Re: [RESEND PATCH] gfs2: do not evict glocks with populated address spaces

Guilherme Giacomo Simoes wrotes:
> Sorry, yes has two GLOCK_BUG_ON() assertions. I talk about the second
> GLOCK_BUG_ON on __gfs2_glock_put(): 
> `GLOCK_BUG_ON(gl, !mapping_empty(mapping))`. 
> 
> NOT ABOUT `GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));` (the first
> GLOCK_BUG_ON())
> 
> The dump_stack() indicates a memory pressure and the
> gfs2_glock_put_eventually() on fs/gfs2/super.c is called.
> But when the __gfs2_glock_put() was called, the glock was has a private folios. 
> I test by this way:
> ```
> struct address_space *mapping = ...;
> pgoff_t index;
> struct folio *folio;
> xa_for_each(&mapping->i_pages, index, folio) {
> 	if (folio_test_private(folio)) 
> 		pr_err("I have private folios")
> }
> ```
> 
> And, I can see the glock is about metadata:
> `gl->gl_name.ln_type != LM_TYPE_INODE`
> 
> the truncate_inode_pages_final() failed silently when the folio is private.
> 
> I guess maybe evict metadata (or locked) glock is not a good idea.

Andreas, thoughs?