linux-kernel - [PATCH 04/10] lightnvm: pblk: schedule if data is not ready

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Date:   Fri, 30 Jun 2017 17:56:37 +0200
From:   "Javier González" <jg@...htnvm.io>
To:     mb@...htnvm.io, axboe@...com
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        Javier González <javier@...xlabs.com>,
        Matias Bjørling <matias@...xlabs.com>
Subject: [PATCH 04/10] lightnvm: pblk: schedule if data is not ready

When user threads place data into the write buffer, they reserve space
and do the memory copy out of the lock. As a consequence, when the write
thread starts persisting data, there is a chance that it is not copied
yet. In this case, avoid polling, and schedule before retrying.

Signed-off-by: Javier González <javier@...xlabs.com>
Signed-off-by: Matias Bjørling <matias@...xlabs.com>
---
 drivers/lightnvm/pblk-rb.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/lightnvm/pblk-rb.c b/drivers/lightnvm/pblk-rb.c
index 665a4ccfe7f5..2dda874af890 100644
--- a/drivers/lightnvm/pblk-rb.c
+++ b/drivers/lightnvm/pblk-rb.c
@@ -578,8 +578,10 @@ unsigned int pblk_rb_read_to_bio(struct pblk_rb *rb, struct nvm_rq *rqd,
 		 */
 try:
 		flags = READ_ONCE(entry->w_ctx.flags);
-		if (!(flags & PBLK_WRITTEN_DATA))
+		if (!(flags & PBLK_WRITTEN_DATA)) {
+			io_schedule();
 			goto try;
+		}
 
 		page = virt_to_page(entry->data);
 		if (!page) {
-- 
2.7.4