- 24 Mar, 2017 15 commits
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Ming Lei authored
Now we allocate one page array for managing resync pages, instead of using bio's vec table to do that, and the old way is very hacky and won't work any more if multipage bvec is enabled. The introduced cost is that we need to allocate (128 + 16) * copies bytes per r10_bio, and it is fine because the inflight r10_bio for resync shouldn't be much, as pointed by Shaohua. Also bio_reset() in raid10_sync_request() and reshape_request() are removed because all bios are freshly new now in these functions and not necessary to reset any more. This patch can be thought as cleanup too. Suggested-by:
Shaohua Li <shli@kernel.org> Signed-off-by:
Ming Lei <tom.leiming@gmail.com> Signed-off-by:
Shaohua Li <shli@fb.com>
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Ming Lei authored
reshape read request is a bit special and requires one extra bio which isn't allocated from r10buf_pool. Refactor the .bi_end_io for read reshape, so that we can use raid10's resync page mangement approach easily in the following patches. Signed-off-by:
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Ming Lei authored
This patch improve handling of write behind in the following ways: - introduce behind master bio to hold all write behind pages - fast clone bios from behind master bio - avoid to change bvec table directly - use bio_copy_data() and make code more clean Suggested-by:
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Ming Lei authored
The 'offset' local variable can't be changed inside the loop, so move it out. Signed-off-by:
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Ming Lei authored
Turns out we can use bio_copy_data in raid1's write behind, and we can make alloc_behind_pages() more clean/efficient, but we need to partial version of bio_copy_data(). Signed-off-by:
Jens Axboe <axboe@fb.com> Signed-off-by:
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Ming Lei authored
Avoid to direct access to bvec table. Signed-off-by:
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Ming Lei authored
Now one page array is allocated for each resync bio, and we can retrieve page from this table directly. Signed-off-by:
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Ming Lei authored
Now we allocate one page array for managing resync pages, instead of using bio's vec table to do that, and the old way is very hacky and won't work any more if multipage bvec is enabled. The introduced cost is that we need to allocate (128 + 16) * raid_disks bytes per r1_bio, and it is fine because the inflight r1_bio for resync shouldn't be much, as pointed by Shaohua. Also the bio_reset() in raid1_sync_request() is removed because all bios are freshly new now and not necessary to reset any more. This patch can be thought as a cleanup too Suggested-by:
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Ming Lei authored
This patch gets each page's reference of each bio for resync, then r1buf_pool_free() gets simplified a lot. The same policy has been taken in raid10's buf pool allocation/free too. Signed-off-by:
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Ming Lei authored
Now resync I/O use bio's bec table to manage pages, this way is very hacky, and may not work any more once multipage bvec is introduced. So introduce helpers and new data structure for managing resync I/O pages more cleanly. Signed-off-by:
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Ming Lei authored
Both raid1 and raid10 share common resync block size and page count, so move them into md.h. Signed-off-by:
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Ming Lei authored
All bio_add_page() is for adding one page into resync bio, which is big enough to hold RESYNC_PAGES pages, and the current bio_add_page() doesn't check queue limit any more, so it won't fail at all. remove unused label (shaohua) Signed-off-by:
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Zhilong Liu authored
Signed-off-by:
Zhilong Liu <zlliu@suse.com> Signed-off-by:
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Guoqing Jiang authored
Previously, we clone both bio and repl_bio in raid10_write_request, then add the cloned bio to plug->pending or conf->pending_bio_list based on plug or not, and most of the logics are same for the two conditions. So introduce raid10_write_one_disk for it, and use replacement parameter to distinguish the difference. No functional changes in the patch. Signed-off-by:
Guoqing Jiang <gqjiang@suse.com> Signed-off-by:
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Dan Carpenter authored
The "need_cache_flush" variable is never set to false. When the variable is true that means we print a warning message at the end of the function. Fixes: 3418d036 ("raid5-ppl: Partial Parity Log write logging implementation") Signed-off-by:
Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by:
Artur Paszkiewicz <artur.paszkiewicz@intel.com> Signed-off-by:
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- 23 Mar, 2017 14 commits
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NeilBrown authored
