- 27 9月, 2012 2 次提交
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由 Mike Snitzer 提交于
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 fe86cdce ("block: do not artificially constrain max_sectors for stacking drivers"). Reported-by: NDavid Jeffery <djeffery@redhat.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mike Snitzer 提交于
The access beyond the end of device BUG_ON that was introduced to dm_request_fn via commit 29e4013d ("dm: implement REQ_FLUSH/FUA support for request-based dm") was an overly drastic (but simple) response to this situation. I have received a report that this BUG_ON was hit and now think it would be better to use dm_kill_unmapped_request() to fail the clone and original request with -EIO. map_request() will assign the valid target returned by dm_table_find_target to tio->ti. But when the target isn't valid tio->ti is never assigned (because map_request isn't called); so add a check for tio->ti != NULL to dm_done(). Reported-by: NMike Christie <michaelc@cs.wisc.edu> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NJun'ichi Nomura <j-nomura@ce.jp.nec.com> Cc: stable@vger.kernel.org # v2.6.37+ Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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- 27 7月, 2012 2 次提交
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由 Mikulas Patocka 提交于
This patch introduces a new variable split_discard_requests. It can be set by targets so that discard requests are split on max_io_len boundaries. When split_discard_requests is not set, discard requests are only split on boundaries between targets, as was the case before this patch. Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mike Snitzer 提交于
Remove the restriction that limits a target's specified maximum incoming I/O size to be a power of 2. Rename this setting from 'split_io' to the less-ambiguous 'max_io_len'. Change it from sector_t to uint32_t, which is plenty big enough, and introduce a wrapper function dm_set_target_max_io_len() to set it. Use sector_div() to process it now that it is not necessarily a power of 2. Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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- 29 3月, 2012 1 次提交
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由 Hannes Reinecke 提交于
As a precaution, set bi_end_io to NULL when failing to remap. Signed-off-by: NHannes Reinecke <hare@suse.de> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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- 04 1月, 2012 1 次提交
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由 Al Viro 提交于
Move invalidate_bdev, block_sync_page into fs/block_dev.c. Export kill_bdev as well, so brd doesn't have to open code it. Reduce buffer_head.h requirement accordingly. Removed a rather large comment from invalidate_bdev, as it looked a bit obsolete to bother moving. The small comment replacing it says enough. Signed-off-by: NNick Piggin <npiggin@suse.de> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 01 11月, 2011 4 次提交
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由 Alasdair G Kergon 提交于
Export dm_get_md() for the new thin provisioning target to use. Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Alasdair G Kergon 提交于
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: NAlasdair G Kergon <agk@redhat.com>
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由 Namhyung Kim 提交于
Since set_current_state() contains a memory barrier in it, an additional barrier isn't needed. Signed-off-by: NNamhyung Kim <namhyung@gmail.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Namhyung Kim 提交于
printk_ratelimit() shares global ratelimiting state with all other subsystems, so its usage is discouraged. Instead, define and use dm's local state. Signed-off-by: NNamhyung Kim <namhyung@gmail.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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- 12 9月, 2011 3 次提交
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由 Christoph Hellwig 提交于
There is very little benefit in allowing to let a ->make_request instance update the bios device and sector and loop around it in __generic_make_request when we can archive the same through calling generic_make_request from the driver and letting the loop in generic_make_request handle it. Note that various drivers got the return value from ->make_request and returned non-zero values for errors. Signed-off-by: NChristoph Hellwig <hch@lst.de> Acked-by: NNeilBrown <neilb@suse.de> Signed-off-by: NJens Axboe <jaxboe@fusionio.com>
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由 Jens Axboe 提交于
Now that it's exported, lets put it in a more sane namespace. Signed-off-by: NJens Axboe <jaxboe@fusionio.com>
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由 Christoph Hellwig 提交于
Avoid the hacks need for request based device mappers currently by simply exporting the symbol instead of trying to get it through the back door. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <jaxboe@fusionio.com>
