md: Use enum for overloaded magic numbers used by mddev->curr_resync

Comments in the code document special values used for
mddev->curr_resync. Make this clearer by using an enum to label these
values.

The only functional change is a couple places use the wrong comparison
operator that implied 3 is another special value. They are all
fixed to imply that 3 or greater is an active resync.
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/md/md.c

@@ -5001,7 +5001,7 @@ static ssize_t
 sync_speed_show(struct mddev *mddev, char *page)
 {
 	unsigned long resync, dt, db;
-	if (mddev->curr_resync == 0)
+	if (mddev->curr_resync == MD_RESYNC_NONE)
 		return sprintf(page, "none\n");
 	resync = mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active);
 	dt = (jiffies - mddev->resync_mark) / HZ;
@@ -5020,8 +5020,8 @@ sync_completed_show(struct mddev *mddev, char *page)
 	if (!test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
 		return sprintf(page, "none\n");
 
-	if (mddev->curr_resync == 1 ||
-	    mddev->curr_resync == 2)
+	if (mddev->curr_resync == MD_RESYNC_YIELDED ||
+	    mddev->curr_resync == MD_RESYNC_DELAYED)
 		return sprintf(page, "delayed\n");
 
 	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
@@ -8018,7 +8018,7 @@ static int status_resync(struct seq_file *seq, struct mddev *mddev)
 		max_sectors = mddev->dev_sectors;
 
 	resync = mddev->curr_resync;
-	if (resync <= 3) {
+	if (resync < MD_RESYNC_ACTIVE) {
 		if (test_bit(MD_RECOVERY_DONE, &mddev->recovery))
 			/* Still cleaning up */
 			resync = max_sectors;
@@ -8027,7 +8027,7 @@ static int status_resync(struct seq_file *seq, struct mddev *mddev)
 	else
 		resync -= atomic_read(&mddev->recovery_active);
 
-	if (resync == 0) {
+	if (resync == MD_RESYNC_NONE) {
 		if (test_bit(MD_RESYNCING_REMOTE, &mddev->recovery)) {
 			struct md_rdev *rdev;
 
@@ -8051,7 +8051,7 @@ static int status_resync(struct seq_file *seq, struct mddev *mddev)
 		}
 		return 0;
 	}
-	if (resync < 3) {
+	if (resync < MD_RESYNC_ACTIVE) {
 		seq_printf(seq, "\tresync=DELAYED");
 		return 1;
 	}
@@ -8729,13 +8729,7 @@ void md_do_sync(struct md_thread *thread)
 
 	mddev->last_sync_action = action ?: desc;
 
-	/* we overload curr_resync somewhat here.
-	 * 0 == not engaged in resync at all
-	 * 2 == checking that there is no conflict with another sync
-	 * 1 == like 2, but have yielded to allow conflicting resync to
-	 *		commence
-	 * other == active in resync - this many blocks
-	 *
+	/*
 	 * Before starting a resync we must have set curr_resync to
 	 * 2, and then checked that every "conflicting" array has curr_resync
 	 * less than ours.  When we find one that is the same or higher
@@ -8747,7 +8741,7 @@ void md_do_sync(struct md_thread *thread)
 
 	do {
 		int mddev2_minor = -1;
-		mddev->curr_resync = 2;
+		mddev->curr_resync = MD_RESYNC_DELAYED;
 
 	try_again:
 		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
@@ -8759,12 +8753,14 @@ void md_do_sync(struct md_thread *thread)
 			&&  mddev2->curr_resync
 			&&  match_mddev_units(mddev, mddev2)) {
 				DEFINE_WAIT(wq);
-				if (mddev < mddev2 && mddev->curr_resync == 2) {
+				if (mddev < mddev2 &&
+				    mddev->curr_resync == MD_RESYNC_DELAYED) {
 					/* arbitrarily yield */
-					mddev->curr_resync = 1;
+					mddev->curr_resync = MD_RESYNC_YIELDED;
 					wake_up(&resync_wait);
 				}
-				if (mddev > mddev2 && mddev->curr_resync == 1)
+				if (mddev > mddev2 &&
+				    mddev->curr_resync == MD_RESYNC_YIELDED)
 					/* no need to wait here, we can wait the next
 					 * time 'round when curr_resync == 2
 					 */
@@ -8792,7 +8788,7 @@ void md_do_sync(struct md_thread *thread)
 				finish_wait(&resync_wait, &wq);
 			}
 		}
-	} while (mddev->curr_resync < 2);
+	} while (mddev->curr_resync < MD_RESYNC_DELAYED);
 
 	j = 0;
 	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
@@ -8876,7 +8872,7 @@ void md_do_sync(struct md_thread *thread)
 			 desc, mdname(mddev));
 		mddev->curr_resync = j;
 	} else
-		mddev->curr_resync = 3; /* no longer delayed */
+		mddev->curr_resync = MD_RESYNC_ACTIVE; /* no longer delayed */
 	mddev->curr_resync_completed = j;
 	sysfs_notify_dirent_safe(mddev->sysfs_completed);
 	md_new_event();
@@ -9011,14 +9007,14 @@ void md_do_sync(struct md_thread *thread)
 
 	if (!test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
 	    !test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
-	    mddev->curr_resync > 3) {
+	    mddev->curr_resync >= MD_RESYNC_ACTIVE) {
 		mddev->curr_resync_completed = mddev->curr_resync;
 		sysfs_notify_dirent_safe(mddev->sysfs_completed);
 	}
 	mddev->pers->sync_request(mddev, max_sectors, &skipped);
 
 	if (!test_bit(MD_RECOVERY_CHECK, &mddev->recovery) &&
-	    mddev->curr_resync > 3) {
+	    mddev->curr_resync >= MD_RESYNC_ACTIVE) {
 		if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
 			if (test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
 				if (mddev->curr_resync >= mddev->recovery_cp) {
@@ -9082,7 +9078,7 @@ void md_do_sync(struct md_thread *thread)
 	} else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
 		mddev->resync_min = mddev->curr_resync_completed;
 	set_bit(MD_RECOVERY_DONE, &mddev->recovery);
-	mddev->curr_resync = 0;
+	mddev->curr_resync = MD_RESYNC_NONE;
 	spin_unlock(&mddev->lock);
 
 	wake_up(&resync_wait);

drivers/md/md.h

@@ -288,6 +288,21 @@ struct serial_info {
 	sector_t _subtree_last; /* highest sector in subtree of rb node */
 };
 
+/*
+ * mddev->curr_resync stores the current sector of the resync but
+ * also has some overloaded values.
+ */
+enum {
+	/* No resync in progress */
+	MD_RESYNC_NONE = 0,
+	/* Yielded to allow another conflicting resync to commence */
+	MD_RESYNC_YIELDED = 1,
+	/* Delayed to check that there is no conflict with another sync */
+	MD_RESYNC_DELAYED = 2,
+	/* Any value greater than or equal to this is in an active resync */
+	MD_RESYNC_ACTIVE = 3,
+};
+
 struct mddev {
 	void				*private;
 	struct md_personality		*pers;