On Tue, Sep 18, 2018 at 6:11 PM Heiner Litz <hlitz@xxxxxxxx> wrote:
>
> On Tue, Sep 18, 2018 at 4:28 AM Hans Holmberg
> <hans.ml.holmberg@xxxxxxxxxxxxx> wrote:
> >
> > On Mon, Sep 17, 2018 at 7:30 AM Heiner Litz <hlitz@xxxxxxxx> wrote:
> > >
> > > In prepartion of supporting RAIL, add the RAIL API.
> > >
> > > Signed-off-by: Heiner Litz <hlitz@xxxxxxxx>
> > > ---
> > > drivers/lightnvm/pblk-rail.c | 808 +++++++++++++++++++++++++++++++++++
> > > drivers/lightnvm/pblk.h | 63 ++-
> > > 2 files changed, 870 insertions(+), 1 deletion(-)
> > > create mode 100644 drivers/lightnvm/pblk-rail.c
> > >
> > > diff --git a/drivers/lightnvm/pblk-rail.c b/drivers/lightnvm/pblk-rail.c
> > > new file mode 100644
> > > index 000000000000..a48ed31a0ba9
> > > --- /dev/null
> > > +++ b/drivers/lightnvm/pblk-rail.c
> > > @@ -0,0 +1,808 @@
> > > +/*
> > > + * Copyright (C) 2018 Heiner Litz
> > > + * Initial release: Heiner Litz <hlitz@xxxxxxxx>
> > > + *
> > > + * 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-rail.c - pblk's RAIL path
> > > + */
> > > +
> > > +#include "pblk.h"
> > > +
> > > +#define PBLK_RAIL_EMPTY ~0x0
> > This constant is not being used.
>
> thanks, will remove
>
> > > +#define PBLK_RAIL_PARITY_WRITE 0x8000
> > Where does this magic number come from? Please document.
>
> ok , will document
>
> >
> > > +
> > > +/* RAIL auxiliary functions */
> > > +static unsigned int pblk_rail_nr_parity_luns(struct pblk *pblk)
> > > +{
> > > + struct pblk_line_meta *lm = &pblk->lm;
> > > +
> > > + return lm->blk_per_line / PBLK_RAIL_STRIDE_WIDTH;
> > > +}
> > > +
> > > +static unsigned int pblk_rail_nr_data_luns(struct pblk *pblk)
> > > +{
> > > + struct pblk_line_meta *lm = &pblk->lm;
> > > +
> > > + return lm->blk_per_line - pblk_rail_nr_parity_luns(pblk);
> > > +}
> > > +
> > > +static unsigned int pblk_rail_sec_per_stripe(struct pblk *pblk)
> > > +{
> > > + struct pblk_line_meta *lm = &pblk->lm;
> > > +
> > > + return lm->blk_per_line * pblk->min_write_pgs;
> > > +}
> > > +
> > > +static unsigned int pblk_rail_psec_per_stripe(struct pblk *pblk)
> > > +{
> > > + return pblk_rail_nr_parity_luns(pblk) * pblk->min_write_pgs;
> > > +}
> > > +
> > > +static unsigned int pblk_rail_dsec_per_stripe(struct pblk *pblk)
> > > +{
> > > + return pblk_rail_sec_per_stripe(pblk) - pblk_rail_psec_per_stripe(pblk);
> > > +}
> > > +
> > > +static unsigned int pblk_rail_wrap_lun(struct pblk *pblk, unsigned int lun)
> > > +{
> > > + struct pblk_line_meta *lm = &pblk->lm;
> > > +
> > > + return (lun & (lm->blk_per_line - 1));
> > > +}
> > > +
> > > +bool pblk_rail_meta_distance(struct pblk_line *data_line)
> > > +{
> > > + return (data_line->meta_distance % PBLK_RAIL_STRIDE_WIDTH) == 0;
> > > +}
> > > +
> > > +/* Notify readers that LUN is serving high latency operation */
> > > +static void pblk_rail_notify_reader_down(struct pblk *pblk, int lun)
> > > +{
> > > + WARN_ON(test_and_set_bit(lun, pblk->rail.busy_bitmap));
> > > + /* Make sure that busy bit is seen by reader before proceeding */
> > > + smp_mb__after_atomic();
> > > +}
> > > +
> > > +static void pblk_rail_notify_reader_up(struct pblk *pblk, int lun)
> > > +{
> > > + /* Make sure that write is completed before releasing busy bit */
> > > + smp_mb__before_atomic();
> > > + WARN_ON(!test_and_clear_bit(lun, pblk->rail.busy_bitmap));
> > > +}
> > > +
> > > +int pblk_rail_lun_busy(struct pblk *pblk, struct ppa_addr ppa)
> > > +{
> > > + struct nvm_tgt_dev *dev = pblk->dev;
> > > + struct nvm_geo *geo = &dev->geo;
> > > + int lun_pos = pblk_ppa_to_pos(geo, ppa);
> > > +
> > > + return test_bit(lun_pos, pblk->rail.busy_bitmap);
> > > +}
> > > +
> > > +/* Enforces one writer per stride */
> > > +int pblk_rail_down_stride(struct pblk *pblk, int lun_pos, int timeout)
> > > +{
> > > + struct pblk_lun *rlun;
> > > + int strides = pblk_rail_nr_parity_luns(pblk);
> > > + int stride = lun_pos % strides;
> > > + int ret;
> > > +
> > > + rlun = &pblk->luns[stride];
> > > + ret = down_timeout(&rlun->wr_sem, timeout);
> > > + pblk_rail_notify_reader_down(pblk, lun_pos);
> > > +
> > > + return ret;
> > > +}
> > > +
> > > +void pblk_rail_up_stride(struct pblk *pblk, int lun_pos)
> > > +{
> > > + struct pblk_lun *rlun;
> > > + int strides = pblk_rail_nr_parity_luns(pblk);
> > > + int stride = lun_pos % strides;
> > > +
> > > + pblk_rail_notify_reader_up(pblk, lun_pos);
> > > + rlun = &pblk->luns[stride];
> > > + up(&rlun->wr_sem);
> > > +}
> > > +
> > > +/* Determine whether a sector holds data, meta or is bad*/
> > > +bool pblk_rail_valid_sector(struct pblk *pblk, struct pblk_line *line, int pos)
> > > +{
> > > + struct pblk_line_meta *lm = &pblk->lm;
> > > + struct nvm_tgt_dev *dev = pblk->dev;
> > > + struct nvm_geo *geo = &dev->geo;
> > > + struct ppa_addr ppa;
