linux-stable/drivers/lightnvm/pblk-rl.c
Hans Holmberg 48b8d20895 lightnvm: pblk: garbage collect lines with failed writes
Write failures should not happen under normal circumstances,
so in order to bring the chunk back into a known state as soon
as possible, evacuate all the valid data out of the line and let the
fw judge if the block can be written to in the next reset cycle.

Do this by introducing a new gc list for lines with failed writes,
and ensure that the rate limiter allocates a small portion of
the write bandwidth to get the job done.

The lba list is saved in memory for use during gc as we
cannot gurantee that the emeta data is readable if a write
error occurred.

Signed-off-by: Hans Holmberg <hans.holmberg@cnexlabs.com>
Reviewed-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-06-01 09:02:53 -06:00

250 lines
6.1 KiB
C

/*
* Copyright (C) 2016 CNEX Labs
* Initial release: Javier Gonzalez <javier@cnexlabs.com>
* Matias Bjorling <matias@cnexlabs.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* pblk-rl.c - pblk's rate limiter for user I/O
*
*/
#include "pblk.h"
static void pblk_rl_kick_u_timer(struct pblk_rl *rl)
{
mod_timer(&rl->u_timer, jiffies + msecs_to_jiffies(5000));
}
int pblk_rl_is_limit(struct pblk_rl *rl)
{
int rb_space;
rb_space = atomic_read(&rl->rb_space);
return (rb_space == 0);
}
int pblk_rl_user_may_insert(struct pblk_rl *rl, int nr_entries)
{
int rb_user_cnt = atomic_read(&rl->rb_user_cnt);
int rb_space = atomic_read(&rl->rb_space);
if (unlikely(rb_space >= 0) && (rb_space - nr_entries < 0))
return NVM_IO_ERR;
if (rb_user_cnt >= rl->rb_user_max)
return NVM_IO_REQUEUE;
return NVM_IO_OK;
}
void pblk_rl_inserted(struct pblk_rl *rl, int nr_entries)
{
int rb_space = atomic_read(&rl->rb_space);
if (unlikely(rb_space >= 0))
atomic_sub(nr_entries, &rl->rb_space);
}
int pblk_rl_gc_may_insert(struct pblk_rl *rl, int nr_entries)
{
int rb_gc_cnt = atomic_read(&rl->rb_gc_cnt);
int rb_user_active;
/* If there is no user I/O let GC take over space on the write buffer */
rb_user_active = READ_ONCE(rl->rb_user_active);
return (!(rb_gc_cnt >= rl->rb_gc_max && rb_user_active));
}
void pblk_rl_user_in(struct pblk_rl *rl, int nr_entries)
{
atomic_add(nr_entries, &rl->rb_user_cnt);
/* Release user I/O state. Protect from GC */
smp_store_release(&rl->rb_user_active, 1);
pblk_rl_kick_u_timer(rl);
}
void pblk_rl_werr_line_in(struct pblk_rl *rl)
{
atomic_inc(&rl->werr_lines);
}
void pblk_rl_werr_line_out(struct pblk_rl *rl)
{
atomic_dec(&rl->werr_lines);
}
void pblk_rl_gc_in(struct pblk_rl *rl, int nr_entries)
{
atomic_add(nr_entries, &rl->rb_gc_cnt);
}
void pblk_rl_out(struct pblk_rl *rl, int nr_user, int nr_gc)
{
atomic_sub(nr_user, &rl->rb_user_cnt);
atomic_sub(nr_gc, &rl->rb_gc_cnt);
}
unsigned long pblk_rl_nr_free_blks(struct pblk_rl *rl)
{
return atomic_read(&rl->free_blocks);
}
unsigned long pblk_rl_nr_user_free_blks(struct pblk_rl *rl)
{
return atomic_read(&rl->free_user_blocks);
}
static void __pblk_rl_update_rates(struct pblk_rl *rl,
unsigned long free_blocks)
{
struct pblk *pblk = container_of(rl, struct pblk, rl);
int max = rl->rb_budget;
int werr_gc_needed = atomic_read(&rl->werr_lines);
if (free_blocks >= rl->high) {
if (werr_gc_needed) {
