iov_iter: massage calling conventions for first_{iovec,bvec}_segment()

Pass maxsize by reference, return length via the same.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 45dccecae9467e96daf061c24f75d2c5bd487633..d93c6a1ffe265140d10c6f2988787cac71bec7e4 100644 (file)
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1294,8 +1294,7 @@ static ssize_t iter_xarray_get_pages(struct iov_iter *i,
 
 /* must be done on non-empty ITER_IOVEC one */
 static unsigned long first_iovec_segment(const struct iov_iter *i,
-                                        size_t *size, size_t *start,
-                                        size_t maxsize)
+                                        size_t *size, size_t *start)
 {
        size_t skip;
        long k;
@@ -1306,10 +1305,9 @@ static unsigned long first_iovec_segment(const struct iov_iter *i,
 
                if (unlikely(!len))
                        continue;
-               if (len > maxsize)
-                       len = maxsize;
+               if (*size > len)
+                       *size = len;
                *start = addr % PAGE_SIZE;
-               *size = len;
                return addr & PAGE_MASK;
        }
        BUG(); // if it had been empty, we wouldn't get called
@@ -1317,19 +1315,17 @@ static unsigned long first_iovec_segment(const struct iov_iter *i,
 
 /* must be done on non-empty ITER_BVEC one */
 static struct page *first_bvec_segment(const struct iov_iter *i,
-                                      size_t *size, size_t *start,
-                                      size_t maxsize)
+                                      size_t *size, size_t *start)
 {
        struct page *page;
        size_t skip = i->iov_offset, len;
 
        len = i->bvec->bv_len - skip;
-       if (len > maxsize)
-               len = maxsize;
+       if (*size > len)
+               *size = len;
        skip += i->bvec->bv_offset;
        page = i->bvec->bv_page + skip / PAGE_SIZE;
        *start = skip % PAGE_SIZE;
-       *size = len;
        return page;
 }
 
@@ -1337,7 +1333,6 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
                   struct page **pages, size_t maxsize, unsigned maxpages,
                   size_t *start)
 {
-       size_t len;
        int n, res;
 
        if (maxsize > i->count)
@@ -1356,25 +1351,25 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
                if (i->nofault)
                        gup_flags |= FOLL_NOFAULT;
 
-               addr = first_iovec_segment(i, &len, start, maxsize);
-               n = DIV_ROUND_UP(len + *start, PAGE_SIZE);
+               addr = first_iovec_segment(i, &maxsize, start);
+               n = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
                if (n > maxpages)
                        n = maxpages;
                res = get_user_pages_fast(addr, n, gup_flags, pages);
                if (unlikely(res <= 0))
                        return res;
-               return min_t(size_t, len, res * PAGE_SIZE - *start);
+               return min_t(size_t, maxsize, res * PAGE_SIZE - *start);
        }
        if (iov_iter_is_bvec(i)) {
                struct page *page;
 
-               page = first_bvec_segment(i, &len, start, maxsize);
-               n = DIV_ROUND_UP(len + *start, PAGE_SIZE);
+               page = first_bvec_segment(i, &maxsize, start);
+               n = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
                if (n > maxpages)
                        n = maxpages;
                for (int k = 0; k < n; k++)
                        get_page(*pages++ = page++);
-               return min_t(size_t, len, n * PAGE_SIZE - *start);
+               return min_t(size_t, maxsize, n * PAGE_SIZE - *start);
        }
        if (iov_iter_is_pipe(i))
                return pipe_get_pages(i, pages, maxsize, maxpages, start);
@@ -1469,7 +1464,6 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
                   size_t *start)
 {
        struct page **p;
-       size_t len;
        int n, res;
 
        if (maxsize > i->count)
@@ -1488,8 +1482,8 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
                if (i->nofault)
                        gup_flags |= FOLL_NOFAULT;
 
-               addr = first_iovec_segment(i, &len, start, maxsize);
-               n = DIV_ROUND_UP(len + *start, PAGE_SIZE);
+               addr = first_iovec_segment(i, &maxsize, start);
+               n = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
                p = get_pages_array(n);
                if (!p)
                        return -ENOMEM;
@@ -1500,19 +1494,19 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
                        return res;
                }
                *pages = p;
-               return min_t(size_t, len, res * PAGE_SIZE - *start);
+               return min_t(size_t, maxsize, res * PAGE_SIZE - *start);
        }
        if (iov_iter_is_bvec(i)) {
                struct page *page;
 
-               page = first_bvec_segment(i, &len, start, maxsize);
-               n = DIV_ROUND_UP(len + *start, PAGE_SIZE);
+               page = first_bvec_segment(i, &maxsize, start);
+               n = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
                *pages = p = get_pages_array(n);
                if (!p)
                        return -ENOMEM;
                for (int k = 0; k < n; k++)
                        get_page(*p++ = page++);
-               return min_t(size_t, len, n * PAGE_SIZE - *start);
+               return min_t(size_t, maxsize, n * PAGE_SIZE - *start);
        }
        if (iov_iter_is_pipe(i))
                return pipe_get_pages_alloc(i, pages, maxsize, start);