![Igor Konopko](/assets/img/avatar_default.png)
This patch changes the approach to handling partial read path. In old approach merging of data from round buffer and drive was fully made by drive. This had some disadvantages - code was complex and relies on bio internals, so it was hard to maintain and was strongly dependent on bio changes. In new approach most of the handling is done mostly by block layer functions such as bio_split(), bio_chain() and generic_make request() and generally is less complex and easier to maintain. Below some more details of the new approach. When read bio arrives, it is cloned for pblk internal purposes. All the L2P mapping, which includes copying data from round buffer to bio and thus bio_advance() calls is done on the cloned bio, so the original bio is untouched. If we found that we have partial read case, we still have original bio untouched, so we can split it and continue to process only first part of it in current context, when the rest will be called as separate bio request which is passed to generic_make_request() for further processing. Signed-off-by: Igor Konopko <igor.j.konopko@intel.com> Reviewed-by: Heiner Litz <hlitz@ucsc.edu> Reviewed-by: Javier González <javier@javigon.com> Signed-off-by: Matias Bjørling <mb@lightnvm.io> Signed-off-by: Jens Axboe <axboe@kernel.dk>
498 lines
12 KiB
C
498 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2016 CNEX Labs
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* Initial release: Javier Gonzalez <javier@cnexlabs.com>
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* Matias Bjorling <matias@cnexlabs.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version
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* 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* pblk-read.c - pblk's read path
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*/
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#include "pblk.h"
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/*
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* There is no guarantee that the value read from cache has not been updated and
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* resides at another location in the cache. We guarantee though that if the
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* value is read from the cache, it belongs to the mapped lba. In order to
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* guarantee and order between writes and reads are ordered, a flush must be
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* issued.
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*/
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static int pblk_read_from_cache(struct pblk *pblk, struct bio *bio,
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sector_t lba, struct ppa_addr ppa)
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{
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#ifdef CONFIG_NVM_PBLK_DEBUG
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/* Callers must ensure that the ppa points to a cache address */
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BUG_ON(pblk_ppa_empty(ppa));
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BUG_ON(!pblk_addr_in_cache(ppa));
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#endif
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return pblk_rb_copy_to_bio(&pblk->rwb, bio, lba, ppa);
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}
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static int pblk_read_ppalist_rq(struct pblk *pblk, struct nvm_rq *rqd,
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struct bio *bio, sector_t blba,
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bool *from_cache)
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{
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void *meta_list = rqd->meta_list;
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int nr_secs, i;
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retry:
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nr_secs = pblk_lookup_l2p_seq(pblk, rqd->ppa_list, blba, rqd->nr_ppas,
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from_cache);
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if (!*from_cache)
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goto end;
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for (i = 0; i < nr_secs; i++) {
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struct pblk_sec_meta *meta = pblk_get_meta(pblk, meta_list, i);
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sector_t lba = blba + i;
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if (pblk_ppa_empty(rqd->ppa_list[i])) {
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__le64 addr_empty = cpu_to_le64(ADDR_EMPTY);
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meta->lba = addr_empty;
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} else if (pblk_addr_in_cache(rqd->ppa_list[i])) {
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/*
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* Try to read from write buffer. The address is later
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* checked on the write buffer to prevent retrieving
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* overwritten data.
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*/
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if (!pblk_read_from_cache(pblk, bio, lba,
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rqd->ppa_list[i])) {
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if (i == 0) {
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/*
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* We didn't call with bio_advance()
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* yet, so we can just retry.
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*/
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goto retry;
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} else {
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/*
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* We already call bio_advance()
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* so we cannot retry and we need
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* to quit that function in order
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* to allow caller to handle the bio
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* splitting in the current sector
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* position.
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*/
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nr_secs = i;
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goto end;
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}
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}
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meta->lba = cpu_to_le64(lba);
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#ifdef CONFIG_NVM_PBLK_DEBUG
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atomic_long_inc(&pblk->cache_reads);
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#endif
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}
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bio_advance(bio, PBLK_EXPOSED_PAGE_SIZE);
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}
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end:
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if (pblk_io_aligned(pblk, nr_secs))
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rqd->is_seq = 1;
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#ifdef CONFIG_NVM_PBLK_DEBUG
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atomic_long_add(nr_secs, &pblk->inflight_reads);
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#endif
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return nr_secs;
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}
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static void pblk_read_check_seq(struct pblk *pblk, struct nvm_rq *rqd,
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sector_t blba)
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{
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void *meta_list = rqd->meta_list;
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int nr_lbas = rqd->nr_ppas;
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int i;
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if (!pblk_is_oob_meta_supported(pblk))
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return;
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for (i = 0; i < nr_lbas; i++) {
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struct pblk_sec_meta *meta = pblk_get_meta(pblk, meta_list, i);
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u64 lba = le64_to_cpu(meta->lba);
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if (lba == ADDR_EMPTY)
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continue;
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if (lba != blba + i) {
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#ifdef CONFIG_NVM_PBLK_DEBUG
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struct ppa_addr *ppa_list = nvm_rq_to_ppa_list(rqd);
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print_ppa(pblk, &ppa_list[i], "seq", i);
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#endif
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pblk_err(pblk, "corrupted read LBA (%llu/%llu)\n",
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lba, (u64)blba + i);
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WARN_ON(1);
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}
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}
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}
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/*
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* There can be holes in the lba list.