> > > + int lun;
> > > +
> > > + if (pos >= line->smeta_ssec && pos < (line->smeta_ssec + lm->smeta_sec))
> > > + return false;
> > > +
> > > + if (pos >= line->emeta_ssec &&
> > > + pos < (line->emeta_ssec + lm->emeta_sec[0]))
> > > + return false;
> > > +
> > > + ppa = addr_to_gen_ppa(pblk, pos, line->id);
> > > + lun = pblk_ppa_to_pos(geo, ppa);
> > > +
> > > + return !test_bit(lun, line->blk_bitmap);
> > > +}
> > > +
> > > +/* Delay rb overwrite until whole stride has been written */
> > > +int pblk_rail_rb_delay(struct pblk_rb *rb)
> > > +{
> > > + struct pblk *pblk = container_of(rb, struct pblk, rwb);
> > > +
> > > + return pblk_rail_sec_per_stripe(pblk);
> > > +}
> > > +
> > > +static unsigned int pblk_rail_sec_to_stride(struct pblk *pblk, unsigned int sec)
> > > +{
> > > + unsigned int sec_in_stripe = sec % pblk_rail_sec_per_stripe(pblk);
> > > + int page = sec_in_stripe / pblk->min_write_pgs;
> > > +
> > > + return page % pblk_rail_nr_parity_luns(pblk);
> > > +}
> > > +
> > > +static unsigned int pblk_rail_sec_to_idx(struct pblk *pblk, unsigned int sec)
> > > +{
> > > + unsigned int sec_in_stripe = sec % pblk_rail_sec_per_stripe(pblk);
> > > +
> > > + return sec_in_stripe / pblk_rail_psec_per_stripe(pblk);
> > > +}
> > > +
> > > +static void pblk_rail_data_parity(void *dest, void *src)
> > > +{
> > > + unsigned int i;
> > > +
> > > + for (i = 0; i < PBLK_EXPOSED_PAGE_SIZE / sizeof(unsigned long); i++)
> > > + ((unsigned long *)dest)[i] ^= ((unsigned long *)src)[i];
> > > +}
> > > +
> > > +static void pblk_rail_lba_parity(u64 *dest, u64 *src)
> > > +{
> > > + *dest ^= *src;
> > > +}
> > > +
> > > +/* Tracks where a sector is located in the rwb */
> > > +void pblk_rail_track_sec(struct pblk *pblk, struct pblk_line *line, int cur_sec,
> > > + int sentry, int nr_valid)
> > > +{
> > > + int stride, idx, pos;
> > > +
> > > + stride = pblk_rail_sec_to_stride(pblk, cur_sec);
> > > + idx = pblk_rail_sec_to_idx(pblk, cur_sec);
> > > + pos = pblk_rb_wrap_pos(&pblk->rwb, sentry);
> > > + pblk->rail.p2b[stride][idx].pos = pos;
> > > + pblk->rail.p2b[stride][idx].nr_valid = nr_valid;
> > > +}
> > > +
> > > +/* RAIL's sector mapping function */
> > > +static void pblk_rail_map_sec(struct pblk *pblk, struct pblk_line *line,
> > > + int sentry, struct pblk_sec_meta *meta_list,
> > > + __le64 *lba_list, struct ppa_addr ppa)
> > > +{
> > > + struct pblk_w_ctx *w_ctx;
> > > + __le64 addr_empty = cpu_to_le64(ADDR_EMPTY);
> > > +
> > > + kref_get(&line->ref);
> > > +
> > > + if (sentry & PBLK_RAIL_PARITY_WRITE) {
> > > + u64 *lba;
> > > +
> > > + sentry &= ~PBLK_RAIL_PARITY_WRITE;
> > > + lba = &pblk->rail.lba[sentry];
> > > + meta_list->lba = cpu_to_le64(*lba);
> > > + *lba_list = cpu_to_le64(*lba);
> > > + line->nr_valid_lbas++;
> > > + } else {
> > > + w_ctx = pblk_rb_w_ctx(&pblk->rwb, sentry);
> > > + w_ctx->ppa = ppa;
> > > + meta_list->lba = cpu_to_le64(w_ctx->lba);
> > > + *lba_list = cpu_to_le64(w_ctx->lba);
> > > +
> > > + if (*lba_list != addr_empty)
> > > + line->nr_valid_lbas++;
> > > + else
> > > + atomic64_inc(&pblk->pad_wa);
> > > + }
> > > +}
> > > +
> > > +int pblk_rail_map_page_data(struct pblk *pblk, unsigned int sentry,
> > > + struct ppa_addr *ppa_list,
> > > + unsigned long *lun_bitmap,
> > > + struct pblk_sec_meta *meta_list,
> > > + unsigned int valid_secs)
> > > +{
> > > + struct pblk_line *line = pblk_line_get_data(pblk);
> > > + struct pblk_emeta *emeta;
> > > + __le64 *lba_list;
> > > + u64 paddr;
> > > + int nr_secs = pblk->min_write_pgs;
> > > + int i;
> > > +
> > > + if (pblk_line_is_full(line)) {
> > > + struct pblk_line *prev_line = line;
> > > +
> > > + /* If we cannot allocate a new line, make sure to store metadata
> > > + * on current line and then fail
> > > + */
> > > + line = pblk_line_replace_data(pblk);
> > > + pblk_line_close_meta(pblk, prev_line);
> > > +
> > > + if (!line)
> > > + return -EINTR;
> > > + }
> > > +
> > > + emeta = line->emeta;
> > > + lba_list = emeta_to_lbas(pblk, emeta->buf);
> > > +
> > > + paddr = pblk_alloc_page(pblk, line, nr_secs);
> > > +
> > > + pblk_rail_track_sec(pblk, line, paddr, sentry, valid_secs);
> > > +
> > > + for (i = 0; i < nr_secs; i++, paddr++) {
> > > + __le64 addr_empty = cpu_to_le64(ADDR_EMPTY);
> > > +
> > > + /* ppa to be sent to the device */
> > > + ppa_list[i] = addr_to_gen_ppa(pblk, paddr, line->id);
> > > +
> > > + /* Write context for target bio completion on write buffer. Note
> > > + * that the write buffer is protected by the sync backpointer,
> > > + * and a single writer thread have access to each specific entry
> > > + * at a time. Thus, it is safe to modify the context for the
> > > + * entry we are setting up for submission without taking any
> > > + * lock or memory barrier.
