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path: root/drivers/md/dm-raid1.c
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* dm kcopyd: return client directly and not through a pointerMikulas Patocka2011-05-29
| | | | | | | | Return client directly from dm_kcopyd_client_create, not through a parameter, making it consistent with dm_io_client_create. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm kcopyd: reserve fewer pagesMikulas Patocka2011-05-29
| | | | | | | | | | | Reserve just the minimum of pages needed to process one job. Because we allocate pages from page allocator, we don't need to reserve a large number of pages. The maximum job size is SUB_JOB_SIZE and we calculate the number of reserved pages based on this. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm io: use fixed initial mempool sizeMikulas Patocka2011-05-29
| | | | | | | | | | | | | | | | | Replace the arbitrary calculation of an initial io struct mempool size with a constant. The code calculated the number of reserved structures based on the request size and used a "magic" multiplication constant of 4. This patch changes it to reserve a fixed number - itself still chosen quite arbitrarily. Further testing might show if there is a better number to choose. Note that if there is no memory pressure, we can still allocate an arbitrary number of "struct io" structures. One structure is enough to process the whole request. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* block: remove per-queue pluggingJens Axboe2011-03-10
| | | | | | | | Code has been converted over to the new explicit on-stack plugging, and delay users have been converted to use the new API for that. So lets kill off the old plugging along with aops->sync_page(). Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* dm: use non reentrant workqueues if equivalentTejun Heo2011-01-13
| | | | | | | | | | | | kmirrord_wq, kcopyd_work and md->wq are created per dm instance and serve only a single work item from the dm instance, so non-reentrant workqueues would provide the same ordering guarantees as ordered ones while allowing CPU affinity and use of the workqueues for other purposes. Switch them to non-reentrant workqueues. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: convert workqueues to alloc_orderedTejun Heo2011-01-13
| | | | | | | | | | Convert all create[_singlethread]_work() users to the new alloc[_ordered]_workqueue(). This conversion is mechanical and doesn't introduce any behavior change. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: dont use flush_scheduled_workTejun Heo2011-01-13
| | | | | | | | | | flush_scheduled_work() is being deprecated. Flush the used work directly instead. In all dm targets, the only work which uses system_wq is ->trigger_event. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid1: support discardMike Snitzer2011-01-13
| | | | | | | | Enable discard support in the DM mirror target. Also change an existing use of 'bvec' to 'addr' in the union. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: implement REQ_FLUSH/FUA support for bio-based dmTejun Heo2010-09-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch converts bio-based dm to support REQ_FLUSH/FUA instead of now deprecated REQ_HARDBARRIER. * -EOPNOTSUPP handling logic dropped. * Preflush is handled as before but postflush is dropped and replaced with passing down REQ_FUA to member request_queues. This replaces one array wide cache flush w/ member specific FUA writes. * __split_and_process_bio() now calls __clone_and_map_flush() directly for flushes and guarantees all FLUSH bio's going to targets are zero ` length. * It's now guaranteed that all FLUSH bio's which are passed onto dm targets are zero length. bio_empty_barrier() tests are replaced with REQ_FLUSH tests. * Empty WRITE_BARRIERs are replaced with WRITE_FLUSHes. * Dropped unlikely() around REQ_FLUSH tests. Flushes are not unlikely enough to be marked with unlikely(). * Block layer now filters out REQ_FLUSH/FUA bio's if the request_queue doesn't support cache flushing. Advertise REQ_FLUSH | REQ_FUA capability. * Request based dm isn't converted yet. dm_init_request_based_queue() resets flush support to 0 for now. To avoid disturbing request based dm code, dm->flush_error is added for bio based dm while requested based dm continues to use dm->barrier_error. Lightly tested linear, stripe, raid1, snap and crypt targets. Please proceed with caution as I'm not familiar with the code base. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: dm-devel@redhat.com Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* dm: use dm_target_offset macroAlasdair G Kergon2010-08-11
| | | | | | | Use new dm_target_offset() macro to avoid most references to ti->begin in dm targets. Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* block: unify flags for struct bio and struct requestChristoph Hellwig2010-08-07
| | | | | | | | | | | | | | Remove the current bio flags and reuse the request flags for the bio, too. This allows to more easily trace the type of I/O from the filesystem down to the block driver. There were two flags in the bio that were missing in the requests: BIO_RW_UNPLUG and BIO_RW_AHEAD. Also I've renamed two request flags that had a superflous RW in them. Note that the flags are in bio.h despite having the REQ_ name - as blkdev.h includes bio.h that is the only way to go for now. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* dm raid1: fix deadlock when suspending failed deviceTakahiro Yasui2010-03-05
| | | | | | | | | | | | | | | | | | | To prevent deadlock, bios in the hold list should be flushed before dm_rh_stop_recovery() is called in mirror_suspend(). The recovery can't start because there are pending bios and therefore dm_rh_stop_recovery deadlocks. When there are pending bios in the hold list, the recovery waits for the completion of the bios after recovery_count is acquired. The recovery_count is released when the recovery finished, however, the bios in the hold list are processed after dm_rh_stop_recovery() in mirror_presuspend(). dm_rh_stop_recovery() also acquires recovery_count, then deadlock occurs. Signed-off-by: Takahiro Yasui <tyasui@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
* dm table: remove unused dm_get_device range parametersNikanth Karthikesan2010-03-05
| | | | | | | | Remove unused parameters(start and len) of dm_get_device() and fix the callers. Signed-off-by: Nikanth Karthikesan <knikanth@suse.de> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid1: always return error if all legs failMikulas Patocka2010-03-05
| | | | | | | | | | | | | | | | If all mirror legs fail, always return an error instead of holding the bio, even if the handle_errors option was set. At present it is the responsibility of the driver underneath us to deal with retries, multipath etc. The patch adds the bio to the failures list instead of holding it directly. do_failures tests first if all legs failed and, if so, returns the bio with -EIO. If any leg is still alive and handle_errors is set, do_failures calls hold_bio. Reviewed-by: Takahiro Yasui <tyasui@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid1: fail writes if errors are not handled and log failsMikulas Patocka2010-02-16
| | | | | | | | | | | | | | | | | | | | | | | | If the mirror log fails when the handle_errors option was not selected and there is no remaining valid mirror leg, writes return success even though they weren't actually written to any device. This patch completes them with EIO instead. This code path is taken: do_writes: bio_list_merge(&ms->failures, &sync); do_failures: if (!get_valid_mirror(ms)) (false) else if (errors_handled(ms)) (false) else bio_endio(bio, 0); The logic in do_failures is based on presuming that the write was already tried: if it succeeded at least on one leg (without handle_errors) it is reported as success. Reference: https://bugzilla.redhat.com/show_bug.cgi?id=555197 Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid1: explicitly initialise bio_listsMikulas Patocka2009-12-10
| | | | | | | | | Explicitly initialize bio lists instead of relying on kzalloc. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Takahiro Yasui <tyasui@redhat.com> Tested-by: Takahiro Yasui <tyasui@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid1: hold all write bios when leg failsMikulas Patocka2009-12-10
| | | | | | | | | | | | | | | | Hold all write bios when leg fails and errors are handled When using a userspace daemon such as dmeventd to handle errors, we must delay completing bios until it has done its job. This patch prevents the following race: - primary leg fails - write "1" fail, the write is held, secondary leg is set default - write "2" goes straight to the secondary leg Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Takahiro Yasui <tyasui@redhat.com> Tested-by: Takahiro Yasui <tyasui@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid1: hold write bios when errors are handledMikulas Patocka2009-12-10
| | | | | | | | | | | | | | | | | | | | | | | Hold all write bios when errors are handled. Previously the failures list was used only when handling errors with a userspace daemon such as dmeventd. Now, it is always used for all bios. The regions where some writes failed must be marked as nosync. This can only be done in process context (i.e. in raid1 workqueue), not in the write_callback function. Previously the write would succeed if writing to at least one leg succeeded. This is wrong because data from the failed leg may be replicated to the correct leg. Now, if using a userspace daemon, the write with some failures will be held until the daemon has done its job and reconfigured the array. If not using a daemon, the write still succeeds if at least one leg succeeds. This is bad, but it is consistent with current behavior. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Takahiro Yasui <tyasui@redhat.com> Tested-by: Takahiro Yasui <tyasui@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid1: remove bio_endio from dm_rh_mark_nosyncMikulas Patocka2009-12-10
| | | | | | | | | | Move bio completion out of dm_rh_mark_nosync in preparation for the next patch. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Takahiro Yasui <tyasui@redhat.com> Tested-by: Takahiro Yasui <tyasui@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid1: abstract get_valid_mirror functionMikulas Patocka2009-12-10
| | | | | | | | | | Move the logic to get a valid mirror leg into a function for re-use in a later patch. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Takahiro Yasui <tyasui@redhat.com> Tested-by: Takahiro Yasui <tyasui@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid1: use hold framework in do_failuresMikulas Patocka2009-12-10
| | | | | | | | | | | | Use the hold framework in do_failures. This patch doesn't change the bio processing logic, it just simplifies failure handling and avoids periodically polling the failures list. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Takahiro Yasui <tyasui@redhat.com> Tested-by: Takahiro Yasui <tyasui@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid1: add framework to hold bios during suspendMikulas Patocka2009-12-10
| | | | | | | | | | | Add framework to delay bios until a suspend and then resubmit them with either DM_ENDIO_REQUEUE (if the suspend was noflush) or complete them with -EIO. I/O barrier support will use this. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Takahiro Yasui <tyasui@redhat.com> Tested-by: Takahiro Yasui <tyasui@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid1: report flush errors separately in statusMikulas Patocka2009-12-10
| | | | | | | Report flush errors as 'F' instead of 'D' for log and mirror devices. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid1: implement mirror_flushMikulas Patocka2009-12-10
| | | | | | | | Implement flush callee. It uses dm_io to send zero-size barrier synchronously and concurrently to all the mirror legs. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm log: add flush callback fnMikulas Patocka2009-12-10
| | | | | | | | | | | | | Introduce a callback pointer from the log to dm-raid1 layer. Before some region is set as "in-sync", we need to flush hardware cache on all the disks. But the log module doesn't have access to the mirror_set structure. So it will use this callback. So far the callback is unused, it will be used in further patches. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid1: support flushMikulas Patocka2009-12-10
| | | | | | | | | Flush support for dm-raid1. When it receives an empty barrier, submit it to all the devices via dm-io. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* bio: first step in sanitizing the bio->bi_rw flag testingJens Axboe2009-09-11
| | | | | | | | Get rid of any functions that test for these bits and make callers use bio_rw_flagged() directly. Then it is at least directly apparent what variable and flag they check. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* dm raid1: do not allow log_failure variable to unset after being setJonathan Brassow2009-09-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch fixes a bug which was triggering a case where the primary leg could not be changed on failure even when the mirror was in-sync. The case involves the failure of the primary device along with the transient failure of the log device. The problem is that bios can be put on the 'failures' list (due to log failure) before 'fail_mirror' is called due to the primary device failure. Normally, this is fine, but if the log device failure is transient, a subsequent iteration of the work thread, 'do_mirror', will reset 'log_failure'. The 'do_failures' function then resets the 'in_sync' variable when processing bios on the failures list. The 'in_sync' variable is what is used to determine if the primary device can be switched in the event of a failure. Since this has been reset, the primary device is incorrectly assumed to be not switchable. The case has been seen in the cluster mirror context, where one machine realizes the log device is dead before the other machines. As the responsibilities of the server migrate from one node to another (because the mirror is being reconfigured due to the failure), the new server may think for a moment that the log device is fine - thus resetting the 'log_failure' variable. In any case, it is inappropiate for us to reset the 'log_failure' variable. The above bug simply illustrates that it can actually hurt us. Cc: stable@kernel.org Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm table: pass correct dev area size to device_area_is_validMike Snitzer2009-07-23
| | | | | | | | | | | | | | | | Incorrect device area lengths are being passed to device_area_is_valid(). The regression appeared in 2.6.31-rc1 through commit 754c5fc7ebb417b23601a6222a6005cc2e7f2913. With the dm-stripe target, the size of the target (ti->len) was used instead of the stripe_width (ti->len/#stripes). An example of a consequent incorrect error message is: device-mapper: table: 254:0: sdb too small for target Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid1: wake kmirrord when requeueing delayed bios after remote recoveryMikulas Patocka2009-07-23
