process_vm_access: switch to iov_iter

instead of keeping its pieces in separate variables and passing
pointers to all of them...

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

1 files changed, 28 insertions, 34 deletions

diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
index 4bbd495fcedd..1e3c81103b2c 100644
--- a/mm/process_vm_access.c
+++ b/mm/process_vm_access.c
@@ -45,9 +45,7 @@ static int process_vm_rw_pages(struct task_struct *task,
                                unsigned long pa,
                                unsigned long start_offset,
                                unsigned long len,
-                               const struct iovec **iovp,
-                               unsigned long *left,
-                               size_t *lvec_offset,
+                               struct iov_iter *iter,
                                int vm_write,
                                unsigned int nr_pages_to_copy,
                                ssize_t *bytes_copied)
@@ -59,7 +57,7 @@ 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 = *iovp;
+        const struct iovec *iov = iter->iov;
 
         *bytes_copied = 0;
 
@@ -77,14 +75,14 @@ static int process_vm_rw_pages(struct task_struct *task,
 
         /* Do the copy for each page */
         for (pgs_copied = 0;
-             (pgs_copied < nr_pages_to_copy) && *left;
+             (pgs_copied < nr_pages_to_copy) && iter->nr_segs;
              pgs_copied++) {
                 /* Make sure we have a non zero length iovec */
-                while (*left && iov->iov_len == 0) {
+                while (iter->nr_segs && iov->iov_len == 0) {
                         iov++;
-                        (*left)--;
+                        iter->nr_segs--;
                 }
-                if (!*left)
+                if (!iter->nr_segs)
                         break;
 
                 /*
@@ -96,18 +94,18 @@ static int process_vm_rw_pages(struct task_struct *task,
                                       len - *bytes_copied);
                 bytes_to_copy = min_t(ssize_t, bytes_to_copy,
                                       iov->iov_len
-                                      - *lvec_offset);
+                                      - iter->iov_offset);
 
                 target_kaddr = kmap(process_pages[pgs_copied]) + start_offset;
 
                 if (vm_write)
                         ret = copy_from_user(target_kaddr,
                                              iov->iov_base
-                                             + *lvec_offset,
+                                             + iter->iov_offset,
                                              bytes_to_copy);
                 else
                         ret = copy_to_user(iov->iov_base
-                                           + *lvec_offset,
+                                           + iter->iov_offset,
                                            target_kaddr, bytes_to_copy);
                 kunmap(process_pages[pgs_copied]);
                 if (ret) {
@@ -117,15 +115,15 @@ static int process_vm_rw_pages(struct task_struct *task,
                         goto end;
                 }
                 *bytes_copied += bytes_to_copy;
-                *lvec_offset += bytes_to_copy;
-                if (*lvec_offset == iov->iov_len) {
+                iter->iov_offset += bytes_to_copy;
+                if (iter->iov_offset == iov->iov_len) {
                         /*
                          * Need to copy remaining part of page into the
                          * next iovec if there are any bytes left in page
                          */
-                        (*left)--;
+                        iter->nr_segs--;
                         iov++;
-                        *lvec_offset = 0;
+                        iter->iov_offset = 0;
                         start_offset = (start_offset + bytes_to_copy)
                                 % PAGE_SIZE;
                         if (start_offset)
@@ -147,7 +145,7 @@ end:
                         put_page(process_pages[j]);
         }
 
-        *iovp = iov;
+        iter->iov = iov;
         return rc;
 }
 
@@ -172,9 +170,7 @@ end:
  */
 static int process_vm_rw_single_vec(unsigned long addr,
                                     unsigned long len,
-                                    const struct iovec **iovp,
-                                    unsigned long *left,
-                                    size_t *lvec_offset,
+                                    struct iov_iter *iter,
                                     struct page **process_pages,
                                     struct mm_struct *mm,
                                     struct task_struct *task,
@@ -198,14 +194,12 @@ static int process_vm_rw_single_vec(unsigned long addr,
                 return 0;
         nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;
 
