[PATCH] Revert "nvme-fc: fold t fc_update_appid into fc_appid_store"

["Ewan D. Milne" <emilne@redhat.com>]

This reverts commit c814153c83a892dfd42026eaa661ae2c1f298792.

The commit c814153c83a8 "nvme-fc: fold t fc_update_appid into fc_appid_store"
changed the userspace interface, because the code that decrements "count"
to remove a trailing '\n' in the parsing results in the decremented value being
incorrectly be returned from the sysfs write.  Fix this by revering the commit.

Cc: stable@vger.kernel.org
Signed-off-by: Ewan D. Milne <emilne@redhat.com>
---
 drivers/nvme/host/fc.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index 9987797620b6..27f6dfad5d3b 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -3873,10 +3873,12 @@ static int fc_parse_cgrpid(const char *buf, u64 *id)
 }
 
 /*
- * Parse and update the appid in the blkcg associated with the cgroupid.
+ * fc_update_appid: Parse and update the appid in the blkcg associated with
+ * cgroupid.
+ * @buf: buf contains both cgrpid and appid info
+ * @count: size of the buffer
  */
-static ssize_t fc_appid_store(struct device *dev,
-		struct device_attribute *attr, const char *buf, size_t count)
+static int fc_update_appid(const char *buf, size_t count)
 {
 	u64 cgrp_id;
 	int appid_len = 0;
@@ -3904,6 +3906,17 @@ static ssize_t fc_appid_store(struct device *dev,
 		return ret;
 	return count;
 }
+
+static ssize_t fc_appid_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	int ret  = 0;
+
+	ret = fc_update_appid(buf, count);
+	if (ret < 0)
+		return -EINVAL;
+	return count;
+}
 static DEVICE_ATTR(appid_store, 0200, NULL, fc_appid_store);
 #endif /* CONFIG_BLK_CGROUP_FC_APPID */
 
-- 
2.20.1