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path: root/drivers/lightnvm/pblk-rl.c
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2019-03-07pblk: fix max_io calculationJavier González
When calculating the maximun I/O size allowed into the buffer, consider the write size (ws_opt) used by the write thread in order to cover the case in which, due to flushes, the mem and subm pointers are disaligned by (ws_opt - 1). This case currently translates into a stall when an I/O of the largest possible size is submitted. Fixes: f9f9d1ae2c66 ("lightnvm: pblk: prevent stall due to wb threshold") Signed-off-by: Javier González <javier@javigon.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-02-11lightnvm: pblk: prevent stall due to wb thresholdJavier González
In order to respect mw_cuinits, pblk's write buffer maintains a backpointer to protect data not yet persisted; when writing to the write buffer, this backpointer defines a threshold that pblk's rate-limiter enforces. On small PU configurations, the following scenarios might take place: (i) the threshold is larger than the write buffer and (ii) the threshold is smaller than the write buffer, but larger than the maximun allowed split bio - 256KB at this moment (Note that writes are not always split - we only do this when we the size of the buffer is smaller than the buffer). In both cases, pblk's rate-limiter prevents the I/O to be written to the buffer, thus stalling. This patch fixes the original backpointer implementation by considering the threshold both on buffer creation and on the rate-limiters path, when bio_split is triggered (case (ii) above). Fixes: 766c8ceb16fc ("lightnvm: pblk: guarantee that backpointer is respected on writer stall") Signed-off-by: Javier González <javier@javigon.com> Reviewed-by: Hans Holmberg <hans.holmberg@cnexlabs.com> Signed-off-by: Matias Bjørling <mb@lightnvm.io> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-11lightnvm: pblk: set conservative threshold for user writesHans Holmberg
In a worst-case scenario (random writes), OP% of sectors in each line will be invalid, and we will then need to move data out of 100/OP% lines to free a single line. So, to prevent the possibility of running out of lines, temporarily block user writes when there is less than 100/OP% free lines. Also ensure that pblk creation does not produce instances with insufficient over provisioning. Insufficient over-provising is not a problem on real hardware, but often an issue when running QEMU simulations (with few lines). 100 lines is enough to create a sane instance with the standard (11%) over provisioning. Signed-off-by: Hans Holmberg <hans.holmberg@cnexlabs.com> Reviewed-by: Javier González <javier@javigon.com> Signed-off-by: Matias Bjørling <mb@lightnvm.io> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-10-09lightnvm: pblk: add SPDX license tagJavier González
Add GLP-2.0 SPDX license tag to all pblk files Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <mb@lightnvm.io> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-10-09lightnvm: pblk: unify vector max req constantsMatias Bjørling
Both NVM_MAX_VLBA and PBLK_MAX_REQ_ADDRS define how many LBAs that are available in a vector command. pblk uses them interchangeably in its implementation. Use NVM_MAX_VLBA as the main one and remove usages of PBLK_MAX_REQ_ADDRS. Also remove the power representation that only has one user, and instead calculate it at runtime. Signed-off-by: Matias Bjørling <mb@lightnvm.io> Reviewed-by: Javier González <javier@cnexlabs.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-06-01lightnvm: pblk: garbage collect lines with failed writesHans Holmberg
Write failures should not happen under normal circumstances, so in order to bring the chunk back into a known state as soon as possible, evacuate all the valid data out of the line and let the fw judge if the block can be written to in the next reset cycle. Do this by introducing a new gc list for lines with failed writes, and ensure that the rate limiter allocates a small portion of the write bandwidth to get the job done. The lba list is saved in memory for use during gc as we cannot gurantee that the emeta data is readable if a write error occurred. Signed-off-by: Hans Holmberg <hans.holmberg@cnexlabs.com> Reviewed-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <mb@lightnvm.io> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-03-29lightnvm: simplify geometry structureJavier González
Currently, the device geometry is stored redundantly in the nvm_id and nvm_geo structures at a device level. Moreover, when instantiating targets on a specific number of LUNs, these structures are replicated and manually modified to fit the instance channel and LUN partitioning. Instead, create a generic geometry around nvm_geo, which can be used by (i) the underlying device to describe the geometry of the whole device, and (ii) instances to describe their geometry independently. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <mb@lightnvm.io> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-05lightnvm: pblk: use exact free block counter in RLJavier González
Until now, pblk's rate-limiter has used a heuristic to reserve space for GC I/O given that the over-provision area was fixed. In preparation for allowing to define the over-provision area on target creation, define a dedicated free_block counter in the rate-limiter to track the number of blocks being used for user data. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Hans Holmberg <hans.holmberg@cnexlabs.com> Signed-off-by: Matias Bjørling <m@bjorling.me> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-11-21lightnvm: Convert timers to use timer_setup()Kees Cook
In preparation for unconditionally passing the struct timer_list pointer to all timer callbacks, switch to using the new timer_setup() and from_timer() to pass the timer pointer explicitly. Cc: Matias Bjorling <mb@lightnvm.io> Cc: linux-block@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org>
2017-10-13lightnvm: pblk: cleanup unused and static functionsJavier González
Cleanup up unused and static functions across the whole codebase. 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: start gc if needed during initHans Holmberg
Start GC if needed, directly after init, as we might need to garbage collect in order to make room for user writes. Create a helper function that allows to kick GC without exposing the internals of the GC/rate-limiter interaction. Signed-off-by: Hans Holmberg <hans.holmberg@cnexlabs.com> Signed-off-by: Matias Bjørling <m@bjorling.me> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-13lightnvm: pblk: avoid deadlock on low LUN configJavier González
On low LUN configurations, make sure not to send bios that are bigger than the buffer size. 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>
2017-10-13lightnvm: pblk: reuse pblk_gc_should_kickRakesh Pandit
This is a trivial change which reuses pblk_gc_should_kick instead of repeating it again in pblk_rl_free_lines_inc. Signed-off-by: Rakesh Pandit <rakesh@tuxera.com> Made it apply to the common case. Reviewed-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <m@bjorling.me> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-26lightnvm: pblk: fail gracefully on irrec. errorJavier González
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: redesign GC algorithmJavier González
At the moment, in order to get enough read parallelism, we have recycled several lines at the same time. This approach has proven not to work well when reaching capacity, since we end up mixing valid data from all lines, thus not maintaining a sustainable free/recycled line ratio. The new design, relies on a two level workqueue mechanism. In the first level, we read the metadata for a number of lines based on the GC list they reside on (this is governed by the number of valid sectors in each line). In the second level, we recycle a single line at a time. Here, we issue reads in parallel, while a single GC write thread places data in the write buffer. This design allows to (i) only move data from one line at a time, thus maintaining a sane free/recycled ration and (ii) maintain the GC writer busy with recycled data. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <matias@cnexlabs.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-04-23lightnvm: pblk: fix erase counters on error failJavier González
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>
2017-04-16lightnvm: physical block device (pblk) targetJavier González
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>