md: merge mddev faillast_dev into mddev_flags

There is not need to use a separate field in struct mddev, there are no
functional changes.

Link: https://lore.kernel.org/linux-raid/20260114171241.3043364-4-yukuai@fnnas.com
Signed-off-by: Yu Kuai <yukuai@fnnas.com>
Reviewed-by: Li Nan <linan122@huawei.com>

6 files changed, 18 insertions, 11 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index bf7666e227a1..b955eba7f461 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5864,11 +5864,11 @@ __ATTR(consistency_policy, S_IRUGO | S_IWUSR, consistency_policy_show,
 
 static ssize_t fail_last_dev_show(struct mddev *mddev, char *page)
 {
-	return sprintf(page, "%d\n", mddev->fail_last_dev);
+	return sprintf(page, "%d\n", test_bit(MD_FAILLAST_DEV, &mddev->flags));
 }
 
 /*
- * Setting fail_last_dev to true to allow last device to be forcibly removed
+ * Setting MD_FAILLAST_DEV to allow last device to be forcibly removed
  * from RAID1/RAID10.
  */
 static ssize_t
@@ -5881,8 +5881,10 @@ fail_last_dev_store(struct mddev *mddev, const char *buf, size_t len)
 	if (ret)
 		return ret;
 
-	if (value != mddev->fail_last_dev)
-		mddev->fail_last_dev = value;
+	if (value)
+		set_bit(MD_FAILLAST_DEV, &mddev->flags);
+	else
+		clear_bit(MD_FAILLAST_DEV, &mddev->flags);
 
 	return len;
 }
diff --git a/drivers/md/md.h b/drivers/md/md.h
index b4c9aa600edd..297a104fba88 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -341,6 +341,7 @@ struct md_cluster_operations;
  * @MD_BROKEN: This is used to stop writes and mark array as failed.
  * @MD_DELETED: This device is being deleted
  * @MD_HAS_SUPERBLOCK: There is persistence sb in member disks.
+ * @MD_FAILLAST_DEV: Allow last rdev to be removed.
  *
  * change UNSUPPORTED_MDDEV_FLAGS for each array type if new flag is added
  */
@@ -358,6 +359,7 @@ enum mddev_flags {
 	MD_DO_DELETE,
 	MD_DELETED,
 	MD_HAS_SUPERBLOCK,
+	MD_FAILLAST_DEV,
 };
 
 enum mddev_sb_flags {
@@ -625,7 +627,6 @@ struct mddev {
 	/* The sequence number for sync thread */
 	atomic_t sync_seq;
 
-	bool	fail_last_dev:1;
 	bool	serialize_policy:1;
 };
 
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index 985c377356eb..4d567fcf6a7c 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -27,7 +27,8 @@ module_param(default_layout, int, 0644);
 	 (1L << MD_JOURNAL_CLEAN) |	\
 	 (1L << MD_FAILFAST_SUPPORTED) |\
 	 (1L << MD_HAS_PPL) |		\
-	 (1L << MD_HAS_MULTIPLE_PPLS))
+	 (1L << MD_HAS_MULTIPLE_PPLS) |	\
+	 (1L << MD_FAILLAST_DEV))
 
 /*
  * inform the user of the raid configuration
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 57d50465eed1..98b5c93810bb 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1746,7 +1746,7 @@ static void raid1_status(struct seq_file *seq, struct mddev *mddev)
  *	- &mddev->degraded is bumped.
  *
  * @rdev is marked as &Faulty excluding case when array is failed and
- * &mddev->fail_last_dev is off.
+ * MD_FAILLAST_DEV is not set.
  */
 static void raid1_error(struct mddev *mddev, struct md_rdev *rdev)
 {
@@ -1759,7 +1759,7 @@ static void raid1_error(struct mddev *mddev, struct md_rdev *rdev)
 	    (conf->raid_disks - mddev->degraded) == 1) {
 		set_bit(MD_BROKEN, &mddev->flags);
 
-		if (!mddev->fail_last_dev) {
+		if (!test_bit(MD_FAILLAST_DEV, &mddev->flags)) {
 			conf->recovery_disabled = mddev->recovery_disabled;
 			spin_unlock_irqrestore(&conf->device_lock, flags);
 			return;
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 84be4cc7e873..09328e032f14 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1990,7 +1990,7 @@ static int enough(struct r10conf *conf, int ignore)
  *	- &mddev->degraded is bumped.
  *
  * @rdev is marked as &Faulty excluding case when array is failed and
- * &mddev->fail_last_dev is off.
+ * MD_FAILLAST_DEV is not set.
  */
 static void raid10_error(struct mddev *mddev, struct md_rdev *rdev)
 {
@@ -2002,7 +2002,7 @@ static void raid10_error(struct mddev *mddev, struct md_rdev *rdev)
 	if (test_bit(In_sync, &rdev->flags) && !enough(conf, rdev->raid_disk)) {
 		set_bit(MD_BROKEN, &mddev->flags);
 
-		if (!mddev->fail_last_dev) {
+		if (!test_bit(MD_FAILLAST_DEV, &mddev->flags)) {
 			spin_unlock_irqrestore(&conf->device_lock, flags);
 			return;
 		}
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index a85878b009f9..055293e56a7e 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -56,7 +56,10 @@
 #include "md-bitmap.h"
 #include "raid5-log.h"
 
-#define UNSUPPORTED_MDDEV_FLAGS	(1L << MD_FAILFAST_SUPPORTED)
+#define UNSUPPORTED_MDDEV_FLAGS		\
+	((1L << MD_FAILFAST_SUPPORTED) |	\
+	 (1L << MD_FAILLAST_DEV))
+
 
 #define cpu_to_group(cpu) cpu_to_node(cpu)
 #define ANY_GROUP NUMA_NO_NODE