diff options
Diffstat (limited to 'drivers/md/dm-vdo/data-vio.c')
| -rw-r--r-- | drivers/md/dm-vdo/data-vio.c | 2063 |
1 files changed, 2063 insertions, 0 deletions
diff --git a/drivers/md/dm-vdo/data-vio.c b/drivers/md/dm-vdo/data-vio.c new file mode 100644 index 000000000..94f6f1ccf --- /dev/null +++ b/drivers/md/dm-vdo/data-vio.c @@ -0,0 +1,2063 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright 2023 Red Hat + */ + +#include "data-vio.h" + +#include <linux/atomic.h> +#include <linux/bio.h> +#include <linux/blkdev.h> +#include <linux/delay.h> +#include <linux/device-mapper.h> +#include <linux/jiffies.h> +#include <linux/kernel.h> +#include <linux/list.h> +#include <linux/lz4.h> +#include <linux/minmax.h> +#include <linux/sched.h> +#include <linux/spinlock.h> +#include <linux/wait.h> + +#include "logger.h" +#include "memory-alloc.h" +#include "murmurhash3.h" +#include "permassert.h" + +#include "block-map.h" +#include "dump.h" +#include "encodings.h" +#include "int-map.h" +#include "io-submitter.h" +#include "logical-zone.h" +#include "packer.h" +#include "recovery-journal.h" +#include "slab-depot.h" +#include "status-codes.h" +#include "types.h" +#include "vdo.h" +#include "vio.h" +#include "wait-queue.h" + +/** + * DOC: Bio flags. + * + * For certain flags set on user bios, if the user bio has not yet been acknowledged, setting those + * flags on our own bio(s) for that request may help underlying layers better fulfill the user + * bio's needs. This constant contains the aggregate of those flags; VDO strips all the other + * flags, as they convey incorrect information. + * + * These flags are always irrelevant if we have already finished the user bio as they are only + * hints on IO importance. If VDO has finished the user bio, any remaining IO done doesn't care how + * important finishing the finished bio was. + * + * Note that bio.c contains the complete list of flags we believe may be set; the following list + * explains the action taken with each of those flags VDO could receive: + * + * * REQ_SYNC: Passed down if the user bio is not yet completed, since it indicates the user bio + * completion is required for further work to be done by the issuer. + * * REQ_META: Passed down if the user bio is not yet completed, since it may mean the lower layer + * treats it as more urgent, similar to REQ_SYNC. + * * REQ_PRIO: Passed down if the user bio is not yet completed, since it indicates the user bio is + * important. + * * REQ_NOMERGE: Set only if the incoming bio was split; irrelevant to VDO IO. + * * REQ_IDLE: Set if the incoming bio had more IO quickly following; VDO's IO pattern doesn't + * match incoming IO, so this flag is incorrect for it. + * * REQ_FUA: Handled separately, and irrelevant to VDO IO otherwise. + * * REQ_RAHEAD: Passed down, as, for reads, it indicates trivial importance. + * * REQ_BACKGROUND: Not passed down, as VIOs are a limited resource and VDO needs them recycled + * ASAP to service heavy load, which is the only place where REQ_BACKGROUND might aid in load + * prioritization. + */ +static blk_opf_t PASSTHROUGH_FLAGS = (REQ_PRIO | REQ_META | REQ_SYNC | REQ_RAHEAD); + +/** + * DOC: + * + * The data_vio_pool maintains the pool of data_vios which a vdo uses to service incoming bios. For + * correctness, and in order to avoid potentially expensive or blocking memory allocations during + * normal operation, the number of concurrently active data_vios is capped. Furthermore, in order + * to avoid starvation of reads and writes, at most 75% of the data_vios may be used for + * discards. The data_vio_pool is responsible for enforcing these limits. Threads submitting bios + * for which a data_vio or discard permit are not available will block until the necessary + * resources are available. The pool is also responsible for distributing resources to blocked + * threads and waking them. Finally, the pool attempts to batch the work of recycling data_vios by + * performing the work of actually assigning resources to blocked threads or placing data_vios back + * into the pool on a single cpu at a time. + * + * The pool contains two "limiters", one for tracking data_vios and one for tracking discard + * permits. The limiters also provide safe cross-thread access to pool statistics without the need + * to take the pool's lock. When a thread submits a bio to a vdo device, it will first attempt to + * get a discard permit if it is a discard, and then to get a data_vio. If the necessary resources + * are available, the incoming bio will be assigned to the acquired data_vio, and it will be + * launched. However, if either of these are unavailable, the arrival time of the bio is recorded + * in the bio's bi_private field, the bio and its submitter are both queued on the appropriate + * limiter and the submitting thread will then put itself to sleep. (note that this mechanism will + * break if jiffies are only 32 bits.) + * + * Whenever a data_vio has completed processing for the bio it was servicing, release_data_vio() + * will be called on it. This function will add the data_vio to a funnel queue, and then check the + * state of the pool. If the pool is not currently processing released data_vios, the pool's + * completion will be enqueued on a cpu queue. This obviates the need for the releasing threads to + * hold the pool's lock, and also batches release work while avoiding starvation of the cpu + * threads. + * + * Whenever the pool's completion is run on a cpu thread, it calls process_release_callback() which + * processes a batch of returned data_vios (currently at most 32) from the pool's funnel queue. For + * each data_vio, it first checks whether that data_vio was processing a discard. If so, and there + * is a blocked bio waiting for a discard permit, that permit is notionally transferred to the + * eldest discard waiter, and that waiter is moved to the end of the list of discard bios waiting + * for a data_vio. If there are no discard waiters, the discard permit is returned to the pool. + * Next, the data_vio is assigned to the oldest blocked bio which either has a discard permit, or + * doesn't need one and relaunched. If neither of these exist, the data_vio is returned to the + * pool. Finally, if any waiting bios were launched, the threads which blocked trying to submit + * them are awakened. + */ + +#define DATA_VIO_RELEASE_BATCH_SIZE 128 + +static const unsigned int VDO_SECTORS_PER_BLOCK_MASK = VDO_SECTORS_PER_BLOCK - 1; +static const u32 COMPRESSION_STATUS_MASK = 0xff; +static const u32 MAY_NOT_COMPRESS_MASK = 0x80000000; + +struct limiter; +typedef void (*assigner_fn)(struct limiter *limiter); + +/* Bookkeeping structure for a single type of resource. */ +struct limiter { + /* The data_vio_pool to which this limiter belongs */ + struct data_vio_pool *pool; + /* The maximum number of data_vios available */ + data_vio_count_t limit; + /* The number of resources in use */ + data_vio_count_t busy; + /* The maximum number of resources ever simultaneously in use */ + data_vio_count_t max_busy; + /* The number of resources to release */ + data_vio_count_t release_count; + /* The number of waiters to wake */ + data_vio_count_t wake_count; + /* The list of waiting bios which are known to process_release_callback() */ + struct bio_list waiters; + /* The list of waiting bios which are not yet known to process_release_callback() */ + struct bio_list new_waiters; + /* The list of waiters which have their permits */ + struct bio_list *permitted_waiters; + /* The function for assigning a resource to a waiter */ + assigner_fn assigner; + /* The queue of blocked threads */ + wait_queue_head_t blocked_threads; + /* The arrival time of the eldest waiter */ + u64 arrival; +}; + +/* + * A data_vio_pool is a collection of preallocated data_vios which may be acquired from any thread, + * and are released in batches. + */ +struct data_vio_pool { + /* Completion for scheduling releases */ + struct vdo_completion completion; + /* The administrative state of the pool */ + struct admin_state state; + /* Lock protecting the pool */ + spinlock_t lock; + /* The main limiter controlling the total data_vios in the pool. */ + struct limiter limiter; + /* The limiter controlling data_vios for discard */ + struct limiter discard_limiter; + /* The list of bios which have discard permits but still need a data_vio */ + struct bio_list