On Mon, Apr 06, 2015 at 05:02:31PM +0100, Al Viro wrote:
7) commit 3a83b342c87e6d21290de8dc76ec20a67821261d
Author: Joseph Qi <joseph.qi@xxxxxxxxxx>
Date: Mon Feb 16 16:00:09 2015 -0800
ocfs2: complete the rest request through buffer io
appears to be very odd. Look:
written = generic_file_direct_write(iocb, from, *ppos);
- if (written < 0) {
+ if (written < 0 || written == count) {
ret = written;
goto out_dio;
}
+
+ /*
+ * for completing the rest of the request.
+ */
+ *ppos += written;
ppos here is &iocb->ki_pos. Now, take a look at the end of
generic_file_direct_write():
if (written > 0) {
pos += written;
iov_iter_advance(from, written);
if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
i_size_write(inode, pos);
mark_inode_dirty(inode);
}
iocb->ki_pos = pos;
}
out:
return written;
In other words, after short write done by ->direct_IO(), we end up incrementing
position by *twice* the amount written by it. And if it's short, but not
empty, we appear to be buggered...
Unless I hear "Al, you idiot, it's doing the right thing, here's what you've
missed: ...", I'm going to take that increment in ocfs2_file_write_iter()
out, and send it to Linus for 4.0 - it's post-3.19 regression.
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