The 'writes_pending' counter is used to determine when the array is stable so that it can be marked in the superblock as "Clean". Consequently it needs to be updated frequently but only checked for zero occasionally. Recent changes to raid5 cause the count to be updated even more often - once per 4K rather than once per bio. This provided justification for making the updates more efficient. So we replace the atomic counter a percpu-refcount. This can be incremented and decremented cheaply most of the time, and can be switched to "atomic" mode when more precise counting is needed. As it is possible for multiple threads to want a precise count, we introduce a "sync_checker" counter to count the number of threads in "set_in_sync()", and only switch the refcount back to percpu mode when that is zero. We need to be careful about races between set_in_sync() setting ->in_sync to 1, and md_write_start() setting it to zero. md_write_start() holds the rcu_read_lock() while checking if the refcount is in percpu mode. If it is, then we know a switch to 'atomic' will not happen until after we call rcu_read_unlock(), in which case set_in_sync() will see the elevated count, and not set in_sync to 1. If it is not in percpu mode, we take the mddev->lock to ensure proper synchronization. It is no longer possible to quickly check if the count is zero, which we previously did to update a timer or to schedule the md_thread. So now we do these every time we decrement that counter, but make sure they are fast. mod_timer() already optimizes the case where the timeout value doesn't actually change. We leverage that further by always rounding off the jiffies to the timeout value. This may delay the marking of 'clean' slightly, but ensure we only perform atomic operation here when absolutely needed. md_wakeup_thread() current always calls wake_up(), even if THREAD_WAKEUP is already set. That too can be optimised to avoid calls to wake_up(). Signed-off-by:
NeilBrown <neilb@suse.com> Signed-off-by:
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NeilBrown authored
percpu_ref_switch_to_atomic_sync() schedules the switch to atomic mode, then waits for it to complete. Also export percpu_ref_switch_to_* so they can be used from modules. This will be used in md/raid to count the number of pending write requests to an array. We occasionally need to check if the count is zero, but most often we don't care. We always want updates to the counter to be fast, as in some cases we count every 4K page. Signed-off-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
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NeilBrown authored
If ->in_sync is being set just as md_write_start() is being called, it is possible that set_in_sync() won't see the elevated ->writes_pending, and md_write_start() won't see the set ->in_sync. To close this race, re-test ->writes_pending after setting ->in_sync, and add memory barriers to ensure the increment of ->writes_pending will be seen by the time of this second test, or the new ->in_sync will be seen by md_write_start(). Add a spinlock to array_state_show() to ensure this temporary instability is never visible from userspace. Signed-off-by:
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NeilBrown authored
Three separate places in md.c check if the number of active writes is zero and, if so, sets mddev->in_sync. There are a few differences, but there shouldn't be: - it is always appropriate to notify the change in sysfs_state, and there is no need to do this outside a spin-locked region. - we never need to check ->recovery_cp. The state of resync is not relevant for whether there are any pending writes or not (which is what ->in_sync reports). So create set_in_sync() which does the correct tests and makes the correct changes, and call this in all three places. Any behaviour changes here a minor and cosmetic. Signed-off-by:
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NeilBrown authored
This test on ->writes_pending cannot be safe as the counter can be incremented at any moment and cannot be locked against. Change it to test conf->active_stripes, which at least can be locked against. More changes are still needed. A future patch will change ->writes_pending, and testing it here will be very inconvenient. Signed-off-by:
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NeilBrown authored
Change to use bio->__bi_remaining to count number of r1bio attached to a bio. See precious raid10 patch for more details. Like the raid10.c patch, this fixes a bug as nr_queued and nr_pending used to measure different things, but were being compared. This patch fixes another bug in that nr_pending previously did not could write-behind requests, so behind writes could continue while resync was happening. How that nr_pending counts all r1_bio, the resync cannot commence until the behind writes have completed. Signed-off-by:
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NeilBrown authored
