// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright 2023 Red Hat
*/
#include "io-submitter.h"
#include <linux/bio.h>
#include <linux/kernel.h>
#include <linux/mutex.h>
#include "memory-alloc.h"
#include "permassert.h"
#include "data-vio.h"
#include "logger.h"
#include "types.h"
#include "vdo.h"
#include "vio.h"
/*
* Submission of bio operations to the underlying storage device will go through a separate work
* queue thread (or more than one) to prevent blocking in other threads if the storage device has a
* full queue. The plug structure allows that thread to do better batching of requests to make the
* I/O more efficient.
*
* When multiple worker threads are used, a thread is chosen for a I/O operation submission based
* on the PBN, so a given PBN will consistently wind up on the same thread. Flush operations are
* assigned round-robin.
*
* The map (protected by the mutex) collects pending I/O operations so that the worker thread can
* reorder them to try to encourage I/O request merging in the request queue underneath.
*/
struct bio_queue_data {
struct vdo_work_queue *queue;
struct blk_plug plug;
struct int_map *map;
struct mutex lock;
unsigned int queue_number;
};
struct io_submitter {
unsigned int num_bio_queues_used;
unsigned int bio_queue_rotation_interval;
struct bio_queue_data bio_queue_data[];
};
static void start_bio_queue(void *ptr)
{
struct bio_queue_data *bio_queue_data = ptr;
blk_start_plug(&bio_queue_data->plug);
}
static void finish_bio_queue(void *ptr)
{
struct bio_queue_data *bio_queue_data = ptr;
blk_finish_plug(&bio_queue_data->plug);
}
static const struct vdo_work_queue_type bio_queue_type = {
.start = start_bio_queue,
.finish = finish_bio_queue,
.max_priority = BIO_Q_MAX_PRIORITY,
.default_priority = BIO_Q_DATA_PRIORITY,
};
/**
* count_all_bios() - Determine which bio counter to use.
* @vio: The vio associated with the bio.
* @bio: The bio to count.
*/
static void count_all_bios(struct vio *vio, struct bio *bio)
{
struct atomic_statistics *stats = &vio->completion.vdo->stats;
if (is_data_vio(vio)) {
vdo_count_bios(&stats->bios_out, bio);
return;
}
vdo_count_bios(&stats->bios_meta, bio);
if (vio->type == VIO_TYPE_RECOVERY_JOURNAL)
vdo_count_bios(&stats->bios_journal, bio);
else if (vio->type == VIO_TYPE_BLOCK_MAP)
vdo_count_bios(&stats->bios_page_cache, bio);
}
/**
* assert_in_bio_zone() - Assert that a vio is in the correct bio zone and not in interrupt
* context.
* @vio: The vio to check.
*/
static void assert_in_bio_zone(struct vio *vio)
{
VDO_ASSERT_LOG_ONLY(!in_interrupt(), "not in interrupt context");
assert_vio_in_bio_zone(vio);
}
/**
* send_bio_to_device() - Update stats and tracing info, then submit the supplied bio to the OS for
* processing.
* @vio: The vio associated with the bio.
* @bio: The bio to submit to the OS.
*/
static void send_bio_to_device(struct vio *vio, struct bio *bio)
{
struct vdo *vdo = vio->completion.vdo;
assert_in_bio_zone(vio);
atomic64_inc(&vdo->stats.bios_submitted);
count_all_bios(vio, bio);
bio_set_dev(bio, vdo_get_backing_device(vdo));
submit_bio_noacct(bio);
}
/**
* vdo_submit_vio() - Submits a vio's bio to the underlying block device. May block if the device
* is busy. This callback should be used by vios which did not attempt to merge.
*/
void vdo_submit_vio(struct vdo_completion *completion)
{
struct vio *vio = as_vio(completion);
send_bio_to_device(vio, vio->bio);
}
/**
* get_bio_list() - Extract the list of bios to submit from a vio.
* @vio: The vio submitting I/O.
*
* The list will always contain at least one entry (the bio for the vio on which it is called), but
* other bios may have been merged with it as well.
