On Thu, Jun 25, 2020 at 11:02 AM Vasily Averin wrote: > > In current implementation fuse_writepages_fill() tries to share the code: > for new wpa it calls tree_insert() with num_pages = 0 > then switches to common code used non-modified num_pages > and increments it at the very end. > > Though it triggers WARN_ON(!wpa->ia.ap.num_pages) in tree_insert() > WARNING: CPU: 1 PID: 17211 at fs/fuse/file.c:1728 tree_insert+0xab/0xc0 [fuse] > RIP: 0010:tree_insert+0xab/0xc0 [fuse] > Call Trace: > fuse_writepages_fill+0x5da/0x6a0 [fuse] > write_cache_pages+0x171/0x470 > fuse_writepages+0x8a/0x100 [fuse] > do_writepages+0x43/0xe0 > > This patch re-works fuse_writepages_fill() to call tree_insert() > with num_pages = 1 and avoids its subsequent increment and > an extra spin_lock(&fi->lock) for newly added wpa. Looks good. However, I don't like the way fuse_writepage_in_flight() is silently changed to insert page into the rb_tree. Also the insertion can be merged with the search for in-flight and be done unconditionally to simplify the logic. See attached patch. Thanks, Miklos