sg_copy_buffer() can't meet demand for some drrivers(such usb
mass storage), so we have to use the sg_miter_* APIs to access
sg buffer, then need export sg_miter_skip() for these drivers.

The API is needed for converting to sg_miter_* APIs in USB storage
driver for accessing sg buffer.

Cc: Andrew Morton <a...@linux-foundation.org>,
Cc: FUJITA Tomonori <fujita.tomon...@lab.ntt.co.jp>,
Cc: Tejun Heo <t...@kernel.org>,
Cc: Jens Axboe <ax...@kernel.dk>
Signed-off-by: Ming Lei <ming....@canonical.com>
---
 include/linux/scatterlist.h |    1 +
 lib/scatterlist.c           |    3 ++-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index adae88f..a964f72 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -345,6 +345,7 @@ struct sg_mapping_iter {
 
 void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
                    unsigned int nents, unsigned int flags);
+bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset);
 bool sg_miter_next(struct sg_mapping_iter *miter);
 void sg_miter_stop(struct sg_mapping_iter *miter);
 
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index d16fa29..3a8e8e8 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -495,7 +495,7 @@ static bool sg_miter_get_next_page(struct sg_mapping_iter 
*miter)
  *   true if @miter contains the valid mapping.  false if end of sg
  *   list is reached.
  */
-static bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset)
+bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset)
 {
        sg_miter_stop(miter);
 
@@ -513,6 +513,7 @@ static bool sg_miter_skip(struct sg_mapping_iter *miter, 
off_t offset)
 
        return true;
 }
+EXPORT_SYMBOL(sg_miter_skip);
 
 /**
  * sg_miter_next - proceed mapping iterator to the next mapping
-- 
1.7.9.5

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