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*/
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static void pblk_read_check_rand(struct pblk *pblk, struct nvm_rq *rqd,
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u64 *lba_list, int nr_lbas)
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{
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void *meta_lba_list = rqd->meta_list;
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int i, j;
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if (!pblk_is_oob_meta_supported(pblk))
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return;
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for (i = 0, j = 0; i < nr_lbas; i++) {
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struct pblk_sec_meta *meta = pblk_get_meta(pblk,
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meta_lba_list, j);
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u64 lba = lba_list[i];
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u64 meta_lba;
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if (lba == ADDR_EMPTY)
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continue;
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meta_lba = le64_to_cpu(meta->lba);
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if (lba != meta_lba) {
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#ifdef CONFIG_NVM_PBLK_DEBUG
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struct ppa_addr *ppa_list = nvm_rq_to_ppa_list(rqd);
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print_ppa(pblk, &ppa_list[j], "rnd", j);
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#endif
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pblk_err(pblk, "corrupted read LBA (%llu/%llu)\n",
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meta_lba, lba);
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WARN_ON(1);
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}
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j++;
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}
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WARN_ONCE(j != rqd->nr_ppas, "pblk: corrupted random request\n");
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}
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static void pblk_end_user_read(struct bio *bio, int error)
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{
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if (error && error != NVM_RSP_WARN_HIGHECC)
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bio_io_error(bio);
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else
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bio_endio(bio);
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}
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static void __pblk_end_io_read(struct pblk *pblk, struct nvm_rq *rqd,
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bool put_line)
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{
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struct nvm_tgt_dev *dev = pblk->dev;
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struct pblk_g_ctx *r_ctx = nvm_rq_to_pdu(rqd);
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struct bio *int_bio = rqd->bio;
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unsigned long start_time = r_ctx->start_time;
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generic_end_io_acct(dev->q, REQ_OP_READ, &pblk->disk->part0, start_time);
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if (rqd->error)
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pblk_log_read_err(pblk, rqd);
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pblk_read_check_seq(pblk, rqd, r_ctx->lba);
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bio_put(int_bio);
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if (put_line)
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pblk_rq_to_line_put(pblk, rqd);
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#ifdef CONFIG_NVM_PBLK_DEBUG
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atomic_long_add(rqd->nr_ppas, &pblk->sync_reads);
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atomic_long_sub(rqd->nr_ppas, &pblk->inflight_reads);
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#endif
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pblk_free_rqd(pblk, rqd, PBLK_READ);
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atomic_dec(&pblk->inflight_io);
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}
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static void pblk_end_io_read(struct nvm_rq *rqd)
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{
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struct pblk *pblk = rqd->private;
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struct pblk_g_ctx *r_ctx = nvm_rq_to_pdu(rqd);
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struct bio *bio = (struct bio *)r_ctx->private;
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pblk_end_user_read(bio, rqd->error);
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__pblk_end_io_read(pblk, rqd, true);
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}
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static void pblk_read_rq(struct pblk *pblk, struct nvm_rq *rqd, struct bio *bio,
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sector_t lba, bool *from_cache)
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{
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struct pblk_sec_meta *meta = pblk_get_meta(pblk, rqd->meta_list, 0);
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struct ppa_addr ppa;
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pblk_lookup_l2p_seq(pblk, &ppa, lba, 1, from_cache);
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#ifdef CONFIG_NVM_PBLK_DEBUG
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atomic_long_inc(&pblk->inflight_reads);
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#endif
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retry:
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if (pblk_ppa_empty(ppa)) {
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__le64 addr_empty = cpu_to_le64(ADDR_EMPTY);
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meta->lba = addr_empty;
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return;
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}
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/* Try to read from write buffer. The address is later checked on the
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* write buffer to prevent retrieving overwritten data.
