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>
diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
index 61f13e5..8d849da 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -810,11 +810,25 @@
if (unlikely(!list_empty(&ei->i_completed_io_list)))
ext4_flush_completed_IO(inode);
+ /*
+ * Nolock dioread optimization may be dynamically disabled
+ * via ext4_inode_block_unlocked_dio(). Check inode's state
+ * while holding extra i_dio_count ref.
+ */
+ atomic_inc(&inode->i_dio_count);
+ smp_mb();
+ if (unlikely(ext4_test_inode_state(inode,
+ EXT4_STATE_DIOREAD_LOCK))) {
+ inode_dio_done(inode);
+ goto locked;
+ }
ret = __blockdev_direct_IO(rw, iocb, inode,
inode->i_sb->s_bdev, iov,
offset, nr_segs,
ext4_get_block, NULL, NULL, 0);
+ inode_dio_done(inode);
} else {
+locked:
ret = blockdev_direct_IO(rw, iocb, inode, iov,
offset, nr_segs, ext4_get_block);