raid10 currently repurposes bi_phys_segments on each incoming bio to count how many r10bio was used to encode the request. We need to know when the number of attached r10bio reaches zero to: 1/ call bio_endio() when all IO on the bio is finished 2/ decrement ->nr_pending so that resync IO can proceed. Now that the bio has its own __bi_remaining counter, that can be used instead. We can call bio_inc_remaining to increment the counter and call bio_endio() every time an r10bio completes, rather than only when bi_phys_segments reaches zero. This addresses point 1, but not point 2. bio_endio() doesn't (and cannot) report when the last r10bio has finished, so a different approach is needed. So: instead of counting bios in ->nr_pending, count r10bios. i.e. every time we attach a bio, increment nr_pending. Every time an r10bio completes, decrement nr_pending. Normally we only increment nr_pending after first checking that ->barrier is zero, or some other non-trivial tests and possible waiting. When attaching multiple r10bios to a bio, we only need the tests and the waiting once. After the first increment, subsequent increments can happen unconditionally as they are really all part of the one request. So introduce inc_pending() which can be used when we know that nr_pending is already elevated. Note that this fixes a bug. freeze_array() contains the line atomic_read(&conf->nr_pending) == conf->nr_queued+extra, which implies that the units for ->nr_pending, ->nr_queued and extra are the same. ->nr_queue and extra count r10_bios, but prior to this patch, ->nr_pending counted bios. If a bio ever resulted in multiple r10_bios (due to bad blocks), freeze_array() would not work correctly. Now it does. Signed-off-by:
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NeilBrown authored
When raid1 or raid10 find they will need to allocate a new r1bio/r10bio, in order to work around a known bad block, they account for the allocation well before the allocation is made. This separation makes the correctness less obvious and requires comments. The accounting needs to be a little before: before the first rXbio is submitted, but that is all. So move the accounting down to where it makes more sense. Signed-off-by:
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NeilBrown authored
This reverts commit e8d7c332. Now that raid5 doesn't abuse bi_phys_segments any more, we no longer need to impose these limits. Signed-off-by:
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NeilBrown authored
When a read request, which bypassed the cache, fails, we need to retry it through the cache. This involves attaching it to a sequence of stripe_heads, and it may not be possible to get all the stripe_heads we need at once. We do what we can, and record how far we got in ->bi_phys_segments so we can pick up again later. There is only ever one bio which may have a non-zero offset stored in ->bi_phys_segments, the one that is either active in the single thread which calls retry_aligned_read(), or is in conf->retry_read_aligned waiting for retry_aligned_read() to be called again. So we only need to store one offset value. This can be in a local variable passed between remove_bio_from_retry() and retry_aligned_read(), or in the r5conf structure next to the ->retry_read_aligned pointer. Storing it there allows the last usage of ->bi_phys_segments to be removed from md/raid5.c. Signed-off-by:
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NeilBrown authored
md/raid5 needs to keep track of how many stripe_heads are processing a bio so that it can delay calling bio_endio() until all stripe_heads have completed. It currently uses 16 bits of ->bi_phys_segments for this purpose. 16 bits is only enough for 256M requests, and it is possible for a single bio to be larger than this, which causes problems. Also, the bio struct contains a larger counter, __bi_remaining, which has a purpose very similar to the purpose of our counter. So stop using ->bi_phys_segments, and instead use __bi_remaining. This means we don't need to initialize the counter, as our caller initializes it to '1'. It also means we can call bio_endio() directly as it tests this counter internally. Signed-off-by:
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NeilBrown authored
We currently gather bios that need to be returned into a bio_list and call bio_endio() on them all together. The original reason for this was to avoid making the calls while holding a spinlock. Locking has changed a lot since then, and that reason is no longer valid. So discard return_io() and various return_bi lists, and just call bio_endio() directly as needed. Signed-off-by:
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NeilBrown authored
If a device fails during a write, we must ensure the failure is recorded in the metadata before the completion of the write is acknowleged. Commit c3cce6cd ("md/raid5: ensure device failure recorded before write request returns.") added code for this, but it was unnecessarily complicated. We already had similar functionality for handling updates to the bad-block-list, thanks to Commit de393cde ("md: make it easier to wait for bad blocks to be acknowledged.") So revert most of the former commit, and instead avoid collecting completed writes if MD_CHANGE_PENDING is set. raid5d() will then flush the metadata and retry the stripe_head. As this change can leave a stripe_head ready for handling immediately after handle_active_stripes() returns, we change raid5_do_work() to pause when MD_CHANGE_PENDING is set, so that it doesn't spin. We check MD_CHANGE_PENDING *after* analyse_stripe() as it could be set asynchronously. After analyse_stripe(), we have collected stable data about the state of devices, which will be used to make decisions. Signed-off-by:
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NeilBrown authored
We use md_write_start() to increase the count of pending writes, and md_write_end() to decrement the count. We currently count bios submitted to md/raid5. Change it count stripe_heads that a WRITE bio has been attached to. So now, raid5_make_request() calls md_write_start() and then md_write_end() to keep the count elevated during the setup of the request. add_stripe_bio() calls md_write_start() for each stripe_head, and the completion routines always call md_write_end(), instead of only calling it when raid5_dec_bi_active_stripes() returns 0. make_discard_request also calls md_write_start/end(). The parallel between md_write_{start,end} and use of bi_phys_segments can be seen in that: Whenever we set bi_phys_segments to 1, we now call md_write_start. Whenever we increment it on non-read requests with raid5_inc_bi_active_stripes(), we now call md_write_start(). Whenever we decrement bi_phys_segments on non-read requsts with raid5_dec_bi_active_stripes(), we now call md_write_end(). This reduces our dependence on keeping a per-bio count of active stripes in bi_phys_segments. md_write_inc() is added which parallels md_write_start(), but requires that a write has already been started, and is certain never to sleep. This can be used inside a spinlocked region when adding to a write request. Signed-off-by:
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- 16 Mar, 2017 11 commits
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Guoqing Jiang authored
Since we have switched to sync way to handle METADATA_UPDATED msg for md-cluster, then process_metadata_update is depended on mddev->thread->wqueue. With the new change, clustered raid could possible hang if array received a METADATA_UPDATED msg after array unregistered mddev->thread, so we need to stop clustered raid (bitmap_destroy -> bitmap_free -> md_cluster_stop) earlier than unregister thread (mddev_detach -> md_unregister_thread). And this change should be safe for non-clustered raid since all writes are stopped before the destroy. Also in md_run, we activate the personality (pers->run()) before activating the bitmap (bitmap_create()). So it is pleasingly symmetric to stop the bitmap (bitmap_destroy()) before stopping the personality (__md_stop() calls pers->free()), we achieve this by move bitmap_destroy to the beginning of __md_stop. But we don't want to break the codes for waiting behind IO as Shaohua mentioned, so introduce bitmap_wait_behind_writes to call the codes, and call the new fun in both mddev_detach and bitmap_destroy, then we will not break original behind IO code and also fit the new condition well. Signed-off-by:
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Song Liu authored
In r5c_finish_stripe_write_out(), R5LOG_PAYLOAD_FLUSH is append to log->current_io. Appending R5LOG_PAYLOAD_FLUSH in quiesce needs extra writes to journal. To simplify the logic, we just skip R5LOG_PAYLOAD_FLUSH in quiesce. Even R5LOG_PAYLOAD_FLUSH supports multiple stripes per payload. However, current implementation is one stripe per R5LOG_PAYLOAD_FLUSH, which is simpler. Signed-off-by:
Song Liu <songliubraving@fb.com> Signed-off-by:
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Song Liu authored
This patch adds handling of R5LOG_PAYLOAD_FLUSH in journal recovery. Next patch will add logic that generate R5LOG_PAYLOAD_FLUSH on flush finish. When R5LOG_PAYLOAD_FLUSH is seen in recovery, pending data and parity will be dropped from recovery. This will reduce the number of stripes to replay, and thus accelerate the recovery process. Signed-off-by:
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Artur Paszkiewicz authored
Allow writing to 'consistency_policy' attribute when the array is active. Add a new function 'change_consistency_policy' to the md_personality operations structure to handle the change in the personality code. Values "ppl" and "resync" are accepted and turn PPL on and off respectively. When enabling PPL its location and size should first be set using 'ppl_sector' and 'ppl_size' attributes and a valid PPL header should be written at this location on each member device. Enabling or disabling PPL is performed under a suspended array. The raid5_reset_stripe_cache function frees the stripe cache and allocates it again in order to allocate or free the ppl_pages for the stripes in the stripe cache. Signed-off-by:
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Artur Paszkiewicz authored
