On Wed, Aug 07, 2019 at 07:30:09AM -0400, Brian Foster wrote: > Second (and not necessarily caused by this patch), the ireclaim flag > semantics are kind of a mess. As you've already noted, we currently > block on some locks even with SYNC_TRYLOCK, yet the cluster flushing > code has no concept of these flags (so we always trylock, never wait on > unpin, for some reason use the shared ilock vs. the exclusive ilock, > etc.). Further, with this patch TRYLOCK|WAIT basically means that if we > happen to get the lock, we flush and wait on I/O so we can free the > inode(s), but if somebody else has flushed the inode (we don't get the > flush lock) we decide not to wait on the I/O that might (or might not) > already be in progress. I find that a bit inconsistent. It also makes me > slightly concerned that we're (ab)using flag semantics for a bug fix > (waiting on inodes we've just flushed from the same task), but it looks > like this is all going to change quite a bit still so I'm not going to > worry too much about this mostly existing mess until I grok the bigger > picture changes... :P Yes, SYNC_TRYLOCK/SYNC_WAIT semantics are a mess, but they all go away later in the patchset. Non-blocking reclaim makes SYNC_TRYLOCK go away because everything becomes try-lock based, and SYNC_WAIT goes away because only the xfs_reclaim_inodes() function needs to wait for reclaim completion and so that gets it's own LRU walker implementation and the mode parameter is removed. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx
