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path: root/drivers/lightnvm/pblk-write.c
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2017-10-13lightnvm: pblk: remove I/O dependency on write pathJavier González1-80/+65
pblk schedules user I/O, metadata I/O and erases on the write path in order to minimize collisions at the media level. Until now, there has been a dependency between user and metadata I/Os that could lead to a deadlock as both take the per-LUN semaphore to schedule submission. This path removes this dependency and guarantees forward progress at a per I/O granurality. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <m@bjorling.me> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-13lightnvm: pblk: refactor rqd alloc/freeJavier González1-7/+0
Refactor the rqd allocation and free functions so that all I/O types can use these helper functions. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <m@bjorling.me> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-13lightnvm: pblk: improve naming for internal req.Javier González1-8/+8
Each request type sent to the LightNVM subsystem requires different metadata. Until now, we have tailored this metadata based on write, read and erase commands. However, pblk uses different metadata for internal writes that do not hit the write buffer. Instead of abusing the metadata for reads, create a new request type - internal write to improve code readability. In the process, create internal values for each I/O type instead of abusing the READ/WRITE macros, as suggested by Christoph. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <m@bjorling.me> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-13lightnvm: pblk: allocate bio size more accuratelyJavier González1-10/+10
Wait until we know the exact number of ppas to be sent to the device, before allocating the bio. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <m@bjorling.me> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-13lightnvm: pblk: put bio on bio completionJavier González1-7/+1
Simplify put bio by doing it on bio end_io instead of manually putting it on the completion path. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <m@bjorling.me> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-13lightnvm: pblk: remove checks on mempool alloc.Javier González1-19/+5
As part of the mempool audit on pblk, remove unnecessary mempool allocation checks on mempools. Reported-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <m@bjorling.me> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-13lightnvm: pblk: do not use a mempool for line bitmapsJavier González1-3/+1
pblk holds two sector bitmaps: one to keep track of the mapped sectors while the line is active and another one to keep track of the invalid sectors. The latter is kept during the whole live of the line, until it is recycled. Since we cannot guarantee forward progress for the mempool in this case, get rid of the mempool and simply allocate memory through kmalloc. Reported-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <m@bjorling.me> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-13lightnvm: pblk: simplify work_queue mempoolJavier González1-2/+2
In pblk, we have a mempool to allocate a generic structure that we pass along workqueues. This is heavily used in the GC path in order to have enough inflight reads and fully utilize the GC bandwidth. However, the current GC path copies data to the host memory and puts it back into the write buffer. This requires a vmalloc allocation for the data and a memory copy. Thus, guaranteeing the allocation by using a mempool for the structure in itself does not give us much. Until we implement support for vector copy to avoid moving data through the host, just allocate the workqueue structure using kmalloc. This allows us to have a much smaller mempool. Reported-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <m@bjorling.me> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-13lightnvm: pblk: fix write I/O sync statJavier González1-1/+1
Fix stat counter to collect the right number of I/Os being synced on the completion path. Fixes: 0880a9aa2d91f ("lightnvm: pblk: delete redundant buffer pointer") Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <m@bjorling.me> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-13lightnvm: pblk: free padded entries in write bufferJavier González1-1/+6
When a REQ_FLUSH reaches pblk, the bio cannot be directly completed. Instead, data on the write buffer is flushed and the bio is completed on the completion pah. This might require some sectors to be padded in order to guarantee a successful write. This patch fixes a memory leak on the padded pages. A consequence of this bad free was that internal bios not containing data (only a flush) were not being completed. Fixes: a4bd217b4326 ("lightnvm: physical block device (pblk) target") Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <m@bjorling.me> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-07-07lightnvm: pblk: remove unnecessary checksJavier González1-6/+1
Remove unnecessary checks when freeing dma memory in the completion path. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <matias@cnexlabs.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-07-07lightnvm: pblk: control I/O flow also on tear downJavier González1-12/+7
When removing a pblk instance, control the write I/O flow to the controller as we do in the fast path. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <matias@cnexlabs.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-30lightnvm: pblk: remove target using async. I/OsJavier González1-1/+1
When removing a pblk instance, pad the current line using asynchronous I/O. This reduces the removal time from ~1 minute in the worst case to a couple of seconds. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <matias@cnexlabs.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-30lightnvm: pblk: use vmalloc for GC data bufferJavier González1-1/+2
For now, we allocate a per I/O buffer for GC data. Since the potential size of the buffer is 256KB and GC is not in the fast path, do this allocation with vmalloc. This puts lets pressure on the memory allocator at no performance cost. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <matias@cnexlabs.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-26lightnvm: pblk: fail gracefully on irrec. errorJavier González1-1/+4
Due to user writes being decoupled from media writes because of the need of an intermediate write buffer, irrecoverable media write errors lead to pblk stalling; user writes fill up the buffer and end up in an infinite retry loop. In order to let user writes fail gracefully, it is necessary for pblk to keep track of its own internal state and prevent further writes from being placed into the write buffer. This patch implements a state machine to keep track of internal errors and, in case of failure, fail further user writes in an standard way. Depending on the type of error, pblk will do its best to persist buffered writes (which are already acknowledged) and close down on a graceful manner. This way, data might be recovered by re-instantiating pblk. Such state machine paves out the way for a state-based FTL log. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <matias@cnexlabs.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-26lightnvm: pblk: set mempool and workqueue params.Javier González1-2/+3
