- 01 Nov, 2015 33 commits
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Shaohua Li authored
Set journal disk ->raid_disk to >=0, I choose raid_disks + 1 instead of 0, because we already have a disk with ->raid_disk 0 and this causes sysfs entry creation conflict. A lot of places assumes disk with ->raid_disk >=0 is normal raid disk, so we add check for journal disk. Signed-off-by:
Shaohua Li <shli@fb.com> Signed-off-by:
NeilBrown <neilb@suse.com>
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Song Liu authored
When journal disk is faulty and we are reassemabling the raid array, the journal disk is old. We don't allow the journal disk added to the raid array. Since journal disk is missing in the array, the raid5 will mark the array readonly. Signed-off-by:
Song Liu <songliubraving@fb.com> Signed-off-by:
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Shaohua Li authored
If raid array is expected to have journal (eg, journal is set in MD superblock feature map) and the array is started without journal disk, start the array readonly. Signed-off-by:
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Song Liu authored
If a raid array has journal feature bit set, add a new bit to indicate this. If the array is started without journal disk existing, we know there is something wrong. Signed-off-by:
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Shaohua Li authored
There are 3 places the raid5-cache dispatches IO. The discard IO error doesn't matter, so we ignore it. The superblock write IO error can be handled in MD core. The remaining are log write and flush. When the IO error happens, we mark log disk faulty and fail all write IO. Read IO is still allowed to run. Userspace will get a notification too and corresponding daemon can choose setting raid array readonly for example. Signed-off-by:
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Shaohua Li authored
raid5-cache uses journal disk rdev->bdev, rdev->mddev in several places. Don't allow journal disk disappear magically. On the other hand, we do need to update superblock for other disks to bump up ->events, so next time journal disk will be identified as stale. Signed-off-by:
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Shaohua Li authored
Since superblock is updated infrequently, we do a simple trim of log disk (a synchronous trim) Signed-off-by:
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Shaohua Li authored
journal disk can be faulty. The Journal and Faulty aren't exclusive with each other. Signed-off-by:
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Christoph Hellwig authored
Simplify the bio completion handler by using bio chaining and submitting bios as soon as they are full. Signed-off-by:
Christoph Hellwig <hch@lst.de> Reviewed-by:
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Christoph Hellwig authored
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Christoph Hellwig authored
Factor out code to reserve log space. Signed-off-by:
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Christoph Hellwig authored
This is the only user, and keeping all code initializing the io_unit structure together improves readbility. Signed-off-by:
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Christoph Hellwig authored
Set up bi_sector properly when we allocate an bio instead of updating it at submission time. Signed-off-by:
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Christoph Hellwig authored
Split out a helper to allocate a bio for log writes. Signed-off-by:
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Christoph Hellwig authored
Remove the only partially used local 'io' variable to simplify the code flow. Signed-off-by:
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Christoph Hellwig authored
For devices without a volatile write cache we don't need to send a FLUSH command to ensure writes are stable on disk, and thus can avoid the whole step of batching up bios for processing by the MD thread. Signed-off-by:
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Christoph Hellwig authored
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Christoph Hellwig authored
After this series we won't nessecarily have flushed the cache for these I/Os, so give the list a more neutral name. Signed-off-by:
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Christoph Hellwig authored
There is no good reason to keep the I/O unit structures around after the stripe has been written back to the RAID array. The only information we need is the log sequence number, and the checkpoint offset of the highest successfull writeback. Store those in the log structure, and free the IO units from __r5l_stripe_write_finished. Besides simplifying the code this also avoid having to keep the allocation for the I/O unit around for a potentially long time as superblock updates that checkpoint the log do not happen very often. This also fixes the previously incorrect calculation of 'free' in r5l_do_reclaim as a side effect: previous if took the last unit which isn't checkpointed into account. Signed-off-by:
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Shaohua Li authored
Move reclaim stop to quiesce handling, where is safer for this stuff. Signed-off-by:
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Shaohua Li authored
Journal disk state sysfs entry should indicate it's journal Signed-off-by:
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Song Liu authored