> > > + */
> > > + if (i < valid_secs) {
> > > + pblk_rail_map_sec(pblk, line, sentry + i, &meta_list[i],
> > > + &lba_list[paddr], ppa_list[i]);
> > > + } else {
> > > + lba_list[paddr] = meta_list[i].lba = addr_empty;
> > > + __pblk_map_invalidate(pblk, line, paddr);
> > > + }
> > > + }
> > > +
> > > + pblk_down_rq(pblk, ppa_list[0], lun_bitmap);
> > > + return 0;
> > > +}
> >
> > This is a lot of duplication of code from the "normal" pblk map
> > function - could you refactor to avoid this?
>
> I wanted to keep the mapping function as general as possible in case
> we want to support other mapping functions at some point. If you think
> this is not needed I can reduce the mapping func to only code that
> differs between the mapping function. E.g. we could turn
> pblk_map_page_data into a pblk_map_sec_data
I think it would be better to try to keep common code as far as we
can, and if we would introduce other mapping functions in the future
we'll rework the common denominator.
>
> >
> > > +
> > > +/* RAIL Initialization and tear down */
> > > +int pblk_rail_init(struct pblk *pblk)
> > > +{
> > > + struct pblk_line_meta *lm = &pblk->lm;
> > > + int i, p2be;
> > > + unsigned int nr_strides;
> > > + unsigned int psecs;
> > > + void *kaddr;
> > > +
> > > + if (!PBLK_RAIL_STRIDE_WIDTH)
> > > + return 0;
> > > +
> > > + if (((lm->blk_per_line % PBLK_RAIL_STRIDE_WIDTH) != 0) ||
> > > + (lm->blk_per_line < PBLK_RAIL_STRIDE_WIDTH)) {
> > > + pr_err("pblk: unsupported RAIL stride %i\n", lm->blk_per_line);
> > > + return -EINVAL;
> > > + }
> >
> > This is just a check of the maximum blocks per line - bad blocks will
> > reduce the number of writable blocks. What happens when a line goes
> > below PBLK_RAIL_STRIDE_WIDTH writable blocks?
>
> This check just guarantees that lm->blk_per_line is a multiple of
> PBLK_RAIL_STRIDE_WIDTH. Bad blocks are handled dynamically at runtime
> via pblk_rail_valid_sector(pblk, line, cur) which skips parity
> computation if the parity block is bad. In theory a line can have
> fewer writable blocks than PBLK_RAIL_STRIDE_WIDTH, in this case parity
> is computed based on fewer number of blocks.
Yes, I see now, it should work.
The only case i see that is problematic is if only the parity block(s)
are non-bad in a line, resulting in no data being written, just parity
(adding a huge write latency penalty) - we could either disable RAIL
for that class of lines or mark them as bad.
>
> >
> > > +
> > > + psecs = pblk_rail_psec_per_stripe(pblk);
> > > + nr_strides = pblk_rail_sec_per_stripe(pblk) / PBLK_RAIL_STRIDE_WIDTH;
> > > +
> > > + pblk->rail.p2b = kmalloc_array(nr_strides, sizeof(struct p2b_entry *),
> > > + GFP_KERNEL);
> > > + if (!pblk->rail.p2b)
> > > + return -ENOMEM;
> > > +
> > > + for (p2be = 0; p2be < nr_strides; p2be++) {
> > > + pblk->rail.p2b[p2be] = kmalloc_array(PBLK_RAIL_STRIDE_WIDTH - 1,
> > > + sizeof(struct p2b_entry),
> > > + GFP_KERNEL);
> > > + if (!pblk->rail.p2b[p2be])
> > > + goto free_p2b_entries;
> > > + }
> > > +
> > > + pblk->rail.data = kmalloc(psecs * sizeof(void *), GFP_KERNEL);
> > > + if (!pblk->rail.data)
> > > + goto free_p2b_entries;
> > > +
> > > + pblk->rail.pages = alloc_pages(GFP_KERNEL, get_count_order(psecs));
> > > + if (!pblk->rail.pages)
> > > + goto free_data;
> > > +
> > > + kaddr = page_address(pblk->rail.pages);
> > > + for (i = 0; i < psecs; i++)
> > > + pblk->rail.data[i] = kaddr + i * PBLK_EXPOSED_PAGE_SIZE;
> > > +
> > > + pblk->rail.lba = kmalloc_array(psecs, sizeof(u64 *), GFP_KERNEL);
> > > + if (!pblk->rail.lba)
> > > + goto free_pages;
> > > +
> > > + /* Subtract parity bits from device capacity */
> > > + pblk->capacity = pblk->capacity * (PBLK_RAIL_STRIDE_WIDTH - 1) /
> > > + PBLK_RAIL_STRIDE_WIDTH;
> > > +
> > > + pblk->map_page = pblk_rail_map_page_data;
> > > +
> > > + return 0;
> > > +
> > > +free_pages:
> > > + free_pages((unsigned long)page_address(pblk->rail.pages),
> > > + get_count_order(psecs));
> > > +free_data:
> > > + kfree(pblk->rail.data);
> > > +free_p2b_entries:
> > > + for (p2be = p2be - 1; p2be >= 0; p2be--)
> > > + kfree(pblk->rail.p2b[p2be]);
> > > + kfree(pblk->rail.p2b);
> > > +
> > > + return -ENOMEM;
> > > +}
> > > +