Make constants to define sizes for internal mempools and workqueues. In this process, adjust the values to be more meaningful given the internal constrains of the FTL. In order to do this for workqueues, separate the current auxiliary workqueue into two dedicated workqueues to manage lines being closed and bad blocks. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <matias@cnexlabs.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-26lightnvm: pblk: cleanup unnecessary codeJavier González1-6/+0
Cleanup unnecessary headers and code lines. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <matias@cnexlabs.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-26lightnvm: pblk: simplify meta. memory allocationJavier González1-1/+2
smeta size will always be suitable for a kmalloc allocation. Simplify the code and leave the vmalloc fallback only for emeta, where the pblk configuration has an impact. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <matias@cnexlabs.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-26lightnvm: pblk: delete redundant buffer pointerJavier González1-12/+1
After refactoring the metadata path, the backpointer controlling synced I/Os in a line becomes unnecessary; metadata is scheduled on the write thread, thus we know when the end of the line is reached and act on it directly. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <matias@cnexlabs.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-26lightnvm: pblk: sched. metadata on write threadJavier González1-23/+228
At the moment, line metadata is persisted on a separate work queue, that is kicked each time that a line is closed. The assumption when designing this was that freeing the write thread from creating a new write request was better than the potential impact of writes colliding on the media (user I/O and metadata I/O). Experimentation has proven that this assumption is wrong; collision can cause up to 25% of bandwidth and introduce long tail latencies on the write thread, which potentially cause user write threads to spend more time spinning to get a free entry on the write buffer. This patch moves the metadata logic to the write thread. When a line is closed, remaining metadata is written in memory and is placed on a metadata queue. The write thread then takes the metadata corresponding to the previous line, creates the write request and schedules it to minimize collisions on the media. Using this approach, we see that we can saturate the media's bandwidth, which helps reducing both write latencies and the spinning time for user writer threads. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <matias@cnexlabs.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-26lightnvm: pblk: generalize erase pathJavier González1-50/+59
Erase I/Os are scheduled with the following goals in mind: (i) minimize LUNs collisions with write I/Os, and (ii) even out the price of erasing on every write, instead of putting all the burden on when garbage collection runs. This works well on the current design, but is specific to the default mapping algorithm. This patch generalizes the erase path so that other mapping algorithms can select an arbitrary line to be erased instead. It also gets rid of the erase semaphore since it creates jittering for user writes. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <matias@cnexlabs.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-09block: switch bios to blk_status_tChristoph Hellwig1-1/+1
Replace bi_error with a new bi_status to allow for a clear conversion. Note that device mapper overloaded bi_error with a private value, which we'll have to keep arround at least for now and thus propagate to a proper blk_status_t value. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-23lightnvm: pblk: fix erase counters on error failJavier González1-2/+2
When block erases fail, these blocks are marked bad. The number of valid blocks in the line was not updated, which could cause an infinite loop on the erase path. Fix this atomic counter and, in order to avoid taking an irq lock on the interrupt context, make the erase counters atomic too. Also, in the case that a significant number of blocks become bad in a line, the result is the double shared metadata buffer (emeta) to stop the pipeline until all metadata is flushed to the media. Increase the number of metadata lines from 2 to 4 to avoid this case. Fixes: a4bd217b4326 "lightnvm: physical block device (pblk) target" Signed-off-by: Javier González <javier@cnexlabs.com> Reviewed-by: Matias Bjørling <matias@cnexlabs.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-23lightnvm: pblk: fix memory leak on error pathJavier González1-0/+3
When write recovery fails, Free memory for the recovery structure. Fixes: a4bd217b4326 "lightnvm: physical block device (pblk) target" Signed-off-by: Javier González <javier@cnexlabs.com> Reviewed-by: Matias Bjørling <matias@cnexlabs.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-16lightnvm: fix some WARN() messagesDan Carpenter1-1/+1
WARN_ON() takes a condition, not an error message. I slightly tweaked some conditions so hopefully it's more clear. Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Matias Bjørling <matias@cnexlabs.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-16lightnvm: physical block device (pblk) targetJavier González1-0/+411
This patch introduces pblk, a host-side translation layer for Open-Channel SSDs to expose them like block devices. The translation layer allows data placement decisions, and I/O scheduling to be managed by the host, enabling users to optimize the SSD for their specific workloads. An open-channel SSD has a set of LUNs (parallel units) and a collection of blocks. Each block can be read in any order, but writes must be sequential. Writes may also fail, and if a block requires it, must also be reset before new writes can be applied. To manage the constraints, pblk maintains a logical to physical address (L2P) table, write cache, garbage collection logic, recovery scheme, and logic to rate-limit user I/Os versus garbage collection I/Os. The L2P table is fully-associative and manages sectors at a 4KB granularity. Pblk stores the L2P table in two places, in the out-of-band area of the media and on the last page of a line. In the cause of a power failure, pblk will perform a scan to recover the L2P table. The user data is organized into lines. A line is data striped across blocks and LUNs. The lines enable the host to reduce the amount of metadata to maintain besides the user data and makes it easier to implement RAID or erasure coding in the future. pblk implements multi-tenant support and can be instantiated multiple times on the same drive. Each instance owns a portion of the SSD - both regarding I/O bandwidth and capacity - providing I/O isolation for each case. Finally, pblk also exposes a sysfs interface that allows user-space to peek into the internals of pblk. The interface is available at /dev/block/*/pblk/ where * is the block device name exposed. This work also contains contributions from: Matias Bjørling <matias@cnexlabs.com> Simon A. F. Lund <slund@cnexlabs.com> Young Tack Jin <youngtack.jin@gmail.com> Huaicheng Li <huaicheng@cs.uchicago.edu> Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <matias@cnexlabs.com> Signed-off-by: Jens Axboe <axboe@fb.com>