match_mddev_units is used to check whether 2 RAID arrays share same disk(s). Arrays that share disk(s) will not do resync at the same time for better performance (fewer HDD seek). However, this check should not apply to Spare, Faulty, and Journal disks, as they do not paticipate in resync. In this patch, match_mddev_units skips check for disks with flag "Faulty" or "Journal" or raid_disk < 0. Signed-off-by:
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Shaohua Li authored
There is a case a stripe gets delayed forever. 1. a stripe finishes construction 2. a new bio hits the stripe 3. handle_stripe runs for the stripe. The stripe gets DELAYED bit set since construction can't run for new bio (the stripe is locked since step 1) Without log, handle_stripe will call ops_run_io. After IO finishes, the stripe gets unlocked and the stripe will restart and run construction for the new bio. With log, ops_run_io need to run two times. If the DELAYED bit set, the stripe can't enter into the handle_list, so the second ops_run_io doesn't run, which leaves the stripe stalled. Signed-off-by:
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Shaohua Li authored
stripes could finish out of order. Hence r5l_move_io_unit_list() of __r5l_stripe_write_finished might not move any entry and leave stripe_end_ios list empty. This applies on top of http://marc.info/?l=linux-raid&m=144122700510667Signed-off-by:
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Shaohua Li authored
If a raid array has journal, the journal can guarantee the consistency, we can skip resync after a unclean shutdown. The exception is raid creation or user initiated resync, which we still do a raid resync. Signed-off-by:
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Shaohua Li authored
With log enabled, bio is written to raid disks after the bio is settled down in log disk. The recovery guarantees we can recovery the bio data from log disk, so we we skip FLUSH IO. Signed-off-by:
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Christoph Hellwig authored
Just keep __r5l_set_io_unit_state as a small set the state wrapper, and remove r5l_set_io_unit_state entirely after moving the real functionality to the two callers that need it. Signed-off-by:
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Shaohua Li authored
r5l_compress_stripe_end_list() can free an io_unit. This breaks the assumption only reclaimer can free io_unit. We can add a reference count based io_unit free, but since only reclaim can wait io_unit becoming to STRIPE_END state, we use a simple global wait queue here. Signed-off-by:
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Shaohua Li authored
Before we write stripe data to raid disks, we must guarantee stripe data is settled down in log disk. To do this, we flush log disk cache and wait the flush finish. That wait introduces sleep time in raid5d thread and impact performance. This patch moves the log disk cache flush process to the stripe handling state machine, which can remove the wait in raid5d. Signed-off-by:
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Shaohua Li authored
Now log is safe to enable for raid array with cache disk Signed-off-by:
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Shaohua Li authored
If cache(log) support is enabled, don't allow resize/reshape in current stage. In the future, we can flush all data from cache(log) to raid before resize/reshape and then allow resize/reshape. Signed-off-by:
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Shaohua Li authored
With log enabled, r5l_write_stripe will add the stripe to log. With batch, several stripes are linked together. The stripes must be in the same state. While with log, the log/reclaim unit is stripe, we can't guarantee the several stripes are in the same state. Disabling batch for log now. Signed-off-by:
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Shaohua Li authored
crc32c has lower overhead with cpu acceleration. It's a shame I didn't use it in first post, sorry. This changes disk format, but we are still ok in current stage. V2: delete unnecessary type conversion as pointed out by Bart Signed-off-by:
Bart Van Assche <bart.vanassche@sandisk.com>
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- 24 Oct, 2015 7 commits
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Shaohua Li authored
This is the log recovery support. The process is quite straightforward. We scan the log and read all valid meta/data/parity into memory. If a stripe's data/parity checksum is correct, the stripe will be recoveried. Otherwise, it's discarded and we don't scan the log further. The reclaim process guarantees stripe which starts to be flushed raid disks has completed data/parity and has correct checksum. To recovery a stripe, we just copy its data/parity to corresponding raid disks. The trick thing is superblock update after recovery. we can't let superblock point to last valid meta block. The log might look like: | meta 1| meta 2| meta 3| meta 1 is valid, meta 2 is invalid. meta 3 could be valid. If superblock points to meta 1, we write a new valid meta 2n. If crash happens again, new recovery will start from meta 1. Since meta 2n is valid, recovery will think meta 3 is valid, which is wrong. The solution is we create a new meta in meta2 with its seq == meta 1's seq + 10 and let superblock points to meta2. recovery will not think meta 3 is a valid meta, because its seq is wrong Signed-off-by:
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Shaohua Li authored
