As an update to this thread, we brought up this issue at LSF/MM, and there is a thought that we should be able to solve this problem by having lock_buffer() check to see if the buffer is locked due to a write being queued, to have the priority of the write bumped up in the write queues to resolve the priority inversion. I believe Jeff Moyer was going to look into this, if I remember correctly. An alternate solution which I've been playing around adds buffer_head flags so we can indicate that a buffer contains metadata and/or should have I/O submitted with the REQ_PRIO flag set. Adding a buffer_head flag for at least BH_Meta is probably a good thing, since that way the blktrace will be properly annotated. Whether we should keep the BH_Prio flag or rely on lock_buffer() automatically raising the priority is, my feeling is that if lock_buffer() can do the right thing, we should probably do it via lock_buffer(). I have a feeling this might be decidedly non-trivial, though, so perhaps we should just doing via BH flags? - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