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*/
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if (pblk_addr_in_cache(ppa)) {
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if (!pblk_read_from_cache(pblk, bio, lba, ppa)) {
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pblk_lookup_l2p_seq(pblk, &ppa, lba, 1, from_cache);
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goto retry;
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}
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meta->lba = cpu_to_le64(lba);
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#ifdef CONFIG_NVM_PBLK_DEBUG
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atomic_long_inc(&pblk->cache_reads);
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#endif
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} else {
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rqd->ppa_addr = ppa;
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}
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}
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void pblk_submit_read(struct pblk *pblk, struct bio *bio)
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{
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struct nvm_tgt_dev *dev = pblk->dev;
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struct request_queue *q = dev->q;
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sector_t blba = pblk_get_lba(bio);
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unsigned int nr_secs = pblk_get_secs(bio);
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bool from_cache;
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struct pblk_g_ctx *r_ctx;
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struct nvm_rq *rqd;
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struct bio *int_bio, *split_bio;
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generic_start_io_acct(q, REQ_OP_READ, bio_sectors(bio),
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&pblk->disk->part0);
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rqd = pblk_alloc_rqd(pblk, PBLK_READ);
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rqd->opcode = NVM_OP_PREAD;
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rqd->nr_ppas = nr_secs;
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rqd->private = pblk;
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rqd->end_io = pblk_end_io_read;
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r_ctx = nvm_rq_to_pdu(rqd);
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r_ctx->start_time = jiffies;
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r_ctx->lba = blba;
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if (pblk_alloc_rqd_meta(pblk, rqd)) {
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bio_io_error(bio);
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pblk_free_rqd(pblk, rqd, PBLK_READ);
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return;
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}
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/* Clone read bio to deal internally with:
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* -read errors when reading from drive
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* -bio_advance() calls during cache reads
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*/
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int_bio = bio_clone_fast(bio, GFP_KERNEL, &pblk_bio_set);
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if (nr_secs > 1)
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nr_secs = pblk_read_ppalist_rq(pblk, rqd, int_bio, blba,
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&from_cache);
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else
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pblk_read_rq(pblk, rqd, int_bio, blba, &from_cache);
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split_retry:
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r_ctx->private = bio; /* original bio */
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rqd->bio = int_bio; /* internal bio */
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if (from_cache && nr_secs == rqd->nr_ppas) {
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/* All data was read from cache, we can complete the IO. */
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pblk_end_user_read(bio, 0);
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atomic_inc(&pblk->inflight_io);
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__pblk_end_io_read(pblk, rqd, false);
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} else if (nr_secs != rqd->nr_ppas) {
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/* The read bio request could be partially filled by the write
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* buffer, but there are some holes that need to be read from
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* the drive. In order to handle this, we will use block layer
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* mechanism to split this request in to smaller ones and make
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* a chain of it.
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*/
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split_bio = bio_split(bio, nr_secs * NR_PHY_IN_LOG, GFP_KERNEL,
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&pblk_bio_set);
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bio_chain(split_bio, bio);
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generic_make_request(bio);
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/* New bio contains first N sectors of the previous one, so
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* we can continue to use existing rqd, but we need to shrink
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* the number of PPAs in it. New bio is also guaranteed that
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* it contains only either data from cache or from drive, newer
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* mix of them.
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*/
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bio = split_bio;
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rqd->nr_ppas = nr_secs;
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if (rqd->nr_ppas == 1)
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rqd->ppa_addr = rqd->ppa_list[0];
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/* Recreate int_bio - existing might have some needed internal
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* fields modified already.
