move timestamp update before data update in fast write path (fix utsa…

…slab#18)

Linux-5.1/fs/winefs/xip.c

@@ -296,6 +296,18 @@ static ssize_t pmfs_file_write_fast(struct super_block *sb, struct inode *inode,
 
  offset = pos & (sb->s_blocksize - 1);
 
+ inode->i_ctime = inode->i_mtime = current_time(inode);
+ if(count + offset <= inode->i_size) {
+ u64 c_m_time;
+ /* make sure that the time is updated before any modified data may be committed */
+ c_m_time = (inode->i_ctime.tv_sec & 0xFFFFFFFF);
+ c_m_time = c_m_time | (c_m_time << 32);
+ pmfs_memunlock_inode(sb, pi);
+ pmfs_memcpy_atomic(&pi->i_ctime, &c_m_time, 8);
+ pmfs_memlock_inode(sb, pi);
+ pmfs_flush_buffer(pi, 1, true);
+ }
+
  PMFS_START_TIMING(memcpy_w_t, memcpy_time);
  pmfs_xip_mem_protect(sb, xmem + offset, count, 1);
  copied = memcpy_to_nvmm((char *)xmem, offset, buf, count);
@@ -311,7 +323,6 @@ static ssize_t pmfs_file_write_fast(struct super_block *sb, struct inode *inode,
  if (unlikely(copied != count && copied == 0))
  ret = -EFAULT;
  *ppos = pos;
- inode->i_ctime = inode->i_mtime = current_time(inode);
  if (pos > inode->i_size) {
  /* make sure written data is persistent before updating
  * time and size */
@@ -321,18 +332,8 @@ static ssize_t pmfs_file_write_fast(struct super_block *sb, struct inode *inode,
  pmfs_memunlock_inode(sb, pi);
  pmfs_update_time_and_size(inode, pi);
  pmfs_memlock_inode(sb, pi);
- } else {
- u64 c_m_time;
- /* update c_time and m_time atomically. We don't need to make the data
- * persistent because the expectation is that the close() or an explicit
- * fsync will do that. */
- c_m_time = (inode->i_ctime.tv_sec & 0xFFFFFFFF);
- c_m_time = c_m_time | (c_m_time << 32);
- pmfs_memunlock_inode(sb, pi);
- pmfs_memcpy_atomic(&pi->i_ctime, &c_m_time, 8);
- pmfs_memlock_inode(sb, pi);
+ pmfs_flush_buffer(pi, 1, barrier);
  }
- pmfs_flush_buffer(pi, 1, barrier);
  return ret;
 }