> > > +void pblk_rail_free(struct pblk *pblk)
> > > +{
> > > + unsigned int i;
> > > + unsigned int nr_strides;
> > > + unsigned int psecs;
> > > +
> > > + psecs = pblk_rail_psec_per_stripe(pblk);
> > > + nr_strides = pblk_rail_sec_per_stripe(pblk) / PBLK_RAIL_STRIDE_WIDTH;
> > > +
> > > + kfree(pblk->rail.lba);
> > > + free_pages((unsigned long)page_address(pblk->rail.pages),
> > > + get_count_order(psecs));
> > > + kfree(pblk->rail.data);
> > > + for (i = 0; i < nr_strides; i++)
> > > + kfree(pblk->rail.p2b[i]);
> > > + kfree(pblk->rail.p2b);
> > > +}
> > > +
> > > +/* PBLK supports 64 ppas max. By performing RAIL reads, a sector is read using
> > > + * multiple ppas which can lead to violation of the 64 ppa limit. In this case,
> > > + * split the bio
> > > + */
> > > +static void pblk_rail_bio_split(struct pblk *pblk, struct bio **bio, int sec)
> > > +{
> > > + struct nvm_tgt_dev *dev = pblk->dev;
> > > + struct bio *split;
> > > +
> > > + sec *= (dev->geo.csecs >> 9);
> > > +
> > > + split = bio_split(*bio, sec, GFP_KERNEL, &pblk_bio_set);
> > > + /* there isn't chance to merge the split bio */
> > > + split->bi_opf |= REQ_NOMERGE;
> > > + bio_set_flag(*bio, BIO_QUEUE_ENTERED);
> > > + bio_chain(split, *bio);
> > > + generic_make_request(*bio);
> > > + *bio = split;
> > > +}
> > > +
> > > +/* RAIL's Write Path */
> > > +static int pblk_rail_sched_parity(struct pblk *pblk)
> > > +{
> > > + struct pblk_line *line = pblk_line_get_data(pblk);
> > > + unsigned int sec_in_stripe;
> > > +
> > > + while (1) {
> > > + sec_in_stripe = line->cur_sec % pblk_rail_sec_per_stripe(pblk);
> > > +
> > > + /* Schedule parity write at end of data section */
> > > + if (sec_in_stripe >= pblk_rail_dsec_per_stripe(pblk))
> > > + return 1;
> > > +
> > > + /* Skip bad blocks and meta sectors until we find a valid sec */
> > > + if (test_bit(line->cur_sec, line->map_bitmap))
> > > + line->cur_sec += pblk->min_write_pgs;
> > > + else
> > > + break;
> > > + }
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +/* Mark RAIL parity sectors as invalid sectors so they will be gc'ed */
> > > +void pblk_rail_line_close(struct pblk *pblk, struct pblk_line *line)
> > > +{
> > > + int off, bit;
> > > +
> > > + for (off = pblk_rail_dsec_per_stripe(pblk);
> > > + off < pblk->lm.sec_per_line;
> > > + off += pblk_rail_sec_per_stripe(pblk)) {
> > > + for (bit = 0; bit < pblk_rail_psec_per_stripe(pblk); bit++)
> > > + set_bit(off + bit, line->invalid_bitmap);
> > > + }
> > > +}
> > > +
> > > +void pblk_rail_end_io_write(struct nvm_rq *rqd)
> > > +{
> > > + struct pblk *pblk = rqd->private;
> > > + struct pblk_c_ctx *c_ctx = nvm_rq_to_pdu(rqd);
> > > +
> > > + if (rqd->error) {
> > > + pblk_log_write_err(pblk, rqd);
> > > + return pblk_end_w_fail(pblk, rqd);
> >
> > The write error recovery path relies on that that sentry in c_ctx is
> > an index in the write buffer, so this won't work.
>
> You mean a RAIL parity write? Yes, good catch.
>
It does not make sense to re-issue failing parity writes anyway, right?
> >
> > Additionally, If a write(data or parity) fails, the whole stride would
> > be broken and need to fall back on "normal" reads, right?
> > One solution could be to check line->w_err_gc->has_write_err on the read path.
>
> when a data write fails it is remapped and the rail mapping function
> tracks that new location in the r2b. The page will be marked bad and
> hence taken into account when computing parity in the case of parity
> writes and RAIL reads, so the line should still be intact. This might
> be insufficiently tested but in theory it should work.
As far as I can tell from the code, pblk_rail_valid_sector only checks
if the sector is occupied by metadata or if the whole block is bad.
In the case of a write failure, the block will not be marked bad. What
we could do is to keep track of the write pointer internally to check
if the sector had been successfully written.
I can create a patch for keeping track of the write pointer for each
block - this would be useful for debugging purposes in any case. Once
this is in place it would be easy to add a check in
pblk_rail_valid_sector ensuring that the sector has actually been
written successfully.