Add a function to modify the log by removing an rdev when a drive fails or adding when a spare/replacement is activated as a raid member. Removing a disk just clears the child log rdev pointer. No new stripes will be accepted for this child log in ppl_write_stripe() and running io units will be processed without writing PPL to the device. Adding a disk sets the child log rdev pointer and writes an empty PPL header. Signed-off-by:
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Artur Paszkiewicz authored
Load the log from each disk when starting the array and recover if the array is dirty. The initial empty PPL is written by mdadm. When loading the log we verify the header checksum and signature. For external metadata arrays the signature is verified in userspace, so here we read it from the header, verifying only if it matches on all disks, and use it later when writing PPL. In addition to the header checksum, each header entry also contains a checksum of its partial parity data. If the header is valid, recovery is performed for each entry until an invalid entry is found. If the array is not degraded and recovery using PPL fully succeeds, there is no need to resync the array because data and parity will be consistent, so in this case resync will be disabled. Due to compatibility with IMSM implementations on other systems, we can't assume that the recovery data block size is always 4K. Writes generated by MD raid5 don't have this issue, but when recovering PPL written in other environments it is possible to have entries with 512-byte sector granularity. The recovery code takes this into account and also the logical sector size of the underlying drives. Signed-off-by:
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Artur Paszkiewicz authored
Add 'consistency_policy' attribute for array. It indicates how the array maintains consistency in case of unexpected shutdown. Add 'ppl_sector' and 'ppl_size' for rdev, which describe the location and size of the PPL space on the device. They can't be changed for active members if the array is started and PPL is enabled, so in the setter functions only basic checks are performed. More checks are done in ppl_validate_rdev() when starting the log. These attributes are writable to allow enabling PPL for external metadata arrays and (later) to enable/disable PPL for a running array. Signed-off-by:
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Artur Paszkiewicz authored
Implement the calculation of partial parity for a stripe and PPL write logging functionality. The description of PPL is added to the documentation. More details can be found in the comments in raid5-ppl.c. Attach a page for holding the partial parity data to stripe_head. Allocate it only if mddev has the MD_HAS_PPL flag set. Partial parity is the xor of not modified data chunks of a stripe and is calculated as follows: - reconstruct-write case: xor data from all not updated disks in a stripe - read-modify-write case: xor old data and parity from all updated disks in a stripe Implement it using the async_tx API and integrate into raid_run_ops(). It must be called when we still have access to old data, so do it when STRIPE_OP_BIODRAIN is set, but before ops_run_prexor5(). The result is stored into sh->ppl_page. Partial parity is not meaningful for full stripe write and is not stored in the log or used for recovery, so don't attempt to calculate it when stripe has STRIPE_FULL_WRITE. Put the PPL metadata structures to md_p.h because userspace tools (mdadm) will also need to read/write PPL. Warn about using PPL with enabled disk volatile write-back cache for now. It can be removed once disk cache flushing before writing PPL is implemented. Signed-off-by:
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Artur Paszkiewicz authored
Move raid5-cache declarations from raid5.h to raid5-log.h, add inline wrappers for functions which will be shared with ppl and use them in raid5 core instead of direct calls to raid5-cache. Remove unused parameter from r5c_cache_data(), move two duplicated pr_debug() calls to r5l_init_log(). Signed-off-by:
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Artur Paszkiewicz authored
Include information about PPL location and size into mdp_superblock_1 and copy it to/from rdev. Because PPL is mutually exclusive with bitmap, put it in place of 'bitmap_offset'. Add a new flag MD_FEATURE_PPL for 'feature_map', analogically to MD_FEATURE_BITMAP_OFFSET. Add MD_HAS_PPL to mddev->flags to indicate that PPL is enabled on an array. Signed-off-by:
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Song Liu authored
In r5cache recovery, the journal device is scanned page by page. Currently, we use sync_page_io() to read journal device. This is not efficient when we have to recovery many stripes from the journal. To improve the speed of recovery, this patch introduces a read ahead page pool (ra_pool) to recovery_ctx. With ra_pool, multiple consecutive pages are read in one IO. Then the recovery code read the journal from ra_pool. With ra_pool, r5l_recovery_ctx has become much bigger. Therefore, r5l_recovery_log() is refactored so r5l_recovery_ctx is not using stack space. Signed-off-by:
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