loop: revert exclusive opener loop status change

This commit effectively reverts the following two commits:

2704024d83fa ("loop: add missing bd_abort_claiming in loop_set_status")
08e136ebd193 ("loop: don't change loop device under exclusive opener in loop_set_status")

as there are reports of them causing issues with unmounting. As we're
close to the 6.19 kernel release and the original author hasn't taken a
closer look at this yet, revert them for release.

Reported-by: nokangaroo <[e-mail]>
Link: https://lore.kernel.org/all/[e-mail]/
Signed-off-by: Jens Axboe <[e-mail]>

drivers/block/loop.c

···
 }
 
 static int
-loop_set_status(struct loop_device *lo, blk_mode_t mode,
-		struct block_device *bdev, const struct loop_info64 *info)
+loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
 {
 	int err;
 	bool partscan = false;
 	bool size_changed = false;
 	unsigned int memflags;
 
-	/*
-	 * If we don't hold exclusive handle for the device, upgrade to it
-	 * here to avoid changing device under exclusive owner.
-	 */
-	if (!(mode & BLK_OPEN_EXCL)) {
-		err = bd_prepare_to_claim(bdev, loop_set_status, NULL);
-		if (err)
-			goto out_reread_partitions;
-	}
-
 	err = mutex_lock_killable(&lo->lo_mutex);
 	if (err)
-		goto out_abort_claiming;
-
+		return err;
 	if (lo->lo_state != Lo_bound) {
 		err = -ENXIO;
 		goto out_unlock;
···
 	}
 out_unlock:
 	mutex_unlock(&lo->lo_mutex);
-out_abort_claiming:
-	if (!(mode & BLK_OPEN_EXCL))
-		bd_abort_claiming(bdev, loop_set_status);
-out_reread_partitions:
 	if (partscan)
 		loop_reread_partitions(lo);
 
···
 }
 
 static int
-loop_set_status_old(struct loop_device *lo, blk_mode_t mode,
-		    struct block_device *bdev,
-		    const struct loop_info __user *arg)
+loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
 {
 	struct loop_info info;
 	struct loop_info64 info64;
···
 	if (copy_from_user(&info, arg, sizeof (struct loop_info)))
 		return -EFAULT;
 	loop_info64_from_old(&info, &info64);
-	return loop_set_status(lo, mode, bdev, &info64);
+	return loop_set_status(lo, &info64);
 }
 
 static int
-loop_set_status64(struct loop_device *lo, blk_mode_t mode,
-		  struct block_device *bdev,
-		  const struct loop_info64 __user *arg)
+loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
 {
 	struct loop_info64 info64;
 
 	if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
 		return -EFAULT;
-	return loop_set_status(lo, mode, bdev, &info64);
+	return loop_set_status(lo, &info64);
 }
 
 static int
···
 	case LOOP_SET_STATUS:
 		err = -EPERM;
 		if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN))
-			err = loop_set_status_old(lo, mode, bdev, argp);
+			err = loop_set_status_old(lo, argp);
 		break;
 	case LOOP_GET_STATUS:
 		return loop_get_status_old(lo, argp);
 	case LOOP_SET_STATUS64:
 		err = -EPERM;
 		if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN))
-			err = loop_set_status64(lo, mode, bdev, argp);
+			err = loop_set_status64(lo, argp);
 		break;
 	case LOOP_GET_STATUS64:
 		return loop_get_status64(lo, argp);
···
 }
 
 static int
-loop_set_status_compat(struct loop_device *lo, blk_mode_t mode,
-		    struct block_device *bdev,
-		    const struct compat_loop_info __user *arg)
+loop_set_status_compat(struct loop_device *lo,
+		       const struct compat_loop_info __user *arg)
 {
 	struct loop_info64 info64;
 	int ret;
···
 	ret = loop_info64_from_compat(arg, &info64);
 	if (ret < 0)
 		return ret;
-	return loop_set_status(lo, mode, bdev, &info64);
+	return loop_set_status(lo, &info64);
 }
 
 static int
···
 
 	switch(cmd) {
 	case LOOP_SET_STATUS:
-		err = loop_set_status_compat(lo, mode, bdev,
+		err = loop_set_status_compat(lo,
 			     (const struct compat_loop_info __user *)arg);
 		break;
 	case LOOP_GET_STATUS: