}
}
+static int cfs_access_process_vm(struct task_struct *tsk,
+ struct mm_struct *mm,
+ unsigned long addr,
+ void *buf, int len, int write)
+{
+ /* Just copied from kernel for the kernels which doesn't
+ * have access_process_vm() exported
+ */
+ struct vm_area_struct *vma;
+ struct page *page;
+ void *old_buf = buf;
+
+ /* Avoid deadlocks on mmap_sem if called from sys_mmap_pgoff(),
+ * which is already holding mmap_sem for writes. If some other
+ * thread gets the write lock in the meantime, this thread will
+ * block, but at least it won't deadlock on itself. LU-1735
+ */
+ if (!mmap_read_trylock(mm))
+ return -EDEADLK;
+
+ /* ignore errors, just check how much was successfully transferred */
+ while (len) {
+ int bytes, rc, offset;
+ void *maddr;
+
+#if defined(HAVE_GET_USER_PAGES_GUP_FLAGS)
+ rc = get_user_pages(addr, 1, write ? FOLL_WRITE : 0, &page,
+ &vma);
+#elif defined(HAVE_GET_USER_PAGES_6ARG)
+ rc = get_user_pages(addr, 1, write, 1, &page, &vma);
+#else
+ rc = get_user_pages(tsk, mm, addr, 1, write, 1, &page, &vma);
+#endif
+ if (rc <= 0)
+ break;
+
+ bytes = len;
+ offset = addr & (PAGE_SIZE-1);
+ if (bytes > PAGE_SIZE-offset)
+ bytes = PAGE_SIZE-offset;
+
+ maddr = kmap(page);
+ if (write) {
+ copy_to_user_page(vma, page, addr,
+ maddr + offset, buf, bytes);
+ set_page_dirty_lock(page);
+ } else {
+ copy_from_user_page(vma, page, addr,
+ buf, maddr + offset, bytes);
+ }
+ kunmap(page);
+ put_page(page);
+ len -= bytes;
+ buf += bytes;
+ addr += bytes;
+ }
+ mmap_read_unlock(mm);
+
+ return buf - old_buf;
+}
+
+/* Read the environment variable of current process specified by @key. */
+static int cfs_get_environ(const char *key, char *value, int *val_len)
+{
+ struct mm_struct *mm;
+ char *buffer;
+ int buf_len = PAGE_SIZE;
+ int key_len = strlen(key);
+ unsigned long addr;
+ int rc;
+ bool skip = false;
+
+ ENTRY;
+ buffer = kmalloc(buf_len, GFP_USER);
+ if (!buffer)
+ RETURN(-ENOMEM);
+
+ mm = get_task_mm(current);
+ if (!mm) {
+ kfree(buffer);
+ RETURN(-EINVAL);
+ }
+
+ addr = mm->env_start;
+ while (addr < mm->env_end) {
+ int this_len, retval, scan_len;
+ char *env_start, *env_end;
+
+ memset(buffer, 0, buf_len);
+
+ this_len = min_t(int, mm->env_end - addr, buf_len);
+ retval = cfs_access_process_vm(current, mm, addr, buffer,
+ this_len, 0);
+ if (retval < 0)
+ GOTO(out, rc = retval);
+ else if (retval != this_len)
+ break;
+
+ addr += retval;
+
+ /* Parse the buffer to find out the specified key/value pair.
+ * The "key=value" entries are separated by '\0'.
+ */
+ env_start = buffer;
+ scan_len = this_len;
+ while (scan_len) {
+ char *entry;
+ int entry_len;
+
+ env_end = memscan(env_start, '\0', scan_len);
+ LASSERT(env_end >= env_start &&
+ env_end <= env_start + scan_len);
+
+ /* The last entry of this buffer cross the buffer
+ * boundary, reread it in next cycle.
+ */
+ if (unlikely(env_end - env_start == scan_len)) {
+ /* Just skip the entry larger than page size,
+ * it can't be jobID env variable.
+ */
+ if (unlikely(scan_len == this_len))
+ skip = true;
+ else
+ addr -= scan_len;
+ break;
+ } else if (unlikely(skip)) {
+ skip = false;
+ goto skip;
+ }
+ entry = env_start;
+ entry_len = env_end - env_start;
+ CDEBUG(D_INFO, "key: %s, entry: %s\n", key, entry);
+
+ /* Key length + length of '=' */
+ if (entry_len > key_len + 1 &&
+ entry[key_len] == '=' &&
+ !memcmp(entry, key, key_len)) {
+ entry += key_len + 1;
+ entry_len -= key_len + 1;
+
+ /* The 'value' buffer passed in is too small.
+ * Copy what fits, but return -EOVERFLOW.
+ */
+ if (entry_len >= *val_len) {
+ memcpy(value, entry, *val_len);
+ value[*val_len - 1] = 0;
+ GOTO(out, rc = -EOVERFLOW);
+ }
+
+ memcpy(value, entry, entry_len);
+ *val_len = entry_len;
+ GOTO(out, rc = 0);
+ }
+skip:
+ scan_len -= (env_end - env_start + 1);
+ env_start = env_end + 1;
+ }
+ }
+ GOTO(out, rc = -ENOENT);
+
+out:
+ mmput(mm);
+ kfree((void *)buffer);
+ return rc;
+}
+
/*
* Get jobid of current process by reading the environment variable
* stored in between the "env_start" & "env_end" of task struct.