vmcore: clean up read_vmcore()

Rewrite part of read_vmcore() that reads objects in vmcore_list in the
same way as part reading ELF headers, by which some duplicated and
redundant codes are removed.

Signed-off-by: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
Cc: Lisa Mitchell <lisa.mitchell@hp.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 17f7e08..ab0c92e 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 = NULL;
 
        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;
 }