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From:   Sergei Shtepa <sergei.shtepa@veeam.com>
To:     <axboe@kernel.dk>, <linux-block@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
CC:     Sergei Shtepa <sergei.shtepa@veeam.com>
Subject: [PATCH 05/20] block, blksnap: interaction with sysfs
Date:   Mon, 13 Jun 2022 18:52:58 +0300
Message-ID: <1655135593-1900-6-git-send-email-sergei.shtepa@veeam.com>
In-Reply-To: <1655135593-1900-1-git-send-email-sergei.shtepa@veeam.com>
References: <1655135593-1900-1-git-send-email-sergei.shtepa@veeam.com>
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Provides creation of a class file /sys/class/blksnap and a device file
/dev/blksnap for module management.

Signed-off-by: Sergei Shtepa <sergei.shtepa@veeam.com>
---
 drivers/block/blksnap/sysfs.c | 81 +++++++++++++++++++++++++++++++++++
 drivers/block/blksnap/sysfs.h |  5 +++
 2 files changed, 86 insertions(+)
 create mode 100644 drivers/block/blksnap/sysfs.c
 create mode 100644 drivers/block/blksnap/sysfs.h

diff --git a/drivers/block/blksnap/sysfs.c b/drivers/block/blksnap/sysfs.c
new file mode 100644
index 000000000000..32a34609d106
--- /dev/null
+++ b/drivers/block/blksnap/sysfs.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0
+#define pr_fmt(fmt) KBUILD_MODNAME "-sysfs: " fmt
+#include <linux/blkdev.h>
+#include <linux/sysfs.h>
+#include <linux/device.h>
+#include <linux/blk_snap.h>
+#ifdef CONFIG_BLK_SNAP_DEBUG_MEMORY_LEAK
+#include "memory_checker.h"
+#endif
+#include "sysfs.h"
+#include "ctrl.h"
+
+static ssize_t major_show(struct class *class, struct class_attribute *attr,
+			  char *buf)
+{
+	sprintf(buf, "%d", get_blk_snap_major());
+	return strlen(buf);
+}
+
+/* Declare class_attr_major */
+CLASS_ATTR_RO(major);
+
+static struct class *blk_snap_class;
+
+static struct device *blk_snap_device;
+
+int sysfs_init(void)
+{
+	struct device *dev;
+	int res;
+
+	blk_snap_class = class_create(THIS_MODULE, BLK_SNAP_MODULE_NAME);
+	if (IS_ERR(blk_snap_class)) {
+		res = PTR_ERR(blk_snap_class);
+
+		pr_err("Bad class create. errno=%d\n", abs(res));
+		return res;
+	}
+
+	pr_info("Create 'major' sysfs attribute\n");
+	res = class_create_file(blk_snap_class, &class_attr_major);
+	if (res) {
+		pr_err("Failed to create 'major' sysfs file\n");
+
+		class_destroy(blk_snap_class);
+		blk_snap_class = NULL;
+		return res;
+	}
+
+	dev = device_create(blk_snap_class, NULL,
+			    MKDEV(get_blk_snap_major(), 0), NULL,
+			    BLK_SNAP_MODULE_NAME);
+	if (IS_ERR(dev)) {
+		res = PTR_ERR(dev);
+		pr_err("Failed to create device, errno=%d\n", abs(res));
+
+		class_remove_file(blk_snap_class, &class_attr_major);
+		class_destroy(blk_snap_class);
+		blk_snap_class = NULL;
+		return res;
+	}
+
+	blk_snap_device = dev;
+	return res;
+}
+
+void sysfs_done(void)
+{
+	pr_info("Cleanup sysfs\n");
+
+	if (blk_snap_device) {
+		device_unregister(blk_snap_device);
+		blk_snap_device = NULL;
+	}
+
+	if (blk_snap_class != NULL) {
+		class_remove_file(blk_snap_class, &class_attr_major);
+		class_destroy(blk_snap_class);
+		blk_snap_class = NULL;
+	}
+}
diff --git a/drivers/block/blksnap/sysfs.h b/drivers/block/blksnap/sysfs.h
new file mode 100644
index 000000000000..b41c301fe33b
--- /dev/null
+++ b/drivers/block/blksnap/sysfs.h
@@ -0,0 +1,5 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#pragma once
+
+int sysfs_init(void);
+void sysfs_done(void);
-- 
2.20.1