suspending md - resuming md bio to request ============== md->queue->make_request_fn() (dm_make_request()) calls __make_request() for a bio submitted to the md. Then, the bio is kept in the queue as a new request or merged into another request in the queue if possible. Cloning and Mapping =================== Cloning and mapping are done in md->queue->request_fn() (dm_request_fn()), when requests are dispatched after they are sorted by the I/O scheduler. dm_request_fn() checks busy state of underlying devices using target's busy() function and stops dispatching requests to keep them on the dm device's queue if busy. It helps better I/O merging, since no merge is done for a request once it is dispatched to underlying devices. Actual cloning and mapping are done in dm_prep_fn() and map_request() called from dm_request_fn(). dm_prep_fn() clones not only request but also bios of the request so that dm can hold bio completion in error cases and prevent the bio submitter from noticing the error. (See the "Completion" section below for details.) After the cloning, the clone is mapped by target's map_rq() function and inserted to underlying device's queue using blk_insert_cloned_request(). Completion ========== Request completion can be hooked by rq->end_io(), but then, all bios in the request will have been completed even error cases, and the bio submitter will have noticed the error. To prevent the bio completion in error cases, request-based dm clones both bio and request and hooks both bio->bi_end_io() and rq->end_io(): bio->bi_end_io(): end_clone_bio() rq->end_io(): end_clone_request() Summary of the request completion flow is below: blk_end_request() for a clone request => blk_update_request() => bio->bi_end_io() == end_clone_bio() for each clone bio => Free the clone bio => Success: Complete the original bio (blk_update_request()) Error: Don't complete the original bio => blk_finish_request() => rq->end_io() == end_clone_request() => blk_complete_request() => dm_softirq_done() => Free the clone request => Success: Complete the original request (blk_end_request()) Error: Requeue the original request end_clone_bio() completes the original request on the size of the original bio in successful cases. Even if all bios in the original request are completed by that completion, the original request must not be completed yet to keep the ordering of request completion for the stacking. So end_clone_bio() uses blk_update_request() instead of blk_end_request(). In error cases, end_clone_bio() doesn't complete the original bio. It just frees the cloned bio and gives over the error handling to end_clone_request(). end_clone_request(), which is called with queue lock held, completes the clone request and the original request in a softirq context (dm_softirq_done()), which has no queue lock, to avoid a deadlock issue on submission of another request during the completion: - The submitted request may be mapped to the same device - Request submission requires queue lock, but the queue lock has been held by itself and it doesn't know that The clone request has no clone bio when dm_softirq_done() is called. So target drivers can't resubmit it again even error cases. Instead, they can ask dm core for requeueing and remapping the original request in that cases. suspend ======= Request-based dm uses stopping md->queue as suspend of the md. For noflush suspend, just stops md->queue. For flush suspend, inserts a marker request to the tail of md->queue. And dispatches all requests in md->queue until the marker comes to the front of md->queue. Then, stops dispatching request and waits for the all dispatched requests to complete. After that, completes the marker request, stops md->queue and wake up the waiter on the suspend queue, md->wait. resume ====== Starts md->queue. Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: calculate queue limits during resume not loadMike Snitzer2009-06-221-1/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, device-mapper maintains a separate instance of 'struct queue_limits' for each table of each device. When the configuration of a device is to be changed, first its table is loaded and this structure is populated, then the device is 'resumed' and the calculated queue_limits are applied. This places restrictions on how userspace may process related devices, where it is often advantageous to 'load' tables for several devices at once before 'resuming' them together. As the new queue_limits only take effect after the 'resume', if they are changing and one device uses another, the latter must be 'resumed' before the former may be 'loaded'. This patch moves the calculation of these queue_limits out of the 'load' operation into 'resume'. Since we are no longer pre-calculating this struct, we no longer need to maintain copies within our dm structs. dm_set_device_limits() now passes the 'start' of the device's data area (aka pe_start) as the 'offset' to blk_stack_limits(). init_valid_queue_limits() is replaced by blk_set_default_limits(). Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: martin.petersen@oracle.com Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm ioctl: support cookies for udevMilan Broz2009-06-221-1/+2
