block: cache the partition index in struct block_device

Signed-off-by: Christoph Hellwig <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
NigelCunningham · Aug 23, 2017 · c2ee070 · c2ee070
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commit c2ee070
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diff --git a/fs/block_dev.c b/fs/block_dev.c
@@ -1451,6 +1451,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
 		bdev->bd_disk = disk;
 		bdev->bd_queue = disk->queue;
 		bdev->bd_contains = bdev;
+		bdev->bd_partno = partno;
 
 		if (!partno) {
 			ret = -ENXIO;

diff --git a/include/linux/fs.h b/include/linux/fs.h
@@ -427,6 +427,7 @@ struct block_device {
 #endif
 	struct block_device *	bd_contains;
 	unsigned		bd_block_size;
+	u8			bd_partno;
 	struct hd_struct *	bd_part;
 	/* number of times partitions within this device have been opened. */
 	unsigned		bd_part_count;