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- 02 8月, 2011 4 次提交
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由 Mike Snitzer 提交于
DM has always advertised both REQ_FLUSH and REQ_FUA flush capabilities regardless of whether or not a given DM device's underlying devices also advertised a need for them. Block's flush-merge changes from 2.6.39 have proven to be more costly for DM devices. Performance regressions have been reported even when DM's underlying devices do not advertise that they have a write cache. Fix the performance regressions by configuring a DM device's flushing capabilities based on those of the underlying devices' capabilities. Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mikulas Patocka 提交于
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: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mike Snitzer 提交于
Remove 'discards_supported' from the dm_table structure. The same information can be easily discovered from the table's target(s) in dm_table_supports_discards(). Before this fix dm_table_supports_discards() would skip checking the individual targets' 'discards_supported' flag if any one target in the table didn't set num_discard_requests > 0. Now the per-target 'discards_supported' flag is effective at insuring the final DM device advertises discard support. But, to be clear, targets that don't support discards (!num_discard_requests) will not receive discard requests. Also DMWARN if a target sets 'discards_supported' override but forgets to set 'num_discard_requests'. Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Alasdair G Kergon 提交于
Destroy _minor_idr when unloading the core dm module. (Found by kmemleak.) Cc: stable@kernel.org Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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- 22 3月, 2011 1 次提交
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由 Shaohua Li 提交于
After the stack plugging introduction, these are called lockless. Ensure that the counters are updated atomically. Signed-off-by: Shaohua Li<shaohua.li@intel.com> Signed-off-by: NJens Axboe <jaxboe@fusionio.com>
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- 17 3月, 2011 1 次提交
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由 Martin K. Petersen 提交于
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: NMartin K. Petersen <martin.petersen@oracle.com> Reported-by: NZdenek Kabelac <zkabelac@redhat.com> Acked-by: NMike Snitzer <snizer@redhat.com> Signed-off-by: NJens Axboe <jaxboe@fusionio.com>
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- 10 3月, 2011 1 次提交
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由 Jens Axboe 提交于
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: NJens Axboe <jaxboe@fusionio.com>
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- 14 1月, 2011 5 次提交
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由 Kiyoshi Ueda 提交于
This patch changes spin_lock_irq() to spin_lock() in dm_request_fn(). This patch is just a clean-up and no functional change. The spin_lock_irq() was leftover from the early request-based dm code, where map_request() used to enable interrupts. Since current map_request() never enables interrupts, we can change it to spin_lock() to match the prior spin_unlock(). Auditing through the dm and block-layer code called from map_request(), I confirmed all functions save/restore interrupt status, so no function returning with interrupts enabled. Also I haven't observed any problem on my test environment which uses scsi and lpfc driver after heavy I/O testing with occasional path down/up. Added BUG_ON() to detect breakage in future. Signed-off-by: NKiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: NJun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Tejun Heo 提交于
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: NTejun Heo <tj@kernel.org> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Tejun Heo 提交于
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: NTejun Heo <tj@kernel.org> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Milan Broz 提交于
This patch replaces dm_mutex with _minor_lock in dm_blk_close() and then removes it. During the BKL conversion, commit 6e9624b8 (block: push down BKL into .open and .release) pushed lock_kernel() down into dm_blk_open/close calls. Commit 2a48fc0a (block: autoconvert trivial BKL users to private mutex) converted it to a local mutex, but _minor_lock is sufficient. Signed-off-by: NMilan Broz <mbroz@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mike Snitzer 提交于
No longer needlessly hold md->bdev->bd_inode->i_mutex when changing the size of a DM device. This additional locking is unnecessary because i_size_write() is already protected by the existing critical section in dm_swap_table(). DM already has a reference on md->bdev so the associated bd_inode may be changed without lifetime concerns. A negative side-effect of having held md->bdev->bd_inode->i_mutex was that a concurrent DM device resize and flush (via fsync) would deadlock. Dropping md->bdev->bd_inode->i_mutex eliminates this potential for deadlock. The following reproducer no longer deadlocks: https://www.redhat.com/archives/dm-devel/2009-July/msg00284.htmlSigned-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com> Cc: stable@kernel.org
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- 07 1月, 2011 1 次提交
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由 Jeff Moyer 提交于
The "error" field in block_bio_complete is not assigned, leaving the memory area uninitialized (keeping garbage data). Pass an additional tracepoint argument to this event to initialize this field. Signed-off-by: NJeff Moyer <jmoyer@redhat.com> Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com> CC: Steven Rostedt <rostedt@goodmis.org> CC: Frederic Weisbecker <fweisbec@gmail.com> CC: Ingo Molnar <mingo@elte.hu> CC: Thomas Gleixner <tglx@linutronix.de> CC: Li Zefan <lizf@cn.fujitsu.com> CC: Alan.Brunelle@hp.com Signed-off-by: NJens Axboe <jaxboe@fusionio.com>
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- 16 11月, 2010 1 次提交
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由 Mike Snitzer 提交于
Signed-off-by: NKiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: NJun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NJens Axboe <jaxboe@fusionio.com>
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- 05 10月, 2010 1 次提交
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由 Arnd Bergmann 提交于
The block device drivers have all gained new lock_kernel calls from a recent pushdown, and some of the drivers were already using the BKL before. This turns the BKL into a set of per-driver mutexes. Still need to check whether this is safe to do. file=$1 name=$2 if grep -q lock_kernel ${file} ; then if grep -q 'include.*linux.mutex.h' ${file} ; then sed -i '/include.*<linux\/smp_lock.h>/d' ${file} else sed -i 's/include.*<linux\/smp_lock.h>.*$/include <linux\/mutex.h>/g' ${file} fi sed -i ${file} \ -e "/^#include.*linux.mutex.h/,$ { 1,/^\(static\|int\|long\)/ { /^\(static\|int\|long\)/istatic DEFINE_MUTEX(${name}_mutex); } }" \ -e "s/\(un\)*lock_kernel\>[ ]*()/mutex_\1lock(\&${name}_mutex)/g" \ -e '/[ ]*cycle_kernel_lock();/d' else sed -i -e '/include.*\<smp_lock.h\>/d' ${file} \ -e '/cycle_kernel_lock()/d' fi Signed-off-by: NArnd Bergmann <arnd@arndb.de>
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- 10 9月, 2010 6 次提交
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由 Mike Snitzer 提交于
Rename __clone_and_map_flush to __clone_and_map_empty_flush for added clarity. Simplify logic associated with REQ_FLUSH conditionals. Introduce a BUG_ON() and add a few more helpful comments to the code so that it is clear that all flushes are empty. Cleanup __split_and_process_bio() so that an empty flush isn't processed by a 'sector_count' focused while loop. Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NTejun Heo <tj@kernel.org> Signed-off-by: NJens Axboe <jaxboe@fusionio.com>
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由 Kiyoshi Ueda 提交于
Now queue_io() is called from dec_pending(), which may be called with interrupts disabled, so queue_io() must not enable interrupts unconditionally and must save/restore the current interrupts status. Signed-off-by: NKiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: NJun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: NTejun Heo <tj@kernel.org> Signed-off-by: NJens Axboe <jaxboe@fusionio.com>
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由 Tejun Heo 提交于
Unlike REQ_HARDBARRIER, REQ_FLUSH/FUA doesn't mandate any ordering against other bio's. This patch relaxes ordering around flushes. * A flush bio is no longer deferred to workqueue directly. It's processed like other bio's but __split_and_process_bio() uses md->flush_bio as the clone source. md->flush_bio is initialized to empty flush during md initialization and shared for all flushes. * As a flush bio now travels through the same execution path as other bio's, there's no need for dedicated error handling path either. It can use the same error handling path in dec_pending(). Dedicated error handling removed along with md->flush_error. * When dec_pending() detects that a flush has completed, it checks whether the original bio has data. If so, the bio is queued to the deferred list w/ REQ_FLUSH cleared; otherwise, it's completed. * As flush sequencing is handled in the usual issue/completion path, dm_wq_work() no longer needs to handle flushes differently. Now its only responsibility is re-issuing deferred bio's the same way as _dm_request() would. REQ_FLUSH handling logic including process_flush() is dropped. * There's no reason for queue_io() and dm_wq_work() write lock dm->io_lock. queue_io() now only uses md->deferred_lock and dm_wq_work() read locks dm->io_lock. * bio's no longer need to be queued on the deferred list while a flush is in progress making DMF_QUEUE_IO_TO_THREAD unncessary. Drop it. This avoids stalling the device during flushes and simplifies the implementation. Signed-off-by: NTejun Heo <tj@kernel.org> Signed-off-by: NJens Axboe <jaxboe@fusionio.com>
