vmcore: clean up read_vmcore()

Clean up read_vmcore().  Part for objects in vmcore_list can be written
uniformly to part for ELF headers.  By this change, duplicate and
complicated codes are removed, so it's more clear to see what's done
there.

Also, by this change, map_offset_to_paddr() is no longer used.  Remove it.

Signed-off-by: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index b85ba329834255ce93b692bf4e83c2ee8f75edcf..7e21d64839923ca712db6c867fb698bbcab4beeb 100644 (file)
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -118,27 +118,6 @@ static ssize_t read_from_oldmem(char *buf, size_t count,
        return read;
 }
 
-/* Maps vmcore file offset to respective physical address in memroy. */
-static u64 map_offset_to_paddr(loff_t offset, struct list_head *vc_list,
-                                       struct vmcore **m_ptr)
-{
-       struct vmcore *m;
-       u64 paddr;
-
-       list_for_each_entry(m, vc_list, list) {
-               u64 start, end;
-               start = m->offset;
-               end = m->offset + m->size - 1;
-               if (offset >= start && offset <= end) {
-                       paddr = m->paddr + offset - start;
-                       *m_ptr = m;
-                       return paddr;
-               }
-       }
-       *m_ptr = NULL;
-       return 0;
-}
-
 /* Read from the ELF header and then the crash dump. On error, negative value is
  * returned otherwise number of bytes read are returned.
  */
@@ -147,8 +126,8 @@ static ssize_t read_vmcore(struct file *file, char __user *buffer,
 {
        ssize_t acc = 0, tmp;
        size_t tsz;
-       u64 start, nr_bytes;
-       struct vmcore *curr_m = NULL;
+       u64 start;
+       struct vmcore *m;
 
        if (buflen == 0 || *fpos >= vmcore_size)
                return 0;
@@ -174,33 +153,26 @@ static ssize_t read_vmcore(struct file *file, char __user *buffer,
                        return acc;
        }
 
-       start = map_offset_to_paddr(*fpos, &vmcore_list, &curr_m);
-       if (!curr_m)
-               return -EINVAL;
-
-       while (buflen) {
-               tsz = min_t(size_t, buflen, PAGE_SIZE - (start & ~PAGE_MASK));
-
-               /* Calculate left bytes in current memory segment. */
-               nr_bytes = (curr_m->size - (start - curr_m->paddr));
-               if (tsz > nr_bytes)
-                       tsz = nr_bytes;
-
-               tmp = read_from_oldmem(buffer, tsz, &start, 1);
-               if (tmp < 0)
-                       return tmp;
-               buflen -= tsz;
-               *fpos += tsz;
-               buffer += tsz;
-               acc += tsz;
-               if (start >= (curr_m->paddr + curr_m->size)) {
-                       if (curr_m->list.next == &vmcore_list)
-                               return acc;     /*EOF*/
-                       curr_m = list_entry(curr_m->list.next,
-                                               struct vmcore, list);
-                       start = curr_m->paddr;
+       list_for_each_entry(m, &vmcore_list, list) {
+               if (*fpos < m->offset + m->size) {
+                       tsz = m->offset + m->size - *fpos;
+                       if (buflen < tsz)
+                               tsz = buflen;
+                       start = m->paddr + *fpos - m->offset;
+                       tmp = read_from_oldmem(buffer, tsz, &start, 1);
+                       if (tmp < 0)
+                               return tmp;
+                       buflen -= tsz;
+                       *fpos += tsz;
+                       buffer += tsz;
+                       acc += tsz;
+
+                       /* leave now if filled buffer already */
+                       if (buflen == 0)
+                               return acc;
                }
        }
+
        return acc;
 }