| | | | | | | | | | | | | | | | | | | | Add support for passing a 32 bit "cookie" into the kernel with the DM_SUSPEND, DM_DEV_RENAME and DM_DEV_REMOVE ioctls. The (unsigned) value of this cookie is returned to userspace alongside the uevents issued by these ioctls in the variable DM_COOKIE. This means the userspace process issuing these ioctls can be notified by udev after udev has completed any actions triggered. To minimise the interface extension, we pass the cookie into the kernel in the event_nr field which is otherwise unused when calling these ioctls. Incrementing the version number allows userspace to determine in advance whether or not the kernel supports the cookie. If the kernel does support this but userspace does not, there should be no impact as the new variable will just get ignored. Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: remove limited barrier supportMikulas Patocka2009-04-091-1/+0
| | | | | | | Prepare for full barrier implementation: first remove the restricted support. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm target: remove struct tt_internalCheng Renquan2009-04-021-1/+1
| | | | | | | | | | | | | | The tt_internal is really just a list_head to manage registered target_type in a double linked list, Here embed the list_head into target_type directly, 1. to avoid kmalloc/kfree; 2. then tt_internal is really unneeded; Cc: stable@kernel.org Signed-off-by: Cheng Renquan <crquan@gmail.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Reviewed-by: Alasdair G Kergon <agk@redhat.com>
* dm: add name and uuid to sysfsMilan Broz2009-01-061-0/+8
| | | | | | | | | | | | | | | | | | | | | Implement simple read-only sysfs entry for device-mapper block device. This patch adds a simple sysfs directory named "dm" under block device properties and implements - name attribute (string containing mapped device name) - uuid attribute (string containing UUID, or empty string if not set) The kobject is embedded in mapped_device struct, so no additional memory allocation is needed for initializing sysfs entry. During the processing of sysfs attribute we need to lock mapped device which is done by a new function dm_get_from_kobj, which returns the md associated with kobject and increases the usage count. Each 'show attribute' function is responsible for its own locking. Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm table: rework reference countingMikulas Patocka2009-01-061-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Rework table reference counting. The existing code uses a reference counter. When the last reference is dropped and the counter reaches zero, the table destructor is called. Table reference counters are acquired/released from upcalls from other kernel code (dm_any_congested, dm_merge_bvec, dm_unplug_all). If the reference counter reaches zero in one of the upcalls, the table destructor is called from almost random kernel code. This leads to various problems: * dm_any_congested being called under a spinlock, which calls the destructor, which calls some sleeping function. * the destructor attempting to take a lock that is already taken by the same process. * stale reference from some other kernel code keeps the table constructed, which keeps some devices open, even after successful return from "dmsetup remove". This can confuse lvm and prevent closing of underlying devices or reusing device minor numbers. The patch changes reference counting so that the table destructor can be called only at predetermined places. The table has always exactly one reference from either mapped_device->map or hash_cell->new_map. After this patch, this reference is not counted in table->holders. A pair of dm_create_table/dm_destroy_table functions is used for table creation/destruction. Temporary references from the other code increase table->holders. A pair of dm_table_get/dm_table_put functions is used to manipulate it. When the table is about to be destroyed, we wait for table->holders to reach 0. Then, we call the table destructor. We use active waiting with msleep(1), because the situation happens rarely (to one user in 5 years) and removing the device isn't performance-critical task: the user doesn't care if it takes one tick more or not. This way, the destructor is called only at specific points (dm_table_destroy function) and the above problems associated with lazy destruction can't happen. Finally remove the temporary protection added to dm_any_congested(). Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: support barriers on simple devicesAndi Kleen2009-01-061-0/+1
| | | | | | | | | | | | | | | | | Implement barrier support for single device DM devices This patch implements barrier support in DM for the common case of dm linear just remapping a single underlying device. In this case we can safely pass the barrier through because there can be no reordering between devices. NB. Any DM device might cease to support barriers if it gets reconfigured so code must continue to allow for a possible -EOPNOTSUPP on every barrier bio submitted. - agk Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: publish array_too_bigMikulas Patocka2008-10-211-9/+0
