give ->direct_IO() a copy of iov_iter
the thing is, we want to advance what's given to ->direct_IO() as we
are forming the request; however, the callers care about the amount
of data actually transferred, not the amount we tried to transfer.
It's more convenient to allow ->direct_IO() instances do use
iov_iter_advance() on the copy of iov_iter, leaving the actual
advancing of the original to caller.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/mm/filemap.c b/mm/filemap.c
index 70c048e..866f4ae 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1699,8 +1699,10 @@
size = i_size_read(inode);
retval = filemap_write_and_wait_range(mapping, pos,
pos + count - 1);
- if (!retval)
- retval = mapping->a_ops->direct_IO(READ, iocb, &i, pos);
+ if (!retval) {
+ struct iov_iter data = i;
+ retval = mapping->a_ops->direct_IO(READ, iocb, &data, pos);
+ }
if (retval > 0) {
*ppos = pos + retval;
@@ -2351,6 +2353,7 @@
ssize_t written;
size_t write_len;
pgoff_t end;
+ struct iov_iter data;
if (count != ocount)
from->nr_segs = iov_shorten((struct iovec *)from->iov, from->nr_segs, count);
@@ -2382,7 +2385,8 @@
}
}
- written = mapping->a_ops->direct_IO(WRITE, iocb, from, pos);
+ data = *from;
+ written = mapping->a_ops->direct_IO(WRITE, iocb, &data, pos);
/*
* Finally, try again to invalidate clean pages which might have been