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Message-Id: <1417724597-17099-10-git-send-email-viro@ZenIV.linux.org.uk>
Date: Thu, 4 Dec 2014 20:23:14 +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 10/13] iov_iter.c: handle ITER_KVEC directly
From: Al Viro <viro@...iv.linux.org.uk>
... without bothering with copy_..._user()
Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
include/linux/uio.h | 1 +
mm/iov_iter.c | 101 +++++++++++++++++++++++++++++++++++++++++++++-------
2 files changed, 89 insertions(+), 13 deletions(-)
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 9b15814..6e16945 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -31,6 +31,7 @@ struct iov_iter {
size_t count;
union {
const struct iovec *iov;
+ const struct kvec *kvec;
const struct bio_vec *bvec;
};
unsigned long nr_segs;
diff --git a/mm/iov_iter.c b/mm/iov_iter.c
index 66665449..d74de6d 100644
--- a/mm/iov_iter.c
+++ b/mm/iov_iter.c
@@ -32,6 +32,29 @@
n = wanted - n; \
}
+#define iterate_kvec(i, n, __v, __p, skip, STEP) { \
+ size_t wanted = n; \
+ __p = i->kvec; \
+ __v.iov_len = min(n, __p->iov_len - skip); \
+ if (likely(__v.iov_len)) { \
+ __v.iov_base = __p->iov_base + skip; \
+ (void)(STEP); \
+ skip += __v.iov_len; \
+ n -= __v.iov_len; \
+ } \
+ while (unlikely(n)) { \
+ __p++; \
+ __v.iov_len = min(n, __p->iov_len); \
+ if (unlikely(!__v.iov_len)) \
+ continue; \
+ __v.iov_base = __p->iov_base; \
+ (void)(STEP); \
+ skip = __v.iov_len; \
+ n -= __v.iov_len; \
+ } \
+ n = wanted; \
+}
+
#define iterate_bvec(i, n, __v, __p, skip, STEP) { \
size_t wanted = n; \
__p = i->bvec; \
@@ -57,12 +80,16 @@
n = wanted; \
}
-#define iterate_all_kinds(i, n, v, I, B) { \
+#define iterate_all_kinds(i, n, v, I, B, K) { \
size_t skip = i->iov_offset; \
if (unlikely(i->type & ITER_BVEC)) { \
const struct bio_vec *bvec; \
struct bio_vec v; \
iterate_bvec(i, n, v, bvec, skip, (B)) \
+ } else if (unlikely(i->type & ITER_KVEC)) { \
+ const struct kvec *kvec; \
+ struct kvec v; \
+ iterate_kvec(i, n, v, kvec, skip, (K)) \
} else { \
const struct iovec *iov; \
struct iovec v; \
@@ -70,7 +97,7 @@
} \
}
-#define iterate_and_advance(i, n, v, I, B) { \
+#define iterate_and_advance(i, n, v, I, B, K) { \
size_t skip = i->iov_offset; \
if (unlikely(i->type & ITER_BVEC)) { \
const struct bio_vec *bvec; \
@@ -82,6 +109,16 @@
} \
i->nr_segs -= bvec - i->bvec; \
i->bvec = bvec; \
+ } else if (unlikely(i->type & ITER_KVEC)) { \
+ const struct kvec *kvec; \
+ struct kvec v; \
+ iterate_kvec(i, n, v, kvec, skip, (K)) \
+ if (skip == kvec->iov_len) { \
+ kvec++; \
+ skip = 0; \
+ } \
+ i->nr_segs -= kvec - i->kvec; \
+ i->kvec = kvec; \
} else { \
const struct iovec *iov; \
struct iovec v; \
@@ -270,7 +307,7 @@ done:
*/
int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
{
- if (!(i->type & ITER_BVEC)) {
+ if (!(i->type & (ITER_BVEC|ITER_KVEC))) {
char __user *buf = i->iov->iov_base + i->iov_offset;
bytes = min(bytes, i->iov->iov_len - i->iov_offset);
return fault_in_pages_readable(buf, bytes);
@@ -284,10 +321,14 @@ void iov_iter_init(struct iov_iter *i, int direction,
size_t count)
{
/* It will get better. Eventually... */
- if (segment_eq(get_fs(), KERNEL_DS))
+ if (segment_eq(get_fs(), KERNEL_DS)) {
direction |= ITER_KVEC;
- i->type = direction;
- i->iov = iov;
+ i->type = direction;
+ i->kvec = (struct kvec *)iov;
+ } else {
+ i->type = direction;
+ i->iov = iov;
+ }
i->nr_segs = nr_segs;
i->iov_offset = 0;
i->count = count;