*
* Return: bio The head of the bio list to submit.
*/
static struct bio *get_bio_list(struct vio *vio)
{
struct bio *bio;
struct io_submitter *submitter = vio->completion.vdo->io_submitter;
struct bio_queue_data *bio_queue_data = &(submitter->bio_queue_data[vio->bio_zone]);
assert_in_bio_zone(vio);
mutex_lock(&bio_queue_data->lock);
vdo_int_map_remove(bio_queue_data->map,
vio->bios_merged.head->bi_iter.bi_sector);
vdo_int_map_remove(bio_queue_data->map,
vio->bios_merged.tail->bi_iter.bi_sector);
bio = vio->bios_merged.head;
bio_list_init(&vio->bios_merged);
mutex_unlock(&bio_queue_data->lock);
return bio;
}
/**
* submit_data_vio() - Submit a data_vio's bio to the storage below along with
* any bios that have been merged with it.
*
* Context: This call may block and so should only be called from a bio thread.
*/
static void submit_data_vio(struct vdo_completion *completion)
{
struct bio *bio, *next;
struct vio *vio = as_vio(completion);
assert_in_bio_zone(vio);
for (bio = get_bio_list(vio); bio != NULL; bio = next) {
next = bio->bi_next;
bio->bi_next = NULL;
send_bio_to_device((struct vio *) bio->bi_private, bio);
}
}
/**
* get_mergeable_locked() - Attempt to find an already queued bio that the current bio can be
* merged with.
* @map: The bio map to use for merging.
* @vio: The vio we want to merge.
* @back_merge: Set to true for a back merge, false for a front merge.
*
* There are two types of merging possible, forward and backward, which are distinguished by a flag
* that uses kernel elevator terminology.
*
* Return: the vio to merge to, NULL if no merging is possible.
*/
static struct vio *get_mergeable_locked(struct int_map *map, struct vio *vio,
bool back_merge)
{
struct bio *bio = vio->bio;
sector_t merge_sector = bio->bi_iter.bi_sector;
struct vio *vio_merge;
if (back_merge)
merge_sector -= VDO_SECTORS_PER_BLOCK;
else
merge_sector += VDO_SECTORS_PER_BLOCK;
vio_merge = vdo_int_map_get(map, merge_sector);
if (vio_merge == NULL)
return NULL;
if (vio->completion.priority != vio_merge->completion.priority)
return NULL;
if (bio_data_dir(bio) != bio_data_dir(vio_merge->bio))
return NULL;
if (bio_list_empty(&vio_merge->bios_merged))
return NULL;
if (back_merge) {
return (vio_merge->bios_merged.tail->bi_iter.bi_sector == merge_sector ?
vio_merge : NULL);
}
return (vio_merge->bios_merged.head->bi_iter.bi_sector == merge_sector ?
vio_merge : NULL);
}
static int map_merged_vio(struct int_map *bio_map, struct vio *vio)
{
int result;
sector_t bio_sector;
bio_sector = vio->bios_merged.head->bi_iter.bi_sector;
result = vdo_int_map_put(bio_map, bio_sector, vio, true, NULL);
if (result != VDO_SUCCESS)
return result;
bio_sector = vio->bios_merged.tail->bi_iter.bi_sector;
return vdo_int_map_put(bio_map, bio_sector, vio, true, NULL);
}
static int merge_to_prev_tail(struct int_map *bio_map, struct vio *vio,
struct vio *prev_vio)
{
vdo_int_map_remove(bio_map, prev_vio->bios_merged.tail->bi_iter.bi_sector);
bio_list_merge(&prev_vio->bios_merged, &vio->bios_merged);
return map_merged_vio(bio_map, prev_vio);
}
static int merge_to_next_head(struct int_map *bio_map, struct vio *vio,
struct vio *next_vio)
{
/*
* Handle "next merge" and "gap fill" cases the same way so as to reorder bios in a way
* that's compatible with using funnel queues in work queues. This avoids removing an
* existing completion.
