Commit 40b8657d authored by Javier González's avatar Javier González Committed by Jens Axboe
Browse files

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: default avatarJavier González <javier@cnexlabs.com>
Signed-off-by: default avatarMatias Bjørling <mb@lightnvm.io>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent dde4aac2

drivers/lightnvm/pblk-rb.c

+13 −8
Original line number Diff line number Diff line
@@ -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);

drivers/lightnvm/pblk-write.c

+2 −5
Original line number Diff line number Diff line
@@ -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);

}

drivers/lightnvm/pblk.h

+2 −0
Original line number Diff line number Diff line
@@ -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);

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