[PATCH 6.6 035/105] dax: skip read lock assertion for read-only filesystems

Greg Kroah-Hartman
2025-10-21T19:54:04Z

From: Yuezhang Mo <Yuezhang.Mo@sony.com>

[ Upstream commit 154d1e7ad9e5ce4b2aaefd3862b3dba545ad978d ]

The commit 168316db3583("dax: assert that i_rwsem is held
exclusive for writes") added lock assertions to ensure proper
locking in DAX operations. However, these assertions trigger
false-positive lockdep warnings since read lock is unnecessary
on read-only filesystems(e.g., erofs).

This patch skips the read lock assertion for read-only filesystems,
eliminating the spurious warnings while maintaining the integrity
checks for writable filesystems.

Fixes: 168316db3583 ("dax: assert that i_rwsem is held exclusive for writes")
Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Reviewed-by: Friendy Su <friendy.su@sony.com>
Reviewed-by: Daniel Palmer <daniel.palmer@sony.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/dax.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/dax.c b/fs/dax.c
index 8c09578fa0357..e1451efaab140 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1578,7 +1578,7 @@ dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
if (iov_iter_rw(iter) == WRITE) {
lockdep_assert_held_write(&iomi.inode->i_rwsem);
iomi.flags |= IOMAP_WRITE;
- } else {
+ } else if (!sb_rdonly(iomi.inode->i_sb)) {
lockdep_assert_held(&iomi.inode->i_rwsem);
}

--
2.51.0