| | | | | | | | | | | | Move array_too_big to include/linux/device-mapper.h because it is used by targets. Remove the test from dm-raid1 as the number of mirror legs is limited such that it can never fail. (Even for stripes it seems rather unlikely.) Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: publish dm_vcallocMikulas Patocka2008-10-101-1/+0
| | | | | | | | Publish dm_vcalloc in include/linux/device-mapper.h because this function is used by targets. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: publish dm_table_unplug_allMikulas Patocka2008-10-101-1/+0
| | | | | | | | Publish dm_table_unplug_all in include/linux/device-mapper.h because this function is used by targets. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: publish dm_get_mapinfoMikulas Patocka2008-10-101-1/+0
| | | | | | | | Publish dm_get_mapinfo in include/linux/device-mapper.h because this function is used by targets. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: export struct dm_devMikulas Patocka2008-10-101-5/+2
| | | | | | | | Split struct dm_dev in two and publish the part that other targets need in include/linux/device-mapper.h. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm log: make dm_dirty_log init and exit staticAdrian Bunk2008-07-211-6/+0
| | | | | | | | dm_dirty_log_{init,exit}() can now become static. Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: expose macrosAlasdair G Kergon2008-04-251-89/+0
| | | | | | Make dm.h macros and inlines available in include/linux/device-mapper.h Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm kcopyd: remove redundant client countingMikulas Patocka2008-04-251-0/+3
| | | | | | | | | | | | Remove client counting code that is no longer needed. Initialization and destruction is made globally from dm_init and dm_exit and is not based on client counts. Initialization allocates only one empty slab cache, so there is no negative impact from performing the initialization always, regardless of whether some client uses kcopyd or not. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm log: clean interfaceHeinz Mauelshagen2008-04-251-0/+6
| | | | | | | Clean up the dm-log interface to prepare for publishing it in include/linux. Signed-off-by: Heinz Mauelshagen <hjm@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: trigger change uevent on renameAlasdair G Kergon2007-12-201-0/+2
| | | | | | | Insert a missing KOBJ_CHANGE notification when a device is renamed. Cc: Scott James Remnant <scott@ubuntu.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: table detect io beyond deviceJun'ichi Nomura2007-12-201-0/+5
| | | | | | | | | | | | | | | | | | | | | This patch fixes a panic on shrinking a DM device if there is outstanding I/O to the part of the device that is being removed. (Normally this doesn't happen - a filesystem would be resized first, for example.) The bug is that __clone_and_map() assumes dm_table_find_target() always returns a valid pointer. It may fail if a bio arrives from the block layer but its target sector is no longer included in the DM btree. This patch appends an empty entry to table->targets[] which will be returned by a lookup beyond the end of the device. After calling dm_table_find_target(), __clone_and_map() and target_message() check for this condition using dm_target_is_valid(). Sample test script to trigger oops:
* block: convert blkdev_issue_flush() to use empty barriersJens Axboe2007-10-161-1/+0
| | | | | | | Then we can get rid of ->issue_flush_fn() and all the driver private implementations of that. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* dm: add ratelimit logging macrosJonathan Brassow2007-07-121-4/+36
| | | | | | | | Add ratelimit extension to dm logging macros. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] dm: suspend: add noflush pushbackKiyoshi Ueda2006-12-081-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In device-mapper I/O is sometimes queued within targets for later processing. For example the multipath target can be configured to store I/O when no paths are available instead of returning it -EIO. This patch allows the device-mapper core to instruct a target to transfer the contents of any such in-target queue back into the core. This frees up the resources used by the target so the core can replace that target with an alternative one and then resend the I/O to it. Without this patch the only way to change the target in such circumstances involves returning the I/O with an error back to the filesystem/application. In the multipath case, this patch will let us add new paths for existing I/O to try after all the existing paths have failed. DMF_NOFLUSH_SUSPENDING ---------------------- If the DM_NOFLUSH_FLAG ioctl option is specified at suspend time, the DMF_NOFLUSH_SUSPENDING flag is set in md->flags during dm_suspend(). It is always cleared before dm_suspend() returns. The flag must be visible while the target is flushing pending I/Os so it is set before presuspend where the flush starts and unset after the wait for md->pending where