[PATCH 3.19 085/101] ocfs2: _really_ sync the right range

Greg Kroah-Hartman
2015-04-17T13:37:39Z

From: Al Viro <viro@zeniv.linux.org.uk>

commit 64b4e2526d1cf6e6a4db6213d6e2b6e6ab59479a upstream.

"ocfs2 syncs the wrong range" had been broken; prior to it the
code was doing the wrong thing in case of O_APPEND, all right,
but _after_ it we were syncing the wrong range in 100% cases.
*ppos, aka iocb->ki_pos is incremented prior to that point,
so we are always doing sync on the area _after_ the one we'd
written to.

Spotted by Joseph Qi <joseph.qi@huawei.com> back in January;
unfortunately, I'd missed his mail back then ;-/

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/ocfs2/file.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)

--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2374,10 +2374,14 @@ out_dio:
/* buffered aio wouldn't have proper lock coverage today */
BUG_ON(ret == -EIOCBQUEUED && !(file->f_flags & O_DIRECT));

+ if (unlikely(written <= 0))
+ goto no_sync;
+
if (((file->f_flags & O_DSYNC) && !direct_io) || IS_SYNC(inode) ||
((file->f_flags & O_DIRECT) && !direct_io)) {
- ret = filemap_fdatawrite_range(file->f_mapping, *ppos,
- *ppos + count - 1);
+ ret = filemap_fdatawrite_range(file->f_mapping,
+ iocb->ki_pos - written,
+ iocb->ki_pos - 1);
if (ret < 0)
written = ret;

@@ -2388,10 +2392,12 @@ out_dio:
}

if (!ret)
- ret = filemap_fdatawait_range(file->f_mapping, *ppos,
- *ppos + count - 1);
+ ret = filemap_fdatawait_range(file->f_mapping,
+ iocb->ki_pos - written,
+ iocb->ki_pos - 1);
}

+no_sync:
/*
* deep in g_f_a_w_n()->ocfs2_direct_IO we pass in a ocfs2_dio_end_io
* function pointer which is called when o_direct io completes so that