From 34cb92c0a5a15b04e285c690b5a7dee77ddeeaf1 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Sat, 23 Jul 2022 08:24:29 +0200
Subject: [PATCH] md: return the allocated devices from md_alloc
Git-commit: 34cb92c0a5a15b04e285c690b5a7dee77ddeeaf1
Patch-mainline: v6.0-rc1
References: jsc#PED-2766

Two callers of md_alloc want to use the newly allocated devices, so
return it instead of letting them find it cumbersomely after the
allocation.

(Coly Li: refreshed for Linux v5.14 based SUSE kernel)

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-and-tested-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Coly Li <colyli@suse.de>

---
 drivers/md/md-autodetect.c |   22 +++++-------------
 drivers/md/md.c            |   54 ++++++++++++++++++---------------------------
 drivers/md/md.h            |    3 +-
 3 files changed, 30 insertions(+), 49 deletions(-)

--- a/drivers/md/md-autodetect.c
+++ b/drivers/md/md-autodetect.c
@@ -125,7 +125,6 @@ static void __init md_setup_drive(struct
 	char *devname = args->device_names;
 	dev_t devices[MD_SB_DISKS + 1], mdev;
 	struct mdu_array_info_s ainfo = { };
-	struct block_device *bdev;
 	struct mddev *mddev;
 	int err = 0, i;
 	char name[16];
@@ -169,25 +168,16 @@ static void __init md_setup_drive(struct
 
 	pr_info("md: Loading %s: %s\n", name, args->device_names);
 
-	md_alloc(mdev, name);
-	bdev = blkdev_get_by_dev(mdev, FMODE_READ, NULL);
-	if (IS_ERR(bdev)) {
-		pr_err("md: open failed - cannot start array %s\n", name);
+	mddev = md_alloc(mdev, name);
+	if (IS_ERR(mddev)) {
+		pr_err("md: md_alloc failed - cannot start array %s\n", name);
 		return;
 	}
 
-	err = -EIO;
-	if (WARN(bdev->bd_disk->fops != &md_fops,
-			"Opening block device %x resulted in non-md device\n",
-			mdev))
-		goto out_blkdev_put;
-
-	mddev = bdev->bd_disk->private_data;
-
 	err = mddev_lock(mddev);
 	if (err) {
 		pr_err("md: failed to lock array %s\n", name);
-		goto out_blkdev_put;
+		goto out_mddev_put;
 	}
 
 	if (!list_empty(&mddev->disks) || mddev->raid_disks) {
@@ -231,8 +221,8 @@ static void __init md_setup_drive(struct
 		pr_warn("md: starting %s failed\n", name);
 out_unlock:
 	mddev_unlock(mddev);
-out_blkdev_put:
-	blkdev_put(bdev, FMODE_READ);
+out_mddev_put:
+	mddev_put(mddev);
 }
 
 static int __init raid_setup(char *str)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -635,7 +635,7 @@ static inline struct mddev *mddev_get(st
 
 static void mddev_delayed_delete(struct work_struct *ws);
 
-static void mddev_put(struct mddev *mddev)
+void mddev_put(struct mddev *mddev)
 {
 	if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
 		return;
@@ -714,24 +714,6 @@ static dev_t mddev_alloc_unit(void)
 	return dev;
 }
 
-#ifndef MODULE
-static struct mddev *mddev_find(dev_t unit)
-{
-	struct mddev *mddev;
-
-	if (MAJOR(unit) != MD_MAJOR)
-		unit &= ~((1 << MdpMinorShift) - 1);
-
-	spin_lock(&all_mddevs_lock);
-	mddev = mddev_find_locked(unit);
-	if (mddev && !mddev_get(mddev))
-		mddev = NULL;
-	spin_unlock(&all_mddevs_lock);
-
-	return mddev;
-}
-#endif
-
 static struct mddev *mddev_alloc(dev_t unit)
 {
 	struct mddev *new;
@@ -5614,7 +5596,7 @@ int mddev_init_writes_pending(struct mdd
 }
 EXPORT_SYMBOL_GPL(mddev_init_writes_pending);
 
-int md_alloc(dev_t dev, char *name)
+struct mddev *md_alloc(dev_t dev, char *name)
 {
 	/*
 	 * If dev is zero, name is the name of a device to allocate with
@@ -5706,17 +5688,16 @@ int md_alloc(dev_t dev, char *name)
 		 * different from a normal close on last release now.
 		 */
 		mddev->hold_active = 0;
-		goto done;
+		mutex_unlock(&disks_mutex);
+		mddev_put(mddev);
+		return ERR_PTR(error);
 	}
 
 	kobject_uevent(&mddev->kobj, KOBJ_ADD);
 	mddev->sysfs_state = sysfs_get_dirent_safe(mddev->kobj.sd, "array_state");
 	mddev->sysfs_level = sysfs_get_dirent_safe(mddev->kobj.sd, "level");
-
-done:
 	mutex_unlock(&disks_mutex);
-	mddev_put(mddev);
-	return error;
+	return mddev;
 
 out_put_disk:
 	blk_cleanup_queue(disk->queue);
@@ -5725,7 +5706,17 @@ out_free_mddev:
 	mddev_free(mddev);
 out_unlock:
 	mutex_unlock(&disks_mutex);
-	return error;
+	return ERR_PTR(error);
+}
+
+static int md_alloc_and_put(dev_t dev, char *name)
+{
+	struct mddev *mddev = md_alloc(dev, name);
+
+	if (IS_ERR(mddev))
+		return PTR_ERR(mddev);
+	mddev_put(mddev);
+	return 0;
 }
 
 static void md_probe(dev_t dev)
@@ -5733,7 +5724,7 @@ static void md_probe(dev_t dev)
 	if (MAJOR(dev) == MD_MAJOR && MINOR(dev) >= 512)
 		return;
 	if (create_on_open)
-		md_alloc(dev, NULL);
+		md_alloc_and_put(dev, NULL);
 }
 
 static int add_named_array(const char *val, const struct kernel_param *kp)
@@ -5755,12 +5746,12 @@ static int add_named_array(const char *v
 		return -E2BIG;
 	strscpy(buf, val, len+1);
 	if (strncmp(buf, "md_", 3) == 0)
-		return md_alloc(0, buf);
+		return md_alloc_and_put(0, buf);
 	if (strncmp(buf, "md", 2) == 0 &&
 	    isdigit(buf[2]) &&
 	    kstrtoul(buf+2, 10, &devnum) == 0 &&
 	    devnum <= MINORMASK)
-		return md_alloc(MKDEV(MD_MAJOR, devnum), NULL);
+		return md_alloc_and_put(MKDEV(MD_MAJOR, devnum), NULL);
 
 	return -EINVAL;
 }
@@ -6501,9 +6492,8 @@ static void autorun_devices(int part)
 			break;
 		}
 
-		md_alloc(dev, NULL);
-		mddev = mddev_find(dev);
-		if (!mddev)
+		mddev = md_alloc(dev, NULL);
+		if (IS_ERR(mddev))
 			break;
 
 		if (mddev_lock(mddev))
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -767,7 +767,8 @@ extern int md_integrity_add_rdev(struct
 extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);
 
 extern void mddev_init(struct mddev *mddev);
-int md_alloc(dev_t dev, char *name);
+struct mddev *md_alloc(dev_t dev, char *name);
+void mddev_put(struct mddev *mddev);
 extern int md_run(struct mddev *mddev);
 extern int md_start(struct mddev *mddev);
 extern void md_stop(struct mddev *mddev);