| | | | | | | | | | | | | | | The recent commit 7513c2a761d69d2a93f17146b3563527d3618ba0 (dm raid1: add is_remote_recovering hook for clusters) changed do_writes() to update the ms->writes list but forgot to wake up kmirrord to process it. The rule is that when anything is being added on ms->reads, ms->writes or ms->failures and the list was empty before we must call wakeup_mirrord (for immediate processing) or delayed_wake (for delayed processing). Otherwise the bios could sit on the list indefinitely. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> CC: stable@kernel.org Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm target:s introduce iterate devices fnMike Snitzer2009-06-22
| | | | | | | | | | | | | | Add .iterate_devices to 'struct target_type' to allow a function to be called for all devices in a DM target. Implemented it for all targets except those in dm-snap.c (origin and snapshot). (The raid1 version number jumps to 1.12 because we originally reserved 1.1 to 1.11 for 'block_on_error' but ended up using 'handle_errors' instead.) Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Cc: martin.petersen@oracle.com
* block: move bio list helpers into bio.hChristoph Hellwig2009-04-15
| | | | | | | | | It's used by DM and MD and generally useful, so move the bio list helpers into bio.h. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* dm raid1: add is_remote_recovering hook for clustersJonathan Brassow2009-04-02
| | | | | | | | | | | | | | | | The logging API needs an extra function to make cluster mirroring possible. This new function allows us to check whether a mirror region is being recovered on another machine in the cluster. This helps us prevent simultaneous recovery I/O and process I/O to the same locations on disk. Cluster-aware log modules will implement this function. Single machine log modules will not. So, there is no performance penalty for single machine mirrors. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Acked-by: Heinz Mauelshagen <heinzm@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid1: switch read_record from kmalloc to slab to save memoryMikulas Patocka2009-04-02
| | | | | | | | | | | | | | | | | | With my previous patch to save bi_io_vec, the size of dm_raid1_read_record is significantly increased (the vector list takes 3072 bytes on 32-bit machines and 4096 bytes on 64-bit machines). The structure dm_raid1_read_record used to be allocated with kmalloc, but kmalloc aligns the size on the next power-of-two so an object slightly greater than 4096 will allocate 8192 bytes of memory and half of that memory will be wasted. This patch turns kmalloc into a slab cache which doesn't have this padding so it will reduce the memory consumed. Cc: stable@kernel.org Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm log: move region_size validationMilan Broz2009-01-05
| | | | | | | | | Move log size validation from mirror target to log constructor. Removed PAGE_SIZE restriction we no longer think necessary. Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: consolidate target deregistration error handlingMikulas Patocka2009-01-05
| | | | | | | | | | | | | | | | | | | | Change dm_unregister_target to return void and use BUG() for error reporting. dm_unregister_target can only fail because of programming bug in the target driver. It can't fail because of user's behavior or disk errors. This patch changes unregister_target to return void and use BUG if someone tries to unregister non-registered target or unregister target that is in use. This patch removes code duplication (testing of error codes in all dm targets) and reports bugs in just one place, in dm_unregister_target. In some target drivers, these return codes were ignored, which could lead to a situation where bugs could be missed. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid1: fix error countJonathan Brassow2009-01-05
| | | | | | | | | | | | | | | | | Always increase the error count when I/O on a leg of a mirror fails. The error count is used to decide whether to select an alternative mirror leg. If the target doesn't use the "handle_errors" feature, the error count is not updated and the bio can get requeued forever by the read callback. Fix it by increasing error_count before the handle_errors feature checking. Cc: stable@kernel.org Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm raid1: flush workqueue before destructionMikulas Patocka2008-11-13
| | | | | | | | | We queue work on keventd queue --- so this queue must be flushed in the destructor. Otherwise, keventd could access mirror_set after it was freed. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Cc: stable@kernel.org
* dm raid1: fix do_failuresIlpo Jarvinen2008-10-30
| | | | | | | | | Missing braces. Commit 1f965b1943 (dm raid1: separate region_hash interface part1) broke it. Signed-off-by: Ilpo Jarvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Cc: Heinz Mauelshagen <hjm@redhat.com>
