untangling process_vm_..., part 1

we want to massage it to use of iov_iter.  This one is an equivalent
transformation - just introduce a local variable mirroring
lvec + *lvec_current.

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

1 files changed, 9 insertions, 5 deletions

diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
index fd26d0433509..7b8d63e6c30b 100644
--- a/mm/process_vm_access.c
+++ b/mm/process_vm_access.c
@@ -60,6 +60,7 @@ static int process_vm_rw_pages(struct task_struct *task,
         int ret;
         ssize_t bytes_to_copy;
         ssize_t rc = 0;
+        const struct iovec *iov = lvec + *lvec_current;
 
         *bytes_copied = 0;
 
@@ -81,8 +82,10 @@ static int process_vm_rw_pages(struct task_struct *task,
              pgs_copied++) {
                 /* Make sure we have a non zero length iovec */
                 while (*lvec_current < lvec_cnt
-                       && lvec[*lvec_current].iov_len == 0)
+                       && iov->iov_len == 0) {
+                        iov++;
                         (*lvec_current)++;
+                }
                 if (*lvec_current == lvec_cnt)
                         break;
 
@@ -94,18 +97,18 @@ static int process_vm_rw_pages(struct task_struct *task,
                 bytes_to_copy = min_t(ssize_t, PAGE_SIZE - start_offset,
                                       len - *bytes_copied);
                 bytes_to_copy = min_t(ssize_t, bytes_to_copy,
-                                      lvec[*lvec_current].iov_len
+                                      iov->iov_len
                                       - *lvec_offset);
 
                 target_kaddr = kmap(process_pages[pgs_copied]) + start_offset;
 
                 if (vm_write)
                         ret = copy_from_user(target_kaddr,
-                                             lvec[*lvec_current].iov_base
+                                             iov->iov_base
                                              + *lvec_offset,
                                              bytes_to_copy);
                 else
-                        ret = copy_to_user(lvec[*lvec_current].iov_base
+                        ret = copy_to_user(iov->iov_base
                                            + *lvec_offset,
                                            target_kaddr, bytes_to_copy);
                 kunmap(process_pages[pgs_copied]);
@@ -117,12 +120,13 @@ static int process_vm_rw_pages(struct task_struct *task,
                 }
                 *bytes_copied += bytes_to_copy;
                 *lvec_offset += bytes_to_copy;
-                if (*lvec_offset == lvec[*lvec_current].iov_len) {
+                if (*lvec_offset == iov->iov_len) {
                         /*
                          * Need to copy remaining part of page into the
                          * next iovec if there are any bytes left in page
                          */
                         (*lvec_current)++;
+                        iov++;
                         *lvec_offset = 0;
                         start_offset = (start_offset + bytes_to_copy)
                                 % PAGE_SIZE;