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lightnvm: pblk: encapsulate rb pointer operations 

pblk's read/write buffer is always a power-of-2, thus wrapping up the
buffer can be done with a bit mask. Since this is an implementation
detail internal to the write buffer, make a helper that hides pointer
increment + wrap, and allows to transparently relax this assumption in
the future.

Signed-off-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Javier González 2018-10-09 13:12:09 +02:00 committed by Jens Axboe
parent dde4aac20b
commit 40b8657dcc
3 changed files with 17 additions and 13 deletions
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21
drivers/lightnvm/pblk-rb.c
View File

@ -169,6 +169,12 @@ static unsigned int pblk_rb_space(struct pblk_rb *rb)
return pblk_rb_ring_space(rb, mem, sync, rb->nr_entries);
}
unsigned int pblk_rb_ptr_wrap(struct pblk_rb *rb, unsigned int p,
unsigned int nr_entries)
{
return (p + nr_entries) & (rb->nr_entries - 1);
}
/*
* Buffer count is calculated with respect to the submission entry signaling the
* entries that are available to send to the media
@ -195,8 +201,7 @@ unsigned int pblk_rb_read_commit(struct pblk_rb *rb, unsigned int nr_entries)
subm = READ_ONCE(rb->subm);
/* Commit read means updating submission pointer */
smp_store_release(&rb->subm,
(subm + nr_entries) & (rb->nr_entries - 1));
smp_store_release(&rb->subm, pblk_rb_ptr_wrap(rb, subm, nr_entries));
return subm;
}
@ -229,7 +234,7 @@ static int __pblk_rb_update_l2p(struct pblk_rb *rb, unsigned int to_update)
line = pblk_ppa_to_line(pblk, w_ctx->ppa);
kref_put(&line->ref, pblk_line_put);
clean_wctx(w_ctx);
rb->l2p_update = (rb->l2p_update + 1) & (rb->nr_entries - 1);
rb->l2p_update = pblk_rb_ptr_wrap(rb, rb->l2p_update, 1);
}
pblk_rl_out(&pblk->rl, user_io, gc_io);
@ -408,7 +413,7 @@ static int pblk_rb_may_write(struct pblk_rb *rb, unsigned int nr_entries,
return 0;
/* Protect from read count */
smp_store_release(&rb->mem, (*pos + nr_entries) & (rb->nr_entries - 1));
smp_store_release(&rb->mem, pblk_rb_ptr_wrap(rb, *pos, nr_entries));
return 1;
}
@ -432,7 +437,7 @@ static int pblk_rb_may_write_flush(struct pblk_rb *rb, unsigned int nr_entries,
if (!__pblk_rb_may_write(rb, nr_entries, pos))
return 0;
mem = (*pos + nr_entries) & (rb->nr_entries - 1);
mem = pblk_rb_ptr_wrap(rb, *pos, nr_entries);
*io_ret = NVM_IO_DONE;
if (bio->bi_opf & REQ_PREFLUSH) {
@ -572,7 +577,7 @@ try:
/* Release flags on context. Protect from writes */
smp_store_release(&entry->w_ctx.flags, flags);
pos = (pos + 1) & (rb->nr_entries - 1);
pos = pblk_rb_ptr_wrap(rb, pos, 1);
}
if (pad) {
@ -652,7 +657,7 @@ out:
struct pblk_w_ctx *pblk_rb_w_ctx(struct pblk_rb *rb, unsigned int pos)
{
unsigned int entry = pos & (rb->nr_entries - 1);
unsigned int entry = pblk_rb_ptr_wrap(rb, pos, 0);
return &rb->entries[entry].w_ctx;
}
@ -698,7 +703,7 @@ unsigned int pblk_rb_sync_advance(struct pblk_rb *rb, unsigned int nr_entries)
}
}
sync = (sync + nr_entries) & (rb->nr_entries - 1);
sync = pblk_rb_ptr_wrap(rb, sync, nr_entries);
/* Protect from counts */
smp_store_release(&rb->sync, sync);

7
drivers/lightnvm/pblk-write.c
View File

@ -140,12 +140,11 @@ static void pblk_prepare_resubmit(struct pblk *pblk, unsigned int sentry,
struct pblk_w_ctx *w_ctx;
struct ppa_addr ppa_l2p;
int flags;
unsigned int pos, i;
unsigned int i;
spin_lock(&pblk->trans_lock);
pos = sentry;
for (i = 0; i < nr_entries; i++) {
entry = &rb->entries[pos];
entry = &rb->entries[pblk_rb_ptr_wrap(rb, sentry, i)];
w_ctx = &entry->w_ctx;
/* Check if the lba has been overwritten */
@ -164,8 +163,6 @@ static void pblk_prepare_resubmit(struct pblk *pblk, unsigned int sentry,
*/
line = pblk_ppa_to_line(pblk, w_ctx->ppa);
kref_put(&line->ref, pblk_line_put);
pos = (pos + 1) & (rb->nr_entries - 1);
}
spin_unlock(&pblk->trans_lock);
}

2
drivers/lightnvm/pblk.h
View File

@ -760,6 +760,8 @@ unsigned int pblk_rb_read_commit(struct pblk_rb *rb, unsigned int entries);
unsigned int pblk_rb_sync_init(struct pblk_rb *rb, unsigned long *flags);
unsigned int pblk_rb_sync_advance(struct pblk_rb *rb, unsigned int nr_entries);
unsigned int pblk_rb_ptr_wrap(struct pblk_rb *rb, unsigned int p,
unsigned int nr_entries);
void pblk_rb_sync_end(struct pblk_rb *rb, unsigned long *flags);
unsigned int pblk_rb_flush_point_count(struct pblk_rb *rb);