ext4: fix mmap write protection for data=journal mode

Commit afb585a97f81 "ext4: data=journal: write-protect pages on
j_submit_inode_data_buffers()") added calls ext4_jbd2_inode_add_write()
to track inode ranges whose mappings need to get write-protected during
transaction commits.  However the added calls use wrong start of a range
(0 instead of page offset) and so write protection is not necessarily
effective.  Use correct range start to fix the problem.

Fixes: afb585a97f81 ("ext4: data=journal: write-protect pages on j_submit_inode_data_buffers()")
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20201027132751.29858-1-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 520a020..b96a186 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1918,7 +1918,7 @@ static int __ext4_journalled_writepage(struct page *page,
        }
        if (ret == 0)
                ret = err;
-       err = ext4_jbd2_inode_add_write(handle, inode, 0, len);
+       err = ext4_jbd2_inode_add_write(handle, inode, page_offset(page), len);
        if (ret == 0)
                ret = err;
        EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
@@ -6159,7 +6159,8 @@ retry_alloc:
                        if (ext4_walk_page_buffers(handle, page_buffers(page),
                                        0, len, NULL, write_end_fn))
                                goto out_error;
-                       if (ext4_jbd2_inode_add_write(handle, inode, 0, len))
+                       if (ext4_jbd2_inode_add_write(handle, inode,
+                                                     page_offset(page), len))
                                goto out_error;
                        ext4_set_inode_state(inode, EXT4_STATE_JDATA);
                } else {