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-rw-r--r--block/blk-settings.c22
-rw-r--r--include/linux/blkdev.h2
2 files changed, 24 insertions, 0 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 127f825..5eeb9e0 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -640,6 +640,28 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
EXPORT_SYMBOL(blk_stack_limits);
/**
+ * bdev_stack_limits - adjust queue limits for stacked drivers
+ * @t: the stacking driver limits (top device)
+ * @bdev: the component block_device (bottom)
+ * @start: first data sector within component device
+ *
+ * Description:
+ * Merges queue limits for a top device and a block_device. Returns
+ * 0 if alignment didn't change. Returns -1 if adding the bottom
+ * device caused misalignment.
+ */
+int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev,
+ sector_t start)
+{
+ struct request_queue *bq = bdev_get_queue(bdev);
+
+ start += get_start_sect(bdev);
+
+ return blk_stack_limits(t, &bq->limits, start << 9);
+}
+EXPORT_SYMBOL(bdev_stack_limits);
+
+/**
* disk_stack_limits - adjust queue limits for stacked drivers
* @disk: MD/DM gendisk (top)
* @bdev: the underlying block device (bottom)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index a41bcc8..5c80189 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -938,6 +938,8 @@ extern void blk_queue_io_opt(struct request_queue *q, unsigned int opt);
extern void blk_set_default_limits(struct queue_limits *lim);
extern int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
sector_t offset);
+extern int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev,
+ sector_t offset);
extern void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
sector_t offset);
extern void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b);
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