On Thu 29-06-23 20:13:05, Baokun Li wrote: > On 2023/6/29 19:08, Jan Kara wrote: > > On Wed 28-06-23 21:21:54, Baokun Li wrote: > > > Now when dqput() drops the last reference count, it will call > > > synchronize_srcu(&dquot_srcu) in quota_release_workfn() to ensure that > > > no other user will use the dquot after the last reference count is dropped, > > > so we don't need to call synchronize_srcu(&dquot_srcu) in drop_dquot_ref() > > > and remove the corresponding logic directly to simplify the code. > > Nice simplification! It is also important that dqput() now cannot sleep > > which was another reason for the logic with tofree_head in > > remove_inode_dquot_ref(). > > I don't understand this sentence very well, so I would appreciate it > > if you could explain it in detail. 🤔 OK, let me phrase it in a "changelog" way :): remove_inode_dquot_ref() currently does not release the last dquot reference but instead adds the dquot to tofree_head list. This is because dqput() can sleep while dropping of the last dquot reference (writing back the dquot and calling ->release_dquot()) and that must not happen under dq_list_lock. Now that dqput() queues the final dquot cleanup into a workqueue, remove_inode_dquot_ref() can call dqput() unconditionally and we can significantly simplify it. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