>
> >
> > > + }
> > > +#ifdef CONFIG_NVM_DEBUG
> > > + else
> > > + WARN_ONCE(rqd->bio->bi_status, "pblk: corrupted write error\n");
> > > +#endif
> > > +
> > > + pblk_up_rq(pblk, c_ctx->lun_bitmap);
> > > +
> > > + pblk_rq_to_line_put(pblk, rqd);
> > > + bio_put(rqd->bio);
> > > + pblk_free_rqd(pblk, rqd, PBLK_WRITE);
> > > +
> > > + atomic_dec(&pblk->inflight_io);
> > > +}
> > > +
> > > +static int pblk_rail_read_to_bio(struct pblk *pblk, struct nvm_rq *rqd,
> > > + struct bio *bio, unsigned int stride,
> > > + unsigned int nr_secs, unsigned int paddr)
> > > +{
> > > + struct pblk_c_ctx *c_ctx = nvm_rq_to_pdu(rqd);
> > > + int sec, i;
> > > + int nr_data = PBLK_RAIL_STRIDE_WIDTH - 1;
> > > + struct pblk_line *line = pblk_line_get_data(pblk);
> > > +
> > > + c_ctx->nr_valid = nr_secs;
> > > + /* sentry indexes rail page buffer, instead of rwb */
> > > + c_ctx->sentry = stride * pblk->min_write_pgs;
> > > + c_ctx->sentry |= PBLK_RAIL_PARITY_WRITE;
> > > +
> > > + for (sec = 0; sec < pblk->min_write_pgs; sec++) {
> > > + void *pg_addr;
> > > + struct page *page;
> > > + u64 *lba;
> > > +
> > > + lba = &pblk->rail.lba[stride * pblk->min_write_pgs + sec];
> > > + pg_addr = pblk->rail.data[stride * pblk->min_write_pgs + sec];
> > > + page = virt_to_page(pg_addr);
> > > +
> > > + if (!page) {
> > > + pr_err("pblk: could not allocate RAIL bio page %p\n",
> > > + pg_addr);
> > > + return -NVM_IO_ERR;
> > > + }
> > > +
> > > + if (bio_add_page(bio, page, pblk->rwb.seg_size, 0) !=
> > > + pblk->rwb.seg_size) {
> > > + pr_err("pblk: could not add page to RAIL bio\n");
> > > + return -NVM_IO_ERR;
> > > + }
> > > +
> > > + *lba = 0;
> > > + memset(pg_addr, 0, PBLK_EXPOSED_PAGE_SIZE);
> > > +
> > > + for (i = 0; i < nr_data; i++) {
> > > + struct pblk_rb_entry *entry;
> > > + struct pblk_w_ctx *w_ctx;
> > > + u64 lba_src;
> > > + unsigned int pos;
> > > + unsigned int cur;
> > > + int distance = pblk_rail_psec_per_stripe(pblk);
> > > +
> > > + cur = paddr - distance * (nr_data - i) + sec;
> > > +
> > > + if (!pblk_rail_valid_sector(pblk, line, cur))
> > > + continue;
> > > +
> > > + pos = pblk->rail.p2b[stride][i].pos;
> > > + pos = pblk_rb_wrap_pos(&pblk->rwb, pos + sec);
> > > + entry = &pblk->rwb.entries[pos];
> > > + w_ctx = &entry->w_ctx;
> > > + lba_src = w_ctx->lba;
> > > +
> > > + if (sec < pblk->rail.p2b[stride][i].nr_valid &&
> > > + lba_src != ADDR_EMPTY) {
> > > + pblk_rail_data_parity(pg_addr, entry->data);
> > > + pblk_rail_lba_parity(lba, &lba_src);
> >
> > What keeps the parity lba values from invalidating "real" data lbas
> > during recovery?
>
> The RAIL geometry is known during recovery so the parity LBAs can be
> ignored, not implemented yet.
Ah, it's not in place yet, then it makes sense.
It would be straight forward to implement, using something like
sector_is_parity(line, paddr) to avoid mapping parity sectors during
recovery.
>
> >
> > > + }
> > > + }
> > > + }
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +int pblk_rail_submit_write(struct pblk *pblk)
> > > +{
> > > + int i;
> > > + struct nvm_rq *rqd;
> > > + struct bio *bio;
> > > + struct pblk_line *line = pblk_line_get_data(pblk);
> > > + int start, end, bb_offset;
> > > + unsigned int stride = 0;
> > > +
> > > + if (!pblk_rail_sched_parity(pblk))
> > > + return 0;
> > > +
> > > + start = line->cur_sec;
> > > + bb_offset = start % pblk_rail_sec_per_stripe(pblk);
> > > + end = start + pblk_rail_sec_per_stripe(pblk) - bb_offset;
> > > +
> > > + for (i = start; i < end; i += pblk->min_write_pgs, stride++) {
> > > + /* Do not generate parity in this slot if the sec is bad
> > > + * or reserved for meta.
