On Tue, Jan 26, 2016 at 10:50:59PM -0700, Ross Zwisler wrote: > On Tuesday, January 26, 2016, Matthew Wilcox <matthew.r.wilcox@xxxxxxxxx> > wrote: > > If I understand the current state of the code correctly, truncate can't > > race with the fault handler, so the re-checks we do of i_size are now > > dead code, which can be deleted. right? > > Yep, I think so. I think we might be able to delete all the i_mmap locking > in dax.c as well, now that the isolation from truncate all happens at the > filesystem level. No; we need to preserve the lock against truncate back down into the MM code. Consider the cow_page case; if truncate comes in after we drop the filesystem lock and before the COWed page is inserted into the page table, truncate won't see the page in order to remove it. And truncate is supposed to remove COWs as well as the underlying file. I'm not sure what purpose it serves in dax_insert_mapping though. Nor the PMD fault handler. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
