Re: [RFC][PATCH 07/13] iov_iter.c: get rid of bvec_copy_page_{to,from}_iter()

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Hello.

On 12/4/2014 11:23 PM, Al Viro wrote:

Looks like you've erred in the subject as you seem to be getting rid of copy_page_{to|from}_iter_bvec() instead of bvec_copy_page_{to|from}_iter()...

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

Just have copy_page_{to,from}_iter() fall back to kmap_atomic +
copy_{to,from}_iter() + kunmap_atomic() in ITER_BVEC case.  As
the matter of fact, that's what we want to do for any iov_iter
kind that isn't blocking - e.g. ITER_KVEC will also go that way
once we recognize it on iov_iter.c primitives level

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
  mm/iov_iter.c | 60 ++++++++++++++++++++++++-----------------------------------
  1 file changed, 24 insertions(+), 36 deletions(-)

diff --git a/mm/iov_iter.c b/mm/iov_iter.c
index 39ad713..17b7144 100644
--- a/mm/iov_iter.c
+++ b/mm/iov_iter.c
@@ -486,30 +486,33 @@ static size_t copy_from_iter_bvec(void *to, size_t bytes, struct iov_iter *i)
  	return wanted;
  }

-static size_t copy_page_to_iter_bvec(struct page *page, size_t offset,
-					size_t bytes, struct iov_iter *i)
+size_t copy_to_iter(void *addr, size_t bytes, struct iov_iter *i)
  {
-	void *kaddr = kmap_atomic(page);
-	size_t wanted = copy_to_iter_bvec(kaddr + offset, bytes, i);
-	kunmap_atomic(kaddr);
-	return wanted;
+	if (i->type & ITER_BVEC)
+		return copy_to_iter_bvec(addr, bytes, i);
+	else
+		return copy_to_iter_iovec(addr, bytes, i);
  }
+EXPORT_SYMBOL(copy_to_iter);

-static size_t copy_page_from_iter_bvec(struct page *page, size_t offset,
-					size_t bytes, struct iov_iter *i)
+size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
  {
-	void *kaddr = kmap_atomic(page);
-	size_t wanted = copy_from_iter_bvec(kaddr + offset, bytes, i);
-	kunmap_atomic(kaddr);
-	return wanted;
+	if (i->type & ITER_BVEC)
+		return copy_from_iter_bvec(addr, bytes, i);
+	else
+		return copy_from_iter_iovec(addr, bytes, i);
  }
+EXPORT_SYMBOL(copy_from_iter);
[...]

WBR, Sergei

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