On Mon, Jan 25, 2016 at 9:25 AM, Matthew Wilcox <matthew.r.wilcox@xxxxxxxxx> wrote: > From: Matthew Wilcox <willy@xxxxxxxxxxxxxxx> > > When we handle a write-fault on a DAX mapping, we currently insert a > read-only mapping and then take the page fault again to convert it to > a writable mapping. This is necessary for the case where we cover a > hole with a read-only zero page, but when we have a data block already > allocated, it is inefficient. > > Use the recently added vmf_insert_pfn_prot() to insert a writable mapping, > even though the default VM flags say to use a read-only mapping. Conceptually, I like this. Do you need to make sure to do all the do_wp_page work, though? (E.g. we currently update mtime in there. Some day I'll fix that, but it'll be replaced with a set_bit to force a deferred mtime update.) --Andy -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>