#include <linux/hardirq.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
+#include <linux/bio.h>
static size_t __iovec_copy_to_user(char *vaddr, const struct iovec *iov,
size_t base, size_t bytes, int atomic)
return 0;
}
- kaddr = kmap(page);
if (likely(i->nr_segs == 1)) {
int left;
char __user *buf = iov->iov_base + i->iov_offset;
+ /*
+ * Faults on the destination of a read are common, so do it
+ * before taking the kmap.
+ */
+ if (!fault_in_pages_writeable(buf, bytes)) {
+ kaddr = kmap_atomic(page);
+ left = __copy_to_user_inatomic(buf, kaddr + offset,
+ bytes);
+ kunmap_atomic(kaddr);
+ if (left == 0)
+ goto success;
+ }
+ kaddr = kmap(page);
left = copy_to_user(buf, kaddr + offset, bytes);
+ kunmap(page);
+success:
copied = bytes - left;
} else {
+ kaddr = kmap(page);
copied = __iovec_copy_to_user(kaddr + offset, iov,
i->iov_offset, bytes, 0);
+ kunmap(page);
}
- kunmap(page);
return copied;
}
+#ifdef CONFIG_BLOCK
+/*
+ * As an easily verifiable first pass, we implement all the methods that
+ * copy data to and from bvec pages with one function. We implement it
+ * all with kmap_atomic().
+ */
+static size_t bvec_copy_tofrom_page(struct iov_iter *iter, struct page *page,
+ unsigned long page_offset, size_t bytes,
+ int topage)
+{
+ struct bio_vec *bvec = (struct bio_vec *)iter->data;
+ size_t bvec_offset = iter->iov_offset;
+ size_t remaining = bytes;
+ void *bvec_map;
+ void *page_map;
+ size_t copy;
+
+ page_map = kmap_atomic(page);
+
+ BUG_ON(bytes > iter->count);
+ while (remaining) {
+ BUG_ON(bvec->bv_len == 0);
+ BUG_ON(bvec_offset >= bvec->bv_len);
+ copy = min(remaining, bvec->bv_len - bvec_offset);
+ bvec_map = kmap_atomic(bvec->bv_page);
+ if (topage)
+ memcpy(page_map + page_offset,
+ bvec_map + bvec->bv_offset + bvec_offset,
+ copy);
+ else
+ memcpy(bvec_map + bvec->bv_offset + bvec_offset,
+ page_map + page_offset,
+ copy);
+ kunmap_atomic(bvec_map);
+ remaining -= copy;
+ bvec_offset += copy;
+ page_offset += copy;
+ if (bvec_offset == bvec->bv_len) {
+ bvec_offset = 0;
+ bvec++;
+ }
+ }
+
+ kunmap_atomic(page_map);
+
+ return bytes;
+}
+
+static size_t ii_bvec_copy_to_user_atomic(struct page *page, struct iov_iter *i,
+ unsigned long offset, size_t bytes)
+{
+ return bvec_copy_tofrom_page(i, page, offset, bytes, 0);
+}
+static size_t ii_bvec_copy_to_user(struct page *page, struct iov_iter *i,
+ unsigned long offset, size_t bytes,
+ int check_access)
+{
+ return bvec_copy_tofrom_page(i, page, offset, bytes, 0);
+}
+static size_t ii_bvec_copy_from_user_atomic(struct page *page,
+ struct iov_iter *i,
+ unsigned long offset, size_t bytes)
+{
+ return bvec_copy_tofrom_page(i, page, offset, bytes, 1);
+}
+static size_t ii_bvec_copy_from_user(struct page *page, struct iov_iter *i,
+ unsigned long offset, size_t bytes)
+{
+ return bvec_copy_tofrom_page(i, page, offset, bytes, 1);
+}
+
+/*
+ * bio_vecs have a stricter structure than iovecs that might have
+ * come from userspace. There are no zero length bio_vec elements.
+ */
+static void ii_bvec_advance(struct iov_iter *i, size_t bytes)
+{
+ struct bio_vec *bvec = (struct bio_vec *)i->data;
+ size_t offset = i->iov_offset;
+ size_t delta;
+
+ BUG_ON(i->count < bytes);
+ while (bytes) {
+ BUG_ON(bvec->bv_len == 0);
+ BUG_ON(bvec->bv_len <= offset);
+ delta = min(bytes, bvec->bv_len - offset);
+ offset += delta;
+ i->count -= delta;
+ bytes -= delta;
+ if (offset == bvec->bv_len) {
+ bvec++;
+ offset = 0;
+ }
+ }
+
+ i->data = (unsigned long)bvec;
+ i->iov_offset = offset;
+}
+
+/*
+ * pages pointed to by bio_vecs are always pinned.
+ */
+static int ii_bvec_fault_in_readable(struct iov_iter *i, size_t bytes)
+{
+ return 0;
+}
+
+static size_t ii_bvec_single_seg_count(const struct iov_iter *i)
+{
+ const struct bio_vec *bvec = (struct bio_vec *)i->data;
+ if (i->nr_segs == 1)
+ return i->count;
+ else
+ return min(i->count, bvec->bv_len - i->iov_offset);
+}
+
+static int ii_bvec_shorten(struct iov_iter *i, size_t count)
+{
+ return -EINVAL;
+}
+
+struct iov_iter_ops ii_bvec_ops = {
+ .ii_copy_to_user_atomic = ii_bvec_copy_to_user_atomic,
+ .ii_copy_to_user = ii_bvec_copy_to_user,
+ .ii_copy_from_user_atomic = ii_bvec_copy_from_user_atomic,
+ .ii_copy_from_user = ii_bvec_copy_from_user,
+ .ii_advance = ii_bvec_advance,
+ .ii_fault_in_readable = ii_bvec_fault_in_readable,
+ .ii_single_seg_count = ii_bvec_single_seg_count,
+ .ii_shorten = ii_bvec_shorten,
+};
+EXPORT_SYMBOL(ii_bvec_ops);
+#endif /* CONFIG_BLOCK */
+
static size_t __iovec_copy_from_user(char *vaddr, const struct iovec *iov,
size_t base, size_t bytes, int atomic)
{
return min(i->count, iov->iov_len - i->iov_offset);
}
+static int ii_iovec_shorten(struct iov_iter *i, size_t count)
+{
+ struct iovec *iov = (struct iovec *)i->data;
+ i->nr_segs = iov_shorten(iov, i->nr_segs, count);
+ i->count = min(i->count, count);
+ return 0;
+}
+
struct iov_iter_ops ii_iovec_ops = {
.ii_copy_to_user_atomic = ii_iovec_copy_to_user_atomic,
.ii_copy_to_user = ii_iovec_copy_to_user,
.ii_advance = ii_iovec_advance,
.ii_fault_in_readable = ii_iovec_fault_in_readable,
.ii_single_seg_count = ii_iovec_single_seg_count,
+ .ii_shorten = ii_iovec_shorten,
};
EXPORT_SYMBOL(ii_iovec_ops);
projects / karo-tx-linux.git / blobdiff