linux-kernel - [PATCH RFC v2 13/14] md/md-llbitmap: implement sysfs APIs

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Message-Id: <20250328060853.4124527-14-yukuai1@huaweicloud.com>
Date: Fri, 28 Mar 2025 14:08:52 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: hch@....de,
	xni@...hat.com,
	colyli@...nel.org,
	axboe@...nel.dk,
	agk@...hat.com,
	snitzer@...nel.org,
	mpatocka@...hat.com,
	song@...nel.org,
	yukuai3@...wei.com
Cc: linux-block@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	dm-devel@...ts.linux.dev,
	linux-raid@...r.kernel.org,
	yukuai1@...weicloud.com,
	yi.zhang@...wei.com,
	yangerkun@...wei.com
Subject: [PATCH RFC v2 13/14] md/md-llbitmap: implement sysfs APIs

From: Yu Kuai <yukuai3@...wei.com>

There are 3 APIs for now:
 - bits: readonly, show status of bitmap bits, the number of each value;
 - metadata: readonly show bitmap metadata, include chunksize, chunkshift,
 chunks, offset and daemon_sleep;
 - daemon_sleep: read-write, default value is 30;

Signed-off-by: Yu Kuai <yukuai3@...wei.com>
---
 drivers/md/md-llbitmap.c | 106 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 106 insertions(+)

diff --git a/drivers/md/md-llbitmap.c b/drivers/md/md-llbitmap.c
index a16bc84d9fa2..88ba29111e13 100644
--- a/drivers/md/md-llbitmap.c
+++ b/drivers/md/md-llbitmap.c
@@ -1234,6 +1234,110 @@ static void llbitmap_free(void *data)
 {
 }
 
+static ssize_t bits_show(struct mddev *mddev, char *page)
+{
+	struct llbitmap *llbitmap;
+	int bits[nr_llbitmap_state] = {0};
+	loff_t start = 0;
+
+	mutex_lock(&mddev->bitmap_info.mutex);
+	llbitmap = mddev->bitmap;
+	if (!llbitmap) {
+		mutex_unlock(&mddev->bitmap_info.mutex);
+		return sprintf(page, "no bitmap\n");
+	}
+
+	if (test_bit(BITMAP_WRITE_ERROR, &llbitmap->flags)) {
+		mutex_unlock(&mddev->bitmap_info.mutex);
+		return sprintf(page, "bitmap io error\n");
+	}
+
+	while (start < llbitmap->chunks) {
+		ssize_t ret;
+		enum llbitmap_state c;
+
+		ret = llbitmap_read(llbitmap, &c, start);
+		if (ret < 0) {
+			set_bit(BITMAP_WRITE_ERROR, &llbitmap->flags);
+			mutex_unlock(&mddev->bitmap_info.mutex);
+			return sprintf(page, "bitmap io error\n");
+		}
+
+		if (c < 0 || c >= nr_llbitmap_state)
+			pr_err("%s: invalid bit %llu state %d\n",
+			       __func__, start, c);
+		else
+			bits[c]++;
+		start++;
+	}
+
+	mutex_unlock(&mddev->bitmap_info.mutex);
+	return sprintf(page, "unwritten %d\nclean %d\ndirty %d\nneed sync %d\nsyncing %d\n",
+		       bits[BitUnwritten], bits[BitClean], bits[BitDirty],
+		       bits[BitNeedSync], bits[BitSyncing]);
+}
+
+static struct md_sysfs_entry llbitmap_bits =
+__ATTR_RO(bits);
+
+static ssize_t metadata_show(struct mddev *mddev, char *page)
+{
+	struct llbitmap *llbitmap;
+	ssize_t ret;
+
+	mutex_lock(&mddev->bitmap_info.mutex);
+	llbitmap = mddev->bitmap;
+	if (!llbitmap) {
+		mutex_unlock(&mddev->bitmap_info.mutex);
+		return sprintf(page, "no bitmap\n");
+	}
+
+	ret =  sprintf(page, "chunksize %lu\nchunkshift %lu\nchunks %lu\noffset %llu\ndaemon_sleep %lu\n",
+		       llbitmap->chunksize, llbitmap->chunkshift,
+		       llbitmap->chunks, mddev->bitmap_info.offset,
+		       llbitmap->mddev->bitmap_info.daemon_sleep);
+	mutex_unlock(&mddev->bitmap_info.mutex);
+
+	return ret;
+}
+
+static struct md_sysfs_entry llbitmap_metadata =
+__ATTR_RO(metadata);
+
+static ssize_t
+daemon_sleep_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%lu\n", mddev->bitmap_info.daemon_sleep);
+}
+
+static ssize_t
+daemon_sleep_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	unsigned long timeout;
+	int rv = kstrtoul(buf, 10, &timeout);
+
+	if (rv)
+		return rv;
+
+	mddev->bitmap_info.daemon_sleep = timeout;
+	return len;
+}
+
+static struct md_sysfs_entry llbitmap_daemon_sleep =
+__ATTR_RW(daemon_sleep);
+
+static struct attribute *md_llbitmap_attrs[] = {
+	&llbitmap_bits.attr,
+	&llbitmap_metadata.attr,
+	&llbitmap_daemon_sleep.attr,
+	NULL
+};
+
+static struct attribute_group md_llbitmap_group = {
+	.name = "llbitmap",
+	.attrs = md_llbitmap_attrs,
+};
+
 static struct bitmap_operations llbitmap_ops = {
 	.head = {
 		.type	= MD_BITMAP,
@@ -1274,4 +1378,6 @@ static struct bitmap_operations llbitmap_ops = {
 	.copy_from_slot		= llbitmap_copy_from_slot,
 	.set_pages		= llbitmap_set_pages,
 	.free			= llbitmap_free,
+
+	.group			= &md_llbitmap_group,
 };
-- 
2.39.2