the flush ends. Target drivers can check this flag by calling dm_noflush_suspending(). DM_MAPIO_REQUEUE / DM_ENDIO_REQUEUE ----------------------------------- A target's map() function can now return DM_MAPIO_REQUEUE to request the device mapper core queue the bio. Similarly, a target's end_io() function can return DM_ENDIO_REQUEUE to request the same. This has been labelled 'pushback'. The __map_bio() and clone_endio() functions in the core treat these return values as errors and call dec_pending() to end the I/O. dec_pending ----------- dec_pending() saves the pushback request in struct dm_io->error. Once all the split clones have ended, dec_pending() will put the original bio on the md->pushback list. Note that this supercedes any I/O errors. It is possible for the suspend with DM_NOFLUSH_FLAG to be aborted while in progress (e.g. by user interrupt). dec_pending() checks for this and returns -EIO if it happened. pushdback list and pushback_lock -------------------------------- The bio is queued on md->pushback temporarily in dec_pending(), and after all pending I/Os return, md->pushback is merged into md->deferred in dm_suspend() for re-issuing at resume time. md->pushback_lock protects md->pushback. The lock should be held with irq disabled because dec_pending() can be called from interrupt context. Queueing bios to md->pushback in dec_pending() must be done atomically with the check for DMF_NOFLUSH_SUSPENDING flag. So md->pushback_lock is held when checking the flag. Otherwise dec_pending() may queue a bio to md->pushback after the interrupted dm_suspend() flushes md->pushback. Then the bio would be left in md->pushback. Flag setting in dm_suspend() can be done without md->pushback_lock because the flag is checked only after presuspend and the set value is already made visible via the target's presuspend function. The flag can be checked without md->pushback_lock (e.g. the first part of the dec_pending() or target drivers), because the flag is checked again with md->pushback_lock held when the bio is really queued to md->pushback as described above. So even if the flag is cleared after the lockless checkings, the bio isn't left in md->pushback but returned to applications with -EIO. Other notes on the current patch -------------------------------- - md->pushback is added to the struct mapped_device instead of using md->deferred directly because md->io_lock which protects md->deferred is rw_semaphore and can't be used in interrupt context like dec_pending(), and md->io_lock protects the DMF_BLOCK_IO flag of md->flags too. - Don't issue lock_fs() in dm_suspend() if the DM_NOFLUSH_FLAG ioctl option is specified, because I/Os generated by lock_fs() would be pushed back and never return if there were no valid devices. - If an error occurs in dm_suspend() after the DMF_NOFLUSH_SUSPENDING flag is set, md->pushback must be flushed because I/Os may be queued to the list already. (flush_and_out label in dm_suspend()) Test results ------------ I have tested using multipath target with the next patch. The following tests are for regression/compatibility: - I/Os succeed when valid paths exist; - I/Os fail when there are no valid paths and queue_if_no_path is not set; - I/Os are queued in the multipath target when there are no valid paths and queue_if_no_path is set; - The queued I/Os above fail when suspend is issued without the DM_NOFLUSH_FLAG ioctl option. I/Os spanning 2 multipath targets also fail. The following tests are for the normal code path of new pushback feature: - Queued I/Os in the multipath target are flushed from the target but don't return when suspend is issued with the DM_NOFLUSH_FLAG ioctl option; - The I/Os above are queued in the multipath target again when resume is issued without path recovery; - The I/Os above succeed when resume is issued after path recovery or table load; - Queued I/Os in the multipath target succeed when resume is issued with the DM_NOFLUSH_FLAG ioctl option after table load. I/Os spanning 2 multipath targets also succeed. The following tests are for the error paths of the new pushback feature: - When the bdget_disk() fails in dm_suspend(), the DMF_NOFLUSH_SUSPENDING flag is cleared and I/Os already queued to the pushback list are flushed properly. - When suspend with the DM_NOFLUSH_FLAG ioctl option is interrupted, o I/Os which had already been queued to the pushback list at the time don't return, and are re-issued at resume time; o I/Os which hadn't been returned at the time return with EIO. Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Cc: dm-devel@redhat.com Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm: ioctl: add noflush suspendKiyoshi Ueda2006-12-081-0/+1
