1 files changed, 557 insertions, 38 deletions

diff --git a/mm/iov_iter.c b/mm/iov_iter.c
index 10e46cd721de..7b5dbd1517b5 100644
--- a/mm/iov_iter.c
+++ b/mm/iov_iter.c
@@ -1,8 +1,10 @@
 #include <linux/export.h>
 #include <linux/uio.h>
 #include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
 
-size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
+static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes,
 			 struct iov_iter *i)
 {
 	size_t skip, copy, left, wanted;
@@ -72,13 +74,97 @@ size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
 	}
 	kunmap(page);
 done:
+	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_from_iter_iovec(struct page *page, size_t offset, size_t bytes,
+			 struct iov_iter *i)
+{
+	size_t skip, copy, left, wanted;
+	const struct iovec *iov;
+	char __user *buf;
+	void *kaddr, *to;
+
+	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);
+
+	if (!fault_in_pages_readable(buf, copy)) {
+		kaddr = kmap_atomic(page);
+		to = kaddr + offset;
+
+		/* first chunk, usually the only one */
+		left = __copy_from_user_inatomic(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_inatomic(to, buf, copy);
+			copy -= left;
+			skip = copy;
+			to += copy;
+			bytes -= copy;
+		}
+		if (likely(!bytes)) {
+			kunmap_atomic(kaddr);
+			goto done;
+		}
+		offset = to - kaddr;
+		buf += copy;
+		kunmap_atomic(kaddr);
+		copy = min(bytes, iov->iov_len - skip);
+	}
+	/* Too bad - revert to non-atomic kmap */
+	kaddr = kmap(page);
+	to = kaddr + offset;
+	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;
+	}
+	kunmap(page);
+done:
+	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;
 }
-EXPORT_SYMBOL(copy_page_to_iter);
 
 static size_t __iovec_copy_from_user_inatomic(char *vaddr,
 			const struct iovec *iov, size_t base, size_t bytes)
@@ -107,7 +193,7 @@ static size_t __iovec_copy_from_user_inatomic(char *vaddr,
  * were successfully copied.  If a fault is encountered then return the number of
  * bytes which were copied.
  */
-size_t iov_iter_copy_from_user_atomic(struct page *page,
+static size_t copy_from_user_atomic_iovec(struct page *page,
 		struct iov_iter *i, unsigned long offset, size_t bytes)
 {
 	char *kaddr;
@@ -127,36 +213,8 @@ size_t iov_iter_copy_from_user_atomic(struct page *page,
 
 	return copied;
 }
-EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
-
-/*
- * This has the same sideeffects and return value as
- * iov_iter_copy_from_user_atomic().
- * The difference is that it attempts to resolve faults.
- * Page must not be locked.
- */
-size_t iov_iter_copy_from_user(struct page *page,
-		struct iov_iter *i, unsigned long offset, size_t bytes)
-{
-	char *kaddr;
-	size_t copied;
-
-	kaddr = kmap(page);
-	if (likely(i->nr_segs == 1)) {
-		int left;
-		char __user *buf = i->iov->iov_base + i->iov_offset;
-		left = __copy_from_user(kaddr + offset, buf, bytes);
-		copied = bytes - left;
-	} else {
-		copied = __iovec_copy_from_user_inatomic(kaddr + offset,
-						i->iov, i->iov_offset, bytes);
-	}
-	kunmap(page);
-	return copied;
-}
-EXPORT_SYMBOL(iov_iter_copy_from_user);
 
-void iov_iter_advance(struct iov_iter *i, size_t bytes)
+static void advance_iovec(struct iov_iter *i, size_t bytes)
 {
 	BUG_ON(i->count < bytes);
 
@@ -191,7 +249,6 @@ void iov_iter_advance(struct iov_iter *i, size_t bytes)
 		i->nr_segs = nr_segs;
 	}
 }
-EXPORT_SYMBOL(iov_iter_advance);
 
 /*
  * Fault in the first iovec of the given iov_iter, to a maximum length
@@ -204,21 +261,483 @@ EXPORT_SYMBOL(iov_iter_advance);
  */
 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
 {
-	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);
+	if (!(i->type & ITER_BVEC)) {
+		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);
+	}
+	return 0;
 }
 EXPORT_SYMBOL(iov_iter_fault_in_readable);
 
+static unsigned long alignment_iovec(const struct iov_iter *i)
+{
+	const struct iovec *iov = i->iov;
+	unsigned long res;
+	size_t size = i->count;
+	size_t n;
+
+	if (!size)
+		return 0;
+
+	res = (unsigned long)iov->iov_base + i->iov_offset;
+	n = iov->iov_len - i->iov_offset;
+	if (n >= size)
+		return res | size;
+	size -= n;
+	res |= n;
+	while (size > (++iov)->iov_len) {
+		res |= (unsigned long)iov->iov_base | iov->iov_len;
+		size -= iov->iov_len;
+	}
+	res |= (unsigned long)iov->iov_base | size;
+	return res;
+}
+
+void iov_iter_init(struct iov_iter *i, int direction,
+			const struct iovec *iov, unsigned long nr_segs,
+			size_t count)
+{
+	/* It will get better.  Eventually... */
+	if (segment_eq(get_fs(), KERNEL_DS))
+		direction |= ITER_KVEC;
+	i->type = direction;
+	i->iov = iov;
+	i->nr_segs = nr_segs;
+	i->iov_offset = 0;
+	i->count = count;
+}
+EXPORT_SYMBOL(iov_iter_init);
+
+static ssize_t get_pages_iovec(struct iov_iter *i,
+		   struct page **pages, size_t maxsize,
+		   size_t *start)
+{
+	size_t offset = i->iov_offset;
+	const struct iovec *iov = i->iov;
+	size_t len;
+	unsigned long addr;
+	int n;
+	int res;
+
+	len = iov->iov_len - offset;
+	if (len > i->count)
+		len = i->count;
+	if (len > maxsize)
+		len = maxsize;
+	addr = (unsigned long)iov->iov_base + offset;
+	len += *start = addr & (PAGE_SIZE - 1);
+	addr &= ~(PAGE_SIZE - 1);
+	n = (len + PAGE_SIZE - 1) / PAGE_SIZE;
+	res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, pages);
+	if (unlikely(res < 0))
+		return res;
+	return (res == n ? len : res * PAGE_SIZE) - *start;
+}
+
+static ssize_t get_pages_alloc_iovec(struct iov_iter *i,
+		   struct page ***pages, size_t maxsize,
+		   size_t *start)
+{
+	size_t offset = i->iov_offset;
+	const struct iovec *iov = i->iov;
+	size_t len;
+	unsigned long addr;
+	void *p;
+	int n;
+	int res;
+
+	len = iov->iov_len - offset;
+	if (len > i->count)
+		len = i->count;
+	if (len > maxsize)
+		len = maxsize;
+	addr = (unsigned long)iov->iov_base + offset;
+	len += *start = addr & (PAGE_SIZE - 1);
+	addr &= ~(PAGE_SIZE - 1);
+	n = (len + PAGE_SIZE - 1) / PAGE_SIZE;
+	
+	p = kmalloc(n * sizeof(struct page *), GFP_KERNEL);
+	if (!p)
+		p = vmalloc(n * sizeof(struct page *));
+	if (!p)
+		return -ENOMEM;
+
+	res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, p);
+	if (unlikely(res < 0)) {
+		kvfree(p);
+		return res;
+	}
+	*pages = p;
+	return (res == n ? len : res * PAGE_SIZE) - *start;
+}
+
+static int iov_iter_npages_iovec(const struct iov_iter *i, int maxpages)
+{
+	size_t offset = i->iov_offset;
+	size_t size = i->count;
+	const struct iovec *iov = i->iov;
+	int npages = 0;
+	int n;
+
+	for (n = 0; size && n < i->nr_segs; n++, iov++) {
+		unsigned long addr = (unsigned long)iov->iov_base + offset;
+		size_t len = iov->iov_len - offset;
+		offset = 0;
+		if (unlikely(!len))	/* empty segment */
+			continue;
+		if (len > size)
+			len = size;
+		npages += (addr + len + PAGE_SIZE - 1) / PAGE_SIZE
+			  - addr / PAGE_SIZE;
+		if (npages >= maxpages)	/* don't bother going further */
+			return maxpages;
+		size -= len;
+		offset = 0;
+	}
+	return min(npages, maxpages);
+}
+
+static void memcpy_from_page(char *to, struct page *page, size_t offset, size_t len)
+{
+	char *from = kmap_atomic(page);
+	memcpy(to, from + offset, len);
+	kunmap_atomic(from);
+}
+
+static void memcpy_to_page(struct page *page, size_t offset, char *from, size_t len)
+{
+	char *to = kmap_atomic(page);
+	memcpy(to + offset, from, len);
+	kunmap_atomic(to);
+}
+
+static size_t copy_page_to_iter_bvec(struct page *page, size_t offset, size_t bytes,
+			 struct iov_iter *i)
+{
+	size_t skip, copy, wanted;
+	const struct bio_vec *bvec;
+	void *kaddr, *from;
+
+	if (unlikely(bytes > i->count))
+		bytes = i->count;
+
+	if (unlikely(!bytes))
+		return 0;
+
+	wanted = bytes;
+	bvec = i->bvec;
+	skip = i->iov_offset;
+	copy = min_t(size_t, bytes, bvec->bv_len - skip);
+
+	kaddr = kmap_atomic(page);
+	from = kaddr + offset;
+	memcpy_to_page(bvec->bv_page, skip + bvec->bv_offset, from, copy);
+	skip += copy;
+	from += copy;
+	bytes -= copy;
+	while (bytes) {
+		bvec++;
+		copy = min(bytes, (size_t)bvec->bv_len);
+		memcpy_to_page(bvec->bv_page, bvec->bv_offset, from, copy);
+		skip = copy;
+		from += copy;
+		bytes -= copy;
+	}
+	kunmap_atomic(kaddr);
+	if (skip == bvec->bv_len) {
+		bvec++;
+		skip = 0;
+	}
+	i->count -= wanted - bytes;
+	i->nr_segs -= bvec - i->bvec;
+	i->bvec = bvec;
+	i->iov_offset = skip;
+	return wanted - bytes;
+}
+
+static size_t copy_page_from_iter_bvec(struct page *page, size_t offset, size_t bytes,
+			 struct iov_iter *i)
+{
+	size_t skip, copy, wanted;
+	const struct bio_vec *bvec;
+	void *kaddr, *to;
+
+	if (unlikely(bytes > i->count))
+		bytes = i->count;
+
+	if (unlikely(!bytes))
+		return 0;
+
+	wanted = bytes;
+	bvec = i->bvec;
+	skip = i->iov_offset;
+
+	kaddr = kmap_atomic(page);
+
+	to = kaddr + 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;
+	}
+	kunmap_atomic(kaddr);
+	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;
+}
+
+static size_t copy_from_user_bvec(struct page *page,
+		struct iov_iter *i, unsigned long offset, size_t bytes)
+{
+	char *kaddr;
+	size_t left;
+	const struct bio_vec *bvec;
+	size_t base = i->iov_offset;
+
+	kaddr = kmap_atomic(page);
+	for (left = bytes, bvec = i->bvec; left; bvec++, base = 0) {
+		size_t copy = min(left, bvec->bv_len - base);
+		if (!bvec->bv_len)
+			continue;
+		memcpy_from_page(kaddr + offset, bvec->bv_page,
+				 bvec->bv_offset + base, copy);
+		offset += copy;
+		left -= copy;
+	}
+	kunmap_atomic(kaddr);
+	return bytes;
+}
+
+static void advance_bvec(struct iov_iter *i, size_t bytes)
+{
+	BUG_ON(i->count < bytes);
+
+	if (likely(i->nr_segs == 1)) {
+		i->iov_offset += bytes;
+		i->count -= bytes;
+	} else {
+		const struct bio_vec *bvec = i->bvec;
+		size_t base = i->iov_offset;
+		unsigned long nr_segs = i->nr_segs;
+
+		/*
+		 * The !iov->iov_len check ensures we skip over unlikely
+		 * zero-length segments (without overruning the iovec).
+		 */
+		while (bytes || unlikely(i->count && !bvec->bv_len)) {
+			int copy;
+
+			copy = min(bytes, bvec->bv_len - base);
+			BUG_ON(!i->count || i->count < copy);
+			i->count -= copy;
+			bytes -= copy;
+			base += copy;
+			if (bvec->bv_len == base) {
+				bvec++;
+				nr_segs--;
+				base = 0;
+			}
+		}
+		i->bvec = bvec;
+		i->iov_offset = base;
+		i->nr_segs = nr_segs;
+	}
+}
+
+static unsigned long alignment_bvec(const struct iov_iter *i)
+{
+	const struct bio_vec *bvec = i->bvec;
+	unsigned long res;
+	size_t size = i->count;
+	size_t n;
+
+	if (!size)
+		return 0;
+
+	res = bvec->bv_offset + i->iov_offset;
+	n = bvec->bv_len - i->iov_offset;
+	if (n >= size)
+		return res | size;
+	size -= n;
+	res |= n;
+	while (size > (++bvec)->bv_len) {
+		res |= bvec->bv_offset | bvec->bv_len;
+		size -= bvec->bv_len;
+	}
+	res |= bvec->bv_offset | size;
+	return res;
+}
+
+static ssize_t get_pages_bvec(struct iov_iter *i,
+		   struct page **pages, size_t maxsize,
+		   size_t *start)
+{
+	const struct bio_vec *bvec = i->bvec;
+	size_t len = bvec->bv_len - i->iov_offset;
+	if (len > i->count)
+		len = i->count;
+	if (len > maxsize)
+		len = maxsize;
+	*start = bvec->bv_offset + i->iov_offset;
+
+	get_page(*pages = bvec->bv_page);
+
+	return len;
+}
+
+static ssize_t get_pages_alloc_bvec(struct iov_iter *i,
+		   struct page ***pages, size_t maxsize,
+		   size_t *start)
+{
+	const struct bio_vec *bvec = i->bvec;
+	size_t len = bvec->bv_len - i->iov_offset;
+	if (len > i->count)
+		len = i->count;
+	if (len > maxsize)
+		len = maxsize;
+	*start = bvec->bv_offset + i->iov_offset;
+
+	*pages = kmalloc(sizeof(struct page *), GFP_KERNEL);
+	if (!*pages)
+		return -ENOMEM;
+
+	get_page(**pages = bvec->bv_page);
+
+	return len;
+}
+
+static int iov_iter_npages_bvec(const struct iov_iter *i, int maxpages)
+{
+	size_t offset = i->iov_offset;
+	size_t size = i->count;
+	const struct bio_vec *bvec = i->bvec;
+	int npages = 0;
+	int n;
+
+	for (n = 0; size && n < i->nr_segs; n++, bvec++) {
+		size_t len = bvec->bv_len - offset;
+		offset = 0;
+		if (unlikely(!len))	/* empty segment */
+			continue;
+		if (len > size)
+			len = size;
+		npages++;
+		if (npages >= maxpages)	/* don't bother going further */
+			return maxpages;
+		size -= len;
+		offset = 0;
+	}
+	return min(npages, maxpages);
+}
+
+size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
+			 struct iov_iter *i)
+{
+	if (i->type & ITER_BVEC)
+		return copy_page_to_iter_bvec(page, offset, bytes, i);
+	else
+		return copy_page_to_iter_iovec(page, offset, bytes, i);
+}
+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)
+		return copy_page_from_iter_bvec(page, offset, bytes, i);
+	else
+		return copy_page_from_iter_iovec(page, offset, bytes, i);
+}
+EXPORT_SYMBOL(copy_page_from_iter);
+
+size_t iov_iter_copy_from_user_atomic(struct page *page,
+		struct iov_iter *i, unsigned long offset, size_t bytes)
+{
+	if (i->type & ITER_BVEC)
+		return copy_from_user_bvec(page, i, offset, bytes);
+	else
+		return copy_from_user_atomic_iovec(page, i, offset, bytes);
+}
+EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
+
+void iov_iter_advance(struct iov_iter *i, size_t size)
+{
+	if (i->type & ITER_BVEC)
+		advance_bvec(i, size);
+	else
+		advance_iovec(i, size);
+}
+EXPORT_SYMBOL(iov_iter_advance);
+
 /*
  * Return the count of just the current iov_iter segment.
  */
 size_t iov_iter_single_seg_count(const struct iov_iter *i)
 {
-	const struct iovec *iov = i->iov;
 	if (i->nr_segs == 1)
 		return i->count;
+	else if (i->type & ITER_BVEC)
+		return min(i->count, i->iov->iov_len - i->iov_offset);
 	else
-		return min(i->count, iov->iov_len - i->iov_offset);
+		return min(i->count, i->bvec->bv_len - i->iov_offset);
 }
 EXPORT_SYMBOL(iov_iter_single_seg_count);
+
+unsigned long iov_iter_alignment(const struct iov_iter *i)
+{
+	if (i->type & ITER_BVEC)
+		return alignment_bvec(i);
+	else
+		return alignment_iovec(i);
+}
+EXPORT_SYMBOL(iov_iter_alignment);
+
+ssize_t iov_iter_get_pages(struct iov_iter *i,
+		   struct page **pages, size_t maxsize,
+		   size_t *start)
+{
+	if (i->type & ITER_BVEC)
+		return get_pages_bvec(i, pages, maxsize, start);
+	else
+		return get_pages_iovec(i, pages, maxsize, start);
+}
+EXPORT_SYMBOL(iov_iter_get_pages);
+
+ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
+		   struct page ***pages, size_t maxsize,
+		   size_t *start)
+{
+	if (i->type & ITER_BVEC)
+		return get_pages_alloc_bvec(i, pages, maxsize, start);
+	else
+		return get_pages_alloc_iovec(i, pages, maxsize, start);
+}
+EXPORT_SYMBOL(iov_iter_get_pages_alloc);
+
+int iov_iter_npages(const struct iov_iter *i, int maxpages)
+{
+	if (i->type & ITER_BVEC)
+		return iov_iter_npages_bvec(i, maxpages);
+	else
+		return iov_iter_npages_iovec(i, maxpages);
+}
+EXPORT_SYMBOL(iov_iter_npages);