permitted_discards; + /* The list of available data_vios */ + struct list_head available; + /* The queue of data_vios waiting to be returned to the pool */ + struct funnel_queue *queue; + /* Whether the pool is processing, or scheduled to process releases */ + atomic_t processing; + /* The data vios in the pool */ + struct data_vio data_vios[]; +}; + +static const char * const ASYNC_OPERATION_NAMES[] = { + "launch", + "acknowledge_write", + "acquire_hash_lock", + "attempt_logical_block_lock", + "lock_duplicate_pbn", + "check_for_duplication", + "cleanup", + "compress_data_vio", + "find_block_map_slot", + "get_mapped_block_for_read", + "get_mapped_block_for_write", + "hash_data_vio", + "journal_remapping", + "vdo_attempt_packing", + "put_mapped_block", + "read_data_vio", + "update_dedupe_index", + "update_reference_counts", + "verify_duplication", + "write_data_vio", +}; + +/* The steps taken cleaning up a VIO, in the order they are performed. */ +enum data_vio_cleanup_stage { + VIO_CLEANUP_START, + VIO_RELEASE_HASH_LOCK = VIO_CLEANUP_START, + VIO_RELEASE_ALLOCATED, + VIO_RELEASE_RECOVERY_LOCKS, + VIO_RELEASE_LOGICAL, + VIO_CLEANUP_DONE +}; + +static inline struct data_vio_pool * __must_check +as_data_vio_pool(struct vdo_completion *completion) +{ + vdo_assert_completion_type(completion, VDO_DATA_VIO_POOL_COMPLETION); + return container_of(completion, struct data_vio_pool, completion); +} + +static inline u64 get_arrival_time(struct bio *bio) +{ + return (u64) bio->bi_private; +} + +/** + * check_for_drain_complete_locked() - Check whether a data_vio_pool has no outstanding data_vios + * or waiters while holding the pool's lock. + */ +static bool check_for_drain_complete_locked(struct data_vio_pool *pool) +{ + if (pool->limiter.busy > 0) + return false; + + VDO_ASSERT_LOG_ONLY((pool->discard_limiter.busy == 0), + "no outstanding discard permits"); + + return (bio_list_empty(&pool->limiter.new_waiters) && + bio_list_empty(&pool->discard_limiter.new_waiters)); +} + +static void initialize_lbn_lock(struct data_vio *data_vio, logical_block_number_t lbn) +{ + struct vdo *vdo = vdo_from_data_vio(data_vio); + zone_count_t zone_number; + struct lbn_lock *lock = &data_vio->logical; + + lock->lbn = lbn; + lock->locked = false; + vdo_waitq_init(&lock->waiters); + zone_number = vdo_compute_logical_zone(data_vio); + lock->zone = &vdo->logical_zones->zones[zone_number]; +} + +static void launch_locked_request(struct data_vio *data_vio) +{ + data_vio->logical.locked = true; + if (data_vio->write) { + struct vdo *vdo = vdo_from_data_vio(data_vio); + + if (vdo_is_read_only(vdo)) { + continue_data_vio_with_error(data_vio, VDO_READ_ONLY); + return; + } + } + + data_vio->last_async_operation = VIO_ASYNC_OP_FIND_BLOCK_MAP_SLOT; + vdo_find_block_map_slot(data_vio); +} + +static void acknowledge_data_vio(struct data_vio *data_vio) +{ + struct vdo *vdo = vdo_from_data_vio(data_vio); + struct bio *bio = data_vio->user_bio; + int error = vdo_status_to_errno(data_vio->vio.completion.result); + + if (bio == NULL) + return; + + VDO_ASSERT_LOG_ONLY((data_vio->remaining_discard <= + (u32) (VDO_BLOCK_SIZE - data_vio->offset)), + "data_vio to acknowledge is not an incomplete discard"); + + data_vio->user_bio = NULL; + vdo_count_bios(&vdo->stats.bios_acknowledged, bio); + if (data_vio->is_partial) + vdo_count_bios(&vdo->stats.bios_acknowledged_partial, bio); + + bio->bi_status = errno_to_blk_status(error); + bio_endio(bio); +} + +static void copy_to_bio(struct bio *bio, char *data_ptr) +{ + struct bio_vec biovec; + struct bvec_iter iter; + + bio_for_each_segment(biovec, bio, iter) { + memcpy_to_bvec(&biovec, data_ptr); + data_ptr += biovec.bv_len; + } +} + +struct data_vio_compression_status get_data_vio_compression_status(struct data_vio *data_vio) +{ + u32 packed = atomic_read(&data_vio->compression.status); + + /* pairs with cmpxchg in set_data_vio_compression_status */ + smp_rmb(); + return (struct data_vio_compression_status) { + .stage = packed & COMPRESSION_STATUS_MASK, + .may_not_compress = ((packed & MAY_NOT_COMPRESS_MASK) != 0), + }; +} + +/** + * pack_status() - Convert a data_vio_compression_status into a u32 which may be stored + * atomically. + * @status: The state to convert. + * + * Return: The compression state packed into a u32. + */ +static u32 __must_check pack_status(struct data_vio_compression_status status) +{ + return status.stage | (status.may_not_compress ? MAY_NOT_COMPRESS_MASK : 0); +} + +/** + * set_data_vio_compression_status() - Set the compression status of a data_vio. + * @state: The expected current status of the data_vio. + * @new_state: The status to set. + * + * Return: true if the new status was set, false if the data_vio's compression status did not + * match the expected state, and so was left unchanged. + */ +static bool __must_check +set_data_vio_compression_status(struct data_vio *data_vio, + struct data_vio_compression_status status, + struct data_vio_compression_status new_status) +{ + u32 actual; + u32 expected = pack_status(status); + u32 replacement = pack_status(new_status); + + /* + * Extra barriers because this was original developed using a CAS operation that implicitly + * had them. + */ + smp_mb__before_atomic(); + actual = atomic_cmpxchg(&data_vio->compression.status, expected, replacement); + /* same as before_atomic */ + smp_mb__after_atomic(); + return (expected == actual); +} + +struct data_vio_compression_status advance_data_vio_compression_stage(struct data_vio *data_vio) +{ + for (;;) { + struct data_vio_compression_status status = + get_data_vio_compression_status(data_vio); + struct data_vio_compression_status new_status = status; + + if (status.stage == DATA_VIO_POST_PACKER) { + /* We're already in the last stage. */ + return status; + } + + if (status.may_not_compress) { + /* + * Compression has been dis-allowed for this VIO, so skip the rest of the + * path and go to the end. + */ + new_status.stage = DATA_VIO_POST_PACKER; + } else { + /* Go to the next state. */ + new_status.stage++; + } + + if (set_data_vio_compression_status(data_vio, status, new_status)) + return new_status; + + /* Another thread changed the status out from under us so try again. */ + } +} + +/** + * cancel_data_vio_compression() - Prevent this data_vio from being compressed or packed. + * + * Return: true if the data_vio is in the packer and the caller was the first caller to cancel it. + */ +bool cancel_data_vio_compression(struct data_vio *data_vio) +{ + struct data_vio_compression_status status, new_status; + + for (;;) { + status = get_data_vio_compression_status(data_vio); + if (status.may_not_compress || (status.stage == DATA_VIO_POST_PACKER)) { + /* This data_vio is already set up to not block in the packer. */ + break; + } + + new_status.stage = status.stage; + new_status.may_not_compress = true; + + if (set_data_vio_compression_status(data_vio, status, new_status)) + break; + } + + return ((status.stage == DATA_VIO_PACKING) && !status.may_not_compress); +} + +/** + * attempt_logical_block_lock() - Attempt to acquire the lock on a logical block. + * @completion: The data_vio for an external data request as a completion. + * + * This is the start of the path for all external requests. It is registered in launch_data_vio(). + */ +static void attempt_logical_block_lock(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + struct lbn_lock *lock = &data_vio->logical; + struct vdo *vdo = vdo_from_data_vio(data_vio); + struct data_vio *lock_holder; + int result; + + assert_data_vio_in_logical_zone(data_vio); + + if (data_vio->logical.lbn >= vdo->states.vdo.config.logical_blocks) { + continue_data_vio_with_error(data_vio, VDO_OUT_OF_RANGE); + return; + } + + result = vdo_int_map_put(lock->zone->lbn_operations, lock->lbn, + data_vio, false, (void **) &lock_holder); + if (result != VDO_SUCCESS) { + continue_data_vio_with_error(data_vio, result); + return; + } + + if (lock_holder == NULL) { + /* We got the lock */ + launch_locked_request(data_vio); + return; + } + + result = VDO_ASSERT(lock_holder->logical.locked, "logical block lock held"); + if (result != VDO_SUCCESS) { + continue_data_vio_with_error(data_vio, result); + return; + } + + /* + * If the new request is a pure read request (not read-modify-write) and the lock_holder is + * writing and has received an allocation, service the read request immediately by copying + * data from the lock_holder