[PATCH nvme] nvme: Revert "nvme: Discard workaround for non-conformant devices"

From: Dakshaja Uppalapati <dakshaja@chelsio.com>
To: eduard@hasenleithner.at, kbusch@kernel.org, sagi@grimberg.me,
	hch@lst.de, gregkh@linuxfoundation.org
Cc: nirranjan@chelsio.com, bharat@chelsio.com,
	Dakshaja Uppalapati <dakshaja@chelsio.com>,
	stable <stable@vger.kernel.org>
Subject: [PATCH nvme] nvme: Revert "nvme: Discard workaround for non-conformant devices"
Date: Wed,  3 Jun 2020 14:48:51 +0530	[thread overview]
Message-ID: <20200603091851.16957-1-dakshaja@chelsio.com> (raw)

This reverts upstream 'commit 530436c45ef2
("nvme: Discard workaround for non-conformant devices")'

Since commit `530436c45ef2` introduced a regression due to which
blk_update_request IO error is observed on formatting device, reverting it.

Fixes: 530436c45ef2 ("nvme: Discard workaround for non-conformant devices")
Cc: stable <stable@vger.kernel.org> # 4.19+
Signed-off-by: Dakshaja Uppalapati <dakshaja@chelsio.com>
---
 drivers/nvme/host/core.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index f3c037f5a9ba..ec598a86f88e 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -607,14 +607,8 @@ static blk_status_t nvme_setup_discard(struct nvme_ns *ns, struct request *req,
 	struct nvme_dsm_range *range;
 	struct bio *bio;
 
-	/*
-	 * Some devices do not consider the DSM 'Number of Ranges' field when
-	 * determining how much data to DMA. Always allocate memory for maximum
-	 * number of segments to prevent device reading beyond end of buffer.
-	 */
-	static const size_t alloc_size = sizeof(*range) * NVME_DSM_MAX_RANGES;
-
-	range = kzalloc(alloc_size, GFP_ATOMIC | __GFP_NOWARN);
+	range = kmalloc_array(segments, sizeof(*range),
+			      GFP_ATOMIC | __GFP_NOWARN);
 	if (!range) {
 		/*
 		 * If we fail allocation our range, fallback to the controller
@@ -654,7 +648,7 @@ static blk_status_t nvme_setup_discard(struct nvme_ns *ns, struct request *req,
 
 	req->special_vec.bv_page = virt_to_page(range);
 	req->special_vec.bv_offset = offset_in_page(range);
-	req->special_vec.bv_len = alloc_size;
+	req->special_vec.bv_len = sizeof(*range) * segments;
 	req->rq_flags |= RQF_SPECIAL_PAYLOAD;
 
 	return BLK_STS_OK;
-- 
2.18.0.232.gb7bd9486b.dirty

