// 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(&data_vio->decrement_completion);
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_init(&limiter->waiters, &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;
u32 discard_size = min_t(u32, data_vio->remaining_discard,
VDO_BLOCK_SIZE - data_vio->offset);
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 <= discard_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 -= discard_size;
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;
data_vio->first_reference_operation_complete = false;
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 ||
data_vio->remaining_discard > (u32) (VDO_BLOCK_SIZE - data_vio->offset)) {
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 > (u32) (VDO_BLOCK_SIZE - data_vio->offset)) {
/* 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);
}
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