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>

diff --git a/drivers/lightnvm/pblk-rb.c b/drivers/lightnvm/pblk-rb.c
index 82829e8151db5977e3c9eaf8536fffb8dab8e036..e46d8cb9d28b3276779b7bd4fef6654fb4ca5cd1 100644 (file)
--- a/drivers/lightnvm/pblk-rb.c
+++ b/drivers/lightnvm/pblk-rb.c
@@ -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);

diff --git a/drivers/lightnvm/pblk-write.c b/drivers/lightnvm/pblk-write.c
index 277abc8633f747229674930cdc68b52a7f4772c1..fa8726493b39f629422311428ee195f4d640e83b 100644 (file)
--- a/drivers/lightnvm/pblk-write.c
+++ b/drivers/lightnvm/pblk-write.c
@@ -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);
 }

diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h
index 22586b78198ac48b8957a9bcdf22dcb2e8fd1f7c..7660811aa8af8e064f5e2f57d690f027b2905017 100644 (file)
--- a/drivers/lightnvm/pblk.h
+++ b/drivers/lightnvm/pblk.h
@@ -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);