1 files changed, 13 insertions, 3 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 7b93df9aa182..f023f0cb46fc 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2247,13 +2247,23 @@ static int mpage_map_and_submit_extent(handle_t *handle,
                         return err;
         } while (map->m_len);
 
-        /* Update on-disk size after IO is submitted */
+        /*
+         * Update on-disk size after IO is submitted.  Races with
+         * truncate are avoided by checking i_size under i_data_sem.
+         */
         disksize = ((loff_t)mpd->first_page) << PAGE_CACHE_SHIFT;
         if (disksize > EXT4_I(inode)->i_disksize) {
                 int err2;
-
-                ext4_wb_update_i_disksize(inode, disksize);
+                loff_t i_size;
+
+                down_write(&EXT4_I(inode)->i_data_sem);
+                i_size = i_size_read(inode);
+                if (disksize > i_size)
+                        disksize = i_size;
+                if (disksize > EXT4_I(inode)->i_disksize)
+                        EXT4_I(inode)->i_disksize = disksize;
                 err2 = ext4_mark_inode_dirty(handle, inode);
+                up_write(&EXT4_I(inode)->i_data_sem);
                 if (err2)
                         ext4_error(inode->i_sb,
                                    "Failed to mark inode %lu dirty",