[PATCH 1/2] md: Add configurability for consistency check feature

Ralph Mueck
2014-03-17T15:00:40Z

This patch adds sysfs configurability for the md level-1 RAID
consistency check.
The feature introduces a new attribute in sysfs named "safe_read".
To toggle consistency checks on/off, simply echo safe_read in
/sys/block/md*/md/safe_read.

Signed-off-by: Ralph Mueck <linux-kernel@rmueck.de>
Signed-off-by: Matthias Oefelein <ma.oefelein@arcor.de>

---
drivers/md/md.c | 27 +++++++++++++++++++++++++++
drivers/md/md.h | 3 +++
2 files changed, 30 insertions(+)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 4ad5cc4..5cc9a00 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4652,6 +4652,32 @@ static struct md_sysfs_entry md_array_size =
__ATTR(array_size, S_IRUGO|S_IWUSR, array_size_show,
array_size_store);

+static ssize_t
+safe_read_show(struct mddev *mddev, char *page)
+{
+ if(mddev->safe_read)
+ return sprintf(page, "enabled\n");
+ else
+ return sprintf(page, "disabled\n");
+}
+
+static ssize_t
+safe_read_store(struct mddev *mddev, const char *buf, size_t len)
+{
+ if(mddev->pers->level != 1) {
+ printk(KERN_NOTICE "RAID level not supported!\n");
+ return len;
+ }
+ if (strncmp(buf, "safe_read", 9) == 0) {
+ mddev->safe_read = !mddev->safe_read;
+ }
+ return len;
+}
+
+static struct md_sysfs_entry md_safe_read =
+__ATTR(safe_read, S_IRUGO|S_IWUSR, safe_read_show,
+ safe_read_store);
+
static struct attribute *md_default_attrs[] = {
&md_level.attr,
&md_layout.attr,
@@ -4667,6 +4693,7 @@ static struct attribute *md_default_attrs[] = {
&md_reshape_direction.attr,
&md_array_size.attr,
&max_corr_read_errors.attr,
+ &md_safe_read.attr,
NULL,
};

diff --git a/drivers/md/md.h b/drivers/md/md.h
index 07bba96..7e59cf1 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -346,6 +346,9 @@ struct mddev {
*/
int recovery_disabled;

+ /* Set to 1 if the user desires a safe read (check for bitrot) */
+ int safe_read;
+
int in_sync; /* know to not need resync */
/* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
* that we are never stopping an array while it is open.
--
1.8.3.2