This is the reclaim support for raid5 log. A stripe write will have following steps: 1. reconstruct the stripe, read data/calculate parity. ops_run_io prepares to write data/parity to raid disks 2. hijack ops_run_io. stripe data/parity is appending to log disk 3. flush log disk cache 4. ops_run_io run again and do normal operation. stripe data/parity is written in raid array disks. raid core can return io to upper layer. 5. flush cache of all raid array disks 6. update super block 7. log disk space used by the stripe can be reused In practice, several stripes consist of an io_unit and we will batch several io_unit in different steps, but the whole process doesn't change. It's possible io return just after data/parity hit log disk, but then read IO will need read from log disk. For simplicity, IO return happens at step 4, where read IO can directly read from raid disks. Currently reclaim run if there is specific reclaimable space (1/4 disk size or 10G) or we are out of space. Reclaim is just to free log disk spaces, it doesn't impact data consistency. The size based force reclaim is to make sure log isn't too big, so recovery doesn't scan log too much. Recovery make sure raid disks and log disk have the same data of a stripe. If crash happens before 4, recovery might/might not recovery stripe's data/parity depending on if data/parity and its checksum matches. In either case, this doesn't change the syntax of an IO write. After step 3, stripe is guaranteed recoverable, because stripe's data/parity is persistent in log disk. In some cases, log disk content and raid disks content of a stripe are the same, but recovery will still copy log disk content to raid disks, this doesn't impact data consistency. space reuse happens after superblock update and cache flush. There is one situation we want to avoid. A broken meta in the middle of a log causes recovery can't find meta at the head of log. If operations require meta at the head persistent in log, we must make sure meta before it persistent in log too. The case is stripe data/parity is in log and we start write stripe to raid disks (before step 4). stripe data/parity must be persistent in log before we do the write to raid disks. The solution is we restrictly maintain io_unit list order. In this case, we only write stripes of an io_unit to raid disks till the io_unit is the first one whose data/parity is in log. The io_unit list order is important for other cases too. For example, some io_unit are reclaimable and others not. They can be mixed in the list, we shouldn't reuse space of an unreclaimable io_unit. Includes fixes to problems which were... Reported-by:
kbuild test robot <fengguang.wu@intel.com> Signed-off-by:
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Shaohua Li authored
This introduces a simple log for raid5. Data/parity writing to raid array first writes to the log, then write to raid array disks. If crash happens, we can recovery data from the log. This can speed up raid resync and fix write hole issue. The log structure is pretty simple. Data/meta data is stored in block unit, which is 4k generally. It has only one type of meta data block. The meta data block can track 3 types of data, stripe data, stripe parity and flush block. MD superblock will point to the last valid meta data block. Each meta data block has checksum/seq number, so recovery can scan the log correctly. We store a checksum of stripe data/parity to the metadata block, so meta data and stripe data/parity can be written to log disk together. otherwise, meta data write must wait till stripe data/parity is finished. For stripe data, meta data block will record stripe data sector and size. Currently the size is always 4k. This meta data record can be made simpler if we just fix write hole (eg, we can record data of a stripe's different disks together), but this format can be extended to support caching in the future, which must record data address/size. For stripe parity, meta data block will record stripe sector. It's size should be 4k (for raid5) or 8k (for raid6). We always store p parity first. This format should work for caching too. flush block indicates a stripe is in raid array disks. Fixing write hole doesn't need this type of meta data, it's for caching extension. Signed-off-by:
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Shaohua Li authored
When a stripe finishes construction, we write the stripe to raid in ops_run_io normally. With log, we do a bunch of other operations before the stripe is written to raid. Mainly write the stripe to log disk, flush disk cache and so on. The operations are still driven by raid5d and run in the stripe state machine. We introduce a new state for such stripe (trapped into log). The stripe is in this state from the time it first enters ops_run_io (finish construction) to the time it is written to raid. Since we know the state is only for log, we bypass other check/operation in handle_stripe. Signed-off-by:
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Shaohua Li authored
Next several patches use some raid5 functions, rename them with raid5 prefix and export out. Signed-off-by:
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Shaohua Li authored
Journal device stores data in a log structure. We need record the log start. Here we override md superblock recovery_offset for this purpose. This field of a journal device is meaningless otherwise. Signed-off-by:
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Song Liu authored
Next patches will use a disk as raid5/6 journaling. We need a new disk role to present the journal device and add MD_FEATURE_JOURNAL to feature_map for backward compability. Signed-off-by:
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