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*/
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bio_put(int_bio);
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int_bio = bio_clone_fast(bio, GFP_KERNEL, &pblk_bio_set);
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goto split_retry;
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} else if (pblk_submit_io(pblk, rqd)) {
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/* Submitting IO to drive failed, let's report an error */
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rqd->error = -ENODEV;
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pblk_end_io_read(rqd);
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}
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}
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static int read_ppalist_rq_gc(struct pblk *pblk, struct nvm_rq *rqd,
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struct pblk_line *line, u64 *lba_list,
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u64 *paddr_list_gc, unsigned int nr_secs)
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{
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struct ppa_addr ppa_list_l2p[NVM_MAX_VLBA];
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struct ppa_addr ppa_gc;
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int valid_secs = 0;
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int i;
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pblk_lookup_l2p_rand(pblk, ppa_list_l2p, lba_list, nr_secs);
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for (i = 0; i < nr_secs; i++) {
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if (lba_list[i] == ADDR_EMPTY)
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continue;
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ppa_gc = addr_to_gen_ppa(pblk, paddr_list_gc[i], line->id);
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if (!pblk_ppa_comp(ppa_list_l2p[i], ppa_gc)) {
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paddr_list_gc[i] = lba_list[i] = ADDR_EMPTY;
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continue;
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}
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rqd->ppa_list[valid_secs++] = ppa_list_l2p[i];
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}
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#ifdef CONFIG_NVM_PBLK_DEBUG
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atomic_long_add(valid_secs, &pblk->inflight_reads);
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#endif
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return valid_secs;
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}
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static int read_rq_gc(struct pblk *pblk, struct nvm_rq *rqd,
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struct pblk_line *line, sector_t lba,
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u64 paddr_gc)
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{
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struct ppa_addr ppa_l2p, ppa_gc;
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int valid_secs = 0;
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if (lba == ADDR_EMPTY)
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goto out;
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/* logic error: lba out-of-bounds */
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if (lba >= pblk->capacity) {
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WARN(1, "pblk: read lba out of bounds\n");
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goto out;
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}
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spin_lock(&pblk->trans_lock);
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ppa_l2p = pblk_trans_map_get(pblk, lba);
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spin_unlock(&pblk->trans_lock);
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ppa_gc = addr_to_gen_ppa(pblk, paddr_gc, line->id);
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if (!pblk_ppa_comp(ppa_l2p, ppa_gc))
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goto out;
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rqd->ppa_addr = ppa_l2p;
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valid_secs = 1;
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#ifdef CONFIG_NVM_PBLK_DEBUG
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atomic_long_inc(&pblk->inflight_reads);
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#endif
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out:
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return valid_secs;
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}
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int pblk_submit_read_gc(struct pblk *pblk, struct pblk_gc_rq *gc_rq)
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{
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struct nvm_tgt_dev *dev = pblk->dev;
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struct nvm_geo *geo = &dev->geo;
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struct bio *bio;
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struct nvm_rq rqd;
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int data_len;
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int ret = NVM_IO_OK;
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memset(&rqd, 0, sizeof(struct nvm_rq));
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ret = pblk_alloc_rqd_meta(pblk, &rqd);
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if (ret)
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return ret;
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if (gc_rq->nr_secs > 1) {
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gc_rq->secs_to_gc = read_ppalist_rq_gc(pblk, &rqd, gc_rq->line,
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gc_rq->lba_list,
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gc_rq->paddr_list,
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gc_rq->nr_secs);
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if (gc_rq->secs_to_gc == 1)
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rqd.ppa_addr = rqd.ppa_list[0];
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} else {
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gc_rq->secs_to_gc = read_rq_gc(pblk, &rqd, gc_rq->line,
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gc_rq->lba_list[0],
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gc_rq->paddr_list[0]);
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}
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if (!(gc_rq->secs_to_gc))
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goto out;
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data_len = (gc_rq->secs_to_gc) * geo->csecs;
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bio = pblk_bio_map_addr(pblk, gc_rq->data, gc_rq->secs_to_gc, data_len,
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PBLK_VMALLOC_META, GFP_KERNEL);
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if (IS_ERR(bio)) {
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pblk_err(pblk, "could not allocate GC bio (%lu)\n",
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PTR_ERR(bio));
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ret = PTR_ERR(bio);
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goto err_free_dma;
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}
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bio->bi_iter.bi_sector = 0; /* internal bio */
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bio_set_op_attrs(bio, REQ_OP_READ, 0);
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rqd.opcode = NVM_OP_PREAD;
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rqd.nr_ppas = gc_rq->secs_to_gc;
|
|
rqd.bio = bio;
|
|
|
|
if (pblk_submit_io_sync(pblk, &rqd)) {
|
|
ret = -EIO;
|
|
goto err_free_bio;
|
|
}
|
|
|
|
pblk_read_check_rand(pblk, &rqd, gc_rq->lba_list, gc_rq->nr_secs);
|
|
|
|
atomic_dec(&pblk->inflight_io);
|
|
|
|
if (rqd.error) {
|
|
atomic_long_inc(&pblk->read_failed_gc);
|
|
#ifdef CONFIG_NVM_PBLK_DEBUG
|
|
pblk_print_failed_rqd(pblk, &rqd, rqd.error);
|
|
#endif
|
|
}
|
|
|
|
#ifdef CONFIG_NVM_PBLK_DEBUG
|
|
atomic_long_add(gc_rq->secs_to_gc, &pblk->sync_reads);
|
|
atomic_long_add(gc_rq->secs_to_gc, &pblk->recov_gc_reads);
|
|
atomic_long_sub(gc_rq->secs_to_gc, &pblk->inflight_reads);
|
|
#endif
|
|
|
|
out:
|
|
pblk_free_rqd_meta(pblk, &rqd);
|
|
return ret;
|
|
|
|
err_free_bio:
|
|
bio_put(bio);
|
|
err_free_dma:
|
|
pblk_free_rqd_meta(pblk, &rqd);
|
|
return ret;
|
|
}
|