@@ -328,7 +369,8 @@ size_t copy_to_iter(void *addr, size_t bytes, struct iov_iter *i)
__copy_to_user(v.iov_base, (from += v.iov_len) - v.iov_len,
v.iov_len),
memcpy_to_page(v.bv_page, v.bv_offset,
- (from += v.bv_len) - v.bv_len, v.bv_len)
+ (from += v.bv_len) - v.bv_len, v.bv_len),
+ memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len)
)
return bytes;
@@ -348,7 +390,8 @@ size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
__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)
+ v.bv_offset, v.bv_len),
+ memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
)
return bytes;
@@ -371,7 +414,7 @@ EXPORT_SYMBOL(copy_page_to_iter);
size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
- if (i->type & ITER_BVEC) {
+ if (i->type & (ITER_BVEC|ITER_KVEC)) {
void *kaddr = kmap_atomic(page);
size_t wanted = copy_from_iter(kaddr + offset, bytes, i);
kunmap_atomic(kaddr);
@@ -391,7 +434,8 @@ size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
iterate_and_advance(i, bytes, v,
__clear_user(v.iov_base, v.iov_len),
- memzero_page(v.bv_page, v.bv_offset, v.bv_len)
+ memzero_page(v.bv_page, v.bv_offset, v.bv_len),
+ memset(v.iov_base, 0, v.iov_len)
)
return bytes;
@@ -406,7 +450,8 @@ size_t iov_iter_copy_from_user_atomic(struct page *page,
__copy_from_user_inatomic((p += v.iov_len) - v.iov_len,
v.iov_base, v.iov_len),
memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page,
- v.bv_offset, v.bv_len)
+ v.bv_offset, v.bv_len),
+ memcpy((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
)
kunmap_atomic(kaddr);
return bytes;
@@ -415,7 +460,7 @@ EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
void iov_iter_advance(struct iov_iter *i, size_t size)
{
- iterate_and_advance(i, size, v, 0, 0)
+ iterate_and_advance(i, size, v, 0, 0, 0)
}
EXPORT_SYMBOL(iov_iter_advance);
@@ -443,7 +488,8 @@ unsigned long iov_iter_alignment(const struct iov_iter *i)
iterate_all_kinds(i, size, v,
(res |= (unsigned long)v.iov_base | v.iov_len, 0),
- res |= v.bv_offset | v.bv_len
+ res |= v.bv_offset | v.bv_len,
+ res |= (unsigned long)v.iov_base | v.iov_len
)
return res;
}
@@ -478,6 +524,16 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
*start = v.bv_offset;
get_page(*pages = v.bv_page);
return v.bv_len;
+ }),({
+ unsigned long addr = (unsigned long)v.iov_base, end;
+ size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
+
+ if (len > maxpages * PAGE_SIZE)
+ len = maxpages * PAGE_SIZE;
+ addr &= ~(PAGE_SIZE - 1);
+ for (end = addr + len; addr < end; addr += PAGE_SIZE)
+ get_page(*pages++ = virt_to_page(addr));
+ return len - *start;
})
)
return 0;
@@ -530,6 +586,19 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
return -ENOMEM;
get_page(*p = v.bv_page);
return v.bv_len;
+ }),({
+ unsigned long addr = (unsigned long)v.iov_base, end;
+ size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
+ int n;
+
+ addr &= ~(PAGE_SIZE - 1);
+ n = DIV_ROUND_UP(len, PAGE_SIZE);
+ *pages = p = get_pages_array(n);
+ if (!p)
+ return -ENOMEM;
+ for (end = addr + len; addr < end; addr += PAGE_SIZE)
+ get_page(*p++ = virt_to_page(addr));
+ return len - *start;
})
)
return 0;
@@ -554,6 +623,12 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages)
npages++;
if (npages >= maxpages)
return maxpages;
+ }),({
+ unsigned long p = (unsigned long)v.iov_base;
+ npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
+ - p / PAGE_SIZE;
+ if (npages >= maxpages)
+ return maxpages;
})
)
return npages;
--
2.1.3
--
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