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由 Tejun Heo 提交于
This patch converts request-based dm to support the new REQ_FLUSH/FUA. The original request-based flush implementation depended on request_queue blocking other requests while a barrier sequence is in progress, which is no longer true for the new REQ_FLUSH/FUA. In general, request-based dm doesn't have infrastructure for cloning one source request to multiple targets, but the original flush implementation had a special mostly independent path which can issue flushes to multiple targets and sequence them. However, the capability isn't currently in use and adds a lot of complexity. Moreoever, it's unlikely to be useful in its current form as it doesn't make sense to be able to send out flushes to multiple targets when write requests can't be. This patch rips out special flush code path and deals handles REQ_FLUSH/FUA requests the same way as other requests. The only special treatment is that REQ_FLUSH requests use the block address 0 when finding target, which is enough for now. * added BUG_ON(!dm_target_is_valid(ti)) in dm_request_fn() as suggested by Mike Snitzer Signed-off-by: NTejun Heo <tj@kernel.org> Acked-by: NMike Snitzer <snitzer@redhat.com> Tested-by: NKiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: NJens Axboe <jaxboe@fusionio.com>
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由 Tejun Heo 提交于
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: NTejun Heo <tj@kernel.org> Cc: dm-devel@redhat.com Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <jaxboe@fusionio.com>
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由 Tejun Heo 提交于
Barrier is deemed too heavy and will soon be replaced by FLUSH/FUA requests. Deprecate barrier. All REQ_HARDBARRIERs are failed with -EOPNOTSUPP and blk_queue_ordered() is replaced with simpler blk_queue_flush(). blk_queue_flush() takes combinations of REQ_FLUSH and FUA. If a device has write cache and can flush it, it should set REQ_FLUSH. If the device can handle FUA writes, it should also set REQ_FUA. All blk_queue_ordered() users are converted. * ORDERED_DRAIN is mapped to 0 which is the default value. * ORDERED_DRAIN_FLUSH is mapped to REQ_FLUSH. * ORDERED_DRAIN_FLUSH_FUA is mapped to REQ_FLUSH | REQ_FUA. Signed-off-by: NTejun Heo <tj@kernel.org> Acked-by: NBoaz Harrosh <bharrosh@panasas.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> Cc: David S. Miller <davem@davemloft.net> Cc: Alasdair G Kergon <agk@redhat.com> Cc: Pierre Ossman <drzeus@drzeus.cx> Cc: Stefan Weinhuber <wein@de.ibm.com> Signed-off-by: NJens Axboe <jaxboe@fusionio.com>
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- 12 8月, 2010 6 次提交
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由 Mike Snitzer 提交于
Update __clone_and_map_discard to loop across all targets in a DM device's table when it processes a discard bio. If a discard crosses a target boundary it must be split accordingly. Update __issue_target_requests and __issue_target_request to allow a cloned discard bio to have a custom start sector and size. Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mike Snitzer 提交于
Split max_io_len_target_boundary out of max_io_len so that the discard support can make use of it without duplicating max_io_len code. Avoiding max_io_len's split_io logic enables DM's discard support to submit the entire discard request to a target. But discards must still be split on target boundaries. Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mike Snitzer 提交于
Rename __flush_target to __issue_target_request now that it is used to issue both flush and discard requests. Introduce __issue_target_requests as a convenient wrapper to __issue_target_request 'num_flush_requests' or 'num_discard_requests' times per target. Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mike Snitzer 提交于
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: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Reviewed-by: NJoe Thornber <thornber@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mike Snitzer 提交于
'target_request_nr' is a more generic name that reflects the fact that it will be used for both flush and discard support. Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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由 Mike Snitzer 提交于
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: NMike Snitzer <snitzer@redhat.com> Acked-by: NKiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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