*/
vdo_int_map_remove(bio_map, next_vio->bios_merged.head->bi_iter.bi_sector);
bio_list_merge_head(&next_vio->bios_merged, &vio->bios_merged);
return map_merged_vio(bio_map, next_vio);
}
/**
* try_bio_map_merge() - Attempt to merge a vio's bio with other pending I/Os.
* @vio: The vio to merge.
*
* Currently this is only used for data_vios, but is broken out for future use with metadata vios.
*
* Return: whether or not the vio was merged.
*/
static bool try_bio_map_merge(struct vio *vio)
{
int result;
bool merged = true;
struct bio *bio = vio->bio;
struct vio *prev_vio, *next_vio;
struct vdo *vdo = vio->completion.vdo;
struct bio_queue_data *bio_queue_data =
&vdo->io_submitter->bio_queue_data[vio->bio_zone];
bio->bi_next = NULL;
bio_list_init(&vio->bios_merged);
bio_list_add(&vio->bios_merged, bio);
mutex_lock(&bio_queue_data->lock);
prev_vio = get_mergeable_locked(bio_queue_data->map, vio, true);
next_vio = get_mergeable_locked(bio_queue_data->map, vio, false);
if (prev_vio == next_vio)
next_vio = NULL;
if ((prev_vio == NULL) && (next_vio == NULL)) {
/* no merge. just add to bio_queue */
merged = false;
result = vdo_int_map_put(bio_queue_data->map,
bio->bi_iter.bi_sector,
vio, true, NULL);
} else if (next_vio == NULL) {
/* Only prev. merge to prev's tail */
result = merge_to_prev_tail(bio_queue_data->map, vio, prev_vio);
} else {
/* Only next. merge to next's head */
result = merge_to_next_head(bio_queue_data->map, vio, next_vio);
}
mutex_unlock(&bio_queue_data->lock);
/* We don't care about failure of int_map_put in this case. */
VDO_ASSERT_LOG_ONLY(result == VDO_SUCCESS, "bio map insertion succeeds");
return merged;
}
/**
* vdo_submit_data_vio() - Submit I/O for a data_vio.
* @data_vio: the data_vio for which to issue I/O.
*
* If possible, this I/O will be merged other pending I/Os. Otherwise, the data_vio will be sent to
* the appropriate bio zone directly.
*/
void vdo_submit_data_vio(struct data_vio *data_vio)
{
if (try_bio_map_merge(&data_vio->vio))
return;
launch_data_vio_bio_zone_callback(data_vio, submit_data_vio);
}
/**
* __submit_metadata_vio() - Submit I/O for a metadata vio.
* @vio: the vio for which to issue I/O
* @physical: the physical block number to read or write
* @callback: the bio endio function which will be called after the I/O completes
* @error_handler: the handler for submission or I/O errors (may be NULL)
* @operation: the type of I/O to perform
* @data: the buffer to read or write (may be NULL)
*
* The vio is enqueued on a vdo bio queue so that bio submission (which may block) does not block
* other vdo threads.
*
* That the error handler will run on the correct thread is only true so long as the thread calling
* this function, and the thread set in the endio callback are the same, as well as the fact that
* no error can occur on the bio queue. Currently this is true for all callers, but additional care
* will be needed if this ever changes.
*/
void __submit_metadata_vio(struct vio *vio, physical_block_number_t physical,
bio_end_io_t callback, vdo_action_fn error_handler,
blk_opf_t operation, char *data)
{
int result;
struct vdo_completion *completion = &vio->completion;
const struct admin_state_code *code = vdo_get_admin_state(completion->vdo);
VDO_ASSERT_LOG_ONLY(!code->quiescent, "I/O not allowed in state %s", code->name);
vdo_reset_completion(completion);
completion->error_handler = error_handler;
result = vio_reset_bio(vio, data, callback, operation | REQ_META, physical);
if (result != VDO_SUCCESS) {
continue_vio(vio, result);
return;
}
vdo_set_completion_callback(completion, vdo_submit_vio,
get_vio_bio_zone_thread_id(vio));
vdo_launch_completion_with_priority(completion, get_metadata_priority(vio));
}
/**
* vdo_make_io_submitter() - Create an io_submitter structure.
