iov_iter: Convert iter_xarray to use folios

Take advantage of how kmap_local_folio() works to simplify the loop.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 66a740e6e153c4846abef78d54dfcff97e96219c..b0e0acdf96c15e73326c217ae7903fcd364ddc99 100644 (file)
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -69,42 +69,40 @@
 #define iterate_xarray(i, n, base, len, __off, STEP) {         \
        __label__ __out;                                        \
        size_t __off = 0;                                       \
-       struct page *head = NULL;                               \
+       struct folio *folio;                                    \
        loff_t start = i->xarray_start + i->iov_offset;         \
-       unsigned offset = start % PAGE_SIZE;                    \
        pgoff_t index = start / PAGE_SIZE;                      \
-       int j;                                                  \
-                                                               \
        XA_STATE(xas, i->xarray, index);                        \
                                                                \
+       len = PAGE_SIZE - offset_in_page(start);                \
        rcu_read_lock();                                        \
-       xas_for_each(&xas, head, ULONG_MAX) {                   \
+       xas_for_each(&xas, folio, ULONG_MAX) {                  \
                unsigned left;                                  \
-               if (xas_retry(&xas, head))                      \
+               size_t offset;                                  \
+               if (xas_retry(&xas, folio))                     \
                        continue;                               \
-               if (WARN_ON(xa_is_value(head)))                 \
+               if (WARN_ON(xa_is_value(folio)))                \
                        break;                                  \
-               if (WARN_ON(PageHuge(head)))                    \
+               if (WARN_ON(folio_test_hugetlb(folio)))         \
                        break;                                  \
-               for (j = (head->index < index) ? index - head->index : 0; \
-                    j < thp_nr_pages(head); j++) {             \
-                       void *kaddr = kmap_local_page(head + j);        \
-                       base = kaddr + offset;                  \
-                       len = PAGE_SIZE - offset;               \
+               offset = offset_in_folio(folio, start + __off); \
+               while (offset < folio_size(folio)) {            \
+                       base = kmap_local_folio(folio, offset); \
                        len = min(n, len);                      \
                        left = (STEP);                          \
-                       kunmap_local(kaddr);                    \
+                       kunmap_local(base);                     \
                        len -= left;                            \
                        __off += len;                           \
                        n -= len;                               \
                        if (left || n == 0)                     \
                                goto __out;                     \
-                       offset = 0;                             \
+                       offset += len;                          \
+                       len = PAGE_SIZE;                        \
                }                                               \
        }                                                       \
 __out:                                                         \
        rcu_read_unlock();                                      \
-       i->iov_offset += __off;                                         \
+       i->iov_offset += __off;                                 \
        n = __off;                                              \
 }