* dm raid1: separate region_hash interface part1Heinz Mauelshagen2008-10-21
| | | | | | | | Separate the region hash code from raid1 so it can be shared by forthcoming targets. Use BUG_ON() for failed async dm_io() calls. Signed-off-by: Heinz Mauelshagen <hjm@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: remove dm header from targetsMikulas Patocka2008-10-21
| | | | | | | | Change #include "dm.h" to #include <linux/device-mapper.h> in all targets. Targets should not need direct access to internal DM structures. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: publish array_too_bigMikulas Patocka2008-10-21
| | | | | | | | | | | | 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 raid1: kcopyd should stop on error if errors handledJonathan Brassow2008-10-10
| | | | | | | | | | | | | | | | | | | | | | | dm-raid1 is setting the 'DM_KCOPYD_IGNORE_ERROR' flag unconditionally when assigning kcopyd work. kcopyd is responsible for copying an assigned section of disk to one or more other disks. The 'DM_KCOPYD_IGNORE_ERROR' flag affects kcopyd in the following way: When not set: kcopyd will immediately stop the copy operation when an error is encountered. When set: kcopyd will try to proceed regardless of errors and try to continue copying any remaining amount. Since dm-raid1 tracks regions of the address space that are (or are not) in sync and it now has the ability to handle these errors, we can safely enable this optimization. This optimization is conditional on whether mirror error handling has been enabled. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: unplug queues in threadsMikulas Patocka2008-04-25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Remove an avoidable 3ms delay on some dm-raid1 and kcopyd I/O. It is specified that any submitted bio without BIO_RW_SYNC flag may plug the queue (i.e. block the requests from being dispatched to the physical device). The queue is unplugged when the caller calls blk_unplug() function. Usually, the sequence is that someone calls submit_bh to submit IO on a buffer. The IO plugs the queue and waits (to be possibly joined with other adjacent bios). Then, when the caller calls wait_on_buffer(), it unplugs the queue and submits the IOs to the disk. This was happenning: When doing O_SYNC writes, function fsync_buffers_list() submits a list of bios to dm_raid1, the bios are added to dm_raid1 write queue and kmirrord is woken up. fsync_buffers_list() calls wait_on_buffer(). That unplugs the queue, but there are no bios on the device queue as they are still in the dm_raid1 queue. wait_on_buffer() starts waiting until the IO is finished. kmirrord is scheduled, kmirrord takes bios and submits them to the devices. The submitted bio plugs the harddisk queue but there is no one to unplug it. (The process that called wait_on_buffer() is already sleeping.) So there is a 3ms timeout, after which the queues on the harddisks are unplugged and requests are processed. This 3ms timeout meant that in certain workloads (e.g. O_SYNC, 8kb writes), dm-raid1 is 10 times slower than md raid1. Every time we submit something asynchronously via dm_io, we must unplug the queue actually to send the request to the device. This patch adds an unplug call to kmirrord - while processing requests, it keeps the queue plugged (so that adjacent bios can be merged); when it finishes processing all the bios, it unplugs the queue to submit the bios. It also fixes kcopyd which has the same potential problem. All kcopyd requests are submitted with BIO_RW_SYNC. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Acked-by: Jens Axboe <jens.axboe@oracle.com>
* dm raid1: use timerMikulas Patocka2008-04-25
| | | | | | | | | | | | This patch replaces the schedule() in the main kmirrord thread with a timer. The schedule() could introduce an unwanted delay when work is ready to be processed. The code instead calls wake() when there's work to be done immediately, and delayed_wake() after a failure to give a short delay before retrying. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: move include filesAlasdair G Kergon2008-04-25
| | | | | | Publish the dm-io, dm-log and dm-kcopyd headers in include/linux. Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm log: clean interfaceHeinz Mauelshagen2008-04-25
| | | | | | | 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 kcopyd: clean interfaceHeinz Mauelshagen2008-04-25
| | | | | | | Clean up the kcopyd 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 io: clean interfaceHeinz Mauelshagen2008-04-25
| | | | | | | Clean up the dm-io 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 log: move dirty region log code into separate moduleHeinz Mauelshagen2008-04-25
| | | | | | | | Move the dirty region log code into a separate module so other targets can share the code. Signed-off-by: Heinz Mauelshagen <hjm@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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