* @thread_count: Number of bio-submission threads to set up.
* @rotation_interval: Interval to use when rotating between bio-submission threads when enqueuing
* completions.
* @max_requests_active: Number of bios for merge tracking.
* @vdo: The vdo which will use this submitter.
* @io_submitter: pointer to the new data structure.
*
* Return: VDO_SUCCESS or an error.
*/
int vdo_make_io_submitter(unsigned int thread_count, unsigned int rotation_interval,
unsigned int max_requests_active, struct vdo *vdo,
struct io_submitter **io_submitter_ptr)
{
unsigned int i;
struct io_submitter *io_submitter;
int result;
result = vdo_allocate_extended(struct io_submitter, thread_count,
struct bio_queue_data, "bio submission data",
&io_submitter);
if (result != VDO_SUCCESS)
return result;
io_submitter->bio_queue_rotation_interval = rotation_interval;
/* Setup for each bio-submission work queue */
for (i = 0; i < thread_count; i++) {
struct bio_queue_data *bio_queue_data = &io_submitter->bio_queue_data[i];
mutex_init(&bio_queue_data->lock);
/*
* One I/O operation per request, but both first & last sector numbers.
*
* If requests are assigned to threads round-robin, they should be distributed
* quite evenly. But if they're assigned based on PBN, things can sometimes be very
* uneven. So for now, we'll assume that all requests *may* wind up on one thread,
* and thus all in the same map.
*/
result = vdo_int_map_create(max_requests_active * 2,
&bio_queue_data->map);
if (result != VDO_SUCCESS) {
/*
* Clean up the partially initialized bio-queue entirely and indicate that
* initialization failed.
*/
vdo_log_error("bio map initialization failed %d", result);
vdo_cleanup_io_submitter(io_submitter);
vdo_free_io_submitter(io_submitter);
return result;
}
bio_queue_data->queue_number = i;
result = vdo_make_thread(vdo, vdo->thread_config.bio_threads[i],
&bio_queue_type, 1, (void **) &bio_queue_data);
if (result != VDO_SUCCESS) {
/*
* Clean up the partially initialized bio-queue entirely and indicate that
* initialization failed.
*/
vdo_int_map_free(vdo_forget(bio_queue_data->map));
vdo_log_error("bio queue initialization failed %d", result);
vdo_cleanup_io_submitter(io_submitter);
vdo_free_io_submitter(io_submitter);
return result;
}
bio_queue_data->queue = vdo->threads[vdo->thread_config.bio_threads[i]].queue;
io_submitter->num_bio_queues_used++;
}
*io_submitter_ptr = io_submitter;
return VDO_SUCCESS;
}
/**
* vdo_cleanup_io_submitter() - Tear down the io_submitter fields as needed for a physical layer.
* @io_submitter: The I/O submitter data to tear down (may be NULL).
*/
void vdo_cleanup_io_submitter(struct io_submitter *io_submitter)
{
int i;
if (io_submitter == NULL)
return;
for (i = io_submitter->num_bio_queues_used - 1; i >= 0; i--)
vdo_finish_work_queue(io_submitter->bio_queue_data[i].queue);
}
/**
* vdo_free_io_submitter() - Free the io_submitter fields and structure as needed.
* @io_submitter: The I/O submitter data to destroy.
*
* This must be called after vdo_cleanup_io_submitter(). It is used to release resources late in
* the shutdown process to avoid or reduce the chance of race conditions.
*/
void vdo_free_io_submitter(struct io_submitter *io_submitter)
{
int i;
if (io_submitter == NULL)
return;
for (i = io_submitter->num_bio_queues_used - 1; i >= 0; i--) {
io_submitter->num_bio_queues_used--;
/* vdo_destroy() will free the work queue, so just give up our reference to it. */
vdo_forget(io_submitter->bio_queue_data[i].queue);
vdo_int_map_free(vdo_forget(io_submitter->bio_queue_data[i].map));
}
vdo_free(io_submitter);
}
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