linux-kernel - [PATCH] lightnvm: invalid offset calculation for lba

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Date:   Thu, 10 Nov 2016 12:26:57 +0100
From:   Matias Bjørling <m@...rling.me>
To:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        axboe@...com
Cc:     keith.busch@...el.com,
        Matias Bjørling <m@...rling.me>
Subject: [PATCH] lightnvm: invalid offset calculation for lba_shift

The ns->lba_shift assumes its value to be the logarithmic of the
LA size. A previous patch duplicated the lba_shift calculation into
lightnvm. It prematurely also subtracted a 512byte shift, which commonly
is applied per-command. The 512byte shift being subtracted twice led to
data loss when restoring the logical to physical mapping table from
device and when issuing I/O commands using rrpc.

Fix offset by removing the 512byte shift subtraction when calculating
lba_shift.

Fixes: b0b4e09c1ae7 "lightnvm: control life of nvm_dev in driver"
Reported-by: Javier González <javier@...xlabs.com>
Signed-off-by: Matias Bjørling <m@...rling.me>
---
 drivers/nvme/host/lightnvm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/host/lightnvm.c b/drivers/nvme/host/lightnvm.c
index f5e3011..5daf2f4 100644
--- a/drivers/nvme/host/lightnvm.c
+++ b/drivers/nvme/host/lightnvm.c
@@ -612,7 +612,7 @@ int nvme_nvm_register(struct nvme_ns *ns, char *disk_name, int node,

 	ret = nvm_register(dev);

-	ns->lba_shift = ilog2(dev->sec_size) - 9;
+	ns->lba_shift = ilog2(dev->sec_size);

 	if (sysfs_create_group(&dev->dev.kobj, attrs))
 		pr_warn("%s: failed to create sysfs group for identification\n",
-- 
2.1.4