-        while ((nr_pages_copied < nr_pages) && *left) {
+        while ((nr_pages_copied < nr_pages) && iter->nr_segs) {
                 nr_pages_to_copy = min(nr_pages - nr_pages_copied,
                                        max_pages_per_loop);
 
                 rc = process_vm_rw_pages(task, mm, process_pages, pa,
-                                         start_offset, len,
-                                         iovp, left,
-                                         lvec_offset,
+                                         start_offset, len, iter,
                                          vm_write, nr_pages_to_copy,
                                          &bytes_copied_loop);
                 start_offset = 0;
@@ -240,8 +234,7 @@ static int process_vm_rw_single_vec(unsigned long addr,
  *  return less bytes than expected if an error occurs during the copying
  *  process.
  */
-static ssize_t process_vm_rw_core(pid_t pid, const struct iovec *lvec,
-                                  unsigned long liovcnt,
+static ssize_t process_vm_rw_core(pid_t pid, struct iov_iter *iter,
                                   const struct iovec *rvec,
                                   unsigned long riovcnt,
                                   unsigned long flags, int vm_write)
@@ -256,8 +249,6 @@ static ssize_t process_vm_rw_core(pid_t pid, const struct iovec *lvec,
         ssize_t bytes_copied = 0;
         unsigned long nr_pages = 0;
         unsigned long nr_pages_iov;
-        unsigned long left = liovcnt;
-        size_t iov_l_curr_offset = 0;
         ssize_t iov_len;
 
         /*
@@ -312,11 +303,11 @@ static ssize_t process_vm_rw_core(pid_t pid, const struct iovec *lvec,
                 goto put_task_struct;
         }
 
-        for (i = 0; i < riovcnt && left; i++) {
+        for (i = 0; i < riovcnt && iter->nr_segs; i++) {
                 rc = process_vm_rw_single_vec(
                         (unsigned long)rvec[i].iov_base, rvec[i].iov_len,
-                        &lvec, &left, &iov_l_curr_offset,
-                        process_pages, mm, task, vm_write, &bytes_copied_loop);
+                        iter, process_pages, mm, task, vm_write,
+                        &bytes_copied_loop);
                 bytes_copied += bytes_copied_loop;
                 if (rc != 0) {
                         /* If we have managed to copy any data at all then
@@ -365,6 +356,7 @@ static ssize_t process_vm_rw(pid_t pid,
         struct iovec iovstack_r[UIO_FASTIOV];
         struct iovec *iov_l = iovstack_l;
         struct iovec *iov_r = iovstack_r;
+        struct iov_iter iter;
         ssize_t rc;
 
         if (flags != 0)
@@ -380,13 +372,14 @@ static ssize_t process_vm_rw(pid_t pid,
         if (rc <= 0)
                 goto free_iovecs;
 
+        iov_iter_init(&iter, iov_l, liovcnt, rc, 0);
+
         rc = rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt, UIO_FASTIOV,
                                    iovstack_r, &iov_r);
         if (rc <= 0)
                 goto free_iovecs;
 
-        rc = process_vm_rw_core(pid, iov_l, liovcnt, iov_r, riovcnt, flags,
-                                vm_write);
+        rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);
 
 free_iovecs:
         if (iov_r != iovstack_r)
@@ -426,6 +419,7 @@ compat_process_vm_rw(compat_pid_t pid,
         struct iovec iovstack_r[UIO_FASTIOV];
         struct iovec *iov_l = iovstack_l;
         struct iovec *iov_r = iovstack_r;
+        struct iov_iter iter;
         ssize_t rc = -EFAULT;
 
         if (flags != 0)
@@ -441,14 +435,14 @@ compat_process_vm_rw(compat_pid_t pid,
                                                   &iov_l);
         if (rc <= 0)
                 goto free_iovecs;
+        iov_iter_init(&iter, iov_l, liovcnt, rc, 0);
         rc = compat_rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt,
                                           UIO_FASTIOV, iovstack_r,
                                           &iov_r);
         if (rc <= 0)
                 goto free_iovecs;
 
-        rc = process_vm_rw_core(pid, iov_l, liovcnt, iov_r, riovcnt, flags,
-                           vm_write);
+        rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);
 
 free_iovecs:
         if (iov_r != iovstack_r)