block: merge disk_scan_partitions and blkdev_reread_part

mainline inclusion
from mainline-v5.17-rc1
commit e16e506c
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6MQLP
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e16e506ccd673a3a888a34f8f694698305840044

--------------------------------

Unify the functionality that implements a partition rescan for a
gendisk.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-6-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

Conflicts:
	block/blk.h
	block/genhd.c
	block/ioctl.c
Signed-off-by: NYu Kuai <yukuai3@huawei.com>
Reviewed-by: NHou Tao <houtao1@huawei.com>
Signed-off-by: NJialin Zhang <zhangjialin11@huawei.com>
(cherry picked from commit 1c0b1b48)

block/blk.h

@@ -186,6 +186,7 @@ bool blk_bio_list_merge(struct request_queue *q, struct list_head *list,
 
 void blk_account_io_start(struct request *req);
 void blk_account_io_done(struct request *req, u64 now);
+int disk_scan_partitions(struct gendisk *disk, fmode_t mode);
 
 /*
  * Plug flush limits

block/genhd.c

@@ -736,17 +736,19 @@ static void register_disk(struct device *parent, struct gendisk *disk,
 	}
 }
 
-static void disk_scan_partitions(struct gendisk *disk)
+int disk_scan_partitions(struct gendisk *disk, fmode_t mode)
 {
 	struct block_device *bdev;
 
-	if (!get_capacity(disk) || !disk_part_scan_enabled(disk))
-		return;
+	if (!disk_part_scan_enabled(disk))
+		return -EINVAL;
 
 	set_bit(GD_NEED_PART_SCAN, &disk->state);
-	bdev = blkdev_get_by_dev(disk_devt(disk), FMODE_READ, NULL);
-	if (!IS_ERR(bdev))
-		blkdev_put(bdev, FMODE_READ);
+	bdev = blkdev_get_by_dev(disk_devt(disk), mode, NULL);
+	if (IS_ERR(bdev))
+		return PTR_ERR(bdev);
+	blkdev_put(bdev, mode);
+	return 0;
 }
 
 static void disk_init_partition(struct gendisk *disk)
@@ -755,7 +757,8 @@ static void disk_init_partition(struct gendisk *disk)
 	struct disk_part_iter piter;
 	struct hd_struct *part;
 
-	disk_scan_partitions(disk);
+	if (get_capacity(disk))
+		disk_scan_partitions(disk, FMODE_READ);
 
 	/* announce disk after possible partitions are created */
 	dev_set_uevent_suppress(ddev, 0);

block/ioctl.c

@@ -90,31 +90,6 @@ static int compat_blkpg_ioctl(struct block_device *bdev,
 }
 #endif
 
-static int blkdev_reread_part(struct block_device *bdev, fmode_t mode)
-{
-	struct block_device *tmp;
-
-	if (!disk_part_scan_enabled(bdev->bd_disk) || bdev_is_partition(bdev))
-		return -EINVAL;
-	if (!capable(CAP_SYS_ADMIN))
-		return -EACCES;
-	if (bdev->bd_part_count)
-		return -EBUSY;
-
-	/*
-	 * Reopen the device to revalidate the driver state and force a
-	 * partition rescan.
-	 */
-	mode &= ~FMODE_EXCL;
-	set_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
-
-	tmp = blkdev_get_by_dev(bdev->bd_dev, mode, NULL);
-	if (IS_ERR(tmp))
-		return PTR_ERR(tmp);
-	blkdev_put(tmp, mode);
-	return 0;
-}
-
 static int blk_ioctl_discard(struct block_device *bdev, fmode_t mode,
 		unsigned long arg, unsigned long flags)
 {
@@ -562,7 +537,13 @@ static int blkdev_common_ioctl(struct block_device *bdev, fmode_t mode,
 		bdev->bd_bdi->ra_pages = (arg * 512) / PAGE_SIZE;
 		return 0;
 	case BLKRRPART:
-		return blkdev_reread_part(bdev, mode);
+		if (!capable(CAP_SYS_ADMIN))
+			return -EACCES;
+		if (bdev_is_partition(bdev))
+			return -EINVAL;
+		if (bdev->bd_part_count)
+			return -EBUSY;
+		return disk_scan_partitions(bdev->bd_disk, mode & ~FMODE_EXCL);
 	case BLKTRACESTART:
 	case BLKTRACESTOP:
 	case BLKTRACETEARDOWN: