On Thu, 8 Feb 2007 14:07:46 +0100 (CET) Nick Piggin <npiggin@xxxxxxx> wrote: > +void page_zero_new_buffers(struct page *page, unsigned from, unsigned to) > +{ > + unsigned int block_start, block_end; > + struct buffer_head *head, *bh; > + > + BUG_ON(!PageLocked(page)); > + if (!page_has_buffers(page)) > + return; > + > + bh = head = page_buffers(page); > + block_start = 0; > + do { > + block_end = block_start + bh->b_size; > + > + if (buffer_new(bh)) { > + if (block_end > from && block_start < to) { > + if (!PageUptodate(page)) { > + unsigned start, end; > + void *kaddr; > + > + start = max(from, block_start); > + end = min(to, block_end); > + > + kaddr = kmap_atomic(page, KM_USER0); > + memset(kaddr+start, 0, block_end-end); > + flush_dcache_page(page); > + kunmap_atomic(kaddr, KM_USER0); > + set_buffer_uptodate(bh); > + } I don't see how this differs from the previous attempts to solve the deadlock via atomic copt_from_user(). Here we temporarily zero out the pagecache page then block_perform_write() unlocks the page. So another thread can come in, read the page and see the temporary zeroes? If so, that might be preventable by leaving the buffer nonuptodate. - 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