Merge branch 'md-next' of https://git.kernel.org/pub/scm/linux/kernel/git/song/md into for-5.16/drivers

Pull MD updates from Song:

"The only significant change here is a fix in back_log sysfs entry, by
 Guoqing Jiang."

* 'md-next' of https://git.kernel.org/pub/scm/linux/kernel/git/song/md:
  raid5-ppl: use swap() to make code cleaner
  md/bitmap: don't set max_write_behind if there is no write mostly device

Author: axboe

drivers/md/md-bitmap.c

@@ -2469,11 +2469,30 @@ backlog_store(struct mddev *mddev, const char *buf, size_t len)
 {
 	unsigned long backlog;
 	unsigned long old_mwb = mddev->bitmap_info.max_write_behind;
+	struct md_rdev *rdev;
+	bool has_write_mostly = false;
 	int rv = kstrtoul(buf, 10, &backlog);
 	if (rv)
 		return rv;
 	if (backlog > COUNTER_MAX)
 		return -EINVAL;
+
+	/*
+	 * Without write mostly device, it doesn't make sense to set
+	 * backlog for max_write_behind.
+	 */
+	rdev_for_each(rdev, mddev) {
+		if (test_bit(WriteMostly, &rdev->flags)) {
+			has_write_mostly = true;
+			break;
+		}
+	}
+	if (!has_write_mostly) {
+		pr_warn_ratelimited("%s: can't set backlog, no write mostly device available\n",
+				    mdname(mddev));
+		return -EINVAL;
+	}
+
 	mddev->bitmap_info.max_write_behind = backlog;
 	if (!backlog && mddev->serial_info_pool) {
 		/* serial_info_pool is not needed if backlog is zero */

drivers/md/raid5-ppl.c

@@ -1081,7 +1081,7 @@ static int ppl_load_distributed(struct ppl_log *log)
 	struct ppl_conf *ppl_conf = log->ppl_conf;
 	struct md_rdev *rdev = log->rdev;
 	struct mddev *mddev = rdev->mddev;
-	struct page *page, *page2, *tmp;
+	struct page *page, *page2;
 	struct ppl_header *pplhdr = NULL, *prev_pplhdr = NULL;
 	u32 crc, crc_stored;
 	u32 signature;
@@ -1156,9 +1156,7 @@ static int ppl_load_distributed(struct ppl_log *log)
 		prev_pplhdr_offset = pplhdr_offset;
 		prev_pplhdr = pplhdr;
 
-		tmp = page;
-		page = page2;
-		page2 = tmp;
+		swap(page, page2);
 
 		/* calculate next potential ppl offset */
 		for (i = 0; i < le32_to_cpu(pplhdr->entries_count); i++)