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>

diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
index fd26d04..7b8d63e 100644 (file)
--- 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;