ext4: serialize dio nonlocked reads with defrag workers

Inode's block defrag and ext4_change_inode_journal_flag() may
affect nonlocked DIO reads result, so proper synchronization
required.

- Add missed inode_dio_wait() calls where appropriate
- Check inode state under extra i_dio_count reference.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 8 insertions, 0 deletions

diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index 8076b96b5299..292daeeed455 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -1323,6 +1323,12 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
         /* Protect orig and donor inodes against a truncate */
         mext_inode_double_lock(orig_inode, donor_inode);
 
+        /* Wait for all existing dio workers */
+        ext4_inode_block_unlocked_dio(orig_inode);
+        ext4_inode_block_unlocked_dio(donor_inode);
+        inode_dio_wait(orig_inode);
+        inode_dio_wait(donor_inode);
+
         /* Protect extent tree against block allocations via delalloc */
         double_down_write_data_sem(orig_inode, donor_inode);
         /* Check the filesystem environment whether move_extent can be done */
@@ -1521,6 +1527,8 @@ out:
                 kfree(holecheck_path);
         }
         double_up_write_data_sem(orig_inode, donor_inode);
+        ext4_inode_resume_unlocked_dio(orig_inode);
+        ext4_inode_resume_unlocked_dio(donor_inode);
         mext_inode_double_unlock(orig_inode, donor_inode);
 
         return ret;