| | | | | | | | | | | | | | | | | | | Provide a dm ioctl option to request noflush suspending. (See next patch for what this is for.) As the interface is extended, the version number is incremented. Other than accepting the new option through the interface, There is no change to existing behaviour. Test results: Confirmed the option is given from user-space correctly. Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Cc: dm-devel@redhat.com Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm: map and endio return code clarificationKiyoshi Ueda2006-12-081-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Tighten the use of return values from the target map and end_io functions. Values of 2 and above are now explictly reserved for future use. There are no existing targets using such values. The patch has no effect on existing behaviour. o Reserve return values of 2 and above from target map functions. Any positive value currently indicates "mapping complete", but all existing drivers use the value 1. We now make that a requirement so we can assign new meaning to higher values in future. The new definition of return values from target map functions is: < 0 : error = 0 : The target will handle the io (DM_MAPIO_SUBMITTED). = 1 : Mapping completed (DM_MAPIO_REMAPPED). > 1 : Reserved (undefined). Previously this was the same as '= 1'. o Reserve return values of 2 and above from target end_io functions for similar reasons. DM_ENDIO_INCOMPLETE is introduced for a return value of 1. Test results: I have tested by using the multipath target. I/Os succeed when valid paths exist. I/Os are queued in the multipath target when there are no valid paths and queue_if_no_path is set. I/Os fail when there are no valid paths and queue_if_no_path is not set. Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Cc: dm-devel@redhat.com Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm: suspend: parameter changeKiyoshi Ueda2006-12-081-0/+5
| | | | | | | | | | | | | | | | | | | Change the interface of dm_suspend() so that we can pass several options without increasing the number of parameters. The existing 'do_lockfs' integer parameter is replaced by a flag DM_SUSPEND_LOCKFS_FLAG. There is no functional change to the code. Test results: I have tested 'dmsetup suspend' command with/without the '--nolockfs' option and confirmed the do_lockfs value is correctly set. Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Cc: dm-devel@redhat.com Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm table: add target preresumeMilan Broz2006-10-031-1/+1
| | | | | | | | | | | | | | | This patch adds a target preresume hook. It is called before the targets are resumed and if it returns an error the resume gets cancelled. The crypt target will use this to indicate that it is unable to process I/O because no encryption key has been supplied. Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm: add debug macroBryn Reeves2006-10-031-0/+5
| | | | | | | | | Add CONFIG_DM_DEBUG and DMDEBUG() macro. Signed-off-by: Bryn Reeves <breeves@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm: improve error message consistencyAlasdair G Kergon2006-06-261-3/+4
| | | | | | | | | Tidy device-mapper error messages to include context information automatically. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm: prevent removal if openAlasdair G Kergon2006-06-261-0/+2
| | | | | | | | | | | | | | | | | If you misuse the device-mapper interface (or there's a bug in your userspace tools) it's possible to end up with 'unlinked' mapped devices that cannot be removed until you reboot (along with uninterruptible processes). This patch prevents you from removing a device that is still open. It introduces dm_lock_for_deletion() which is called when a device is about to be removed to ensure that nothing has it open and nothing further can open it. It uses a private open_count for this which also lets us remove one of the problematic bdget_disk() calls elsewhere. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm: add exportsAlasdair G Kergon2006-06-261-74/+1
| | | | | | | | | | | | | Move definitions of core device-mapper functions for manipulating mapped devices and their tables to <linux/device-mapper.h> advertising their availability for use elsewhere in the kernel. Protect the contents of device-mapper.h with ifdef __KERNEL__. And throw in a few formatting clean-ups and extra comments. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm: consolidate creation functionsAlasdair G Kergon2006-06-261-4/+9
| | | | | | | | | Merge dm_create() and dm_create_with_minor() by introducing the special value DM_ANY_MINOR to request the allocation of the next available minor number. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm store geometryDarrick J. Wong2006-03-271-0/+7
| | | | | | | | | | | Allow drive geometry to be stored with a new DM_DEV_SET_GEOMETRY ioctl. Device-mapper will now respond to HDIO_GETGEO. If the geometry information is not available, zero will be returned for all of the parameters. Signed-off-by: Darrick J. Wong <djwong@us.ibm.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm table: store mdMike Anderson2006-03-271-1/+3
| | | | | | | | | | | | | | | Store an up-pointer to the owning struct mapped_device in every table when it is created. Access it with: struct mapped_device *dm_table_get_md(struct dm_table *t) Tables linked to md must be destroyed before the md itself. Signed-off-by: Mike Anderson <andmike@us.ibm.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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