block: factor out a chunk_size_left helper

Factor out a helper from blk_max_size_offset so that it can be reused
independently.

Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 914c613d81da7cc6b10cddcb49156fe9bfe3e3f2..e66ad451274ec66d3b66b9ce50584ef990ef2641 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -933,6 +933,17 @@ static inline unsigned int blk_queue_get_max_sectors(struct request_queue *q,
        return q->limits.max_sectors;
 }
 
+/*
+ * Return how much of the chunk is left to be used for I/O at a given offset.
+ */
+static inline unsigned int blk_chunk_sectors_left(sector_t offset,
+               unsigned int chunk_sectors)
+{
+       if (unlikely(!is_power_of_2(chunk_sectors)))
+               return chunk_sectors - sector_div(offset, chunk_sectors);
+       return chunk_sectors - (offset & (chunk_sectors - 1));
+}
+
 /*
  * Return maximum size of a request at given offset. Only valid for
  * file system requests.
@@ -948,12 +959,8 @@ static inline unsigned int blk_max_size_offset(struct request_queue *q,
                        return q->limits.max_sectors;
        }
 
-       if (likely(is_power_of_2(chunk_sectors)))
-               chunk_sectors -= offset & (chunk_sectors - 1);
-       else
-               chunk_sectors -= sector_div(offset, chunk_sectors);
-
-       return min(q->limits.max_sectors, chunk_sectors);
+       return min(q->limits.max_sectors,
+                       blk_chunk_sectors_left(offset, chunk_sectors));
 }
 
 /*