ceph_sync_read: stop poking into iov_iter guts

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

1 files changed, 18 insertions, 28 deletions

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index c9a24ba98c9a..672b0fedb17b 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -418,7 +418,7 @@ static ssize_t ceph_sync_read(struct kiocb *iocb, struct iov_iter *i,
         struct page **pages;
         u64 off = iocb->ki_pos;
         int num_pages, ret;
-        size_t len = i->count;
+        size_t len = iov_iter_count(i);
 
         dout("sync_read on file %p %llu~%u %s\n", file, off,
              (unsigned)len,
@@ -436,25 +436,26 @@ static ssize_t ceph_sync_read(struct kiocb *iocb, struct iov_iter *i,
 
         if (file->f_flags & O_DIRECT) {
                 while (iov_iter_count(i)) {
-                        void __user *data = i->iov[0].iov_base + i->iov_offset;
-                        size_t len = i->iov[0].iov_len - i->iov_offset;
+                        size_t start;
+                        ssize_t n;
 
-                        num_pages = calc_pages_for((unsigned long)data, len);
-                        pages = ceph_get_direct_page_vector(data,
-                                                            num_pages, true);
-                        if (IS_ERR(pages))
-                                return PTR_ERR(pages);
+                        n = iov_iter_get_pages_alloc(i, &pages, INT_MAX, &start);
+                        if (n < 0)
+                                return n;
 
-                        ret = striped_read(inode, off, len,
+                        num_pages = (n + start + PAGE_SIZE - 1) / PAGE_SIZE;
+
+                        ret = striped_read(inode, off, n,
                                            pages, num_pages, checkeof,
-                                           1, (unsigned long)data & ~PAGE_MASK);
+                                           1, start);
+
                         ceph_put_page_vector(pages, num_pages, true);
 
                         if (ret <= 0)
                                 break;
                         off += ret;
                         iov_iter_advance(i, ret);
-                        if (ret < len)
+                        if (ret < n)
                                 break;
                 }
         } else {
@@ -466,25 +467,14 @@ static ssize_t ceph_sync_read(struct kiocb *iocb, struct iov_iter *i,
                                         num_pages, checkeof, 0, 0);
                 if (ret > 0) {
                         int l, k = 0;
-                        size_t left = len = ret;
+                        size_t left = ret;
 
                         while (left) {
-                                void __user *data = i->iov[0].iov_base
-                                                        + i->iov_offset;
-                                l = min(i->iov[0].iov_len - i->iov_offset,
-                                        left);
-
-                                ret = ceph_copy_page_vector_to_user(&pages[k],
-                                                                    data, off,
-                                                                    l);
-                                if (ret > 0) {
-                                        iov_iter_advance(i, ret);
-                                        left -= ret;
-                                        off += ret;
-                                        k = calc_pages_for(iocb->ki_pos,
-                                                           len - left + 1) - 1;
-                                        BUG_ON(k >= num_pages && left);
-                                } else
+                                int copy = min_t(size_t, PAGE_SIZE, left);
+                                l = copy_page_to_iter(pages[k++], 0, copy, i);
+                                off += l;
+                                left -= l;
+                                if (l < copy)
                                         break;
                         }
                 }