> > > + * We check on the read path and perform a conventional
> > > + * read, to avoid reading parity from the bad block
> > > + */
> > > + if (!pblk_rail_valid_sector(pblk, line, i))
> > > + continue;
> > > +
> > > + rqd = pblk_alloc_rqd(pblk, PBLK_WRITE);
> > > + if (IS_ERR(rqd)) {
> > > + pr_err("pblk: cannot allocate parity write req.\n");
> > > + return -ENOMEM;
> > > + }
> > > +
> > > + bio = bio_alloc(GFP_KERNEL, pblk->min_write_pgs);
> > > + if (!bio) {
> > > + pr_err("pblk: cannot allocate parity write bio\n");
> > > + pblk_free_rqd(pblk, rqd, PBLK_WRITE);
> > > + return -ENOMEM;
> > > + }
> > > +
> > > + bio->bi_iter.bi_sector = 0; /* internal bio */
> > > + bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
> > > + rqd->bio = bio;
> > > +
> > > + pblk_rail_read_to_bio(pblk, rqd, bio, stride,
> > > + pblk->min_write_pgs, i);
> > > +
> > > + if (pblk_submit_io_set(pblk, rqd, pblk_rail_end_io_write)) {
> > > + bio_put(rqd->bio);
> > > + pblk_free_rqd(pblk, rqd, PBLK_WRITE);
> > > +
> > > + return -NVM_IO_ERR;
> > > + }
> > > + }
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +/* RAIL's Read Path */
> > > +static void pblk_rail_end_io_read(struct nvm_rq *rqd)
> > > +{
> > > + struct pblk *pblk = rqd->private;
> > > + struct pblk_g_ctx *r_ctx = nvm_rq_to_pdu(rqd);
> > > + struct pblk_pr_ctx *pr_ctx = r_ctx->private;
> > > + struct bio *new_bio = rqd->bio;
> > > + struct bio *bio = pr_ctx->orig_bio;
> > > + struct bio_vec src_bv, dst_bv;
> > > + struct pblk_sec_meta *meta_list = rqd->meta_list;
> > > + int bio_init_idx = pr_ctx->bio_init_idx;
> > > + int nr_secs = pr_ctx->orig_nr_secs;
> > > + __le64 *lba_list_mem, *lba_list_media;
> > > + __le64 addr_empty = cpu_to_le64(ADDR_EMPTY);
> > > + void *src_p, *dst_p;
> > > + int i, r, rail_ppa = 0;
> > > + unsigned char valid;
> > > +
> > > + if (unlikely(rqd->nr_ppas == 1)) {
> > > + struct ppa_addr ppa;
> > > +
> > > + ppa = rqd->ppa_addr;
> > > + rqd->ppa_list = pr_ctx->ppa_ptr;
> > > + rqd->dma_ppa_list = pr_ctx->dma_ppa_list;
> > > + rqd->ppa_list[0] = ppa;
> > > + }
> > > +
> > > + /* Re-use allocated memory for intermediate lbas */
> > > + lba_list_mem = (((void *)rqd->ppa_list) + pblk_dma_ppa_size);
> > > + lba_list_media = (((void *)rqd->ppa_list) + 2 * pblk_dma_ppa_size);
> > > +
> > > + for (i = 0; i < rqd->nr_ppas; i++)
> > > + lba_list_media[i] = meta_list[i].lba;
> > > + for (i = 0; i < nr_secs; i++)
> > > + meta_list[i].lba = lba_list_mem[i];
> > > +
> > > + for (i = 0; i < nr_secs; i++) {
> > > + struct pblk_line *line;
> > > + u64 meta_lba = 0x0UL, mlba;
> > > +
> > > + line = pblk_ppa_to_line(pblk, rqd->ppa_list[rail_ppa]);
> > > +
> > > + valid = bitmap_weight(pr_ctx->bitmap, PBLK_RAIL_STRIDE_WIDTH);
> > > + bitmap_shift_right(pr_ctx->bitmap, pr_ctx->bitmap,
> > > + PBLK_RAIL_STRIDE_WIDTH, PR_BITMAP_SIZE);
> > > +
> > > + if (valid == 0) /* Skip cached reads */
> > > + continue;
> > > +
> > > + kref_put(&line->ref, pblk_line_put);
> > > +
> > > + dst_bv = bio->bi_io_vec[bio_init_idx + i];
> > > + dst_p = kmap_atomic(dst_bv.bv_page);
> > > +
> > > + memset(dst_p + dst_bv.bv_offset, 0, PBLK_EXPOSED_PAGE_SIZE);
> > > + meta_list[i].lba = cpu_to_le64(0x0UL);
> > > +
> > > + for (r = 0; r < valid; r++, rail_ppa++) {
> > > + src_bv = new_bio->bi_io_vec[rail_ppa];
> > > +
> > > + if (lba_list_media[rail_ppa] != addr_empty) {
> > > + src_p = kmap_atomic(src_bv.bv_page);
> > > + pblk_rail_data_parity(dst_p + dst_bv.bv_offset,
> > > + src_p + src_bv.bv_offset);
> > > + mlba = le64_to_cpu(lba_list_media[rail_ppa]);
> > > + pblk_rail_lba_parity(&meta_lba, &mlba);
> > > + kunmap_atomic(src_p);
> > > + }
> > > +
> > > + mempool_free(src_bv.bv_page, &pblk->page_bio_pool);
> > > + }
> > > + meta_list[i].lba = cpu_to_le64(meta_lba);
> > > + kunmap_atomic(dst_p);
> > > + }
> > > +
> > > + bio_put(new_bio);
> > > + rqd->nr_ppas = pr_ctx->orig_nr_secs;
> > > + kfree(pr_ctx);
> > > + rqd->bio = NULL;
> > > +
> > > + bio_endio(bio);
> > > + __pblk_end_io_read(pblk, rqd, false);
> > > +}
> > > +
> > > +/* Converts original ppa into ppa list of RAIL reads */
> > > +static int pblk_rail_setup_ppas(struct pblk *pblk, struct ppa_addr ppa,
> > > + struct ppa_addr *rail_ppas,
> > > + unsigned char *pvalid, int *nr_rail_ppas,
> > > + int *rail_reads)
> > > +{
> > > + struct nvm_tgt_dev *dev = pblk->dev;
> > > + struct nvm_geo *geo = &dev->geo;
> > > + struct ppa_addr rail_ppa = ppa;
> > > + unsigned int lun_pos = pblk_ppa_to_pos(geo, ppa);
> > > + unsigned int strides = pblk_rail_nr_parity_luns(pblk);
> > > + struct pblk_line *line;
> > > + unsigned int i;
> > > + int ppas = *nr_rail_ppas;
> > > + int valid = 0;
> > > +
> > > + for (i = 1; i < PBLK_RAIL_STRIDE_WIDTH; i++) {
> > > + unsigned int neighbor, lun, chnl;
> > > + int laddr;
> > > +
> > > + neighbor = pblk_rail_wrap_lun(pblk, lun_pos + i * strides);
> > > +
> > > + lun = pblk_pos_to_lun(geo, neighbor);
> > > + chnl = pblk_pos_to_chnl(geo, neighbor);
> > > + pblk_dev_ppa_set_lun(&rail_ppa, lun);
> > > + pblk_dev_ppa_set_chnl(&rail_ppa, chnl);
> > > +