/* Allocate a small budget for recovering
* lines with write errors
*/
rl->rb_gc_max = 1 << rl->rb_windows_pw;
rl->rb_user_max = max - rl->rb_gc_max;
rl->rb_state = PBLK_RL_WERR;
} else {
rl->rb_user_max = max;
rl->rb_gc_max = 0;
rl->rb_state = PBLK_RL_OFF;
}
} else if (free_blocks < rl->high) {
int shift = rl->high_pw - rl->rb_windows_pw;
int user_windows = free_blocks >> shift;
int user_max = user_windows << PBLK_MAX_REQ_ADDRS_PW;
rl->rb_user_max = user_max;
rl->rb_gc_max = max - user_max;
if (free_blocks <= rl->rsv_blocks) {
rl->rb_user_max = 0;
rl->rb_gc_max = max;
}
/* In the worst case, we will need to GC lines in the low list
* (high valid sector count). If there are lines to GC on high
* or mid lists, these will be prioritized
*/
rl->rb_state = PBLK_RL_LOW;
}
if (rl->rb_state != PBLK_RL_OFF)
pblk_gc_should_start(pblk);
else
pblk_gc_should_stop(pblk);
}
void pblk_rl_update_rates(struct pblk_rl *rl)
{
__pblk_rl_update_rates(rl, pblk_rl_nr_user_free_blks(rl));
}
void pblk_rl_free_lines_inc(struct pblk_rl *rl, struct pblk_line *line)
{
int blk_in_line = atomic_read(&line->blk_in_line);
int free_blocks;
atomic_add(blk_in_line, &rl->free_blocks);
free_blocks = atomic_add_return(blk_in_line, &rl->free_user_blocks);
__pblk_rl_update_rates(rl, free_blocks);
}
void pblk_rl_free_lines_dec(struct pblk_rl *rl, struct pblk_line *line,
bool used)
{
int blk_in_line = atomic_read(&line->blk_in_line);
int free_blocks;
atomic_sub(blk_in_line, &rl->free_blocks);
if (used)
free_blocks = atomic_sub_return(blk_in_line,
&rl->free_user_blocks);
else
free_blocks = atomic_read(&rl->free_user_blocks);
__pblk_rl_update_rates(rl, free_blocks);
}
int pblk_rl_high_thrs(struct pblk_rl *rl)
{
return rl->high;
}
int pblk_rl_max_io(struct pblk_rl *rl)
{
return rl->rb_max_io;
}
static void pblk_rl_u_timer(struct timer_list *t)
{
struct pblk_rl *rl = from_timer(rl, t, u_timer);
/* Release user I/O state. Protect from GC */
smp_store_release(&rl->rb_user_active, 0);
}
void pblk_rl_free(struct pblk_rl *rl)
{
del_timer(&rl->u_timer);
}
void pblk_rl_init(struct pblk_rl *rl, int budget)
{
struct pblk *pblk = container_of(rl, struct pblk, rl);
struct nvm_tgt_dev *dev = pblk->dev;
struct nvm_geo *geo = &dev->geo;
struct pblk_line_mgmt *l_mg = &pblk->l_mg;
struct pblk_line_meta *lm = &pblk->lm;
int min_blocks = lm->blk_per_line * PBLK_GC_RSV_LINE;
int sec_meta, blk_meta;
unsigned int rb_windows;
/* Consider sectors used for metadata */
sec_meta = (lm->smeta_sec + lm->emeta_sec[0]) * l_mg->nr_free_lines;
blk_meta = DIV_ROUND_UP(sec_meta, geo->clba);
rl->high = pblk->op_blks - blk_meta - lm->blk_per_line;
rl->high_pw = get_count_order(rl->high);
rl->rsv_blocks = min_blocks;
/* This will always be a power-of-2 */
rb_windows = budget / PBLK_MAX_REQ_ADDRS;
rl->rb_windows_pw = get_count_order(rb_windows);
/* To start with, all buffer is available to user I/O writers */
rl->rb_budget = budget;
rl->rb_user_max = budget;
rl->rb_max_io = budget >> 1;
rl->rb_gc_max = 0;
rl->rb_state = PBLK_RL_HIGH;
atomic_set(&rl->rb_user_cnt, 0);
atomic_set(&rl->rb_gc_cnt, 0);
atomic_set(&rl->rb_space, -1);
atomic_set(&rl->werr_lines, 0);
timer_setup(&rl->u_timer, pblk_rl_u_timer, 0);
rl->rb_user_active = 0;
rl->rb_gc_active = 0;
}