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>

1 files changed, 20 insertions, 48 deletions

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 17f7e080d7ff..ab0c92e64411 100644
--- 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;
 }