to avoid having to flush the write out of the packer just to + * prevent the read from waiting indefinitely. If the lock_holder does not yet have an + * allocation, prevent it from blocking in the packer and wait on it. This is necessary in + * order to prevent returning data that may not have actually been written. + */ + if (!data_vio->write && READ_ONCE(lock_holder->allocation_succeeded)) { + copy_to_bio(data_vio->user_bio, lock_holder->vio.data + data_vio->offset); + acknowledge_data_vio(data_vio); + complete_data_vio(completion); + return; + } + + data_vio->last_async_operation = VIO_ASYNC_OP_ATTEMPT_LOGICAL_BLOCK_LOCK; + vdo_waitq_enqueue_waiter(&lock_holder->logical.waiters, &data_vio->waiter); + + /* + * Prevent writes and read-modify-writes from blocking indefinitely on lock holders in the + * packer. + */ + if (lock_holder->write && cancel_data_vio_compression(lock_holder)) { + data_vio->compression.lock_holder = lock_holder; + launch_data_vio_packer_callback(data_vio, + vdo_remove_lock_holder_from_packer); + } +} + +/** + * launch_data_vio() - (Re)initialize a data_vio to have a new logical block number, keeping the + * same parent and other state and send it on its way. + */ +static void launch_data_vio(struct data_vio *data_vio, logical_block_number_t lbn) +{ + struct vdo_completion *completion = &data_vio->vio.completion; + + /* + * Clearing the tree lock must happen before initializing the LBN lock, which also adds + * information to the tree lock. + */ + memset(&data_vio->tree_lock, 0, sizeof(data_vio->tree_lock)); + initialize_lbn_lock(data_vio, lbn); + INIT_LIST_HEAD(&data_vio->hash_lock_entry); + INIT_LIST_HEAD(&data_vio->write_entry); + + memset(&data_vio->allocation, 0, sizeof(data_vio->allocation)); + + data_vio->is_duplicate = false; + + memset(&data_vio->record_name, 0, sizeof(data_vio->record_name)); + memset(&data_vio->duplicate, 0, sizeof(data_vio->duplicate)); + vdo_reset_completion(completion); + completion->error_handler = handle_data_vio_error; + set_data_vio_logical_callback(data_vio, attempt_logical_block_lock); + vdo_enqueue_completion(completion, VDO_DEFAULT_Q_MAP_BIO_PRIORITY); +} + +static bool is_zero_block(char *block) +{ + int i; + + for (i = 0; i < VDO_BLOCK_SIZE; i += sizeof(u64)) { + if (*((u64 *) &block[i])) + return false; + } + + return true; +} + +static void copy_from_bio(struct bio *bio, char *data_ptr) +{ + struct bio_vec biovec; + struct bvec_iter iter; + + bio_for_each_segment(biovec, bio, iter) { + memcpy_from_bvec(data_ptr, &biovec); + data_ptr += biovec.bv_len; + } +} + +static void launch_bio(struct vdo *vdo, struct data_vio *data_vio, struct bio *bio) +{ + logical_block_number_t lbn; + /* + * Zero out the fields which don't need to be preserved (i.e. which are not pointers to + * separately allocated objects). + */ + memset(data_vio, 0, offsetof(struct data_vio, vio)); + memset(&data_vio->compression, 0, offsetof(struct compression_state, block)); + + data_vio->user_bio = bio; + data_vio->offset = to_bytes(bio->bi_iter.bi_sector & VDO_SECTORS_PER_BLOCK_MASK); + data_vio->is_partial = (bio->bi_iter.bi_size < VDO_BLOCK_SIZE) || (data_vio->offset != 0); + + /* + * Discards behave very differently than other requests when coming in from device-mapper. + * We have to be able to handle any size discards and various sector offsets within a + * block. + */ + if (bio_op(bio) == REQ_OP_DISCARD) { + data_vio->remaining_discard = bio->bi_iter.bi_size; + data_vio->write = true; + data_vio->is_discard = true; + if (data_vio->is_partial) { + vdo_count_bios(&vdo->stats.bios_in_partial, bio); + data_vio->read = true; + } + } else if (data_vio->is_partial) { + vdo_count_bios(&vdo->stats.bios_in_partial, bio); + data_vio->read = true; + if (bio_data_dir(bio) == WRITE) + data_vio->write = true; + } else if (bio_data_dir(bio) == READ) { + data_vio->read = true; + } else { + /* + * Copy the bio data to a char array so that we can continue to use the data after + * we acknowledge the bio. + */ + copy_from_bio(bio, data_vio->vio.data); + data_vio->is_zero = is_zero_block(data_vio->vio.data); + data_vio->write = true; + } + + if (data_vio->user_bio->bi_opf & REQ_FUA) + data_vio->fua = true; + + lbn = (bio->bi_iter.bi_sector - vdo->starting_sector_offset) / VDO_SECTORS_PER_BLOCK; + launch_data_vio(data_vio, lbn); +} + +static void assign_data_vio(struct limiter *limiter, struct data_vio *data_vio) +{ + struct bio *bio = bio_list_pop(limiter->permitted_waiters); + + launch_bio(limiter->pool->completion.vdo, data_vio, bio); + limiter->wake_count++; + + bio = bio_list_peek(limiter->permitted_waiters); + limiter->arrival = ((bio == NULL) ? U64_MAX : get_arrival_time(bio)); +} + +static void assign_discard_permit(struct limiter *limiter) +{ + struct bio *bio = bio_list_pop(&limiter->waiters); + + if (limiter->arrival == U64_MAX) + limiter->arrival = get_arrival_time(bio); + + bio_list_add(limiter->permitted_waiters, bio); +} + +static void get_waiters(struct limiter *limiter) +{ + bio_list_merge(&limiter->waiters, &limiter->new_waiters); + bio_list_init(&limiter->new_waiters); +} + +static inline struct data_vio *get_available_data_vio(struct data_vio_pool *pool) +{ + struct data_vio *data_vio = + list_first_entry(&pool->available, struct data_vio, pool_entry); + + list_del_init(&data_vio->pool_entry); + return data_vio; +} + +static void assign_data_vio_to_waiter(struct limiter *limiter) +{ + assign_data_vio(limiter, get_available_data_vio(limiter->pool)); +} + +static void update_limiter(struct limiter *limiter) +{ + struct bio_list *waiters = &limiter->waiters; + data_vio_count_t available = limiter->limit - limiter->busy; + + VDO_ASSERT_LOG_ONLY((limiter->release_count <= limiter->busy), + "Release count %u is not more than busy count %u", + limiter->release_count, limiter->busy); + + get_waiters(limiter); + for (; (limiter->release_count > 0) && !bio_list_empty(waiters); limiter->release_count--) + limiter->assigner(limiter); + + if (limiter->release_count > 0) { + WRITE_ONCE(limiter->busy, limiter->busy - limiter->release_count); + limiter->release_count = 0; + return; + } + + for (; (available > 0) && !bio_list_empty(waiters); available--) + limiter->assigner(limiter); + + WRITE_ONCE(limiter->busy, limiter->limit - available); + if (limiter->max_busy < limiter->busy) + WRITE_ONCE(limiter->max_busy, limiter->busy); +} + +/** + * schedule_releases() - Ensure that release processing is scheduled. + * + * If this call switches the state to processing, enqueue. Otherwise, some other thread has already + * done so. + */ +static void schedule_releases(struct data_vio_pool *pool) +{ + /* Pairs with the barrier in process_release_callback(). */ + smp_mb__before_atomic(); + if (atomic_cmpxchg(&pool->processing, false, true)) + return; + + pool->completion.requeue = true; + vdo_launch_completion_with_priority(&pool->completion, + CPU_Q_COMPLETE_VIO_PRIORITY); +} + +static void reuse_or_release_resources(struct data_vio_pool *pool, + struct data_vio *data_vio, + struct list_head *returned) +{ + if (data_vio->remaining_discard > 0) { + if (bio_list_empty(&pool->discard_limiter.waiters)) { + /* Return the data_vio's discard permit. */ + pool->discard_limiter.release_count++; + } else { + assign_discard_permit(&pool->discard_limiter); + } + } + + if (pool->limiter.arrival < pool->discard_limiter.arrival) { + assign_data_vio(&pool->limiter, data_vio); + } else if (pool->discard_limiter.arrival < U64_MAX) { + assign_data_vio(&pool->discard_limiter, data_vio); + } else { + list_add(&data_vio->pool_entry, returned); + pool->limiter.release_count++; + } +} + +/** + * process_release_callback() - Process a batch of data_vio releases. + * @completion: The pool with data_vios to release. + */ +static void process_release_callback(struct vdo_completion *completion) +{ + struct data_vio_pool *pool = as_data_vio_pool(completion); + bool reschedule; + bool drained; + data_vio_count_t processed; + data_vio_count_t to_wake; + data_vio_count_t discards_to_wake; + LIST_HEAD(returned); + + spin_lock(&pool->lock); + get_waiters(&pool->discard_limiter); + get_waiters(&pool->limiter); + spin_unlock(&pool->lock); + + if (pool->limiter.arrival == U64_MAX) { + struct bio *bio = bio_list_peek(&pool->limiter.waiters); + + if (bio != NULL) + pool->limiter.arrival = get_arrival_time(bio); + } + + for (processed = 0; processed < DATA_VIO_RELEASE_BATCH_SIZE; processed++) { + struct data_vio *data_vio; + struct funnel_queue_entry *entry = vdo_funnel_queue_poll(pool->queue); + + if (entry == NULL) + break; + + data_vio = as_data_vio(container_of(entry, struct vdo_completion, + work_queue_entry_link)); + acknowledge_data_vio(data_vio); + reuse_or_release_resources(pool, data_vio, &returned); + } + + spin_lock(&pool->lock); + /* + * There is a race where waiters could be added while we are in the unlocked section above. + * Those waiters could not see the resources we are now about to release, so we assign + * those resources now as we have no guarantee of being rescheduled. This is handled in + * update_limiter(). + */ + update_limiter(&pool->discard_limiter); + list_splice(&returned, &pool->available); + update_limiter(&pool->limiter); + to_wake = pool->limiter.wake_count; + pool->limiter.wake_count = 0; + discards_to_wake = pool->discard_limiter.wake_count; + pool->discard_limiter.wake_count = 0; + + atomic_set(&pool->processing, false); + /* Pairs with the barrier in schedule_releases(). */ + smp_mb(); + + reschedule = !vdo_is_funnel_queue_empty(pool->queue); + drained = (!reschedule && + vdo_is_state_draining(&pool->state) && + check_for_drain_complete_locked(pool)); + spin_unlock(&pool->lock); + + if (to_wake > 0) + wake_up_nr(&pool->limiter.blocked_threads, to_wake); + + if (discards_to_wake > 0) + wake_up_nr(&pool->discard_limiter.blocked_threads, discards_to_wake); + + if (reschedule) + schedule_releases(pool); + else if (drained) + vdo_finish_draining(&pool->state); +} + +static void initialize_limiter(struct limiter *limiter, struct data_vio_pool *pool, + assigner_fn assigner, data_vio_count_t limit) +{ + limiter->pool = pool; + limiter->assigner = assigner; + limiter->limit = limit; + limiter->arrival = U64_MAX; + init_waitqueue_head(&limiter->blocked_threads); +} + +/** + * initialize_data_vio() - Allocate the components of a data_vio. + * + * The caller is responsible for cleaning up the data_vio on error. + * + * Return: VDO_SUCCESS or an error. + */ +static int initialize_data_vio(struct data_vio *data_vio, struct vdo *vdo) +{ + struct bio *bio; + int result; + + BUILD_BUG_ON(VDO_BLOCK_SIZE > PAGE_SIZE); + result = vdo_allocate_memory(VDO_BLOCK_SIZE, 0, "data_vio data", + &data_vio->vio.data); + if (result != VDO_SUCCESS) + return vdo_log_error_strerror(result, + "data_vio data allocation failure"); + + result = vdo_allocate_memory(VDO_BLOCK_SIZE, 0, "compressed block", + &data_vio->compression.block); + if (result != VDO_SUCCESS) { + return vdo_log_error_strerror(result, + "data_vio compressed block allocation failure"); + } + + result = vdo_allocate_memory(VDO_BLOCK_SIZE, 0, "vio scratch", + &data_vio->scratch_block); + if (result != VDO_SUCCESS) + return vdo_log_error_strerror(result, + "data_vio scratch allocation failure"); + + result = vdo_create_bio(&bio); + if (result != VDO_SUCCESS) + return vdo_log_error_strerror(result, + "data_vio data bio allocation failure"); + + vdo_initialize_completion(&data_vio->decrement_completion, vdo, + VDO_DECREMENT_COMPLETION); + initialize_vio(&data_vio->vio, bio, 1, VIO_TYPE_DATA, VIO_PRIORITY_DATA, vdo); + + return VDO_SUCCESS; +} + +static void destroy_data_vio(struct data_vio *data_vio) +{ + if (data_vio == NULL) + return; + + vdo_free_bio(vdo_forget(data_vio->vio.bio)); + vdo_free(vdo_forget(data_vio->vio.data)); + vdo_free(vdo_forget(data_vio->compression.block)); + vdo_free(vdo_forget(data_vio->scratch_block)); +} + +/** + * make_data_vio_pool() - Initialize a data_vio pool. + * @vdo: The vdo to which the pool will belong. + * @pool_size: The number of data_vios in the pool. + * @discard_limit: The maximum number of data_vios which may be used for discards. + * @pool: A pointer to hold the newly allocated pool. + */ +int make_data_vio_pool(struct vdo *vdo, data_vio_count_t pool_size, + data_vio_count_t discard_limit, struct data_vio_pool **pool_ptr) +{ + int result; + struct data_vio_pool *pool; + data_vio_count_t i; + + result = vdo_allocate_extended(struct data_vio_pool, pool_size, struct data_vio, + __func__, &pool); + if (result != VDO_SUCCESS) + return result; + + VDO_ASSERT_LOG_ONLY((discard_limit <= pool_size), + "discard limit does not exceed pool size"); + initialize_limiter(&pool->discard_limiter, pool, assign_discard_permit, + discard_limit); + pool->discard_limiter.permitted_waiters = &pool->permitted_discards; + initialize_limiter(&pool->limiter, pool, assign_data_vio_to_waiter, pool_size); + pool->limiter.permitted_waiters = &pool->limiter.waiters; + INIT_LIST_HEAD(&pool->available); + spin_lock_init(&pool->lock); + vdo_set_admin_state_code(&pool->state, VDO_ADMIN_STATE_NORMAL_OPERATION); + vdo_initialize_completion(&pool->completion, vdo, VDO_DATA_VIO_POOL_COMPLETION); + vdo_prepare_completion(&pool->completion, process_release_callback, + process_release_callback, vdo->thread_config.cpu_thread, + NULL); + + result = vdo_make_funnel_queue(&pool->queue); + if (result != VDO_SUCCESS) { + free_data_vio_pool(vdo_forget(pool)); + return result; + } + + for (i = 0; i < pool_size; i++) { + struct data_vio *data_vio = &pool->data_vios[i]; + + result = initialize_data_vio(data_vio, vdo); + if (result != VDO_SUCCESS) { + destroy_data_vio(data_vio); + free_data_vio_pool(pool); + return result; + } + + list_add(&data_vio->pool_entry, &pool->available); + } + + *pool_ptr = pool; + return VDO_SUCCESS; +} + +/** + * free_data_vio_pool() - Free a data_vio_pool and the data_vios in it. + * + * All data_vios must be returned to the pool before calling this function. + */ +void free_data_vio_pool(struct data_vio_pool *pool) +{ + struct data_vio *data_vio, *tmp; + + if (pool == NULL) + return; + + /* + * Pairs with the barrier in process_release_callback(). Possibly not needed since it + * caters to an enqueue vs. free race. + */ + smp_mb(); + BUG_ON(atomic_read(&pool->processing)); + + spin_lock(&pool->lock); + VDO_ASSERT_LOG_ONLY((pool->limiter.busy == 0), + "data_vio pool must not have %u busy entries when being freed", + pool->limiter.busy); + VDO_ASSERT_LOG_ONLY((bio_list_empty(&pool->limiter.waiters) && + bio_list_empty(&pool->limiter.new_waiters)), + "data_vio pool must not have threads waiting to read or write when being freed"); + VDO_ASSERT_LOG_ONLY((bio_list_empty(&pool->discard_limiter.waiters) && + bio_list_empty(&pool->discard_limiter.new_waiters)), + "data_vio pool must not have threads waiting to discard when being freed"); + spin_unlock(&pool->lock); + + list_for_each_entry_safe(data_vio, tmp, &pool->available, pool_entry) { + list_del_init(&data_vio->pool_entry); + destroy_data_vio(data_vio); + } + + vdo_free_funnel_queue(vdo_forget(pool->queue)); + vdo_free(pool); +} + +static bool acquire_permit(struct limiter *limiter) +{ + if (limiter->busy >= limiter->limit) + return false; + + WRITE_ONCE(limiter->busy, limiter->busy + 1); + if (limiter->max_busy < limiter->busy) + WRITE_ONCE(limiter->max_busy, limiter->busy); + return true; +} + +static void wait_permit(struct limiter *limiter, struct bio *bio) + __releases(&limiter->pool->lock) +{ + DEFINE_WAIT(wait); + + bio_list_add(&limiter->new_waiters, bio); + prepare_to_wait_exclusive(&limiter->blocked_threads, &wait, + TASK_UNINTERRUPTIBLE); + spin_unlock(&limiter->pool->lock); + io_schedule(); + finish_wait(&limiter->blocked_threads, &wait); +} + +/** + * vdo_launch_bio() - Acquire a data_vio from the pool, assign the bio to it, and launch it. + * + * This will block if data_vios or discard permits are not available. + */ +void vdo_launch_bio(struct data_vio_pool *pool, struct bio *bio) +{ + struct data_vio *data_vio; + + VDO_ASSERT_LOG_ONLY(!vdo_is_state_quiescent(&pool->state), + "data_vio_pool not quiescent on acquire"); + + bio->bi_private = (void *) jiffies; + spin_lock(&pool->lock); + if ((bio_op(bio) == REQ_OP_DISCARD) && + !acquire_permit(&pool->discard_limiter)) { + wait_permit(&pool->discard_limiter, bio); + return; + } + + if (!acquire_permit(&pool->limiter)) { + wait_permit(&pool->limiter, bio); + return; + } + + data_vio = get_available_data_vio(pool); + spin_unlock(&pool->lock); + launch_bio(pool->completion.vdo, data_vio, bio); +} + +/* Implements vdo_admin_initiator_fn. */ +static void initiate_drain(struct admin_state *state) +{ + bool drained; + struct data_vio_pool *pool = container_of(state, struct data_vio_pool, state); + + spin_lock(&pool->lock); + drained = check_for_drain_complete_locked(pool); + spin_unlock(&pool->lock); + + if (drained) + vdo_finish_draining(state); +} + +static void assert_on_vdo_cpu_thread(const struct vdo *vdo, const char *name) +{ + VDO_ASSERT_LOG_ONLY((vdo_get_callback_thread_id() == vdo->thread_config.cpu_thread), + "%s called on cpu thread", name); +} + +/** + * drain_data_vio_pool() - Wait asynchronously for all data_vios to be returned to the pool. + * @completion: The completion to notify when the pool has drained. + */ +void drain_data_vio_pool(struct data_vio_pool *pool, struct vdo_completion *completion) +{ + assert_on_vdo_cpu_thread(completion->vdo, __func__); + vdo_start_draining(&pool->state, VDO_ADMIN_STATE_SUSPENDING, completion, + initiate_drain); +} + +/** + * resume_data_vio_pool() - Resume a data_vio pool. + * @completion: The completion to notify when the pool has resumed. + */ +void resume_data_vio_pool(struct data_vio_pool *pool, struct vdo_completion *completion) +{ + assert_on_vdo_cpu_thread(completion->vdo, __func__); + vdo_continue_completion(completion, vdo_resume_if_quiescent(&pool->state)); +} + +static void dump_limiter(const char *name, struct limiter *limiter) +{ + vdo_log_info("%s: %u of %u busy (max %u), %s", name, limiter->busy, + limiter->limit, limiter->max_busy, + ((bio_list_empty(&limiter->waiters) && + bio_list_empty(&limiter->new_waiters)) ? + "no waiters" : "has waiters")); +} + +/** + * dump_data_vio_pool() - Dump a data_vio pool to the log. + * @dump_vios: Whether to dump the details of each busy data_vio as well. + */ +void dump_data_vio_pool(struct data_vio_pool *pool, bool dump_vios) +{ + /* + * In order that syslog can empty its buffer, sleep after 35 elements for 4ms (till the + * second clock tick). These numbers were picked based on experiments with lab machines. + */ + static const int ELEMENTS_PER_BATCH = 35; + static const int SLEEP_FOR_SYSLOG = 4000; + + if (pool == NULL) + return; + + spin_lock(&pool->lock); + dump_limiter("data_vios", &pool->limiter); + dump_limiter("discard permits", &pool->discard_limiter); + if (dump_vios) { + int i; + int dumped = 0; + + for (i = 0; i < pool->limiter.limit; i++) { + struct data_vio *data_vio = &pool->data_vios[i]; + + if (!list_empty(&data_vio->pool_entry)) + continue; + + dump_data_vio(data_vio); + if (++dumped >= ELEMENTS_PER_BATCH) { + spin_unlock(&pool->lock); + dumped = 0; + fsleep(SLEEP_FOR_SYSLOG); + spin_lock(&pool->lock); + } + } + } + + spin_unlock(&pool->lock); +} + +data_vio_count_t get_data_vio_pool_active_discards(struct data_vio_pool *pool) +{ + return READ_ONCE(pool->discard_limiter.busy); +} + +data_vio_count_t get_data_vio_pool_discard_limit(struct data_vio_pool *pool) +{ + return READ_ONCE(pool->discard_limiter.limit); +} + +data_vio_count_t get_data_vio_pool_maximum_discards(struct data_vio_pool *pool) +{ + return READ_ONCE(pool->discard_limiter.max_busy); +} + +int set_data_vio_pool_discard_limit(struct data_vio_pool *pool, data_vio_count_t limit) +{ + if (get_data_vio_pool_request_limit(pool) < limit) { + // The discard limit may not be higher than the data_vio limit. + return -EINVAL; + } + + spin_lock(&pool->lock); + pool->discard_limiter.limit = limit; + spin_unlock(&pool->lock); + + return VDO_SUCCESS; +} + +data_vio_count_t get_data_vio_pool_active_requests(struct data_vio_pool *pool) +{ + return READ_ONCE(pool->limiter.busy); +} + +data_vio_count_t get_data_vio_pool_request_limit(struct data_vio_pool *pool) +{ + return READ_ONCE(pool->limiter.limit); +} + +data_vio_count_t get_data_vio_pool_maximum_requests(struct data_vio_pool *pool) +{ + return READ_ONCE(pool->limiter.max_busy); +} + +static void update_data_vio_error_stats(struct data_vio *data_vio) +{ + u8 index = 0; + static const char * const operations[] = { + [0] = "empty", + [1] = "read", + [2] = "write", + [3] = "read-modify-write", + [5] = "read+fua", + [6] = "write+fua", + [7] = "read-modify-write+fua", + }; + + if (data_vio->read) + index = 1; + + if (data_vio->write) + index += 2; + + if (data_vio->fua) + index += 4; + + update_vio_error_stats(&data_vio->vio, + "Completing %s vio for LBN %llu with error after %s", + operations[index], + (unsigned long long) data_vio->logical.lbn, + get_data_vio_operation_name(data_vio)); +} + +static void perform_cleanup_stage(struct data_vio *data_vio, + enum data_vio_cleanup_stage stage); + +/** + * release_allocated_lock() - Release the PBN lock and/or the reference on the allocated block at + * the end of processing a data_vio. + */ +static void release_allocated_lock(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + + assert_data_vio_in_allocated_zone(data_vio); + release_data_vio_allocation_lock(data_vio, false); + perform_cleanup_stage(data_vio, VIO_RELEASE_RECOVERY_LOCKS); +} + +/** release_lock() - Release an uncontended LBN lock. */ +static void release_lock(struct data_vio *data_vio, struct lbn_lock *lock) +{ + struct int_map *lock_map = lock->zone->lbn_operations; + struct data_vio *lock_holder; + + if (!lock->locked) { + /* The lock is not locked, so it had better not be registered in the lock map. */ + struct data_vio *lock_holder = vdo_int_map_get(lock_map, lock->lbn); + + VDO_ASSERT_LOG_ONLY((data_vio != lock_holder), + "no logical block lock held for block %llu", + (unsigned long long) lock->lbn); + return; + } + + /* Release the lock by removing the lock from the map. */ + lock_holder = vdo_int_map_remove(lock_map, lock->lbn); + VDO_ASSERT_LOG_ONLY((data_vio == lock_holder), + "logical block lock mismatch for block %llu", + (unsigned long long) lock->lbn); + lock->locked = false; +} + +/** transfer_lock() - Transfer a contended LBN lock to the eldest waiter. */ +static void transfer_lock(struct data_vio *data_vio, struct lbn_lock *lock) +{ + struct data_vio *lock_holder, *next_lock_holder; + int result; + + VDO_ASSERT_LOG_ONLY(lock->locked, "lbn_lock with waiters is not locked"); + + /* Another data_vio is waiting for the lock, transfer it in a single lock map operation. */ + next_lock_holder = + vdo_waiter_as_data_vio(vdo_waitq_dequeue_waiter(&lock->waiters)); + + /* Transfer the remaining lock waiters to the next lock holder. */ + vdo_waitq_transfer_all_waiters(&lock->waiters, + &next_lock_holder->logical.waiters); + + result = vdo_int_map_put(lock->zone->lbn_operations, lock->lbn, + next_lock_holder, true, (void **) &lock_holder); + if (result != VDO_SUCCESS) { + continue_data_vio_with_error(next_lock_holder, result); + return; + } + + VDO_ASSERT_LOG_ONLY((lock_holder == data_vio), + "logical block lock mismatch for block %llu", + (unsigned long long) lock->lbn); + lock->locked = false; + + /* + * If there are still waiters, other data_vios must be trying to get the lock we just + * transferred. We must ensure that the new lock holder doesn't block in the packer. + */ + if (vdo_waitq_has_waiters(&next_lock_holder->logical.waiters)) + cancel_data_vio_compression(next_lock_holder); + + /* + * Avoid stack overflow on lock transfer. + * FIXME: this is only an issue in the 1 thread config. + */ + next_lock_holder->vio.completion.requeue = true; + launch_locked_request(next_lock_holder); +} + +/** + * release_logical_lock() - Release the logical block lock and flush generation lock at the end of + * processing a data_vio. + */ +static void release_logical_lock(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + struct lbn_lock *lock = &data_vio->logical; + + assert_data_vio_in_logical_zone(data_vio); + + if (vdo_waitq_has_waiters(&lock->waiters)) + transfer_lock(data_vio, lock); + else + release_lock(data_vio, lock); + + vdo_release_flush_generation_lock(data_vio); + perform_cleanup_stage(data_vio, VIO_CLEANUP_DONE); +} + +/** clean_hash_lock() - Release the hash lock at the end of processing a data_vio. */ +static void clean_hash_lock(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + + assert_data_vio_in_hash_zone(data_vio); + if (completion->result != VDO_SUCCESS) { + vdo_clean_failed_hash_lock(data_vio); + return; + } + + vdo_release_hash_lock(data_vio); + perform_cleanup_stage(data_vio, VIO_RELEASE_LOGICAL); +} + +/** + * finish_cleanup() - Make some assertions about a data_vio which has finished cleaning up. + * + * If it is part of a multi-block discard, starts on the next block, otherwise, returns it to the + * pool. + */ +static void finish_cleanup(struct data_vio *data_vio) +{ + struct vdo_completion *completion = &data_vio->vio.completion; + + VDO_ASSERT_LOG_ONLY(data_vio->allocation.lock == NULL, + "complete data_vio has no allocation lock"); + VDO_ASSERT_LOG_ONLY(data_vio->hash_lock == NULL, + "complete data_vio has no hash lock"); + if ((data_vio->remaining_discard <= VDO_BLOCK_SIZE) || + (completion->result != VDO_SUCCESS)) { + struct data_vio_pool *pool = completion->vdo->data_vio_pool; + + vdo_funnel_queue_put(pool->queue, &completion->work_queue_entry_link); + schedule_releases(pool); + return; + } + + data_vio->remaining_discard -= min_t(u32, data_vio->remaining_discard, + VDO_BLOCK_SIZE - data_vio->offset); + data_vio->is_partial = (data_vio->remaining_discard < VDO_BLOCK_SIZE); + data_vio->read = data_vio->is_partial; + data_vio->offset = 0; + completion->requeue = true; + launch_data_vio(data_vio, data_vio->logical.lbn + 1); +} + +/** perform_cleanup_stage() - Perform the next step in the process of cleaning up a data_vio. */ +static void perform_cleanup_stage(struct data_vio *data_vio, + enum data_vio_cleanup_stage stage) +{ + struct vdo *vdo = vdo_from_data_vio(data_vio); + + switch (stage) { + case VIO_RELEASE_HASH_LOCK: + if (data_vio->hash_lock != NULL) { + launch_data_vio_hash_zone_callback(data_vio, clean_hash_lock); + return; + } + fallthrough; + + case VIO_RELEASE_ALLOCATED: + if (data_vio_has_allocation(data_vio)) { + launch_data_vio_allocated_zone_callback(data_vio, + release_allocated_lock); + return; + } + fallthrough; + + case VIO_RELEASE_RECOVERY_LOCKS: + if ((data_vio->recovery_sequence_number > 0) && + (READ_ONCE(vdo->read_only_notifier.read_only_error) == VDO_SUCCESS) && + (data_vio->vio.completion.result != VDO_READ_ONLY)) + vdo_log_warning("VDO not read-only when cleaning data_vio with RJ lock"); + fallthrough; + + case VIO_RELEASE_LOGICAL: + launch_data_vio_logical_callback(data_vio, release_logical_lock); + return; + + default: + finish_cleanup(data_vio); + } +} + +void complete_data_vio(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + + completion->error_handler = NULL; + data_vio->last_async_operation = VIO_ASYNC_OP_CLEANUP; + perform_cleanup_stage(data_vio, + (data_vio->write ? VIO_CLEANUP_START : VIO_RELEASE_LOGICAL)); +} + +static void enter_read_only_mode(struct vdo_completion *completion) +{ + if (vdo_is_read_only(completion->vdo)) + return; + + if (completion->result != VDO_READ_ONLY) { + struct data_vio *data_vio = as_data_vio(completion); + + vdo_log_error_strerror(completion->result, + "Preparing to enter read-only mode: data_vio for LBN %llu (becoming mapped to %llu, previously mapped to %llu, allocated %llu) is completing with a fatal error after operation %s", + (unsigned long long) data_vio->logical.lbn, + (unsigned long long) data_vio->new_mapped.pbn, + (unsigned long long) data_vio->mapped.pbn, + (unsigned long long) data_vio->allocation.pbn, + get_data_vio_operation_name(data_vio)); + } + + vdo_enter_read_only_mode(completion->vdo, completion->result); +} + +void handle_data_vio_error(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + + if ((completion->result == VDO_READ_ONLY) || (data_vio->user_bio == NULL)) + enter_read_only_mode(completion); + + update_data_vio_error_stats(data_vio); + complete_data_vio(completion); +} + +/** + * get_data_vio_operation_name() - Get the name of the last asynchronous operation performed on a + * data_vio. + */ +const char *get_data_vio_operation_name(struct data_vio *data_vio) +{ + BUILD_BUG_ON((MAX_VIO_ASYNC_OPERATION_NUMBER - MIN_VIO_ASYNC_OPERATION_NUMBER) != + ARRAY_SIZE(ASYNC_OPERATION_NAMES)); + + return ((data_vio->last_async_operation < MAX_VIO_ASYNC_OPERATION_NUMBER) ? + ASYNC_OPERATION_NAMES[data_vio->last_async_operation] : + "unknown async operation"); +} + +/** + * data_vio_allocate_data_block() - Allocate a data block. + * + * @write_lock_type: The type of write lock to obtain on the block. + * @callback: The callback which will attempt an allocation in the current zone and continue if it + * succeeds. + * @error_handler: The handler for errors while allocating. + */ +void data_vio_allocate_data_block(struct data_vio *data_vio, + enum pbn_lock_type write_lock_type, + vdo_action_fn callback, vdo_action_fn error_handler) +{ + struct allocation *allocation = &data_vio->allocation; + + VDO_ASSERT_LOG_ONLY((allocation->pbn == VDO_ZERO_BLOCK), + "data_vio does not have an allocation"); + allocation->write_lock_type = write_lock_type; + allocation->zone = vdo_get_next_allocation_zone(data_vio->logical.zone); + allocation->first_allocation_zone = allocation->zone->zone_number; + + data_vio->vio.completion.error_handler = error_handler; + launch_data_vio_allocated_zone_callback(data_vio, callback); +} + +/** + * release_data_vio_allocation_lock() - Release the PBN lock on a data_vio's allocated block. + * @reset: If true, the allocation will be reset (i.e. any allocated pbn will be forgotten). + * + * If the reference to the locked block is still provisional, it will be released as well. + */ +void release_data_vio_allocation_lock(struct data_vio *data_vio, bool reset) +{ + struct allocation *allocation = &data_vio->allocation; + physical_block_number_t locked_pbn = allocation->pbn; + + assert_data_vio_in_allocated_zone(data_vio); + + if (reset || vdo_pbn_lock_has_provisional_reference(allocation->lock)) + allocation->pbn = VDO_ZERO_BLOCK; + + vdo_release_physical_zone_pbn_lock(allocation->zone, locked_pbn, + vdo_forget(allocation->lock)); +} + +/** + * uncompress_data_vio() - Uncompress the data a data_vio has just read. + * @mapping_state: The mapping state indicating which fragment to decompress. + * @buffer: The buffer to receive the uncompressed data. + */ +int uncompress_data_vio(struct data_vio *data_vio, + enum block_mapping_state mapping_state, char *buffer) +{ + int size; + u16 fragment_offset, fragment_size; + struct compressed_block *block = data_vio->compression.block; + int result = vdo_get_compressed_block_fragment(mapping_state, block, + &fragment_offset, &fragment_size); + + if (result != VDO_SUCCESS) { + vdo_log_debug("%s: compressed fragment error %d", __func__, result); + return result; + } + + size = LZ4_decompress_safe((block->data + fragment_offset), buffer, + fragment_size, VDO_BLOCK_SIZE); + if (size != VDO_BLOCK_SIZE) { + vdo_log_debug("%s: lz4 error", __func__); + return VDO_INVALID_FRAGMENT; + } + + return VDO_SUCCESS; +} + +/** + * modify_for_partial_write() - Do the modify-write part of a read-modify-write cycle. + * @completion: The data_vio which has just finished its read. + * + * This callback is registered in read_block(). + */ +static void modify_for_partial_write(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + char *data = data_vio->vio.data; + struct bio *bio = data_vio->user_bio; + + assert_data_vio_on_cpu_thread(data_vio); + + if (bio_op(bio) == REQ_OP_DISCARD) { + memset(data + data_vio->offset, '\0', min_t(u32, + data_vio->remaining_discard, + VDO_BLOCK_SIZE - data_vio->offset)); + } else { + copy_from_bio(bio, data + data_vio->offset); + } + + data_vio->is_zero = is_zero_block(data); + data_vio->read = false; + launch_data_vio_logical_callback(data_vio, + continue_data_vio_with_block_map_slot); +} + +static void complete_read(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + char *data = data_vio->vio.data; + bool compressed = vdo_is_state_compressed(data_vio->mapped.state); + + assert_data_vio_on_cpu_thread(data_vio); + + if (compressed) { + int result = uncompress_data_vio(data_vio, data_vio->mapped.state, data); + + if (result != VDO_SUCCESS) { + continue_data_vio_with_error(data_vio, result); + return; + } + } + + if (data_vio->write) { + modify_for_partial_write(completion); + return; + } + + if (compressed || data_vio->is_partial) + copy_to_bio(data_vio->user_bio, data + data_vio->offset); + + acknowledge_data_vio(data_vio); + complete_data_vio(completion); +} + +static void read_endio(struct bio *bio) +{ + struct data_vio *data_vio = vio_as_data_vio(bio->bi_private); + int result = blk_status_to_errno(bio->bi_status); + + vdo_count_completed_bios(bio); + if (result != VDO_SUCCESS) { + continue_data_vio_with_error(data_vio, result); + return; + } + + launch_data_vio_cpu_callback(data_vio, complete_read, + CPU_Q_COMPLETE_READ_PRIORITY); +} + +static void complete_zero_read(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + + assert_data_vio_on_cpu_thread(data_vio); + + if (data_vio->is_partial) { + memset(data_vio->vio.data, 0, VDO_BLOCK_SIZE); + if (data_vio->write) { + modify_for_partial_write(completion); + return; + } + } else { + zero_fill_bio(data_vio->user_bio); + } + + complete_read(completion); +} + +/** + * read_block() - Read a block asynchronously. + * + * This is the callback registered in read_block_mapping(). + */ +static void read_block(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + struct vio *vio = as_vio(completion); + int result = VDO_SUCCESS; + + if (data_vio->mapped.pbn == VDO_ZERO_BLOCK) { + launch_data_vio_cpu_callback(data_vio, complete_zero_read, + CPU_Q_COMPLETE_VIO_PRIORITY); + return; + } + + data_vio->last_async_operation = VIO_ASYNC_OP_READ_DATA_VIO; + if (vdo_is_state_compressed(data_vio->mapped.state)) { + result = vio_reset_bio(vio, (char *) data_vio->compression.block, + read_endio, REQ_OP_READ, data_vio->mapped.pbn); + } else { + blk_opf_t opf = ((data_vio->user_bio->bi_opf & PASSTHROUGH_FLAGS) | REQ_OP_READ); + + if (data_vio->is_partial) { + result = vio_reset_bio(vio, vio->data, read_endio, opf, + data_vio->mapped.pbn); + } else { + /* A full 4k read. Use the incoming bio to avoid having to copy the data */ + bio_reset(vio->bio, vio->bio->bi_bdev, opf); + bio_init_clone(data_vio->user_bio->bi_bdev, vio->bio, + data_vio->user_bio, GFP_KERNEL); + + /* Copy over the original bio iovec and opflags. */ + vdo_set_bio_properties(vio->bio, vio, read_endio, opf, + data_vio->mapped.pbn); + } + } + + if (result != VDO_SUCCESS) { + continue_data_vio_with_error(data_vio, result); + return; + } + + vdo_submit_data_vio(data_vio); +} + +static inline struct data_vio * +reference_count_update_completion_as_data_vio(struct vdo_completion *completion) +{ + if (completion->type == VIO_COMPLETION) + return as_data_vio(completion); + + return container_of(completion, struct data_vio, decrement_completion); +} + +/** + * update_block_map() - Rendezvous of the data_vio and decrement completions after each has + * made its reference updates. Handle any error from either, or proceed + * to updating the block map. + * @completion: The completion of the write in progress. + */ +static void update_block_map(struct vdo_completion *completion) +{ + struct data_vio *data_vio = reference_count_update_completion_as_data_vio(completion); + + assert_data_vio_in_logical_zone(data_vio); + + if (!data_vio->first_reference_operation_complete) { + /* Rendezvous, we're first */ + data_vio->first_reference_operation_complete = true; + return; + } + + completion = &data_vio->vio.completion; + vdo_set_completion_result(completion, data_vio->decrement_completion.result); + if (completion->result != VDO_SUCCESS) { + handle_data_vio_error(completion); + return; + } + + completion->error_handler = handle_data_vio_error; + if (data_vio->hash_lock != NULL) + set_data_vio_hash_zone_callback(data_vio, vdo_continue_hash_lock); + else + completion->callback = complete_data_vio; + + data_vio->last_async_operation = VIO_ASYNC_OP_PUT_MAPPED_BLOCK; + vdo_put_mapped_block(data_vio); +} + +static void decrement_reference_count(struct vdo_completion *completion) +{ + struct data_vio *data_vio = container_of(completion, struct data_vio, + decrement_completion); + + assert_data_vio_in_mapped_zone(data_vio); + + vdo_set_completion_callback(completion, update_block_map, + data_vio->logical.zone->thread_id); + completion->error_handler = update_block_map; + vdo_modify_reference_count(completion, &data_vio->decrement_updater); +} + +static void increment_reference_count(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + + assert_data_vio_in_new_mapped_zone(data_vio); + + if (data_vio->downgrade_allocation_lock) { + /* + * Now that the data has been written, it's safe to deduplicate against the + * block. Downgrade the allocation lock to a read lock so it can be used later by + * the hash lock. This is done here since it needs to happen sometime before we + * return to the hash zone, and we are currently on the correct thread. For + * compressed blocks, the downgrade will have already been done. + */ + vdo_downgrade_pbn_write_lock(data_vio->allocation.lock, false); + } + + set_data_vio_logical_callback(data_vio, update_block_map); + completion->error_handler = update_block_map; + vdo_modify_reference_count(completion, &data_vio->increment_updater); +} + +/** journal_remapping() - Add a recovery journal entry for a data remapping. */ +static void journal_remapping(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + + assert_data_vio_in_journal_zone(data_vio); + + data_vio->decrement_updater.operation = VDO_JOURNAL_DATA_REMAPPING; + data_vio->decrement_updater.zpbn = data_vio->mapped; + if (data_vio->new_mapped.pbn == VDO_ZERO_BLOCK) { + data_vio->first_reference_operation_complete = true; + if (data_vio->mapped.pbn == VDO_ZERO_BLOCK) + set_data_vio_logical_callback(data_vio, update_block_map); + } else { + set_data_vio_new_mapped_zone_callback(data_vio, + increment_reference_count); + } + + if (data_vio->mapped.pbn == VDO_ZERO_BLOCK) { + data_vio->first_reference_operation_complete = true; + } else { + vdo_set_completion_callback(&data_vio->decrement_completion, + decrement_reference_count, + data_vio->mapped.zone->thread_id); + } + + data_vio->last_async_operation = VIO_ASYNC_OP_JOURNAL_REMAPPING; + vdo_add_recovery_journal_entry(completion->vdo->recovery_journal, data_vio); +} + +/** + * read_old_block_mapping() - Get the previous PBN/LBN mapping of an in-progress write. + * + * Gets the previous PBN mapped to this LBN from the block map, so as to make an appropriate + * journal entry referencing the removal of this LBN->PBN mapping. + */ +static void read_old_block_mapping(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + + assert_data_vio_in_logical_zone(data_vio); + + data_vio->last_async_operation = VIO_ASYNC_OP_GET_MAPPED_BLOCK_FOR_WRITE; + set_data_vio_journal_callback(data_vio, journal_remapping); + vdo_get_mapped_block(data_vio); +} + +void update_metadata_for_data_vio_write(struct data_vio *data_vio, struct pbn_lock *lock) +{ + data_vio->increment_updater = (struct reference_updater) { + .operation = VDO_JOURNAL_DATA_REMAPPING, + .increment = true, + .zpbn = data_vio->new_mapped, + .lock = lock, + }; + + launch_data_vio_logical_callback(data_vio, read_old_block_mapping); +} + +/** + * pack_compressed_data() - Attempt to pack the compressed data_vio into a block. + * + * This is the callback registered in launch_compress_data_vio(). + */ +static void pack_compressed_data(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + + assert_data_vio_in_packer_zone(data_vio); + + if (!vdo_get_compressing(vdo_from_data_vio(data_vio)) || + get_data_vio_compression_status(data_vio).may_not_compress) { + write_data_vio(data_vio); + return; + } + + data_vio->last_async_operation = VIO_ASYNC_OP_ATTEMPT_PACKING; + vdo_attempt_packing(data_vio); +} + +/** + * compress_data_vio() - Do the actual work of compressing the data on a CPU queue. + * + * This callback is registered in launch_compress_data_vio(). + */ +static void compress_data_vio(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + int size; + + assert_data_vio_on_cpu_thread(data_vio); + + /* + * By putting the compressed data at the start of the compressed block data field, we won't + * need to copy it if this data_vio becomes a compressed write agent. + */ + size = LZ4_compress_default(data_vio->vio.data, + data_vio->compression.block->data, VDO_BLOCK_SIZE, + VDO_MAX_COMPRESSED_FRAGMENT_SIZE, + (char *) vdo_get_work_queue_private_data()); + if ((size > 0) && (size < VDO_COMPRESSED_BLOCK_DATA_SIZE)) { + data_vio->compression.size = size; + launch_data_vio_packer_callback(data_vio, pack_compressed_data); + return; + } + + write_data_vio(data_vio); +} + +/** + * launch_compress_data_vio() - Continue a write by attempting to compress the data. + * + * This is a re-entry point to vio_write used by hash locks. + */ +void launch_compress_data_vio(struct data_vio *data_vio) +{ + VDO_ASSERT_LOG_ONLY(!data_vio->is_duplicate, "compressing a non-duplicate block"); + VDO_ASSERT_LOG_ONLY(data_vio->hash_lock != NULL, + "data_vio to compress has a hash_lock"); + VDO_ASSERT_LOG_ONLY(data_vio_has_allocation(data_vio), + "data_vio to compress has an allocation"); + + /* + * There are 4 reasons why a data_vio which has reached this point will not be eligible for + * compression: + * + * 1) Since data_vios can block indefinitely in the packer, it would be bad to do so if the + * write request also requests FUA. + * + * 2) A data_vio should not be compressed when compression is disabled for the vdo. + * + * 3) A data_vio could be doing a partial write on behalf of a larger discard which has not + * yet been acknowledged and hence blocking in the packer would be bad. + * + * 4) Some other data_vio may be waiting on this data_vio in which case blocking in the + * packer would also be bad. + */ + if (data_vio->fua || + !vdo_get_compressing(vdo_from_data_vio(data_vio)) || + ((data_vio->user_bio != NULL) && (bio_op(data_vio->user_bio) == REQ_OP_DISCARD)) || + (advance_data_vio_compression_stage(data_vio).stage != DATA_VIO_COMPRESSING)) { + write_data_vio(data_vio); + return; + } + + data_vio->last_async_operation = VIO_ASYNC_OP_COMPRESS_DATA_VIO; + launch_data_vio_cpu_callback(data_vio, compress_data_vio, + CPU_Q_COMPRESS_BLOCK_PRIORITY); +} + +/** + * hash_data_vio() - Hash the data in a data_vio and set the hash zone (which also flags the record + * name as set). + + * This callback is registered in prepare_for_dedupe(). + */ +static void hash_data_vio(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + + assert_data_vio_on_cpu_thread(data_vio); + VDO_ASSERT_LOG_ONLY(!data_vio->is_zero, "zero blocks should not be hashed"); + + murmurhash3_128(data_vio->vio.data, VDO_BLOCK_SIZE, 0x62ea60be, + &data_vio->record_name); + + data_vio->hash_zone = vdo_select_hash_zone(vdo_from_data_vio(data_vio)->hash_zones, + &data_vio->record_name); + data_vio->last_async_operation = VIO_ASYNC_OP_ACQUIRE_VDO_HASH_LOCK; + launch_data_vio_hash_zone_callback(data_vio, vdo_acquire_hash_lock); +} + +/** prepare_for_dedupe() - Prepare for the dedupe path after attempting to get an allocation. */ +static void prepare_for_dedupe(struct data_vio *data_vio) +{ + /* We don't care what thread we are on. */ + VDO_ASSERT_LOG_ONLY(!data_vio->is_zero, "must not prepare to dedupe zero blocks"); + + /* + * Before we can dedupe, we need to know the record name, so the first + * step is to hash the block data. + */ + data_vio->last_async_operation = VIO_ASYNC_OP_HASH_DATA_VIO; + launch_data_vio_cpu_callback(data_vio, hash_data_vio, CPU_Q_HASH_BLOCK_PRIORITY); +} + +/** + * write_bio_finished() - This is the bio_end_io function registered in write_block() to be called + * when a data_vio's write to the underlying storage has completed. + */ +static void write_bio_finished(struct bio *bio) +{ + struct data_vio *data_vio = vio_as_data_vio((struct vio *) bio->bi_private); + + vdo_count_completed_bios(bio); + vdo_set_completion_result(&data_vio->vio.completion, + blk_status_to_errno(bio->bi_status)); + data_vio->downgrade_allocation_lock = true; + update_metadata_for_data_vio_write(data_vio, data_vio->allocation.lock); +} + +/** write_data_vio() - Write a data block to storage without compression. */ +void write_data_vio(struct data_vio *data_vio) +{ + struct data_vio_compression_status status, new_status; + int result; + + if (!data_vio_has_allocation(data_vio)) { + /* + * There was no space to write this block and we failed to deduplicate or compress + * it. + */ + continue_data_vio_with_error(data_vio, VDO_NO_SPACE); + return; + } + + new_status = (struct data_vio_compression_status) { + .stage = DATA_VIO_POST_PACKER, + .may_not_compress = true, + }; + + do { + status = get_data_vio_compression_status(data_vio); + } while ((status.stage != DATA_VIO_POST_PACKER) && + !set_data_vio_compression_status(data_vio, status, new_status)); + + /* Write the data from the data block buffer. */ + result = vio_reset_bio(&data_vio->vio, data_vio->vio.data, + write_bio_finished, REQ_OP_WRITE, + data_vio->allocation.pbn); + if (result != VDO_SUCCESS) { + continue_data_vio_with_error(data_vio, result); + return; + } + + data_vio->last_async_operation = VIO_ASYNC_OP_WRITE_DATA_VIO; + vdo_submit_data_vio(data_vio); +} + +/** + * acknowledge_write_callback() - Acknowledge a write to the requestor. + * + * This callback is registered in allocate_block() and continue_write_with_block_map_slot(). + */ +static void acknowledge_write_callback(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + struct vdo *vdo = completion->vdo; + + VDO_ASSERT_LOG_ONLY((!vdo_uses_bio_ack_queue(vdo) || + (vdo_get_callback_thread_id() == vdo->thread_config.bio_ack_thread)), + "%s() called on bio ack queue", __func__); + VDO_ASSERT_LOG_ONLY(data_vio_has_flush_generation_lock(data_vio), + "write VIO to be acknowledged has a flush generation lock"); + acknowledge_data_vio(data_vio); + if (data_vio->new_mapped.pbn == VDO_ZERO_BLOCK) { + /* This is a zero write or discard */ + update_metadata_for_data_vio_write(data_vio, NULL); + return; + } + + prepare_for_dedupe(data_vio); +} + +/** + * allocate_block() - Attempt to allocate a block in the current allocation zone. + * + * This callback is registered in continue_write_with_block_map_slot(). + */ +static void allocate_block(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + + assert_data_vio_in_allocated_zone(data_vio); + + if (!vdo_allocate_block_in_zone(data_vio)) + return; + + completion->error_handler = handle_data_vio_error; + WRITE_ONCE(data_vio->allocation_succeeded, true); + data_vio->new_mapped = (struct zoned_pbn) { + .zone = data_vio->allocation.zone, + .pbn = data_vio->allocation.pbn, + .state = VDO_MAPPING_STATE_UNCOMPRESSED, + }; + + if (data_vio->fua) { + prepare_for_dedupe(data_vio); + return; + } + + data_vio->last_async_operation = VIO_ASYNC_OP_ACKNOWLEDGE_WRITE; + launch_data_vio_on_bio_ack_queue(data_vio, acknowledge_write_callback); +} + +/** + * handle_allocation_error() - Handle an error attempting to allocate a block. + * + * This error handler is registered in continue_write_with_block_map_slot(). + */ +static void handle_allocation_error(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + + if (completion->result == VDO_NO_SPACE) { + /* We failed to get an allocation, but we can try to dedupe. */ + vdo_reset_completion(completion); + completion->error_handler = handle_data_vio_error; + prepare_for_dedupe(data_vio); + return; + } + + /* We got a "real" error, not just a failure to allocate, so fail the request. */ + handle_data_vio_error(completion); +} + +static int assert_is_discard(struct data_vio *data_vio) +{ + int result = VDO_ASSERT(data_vio->is_discard, + "data_vio with no block map page is a discard"); + + return ((result == VDO_SUCCESS) ? result : VDO_READ_ONLY); +} + +/** + * continue_data_vio_with_block_map_slot() - Read the data_vio's mapping from the block map. + * + * This callback is registered in launch_read_data_vio(). + */ +void continue_data_vio_with_block_map_slot(struct vdo_completion *completion) +{ + struct data_vio *data_vio = as_data_vio(completion); + + assert_data_vio_in_logical_zone(data_vio); + if (data_vio->read) { + set_data_vio_logical_callback(data_vio, read_block); + data_vio->last_async_operation = VIO_ASYNC_OP_GET_MAPPED_BLOCK_FOR_READ; + vdo_get_mapped_block(data_vio); + return; + } + + vdo_acquire_flush_generation_lock(data_vio); + + if (data_vio->tree_lock.tree_slots[0].block_map_slot.pbn == VDO_ZERO_BLOCK) { + /* + * This is a discard for a block on a block map page which has not been allocated, so + * there's nothing more we need to do. + */ + completion->callback = complete_data_vio; + continue_data_vio_with_error(data_vio, assert_is_discard(data_vio)); + return; + } + + /* + * We need an allocation if this is neither a full-block discard nor a + * full-block zero write. + */ + if (!data_vio->is_zero && (!data_vio->is_discard || data_vio->is_partial)) { + data_vio_allocate_data_block(data_vio, VIO_WRITE_LOCK, allocate_block, + handle_allocation_error); + return; + } + + + /* + * We don't need to write any data, so skip allocation and just update the block map and + * reference counts (via the journal). + */ + data_vio->new_mapped.pbn = VDO_ZERO_BLOCK; + if (data_vio->is_zero) + data_vio->new_mapped.state = VDO_MAPPING_STATE_UNCOMPRESSED; + + if (data_vio->remaining_discard > VDO_BLOCK_SIZE) { + /* This is not the final block of a discard so we can't acknowledge it yet. */ + update_metadata_for_data_vio_write(data_vio, NULL); + return; + } + + data_vio->last_async_operation = VIO_ASYNC_OP_ACKNOWLEDGE_WRITE; + launch_data_vio_on_bio_ack_queue(data_vio, acknowledge_write_callback); +} |