ext4: fix wrong m_len value after unwritten extent conversion

The ext4_ext_handle_uninitialized_extents() function was assuming the
return value of ext4_ext_map_blocks() is equal to map->m_len.  This
incorrect assumption was harmless until we started use status tree as
a extent cache because we need to update status tree according to
'm_len' value.

Meanwhile this commit marks EXT4_MAP_MAPPED flag after unwritten extent
conversion.  It shouldn't cause a bug because we update status tree
according to checking EXT4_MAP_UNWRITTEN flag.  But it should be fixed.

After applied this commit, the following error message from self-testing
infrastructure disappears.

    ...
    kernel: ES len assertation failed for inode: 230 retval 1 !=
    map->m_len 3 in ext4_map_blocks (allocation)
    ...

Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Dmitry Monakhov <dmonakhov@openvz.org>

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 25c86aa..110e85a 100644 (file)
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3650,6 +3650,10 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
                                                 path, map->m_len);
                } else
                        err = ret;
+               map->m_flags |= EXT4_MAP_MAPPED;
+               if (allocated > map->m_len)
+                       allocated = map->m_len;
+               map->m_len = allocated;
                goto out2;
        }
        /* buffered IO case */