summaryrefslogtreecommitdiff
path: root/lib/iov_iter.c
diff options
context:
space:
mode:
Diffstat (limited to 'lib/iov_iter.c')
-rw-r--r--lib/iov_iter.c112
1 files changed, 96 insertions, 16 deletions
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 6dd5330f7a99..507e732ef7cf 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1268,6 +1268,98 @@ void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count)
}
EXPORT_SYMBOL(iov_iter_discard);
+static bool iov_iter_aligned_iovec(const struct iov_iter *i, unsigned addr_mask,
+ unsigned len_mask)
+{
+ size_t size = i->count;
+ size_t skip = i->iov_offset;
+ unsigned k;
+
+ for (k = 0; k < i->nr_segs; k++, skip = 0) {
+ size_t len = i->iov[k].iov_len - skip;
+
+ if (len > size)
+ len = size;
+ if (len & len_mask)
+ return false;
+ if ((unsigned long)(i->iov[k].iov_base + skip) & addr_mask)
+ return false;
+
+ size -= len;
+ if (!size)
+ break;
+ }
+ return true;
+}
+
+static bool iov_iter_aligned_bvec(const struct iov_iter *i, unsigned addr_mask,
+ unsigned len_mask)
+{
+ size_t size = i->count;
+ unsigned skip = i->iov_offset;
+ unsigned k;
+
+ for (k = 0; k < i->nr_segs; k++, skip = 0) {
+ size_t len = i->bvec[k].bv_len - skip;
+
+ if (len > size)
+ len = size;
+ if (len & len_mask)
+ return false;
+ if ((unsigned long)(i->bvec[k].bv_offset + skip) & addr_mask)
+ return false;
+
+ size -= len;
+ if (!size)
+ break;
+ }
+ return true;
+}
+
+/**
+ * iov_iter_is_aligned() - Check if the addresses and lengths of each segments
+ * are aligned to the parameters.
+ *
+ * @i: &struct iov_iter to restore
+ * @addr_mask: bit mask to check against the iov element's addresses
+ * @len_mask: bit mask to check against the iov element's lengths
+ *
+ * Return: false if any addresses or lengths intersect with the provided masks
+ */
+bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
+ unsigned len_mask)
+{
+ if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i)))
+ return iov_iter_aligned_iovec(i, addr_mask, len_mask);
+
+ if (iov_iter_is_bvec(i))
+ return iov_iter_aligned_bvec(i, addr_mask, len_mask);
+
+ if (iov_iter_is_pipe(i)) {
+ unsigned int p_mask = i->pipe->ring_size - 1;
+ size_t size = i->count;
+
+ if (size & len_mask)
+ return false;
+ if (size && allocated(&i->pipe->bufs[i->head & p_mask])) {
+ if (i->iov_offset & addr_mask)
+ return false;
+ }
+
+ return true;
+ }
+
+ if (iov_iter_is_xarray(i)) {
+ if (i->count & len_mask)
+ return false;
+ if ((i->xarray_start + i->iov_offset) & addr_mask)
+ return false;
+ }
+
+ return true;
+}
+EXPORT_SYMBOL_GPL(iov_iter_is_aligned);
+
static unsigned long iov_iter_alignment_iovec(const struct iov_iter *i)
{
unsigned long res = 0;
@@ -1434,7 +1526,7 @@ static ssize_t iter_xarray_get_pages(struct iov_iter *i,
{
unsigned nr, offset;
pgoff_t index, count;
- size_t size = maxsize, actual;
+ size_t size = maxsize;
loff_t pos;
if (!size || !maxpages)
@@ -1461,13 +1553,7 @@ static ssize_t iter_xarray_get_pages(struct iov_iter *i,
if (nr == 0)
return 0;
- actual = PAGE_SIZE * nr;
- actual -= offset;
- if (nr == count && size > 0) {
- unsigned last_offset = (nr > 1) ? 0 : offset;
- actual -= PAGE_SIZE - (last_offset + size);
- }
- return actual;
+ return min_t(size_t, nr * PAGE_SIZE - offset, maxsize);
}
/* must be done on non-empty ITER_IOVEC one */
@@ -1602,7 +1688,7 @@ static ssize_t iter_xarray_get_pages_alloc(struct iov_iter *i,
struct page **p;
unsigned nr, offset;
pgoff_t index, count;
- size_t size = maxsize, actual;
+ size_t size = maxsize;
loff_t pos;
if (!size)
@@ -1631,13 +1717,7 @@ static ssize_t iter_xarray_get_pages_alloc(struct iov_iter *i,
if (nr == 0)
return 0;
- actual = PAGE_SIZE * nr;
- actual -= offset;
- if (nr == count && size > 0) {
- unsigned last_offset = (nr > 1) ? 0 : offset;
- actual -= PAGE_SIZE - (last_offset + size);
- }
- return actual;
+ return min_t(size_t, nr * PAGE_SIZE - offset, maxsize);
}
ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,