> > > + line = pblk_ppa_to_line(pblk, rail_ppa);
> > > + laddr = pblk_dev_ppa_to_line_addr(pblk, rail_ppa);
> > > +
> > > + /* Do not read from bad blocks */
> > > + if (!pblk_rail_valid_sector(pblk, line, laddr)) {
> > > + /* Perform regular read if parity sector is bad */
> > > + if (neighbor >= pblk_rail_nr_data_luns(pblk))
> > > + return 0;
> > > +
> > > + /* If any other neighbor is bad we can just skip it */
> > > + continue;
> > > + }
> > > +
> > > + rail_ppas[ppas++] = rail_ppa;
> > > + valid++;
> > > + }
> > > +
> > > + if (valid == 1)
> > > + return 0;
> > > +
> > > + *pvalid = valid;
> > > + *nr_rail_ppas = ppas;
> > > + (*rail_reads)++;
> > > + return 1;
> > > +}
> > > +
> > > +static void pblk_rail_set_bitmap(struct pblk *pblk, struct ppa_addr *ppa_list,
> > > + int ppa, struct ppa_addr *rail_ppa_list,
> > > + int *nr_rail_ppas, unsigned long *read_bitmap,
> > > + unsigned long *pvalid, int *rail_reads)
> > > +{
> > > + unsigned char valid;
> > > +
> > > + if (test_bit(ppa, read_bitmap))
> > > + return;
> > > +
> > > + if (pblk_rail_lun_busy(pblk, ppa_list[ppa]) &&
> > > + pblk_rail_setup_ppas(pblk, ppa_list[ppa],
> > > + rail_ppa_list, &valid,
> > > + nr_rail_ppas, rail_reads)) {
> > > + WARN_ON(test_and_set_bit(ppa, read_bitmap));
> > > + bitmap_set(pvalid, ppa * PBLK_RAIL_STRIDE_WIDTH, valid);
> > > + } else {
> > > + rail_ppa_list[(*nr_rail_ppas)++] = ppa_list[ppa];
> > > + bitmap_set(pvalid, ppa * PBLK_RAIL_STRIDE_WIDTH, 1);
> > > + }
> > > +}
> > > +
> > > +int pblk_rail_read_bio(struct pblk *pblk, struct nvm_rq *rqd, int blba,
> > > + unsigned long *read_bitmap, int bio_init_idx,
> > > + struct bio **bio)
> > > +{
> > > + struct pblk_g_ctx *r_ctx = nvm_rq_to_pdu(rqd);
> > > + struct pblk_pr_ctx *pr_ctx;
> > > + struct ppa_addr rail_ppa_list[NVM_MAX_VLBA];
> > > + DECLARE_BITMAP(pvalid, PR_BITMAP_SIZE);
> > > + int nr_secs = rqd->nr_ppas;
> > > + bool read_empty = bitmap_empty(read_bitmap, nr_secs);
> > > + int nr_rail_ppas = 0, rail_reads = 0;
> > > + int i;
> > > + int ret;
> > > +
> > > + /* Fully cached reads should not enter this path */
> > > + WARN_ON(bitmap_full(read_bitmap, nr_secs));
> > > +
> > > + bitmap_zero(pvalid, PR_BITMAP_SIZE);
> > > + if (rqd->nr_ppas == 1) {
> > > + pblk_rail_set_bitmap(pblk, &rqd->ppa_addr, 0, rail_ppa_list,
> > > + &nr_rail_ppas, read_bitmap, pvalid,
> > > + &rail_reads);
> > > +
> > > + if (nr_rail_ppas == 1) {
> > > + memcpy(&rqd->ppa_addr, rail_ppa_list,
> > > + nr_rail_ppas * sizeof(struct ppa_addr));
> > > + } else {
> > > + rqd->ppa_list = rqd->meta_list + pblk_dma_meta_size;
> > > + rqd->dma_ppa_list = rqd->dma_meta_list +
> > > + pblk_dma_meta_size;
> > > + memcpy(rqd->ppa_list, rail_ppa_list,
> > > + nr_rail_ppas * sizeof(struct ppa_addr));
> > > + }
> > > + } else {
> > > + for (i = 0; i < rqd->nr_ppas; i++) {
> > > + pblk_rail_set_bitmap(pblk, rqd->ppa_list, i,
> > > + rail_ppa_list, &nr_rail_ppas,
> > > + read_bitmap, pvalid, &rail_reads);
> > > +
> > > + /* Don't split if this it the last ppa of the rqd */
> > > + if (((nr_rail_ppas + PBLK_RAIL_STRIDE_WIDTH) >=
> > > + NVM_MAX_VLBA) && (i + 1 < rqd->nr_ppas)) {
> > > + struct pblk_g_ctx *r_ctx = nvm_rq_to_pdu(rqd);
> > > +
> > > + pblk_rail_bio_split(pblk, bio, i + 1);
> > > + rqd->nr_ppas = pblk_get_secs(*bio);
> > > + r_ctx->private = *bio;
> > > + break;
> > > + }
> > > + }
> > > + memcpy(rqd->ppa_list, rail_ppa_list,
> > > + nr_rail_ppas * sizeof(struct ppa_addr));
> > > + }
> > > +
> > > + if (bitmap_empty(read_bitmap, rqd->nr_ppas))
> > > + return NVM_IO_REQUEUE;
> > > +
> > > + if (read_empty && !bitmap_empty(read_bitmap, rqd->nr_ppas))
> > > + bio_advance(*bio, (rqd->nr_ppas) * PBLK_EXPOSED_PAGE_SIZE);
> > > +
> > > + if (pblk_setup_partial_read(pblk, rqd, bio_init_idx, read_bitmap,
> > > + nr_rail_ppas))
> > > + return NVM_IO_ERR;
> > > +
> > > + rqd->end_io = pblk_rail_end_io_read;
> > > + pr_ctx = r_ctx->private;
> > > + bitmap_copy(pr_ctx->bitmap, pvalid, PR_BITMAP_SIZE);
> > > +
> > > + ret = pblk_submit_io(pblk, rqd);
> > > + if (ret) {
> > > + bio_put(rqd->bio);
> > > + pr_err("pblk: partial RAIL read IO submission failed\n");
> > > + /* Free allocated pages in new bio */
> > > + pblk_bio_free_pages(pblk, rqd->bio, 0, rqd->bio->bi_vcnt);
> > > + kfree(pr_ctx);
> > > + __pblk_end_io_read(pblk, rqd, false);
> > > + return NVM_IO_ERR;
> > > + }
> > > +
> > > + return NVM_IO_OK;
> > > +}
> > > diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h
> > > index bd88784e51d9..01fe4362b27e 100644
> > > --- a/drivers/lightnvm/pblk.h
> > > +++ b/drivers/lightnvm/pblk.h
> > > @@ -28,6 +28,7 @@
> > > #include <linux/vmalloc.h>
> > > #include <linux/crc32.h>
> > > #include <linux/uuid.h>
> > > +#include <linux/log2.h>
> > >
> > > #include <linux/lightnvm.h>
> > >
> > > @@ -45,7 +46,7 @@
> > > #define PBLK_COMMAND_TIMEOUT_MS 30000
> > >
> > > /* Max 512 LUNs per device */
> > > -#define PBLK_MAX_LUNS_BITMAP (4)
> > > +#define PBLK_MAX_LUNS_BITMAP (512)
> >
> > 512 is probably enough for everyone for now, but why not make this dynamic?
