linux-kernel - [PATCH 22/23] md/md-llbitmap: implement sysfs APIs

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Message-Id: <20250524061320.370630-23-yukuai1@huaweicloud.com>
Date: Sat, 24 May 2025 14:13:19 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: hch@....de,
	xni@...hat.com,
	colyli@...nel.org,
	song@...nel.org,
	yukuai3@...wei.com
Cc: linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-raid@...r.kernel.org,
	yukuai1@...weicloud.com,
	yi.zhang@...wei.com,
	yangerkun@...wei.com,
	johnny.chenyi@...wei.com
Subject: [PATCH 22/23] 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>
---
 Documentation/admin-guide/md.rst | 13 +++++
 drivers/md/md-llbitmap.c         | 96 ++++++++++++++++++++++++++++++++
 2 files changed, 109 insertions(+)

diff --git a/Documentation/admin-guide/md.rst b/Documentation/admin-guide/md.rst
index 356d2a344f08..2030772075b5 100644
--- a/Documentation/admin-guide/md.rst
+++ b/Documentation/admin-guide/md.rst
@@ -444,6 +444,19 @@ If bitmap_type is bitmap, then the md device will also contain:
      once the array becomes non-degraded, and this fact has been
      recorded in the metadata.
 
+If bitmap_type is llbitmap, then the md device will also contain:
+
+  llbitmap/bits
+     This is readonly, show status of bitmap bits, the number of each
+     value.
+
+  llbitmap/metadata
+     This is readonly, show bitmap metadata, include chunksize, chunkshift,
+     chunks, offset and daemon_sleep.
+
+  llbitmap/daemon_sleep
+     This is readwrite, time in seconds that daemon function will be
+     triggered to clear dirty bits.
 As component devices are added to an md array, they appear in the ``md``
 directory as new directories named::
 
diff --git a/drivers/md/md-llbitmap.c b/drivers/md/md-llbitmap.c
index ae664aa110a8..38e67d4582ad 100644
--- a/drivers/md/md-llbitmap.c
+++ b/drivers/md/md-llbitmap.c
@@ -1391,4 +1391,100 @@ static void llbitmap_wait_behind_writes(struct mddev *mddev)
 
 }
 
+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 || !llbitmap->pctl) {
+		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) {
+		enum llbitmap_state c = llbitmap_read(llbitmap, start);
+
+		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,
+};
+
 #endif /* CONFIG_MD_LLBITMAP */
-- 
2.39.2