I have this patch in my tree that I'm thinking about submitting:
+static inline void inode_assert_locked(const struct inode *inode)
+{
+ rwsem_assert_held(&inode->i_rwsem);
+}
+
+static inline void inode_assert_locked_excl(const struct inode *inode)
+{
+ rwsem_assert_held_write(&inode->i_rwsem);
+}
Then we can do a whole bunch of "replace crappy existing assertions with
the shiny new ones".
@@ -2746,7 +2746,7 @@ struct dentry *lookup_one_len(const char *name, struct den
try *base, int len)
struct qstr this;
int err;
- WARN_ON_ONCE(!inode_is_locked(base->d_inode));
+ inode_assert_locked(base->d_inode);
for example.
But the naming is confusing and I can't think of good names.
inode_lock() takes the lock exclusively, whereas inode_assert_locked()
only checks that the lock is held. ie 1-3 pass and 4 fails.
1. inode_lock(inode); inode_assert_locked(inode);
2. inode_lock_shared(inode); inode_assert_locked(inode);
3. inode_lock(inode); inode_assert_locked_excl(inode);
4. inode_lock_shared(inode); inode_assert_locked_excl(inode);
I worry that this abstraction will cause people to write
inode_assert_locked() when they really need to check
inode_assert_locked_excl(). We already had/have this problem:
https://lore.kernel.org/all/20230831101824.qdko4daizgh7phav@f/
So how do we make it that people write the right one?
Renaming inode_assert_locked() to inode_assert_locked_shared() isn't
the answer because it checks that the lock is _at least_ shared, it
might be held exclusively.
Rename inode_assert_locked() to inode_assert_held()? That might be
enough of a disconnect that people would not make bad assumptions.
I don't have a good answer here, or I'd send a patch to do that.
Please suggest something ;-)
