On Wed, Sep 29, 2021 at 04:23:38PM +0530, Shreeya Patel wrote: > There is a soft hang caused by a deadlock in d_alloc_parallel which > waits up on lookups to finish for the dentries in the parent directory's > hash_table. > In case when d_add_ci is called from the fs layer's lookup functions, > the dentry being looked up is already in the hash table (created before > the fs lookup function gets called). We should not be processing the > same dentry that is being looked up, hence, in case of case-insensitive > filesystems we are making it a case-exact match to prevent this from > happening. NAK. What you are doing would lead to parallel calls of ->lookup() in the same directory for names that would compare as equal. Which violates all kinds of assumptions in the analysis of dentry tree locking. d_add_ci() is used to force the "exact" spelling of the name on lookup - that's the whole point of that thing. What are you trying to achieve, and what's the point of mixing that with non-trivial ->d_compare()? If it's "force to exact spelling on lookup, avoid calling ->lookup() on aliases", d_add_ci() is simply not a good match.
