mm: Fully initialize invalidate_lock, amend lock class later

The function __init_rwsem() is not part of the official API, it just a helper
function used by init_rwsem().
Changing the lock's class and name should be done by using
lockdep_set_class_and_name() after the has been fully initialized. The overhead
of the additional class struct and setting it twice is negligible and it works
across all locks.

Fully initialize the lock with init_rwsem() and then set the custom class and
name for the lock.

Fixes: 730633f0b7f95 ("mm: Protect operations adding pages to page cache with invalidate_lock")
Link: https://lore.kernel.org/r/20210901084403.g4fezi23cixemlhh@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/inode.c b/fs/inode.c
index 37710ca863b57be1326785bad9621d55d6bb2283..ed0cab8a32db109c6851ddcf567d8de83d1c5c22 100644 (file)
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -190,8 +190,10 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
        mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
        mapping->private_data = NULL;
        mapping->writeback_index = 0;
-       __init_rwsem(&mapping->invalidate_lock, "mapping.invalidate_lock",
-                    &sb->s_type->invalidate_lock_key);
+       init_rwsem(&mapping->invalidate_lock);
+       lockdep_set_class_and_name(&mapping->invalidate_lock,
+                                  &sb->s_type->invalidate_lock_key,
+                                  "mapping.invalidate_lock");
        inode->i_private = NULL;
        inode->i_mapping = mapping;
        INIT_HLIST_HEAD(&inode->i_dentry);      /* buggered by rcu freeing */