From: Christoph Hellwig <hch@lst.de>
Date: Wed, 8 Feb 2017 19:43:13 +0000 (-0500)
Subject: dax: assert that i_rwsem is held exclusive for writes
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=168316db3583253b9e5d46392e5b9d03d531406f;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

dax: assert that i_rwsem is held exclusive for writes

Make sure all callers follow the same locking protocol, given that DAX
transparantly replaced the normal buffered I/O path.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
---

diff --git a/fs/dax.c b/fs/dax.c
index 5c74f60d0a50..04734daed1bd 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1061,8 +1061,12 @@ dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
 	loff_t pos = iocb->ki_pos, ret = 0, done = 0;
 	unsigned flags = 0;
 
-	if (iov_iter_rw(iter) == WRITE)
+	if (iov_iter_rw(iter) == WRITE) {
+		lockdep_assert_held_exclusive(&inode->i_rwsem);
 		flags |= IOMAP_WRITE;
+	} else {
+		lockdep_assert_held(&inode->i_rwsem);
+	}
 
 	while (iov_iter_count(iter)) {
 		ret = iomap_apply(inode, pos, iov_iter_count(iter), flags, ops,