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Message-Id: <1417724597-17099-8-git-send-email-viro@ZenIV.linux.org.uk>
Date: Thu, 4 Dec 2014 20:23:12 +0000
From: Al Viro <viro@...IV.linux.org.uk>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
netdev@...r.kernel.org
Subject: [RFC][PATCH 08/13] iov_iter.c: convert copy_from_iter() to iterate_and_advance
From: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
mm/iov_iter.c | 106 +++++++++-------------------------------------------------
1 file changed, 15 insertions(+), 91 deletions(-)
diff --git a/mm/iov_iter.c b/mm/iov_iter.c
index 17b7144..791429d 100644
--- a/mm/iov_iter.c
+++ b/mm/iov_iter.c
@@ -142,51 +142,6 @@ static size_t copy_to_iter_iovec(void *from, size_t bytes, struct iov_iter *i)
return wanted - bytes;
}
-static size_t copy_from_iter_iovec(void *to, size_t bytes, struct iov_iter *i)
-{
- size_t skip, copy, left, wanted;
- const struct iovec *iov;
- char __user *buf;
-
- if (unlikely(bytes > i->count))
- bytes = i->count;
-
- if (unlikely(!bytes))
- return 0;
-
- wanted = bytes;
- iov = i->iov;
- skip = i->iov_offset;
- buf = iov->iov_base + skip;
- copy = min(bytes, iov->iov_len - skip);
-
- left = __copy_from_user(to, buf, copy);
- copy -= left;
- skip += copy;
- to += copy;
- bytes -= copy;
- while (unlikely(!left && bytes)) {
- iov++;
- buf = iov->iov_base;
- copy = min(bytes, iov->iov_len);
- left = __copy_from_user(to, buf, copy);
- copy -= left;
- skip = copy;
- to += copy;
- bytes -= copy;
- }
-
- if (skip == iov->iov_len) {
- iov++;
- skip = 0;
- }
- i->count -= wanted - bytes;
- i->nr_segs -= iov - i->iov;
- i->iov = iov;
- i->iov_offset = skip;
- return wanted - bytes;
-}
-
static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
@@ -444,48 +399,6 @@ static size_t copy_to_iter_bvec(void *from, size_t bytes, struct iov_iter *i)
return wanted - bytes;
}
-static size_t copy_from_iter_bvec(void *to, size_t bytes, struct iov_iter *i)
-{
- size_t skip, copy, wanted;
- const struct bio_vec *bvec;
-
- if (unlikely(bytes > i->count))
- bytes = i->count;
-
- if (unlikely(!bytes))
- return 0;
-
- wanted = bytes;
- bvec = i->bvec;
- skip = i->iov_offset;
-
- copy = min(bytes, bvec->bv_len - skip);
-
- memcpy_from_page(to, bvec->bv_page, bvec->bv_offset + skip, copy);
-
- to += copy;
- skip += copy;
- bytes -= copy;
-
- while (bytes) {
- bvec++;
- copy = min(bytes, (size_t)bvec->bv_len);
- memcpy_from_page(to, bvec->bv_page, bvec->bv_offset, copy);
- skip = copy;
- to += copy;
- bytes -= copy;
- }
- if (skip == bvec->bv_len) {
- bvec++;
- skip = 0;
- }
- i->count -= wanted;
- i->nr_segs -= bvec - i->bvec;
- i->bvec = bvec;
- i->iov_offset = skip;
- return wanted;
-}
-
size_t copy_to_iter(void *addr, size_t bytes, struct iov_iter *i)
{
if (i->type & ITER_BVEC)
@@ -497,10 +410,21 @@ EXPORT_SYMBOL(copy_to_iter);
size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
{
- if (i->type & ITER_BVEC)
- return copy_from_iter_bvec(addr, bytes, i);
- else
- return copy_from_iter_iovec(addr, bytes, i);
+ char *to = addr;
+ if (unlikely(bytes > i->count))
+ bytes = i->count;
+
+ if (unlikely(!bytes))
+ return 0;
+
+ iterate_and_advance(i, bytes, v,
+ __copy_from_user((to += v.iov_len) - v.iov_len, v.iov_base,
+ v.iov_len),
+ memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
+ v.bv_offset, v.bv_len)
+ )
+
+ return bytes;
}
EXPORT_SYMBOL(copy_from_iter);
--
2.1.3
--
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