nilfs2: eliminate staggered calls to kunmap in nilfs_rename

In nilfs_rename(), calls to nilfs_put_page() to release pages obtained
with nilfs_find_entry() or nilfs_dotdot() are alternated in the normal
path.

When replacing the kernel memory mapping method from kmap to
kmap_local_{page,folio}, this violates the constraint on the calling order
of kunmap_local().

Swap the order of nilfs_put_page calls where the kmap sections of multiple
pages overlap so that they are nested, allowing direct replacement of
nilfs_put_page() -> unmap_and_put_page().

Without this reordering, that replacement will cause a kernel WARNING in
kunmap_local_indexed() on architectures with high memory mapping.

Link: https://lkml.kernel.org/r/20231127143036.2425-3-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/nilfs2/namei.c b/fs/nilfs2/namei.c
index 99255694cbe960192dfe0bae737cb5189cad27c7..d179db8074c235d1094d2a38e163f65f09e4e53f 100644 (file)
--- a/fs/nilfs2/namei.c
+++ b/fs/nilfs2/namei.c
@@ -411,13 +411,14 @@ static int nilfs_rename(struct mnt_idmap *idmap,
        inode_set_ctime_current(old_inode);
 
        nilfs_delete_entry(old_de, old_page);
-       nilfs_put_page(old_page);
 
        if (dir_de) {
                nilfs_set_link(old_inode, dir_de, dir_page, new_dir);
                nilfs_put_page(dir_page);
                drop_nlink(old_dir);
        }
+       nilfs_put_page(old_page);
+
        nilfs_mark_inode_dirty(old_dir);
        nilfs_mark_inode_dirty(old_inode);