> > Better not waste memory and introduce an artificial limit on number of luns.
>
> I can make it dynamic. It just makes the init path more messy as
> meta_init takes the write semaphore (and hence busy bitmap) so I have
> to init RAIL in the middle of everything else.
>
> >
> > >
> > > #define NR_PHY_IN_LOG (PBLK_EXPOSED_PAGE_SIZE / PBLK_SECTOR)
> > >
> > > @@ -123,6 +124,13 @@ struct pblk_g_ctx {
> > > u64 lba;
> > > };
> > >
> > > +#ifdef CONFIG_NVM_PBLK_RAIL
> > > +#define PBLK_RAIL_STRIDE_WIDTH 4
> > > +#define PR_BITMAP_SIZE (NVM_MAX_VLBA * PBLK_RAIL_STRIDE_WIDTH)
> > > +#else
> > > +#define PR_BITMAP_SIZE NVM_MAX_VLBA
> > > +#endif
> > > +
> > > /* partial read context */
> > > struct pblk_pr_ctx {
> > > struct bio *orig_bio;
> > > @@ -604,6 +612,39 @@ struct pblk_addrf {
> > > int sec_ws_stripe;
> > > };
> > >
> > > +#ifdef CONFIG_NVM_PBLK_RAIL
> > > +
> > > +struct p2b_entry {
> > > + int pos;
> > > + int nr_valid;
> > > +};
> > > +
> > > +struct pblk_rail {
> > > + struct p2b_entry **p2b; /* Maps RAIL sectors to rb pos */
> > > + struct page *pages; /* Pages to hold parity writes */
> > > + void **data; /* Buffer that holds parity pages */
> > > + DECLARE_BITMAP(busy_bitmap, PBLK_MAX_LUNS_BITMAP);
> > > + u64 *lba; /* Buffer to compute LBA parity */
> > > +};
> > > +
> > > +/* Initialize and tear down RAIL */
> > > +int pblk_rail_init(struct pblk *pblk);
> > > +void pblk_rail_free(struct pblk *pblk);
> > > +/* Adjust some system parameters */
> > > +bool pblk_rail_meta_distance(struct pblk_line *data_line);
> > > +int pblk_rail_rb_delay(struct pblk_rb *rb);
> > > +/* Core */
> > > +void pblk_rail_line_close(struct pblk *pblk, struct pblk_line *line);
> > > +int pblk_rail_down_stride(struct pblk *pblk, int lun, int timeout);
> > > +void pblk_rail_up_stride(struct pblk *pblk, int lun);
> > > +/* Write path */
> > > +int pblk_rail_submit_write(struct pblk *pblk);
> > > +/* Read Path */
> > > +int pblk_rail_read_bio(struct pblk *pblk, struct nvm_rq *rqd, int blba,
> > > + unsigned long *read_bitmap, int bio_init_idx,
> > > + struct bio **bio);
> > > +#endif /* CONFIG_NVM_PBLK_RAIL */
> > > +
> > > typedef int (pblk_map_page_fn)(struct pblk *pblk, unsigned int sentry,
> > > struct ppa_addr *ppa_list,
> > > unsigned long *lun_bitmap,
> > > @@ -1115,6 +1156,26 @@ static inline u64 pblk_dev_ppa_to_line_addr(struct pblk *pblk,
> > > return paddr;
> > > }
> > >
> > > +static inline int pblk_pos_to_lun(struct nvm_geo *geo, int pos)
> > > +{
> > > + return pos >> ilog2(geo->num_ch);
> > > +}
> > > +
> > > +static inline int pblk_pos_to_chnl(struct nvm_geo *geo, int pos)
> > > +{
> > > + return pos % geo->num_ch;
> > > +}
> > > +
> > > +static inline void pblk_dev_ppa_set_lun(struct ppa_addr *p, int lun)
> > > +{
> > > + p->a.lun = lun;
> > > +}
> > > +
> > > +static inline void pblk_dev_ppa_set_chnl(struct ppa_addr *p, int chnl)
> > > +{
> > > + p->a.ch = chnl;
> > > +}
> >
> > What is the motivation for adding the lun and chnl setters? They seem
> > uncalled for.
>
> They are used in RAIL's read path to generate the ppas for RAIL reads
It's just a style thing, but they seem a bit redundant to me.
>
> >
> > > +
> > > static inline struct ppa_addr pblk_ppa32_to_ppa64(struct pblk *pblk, u32 ppa32)
> > > {
> > > struct nvm_tgt_dev *dev = pblk->dev;
> > > --
> > > 2.17.1
> > >
