Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754289Ab3JYPqn (ORCPT ); Fri, 25 Oct 2013 11:46:43 -0400 Received: from e28smtp04.in.ibm.com ([122.248.162.4]:59279 "EHLO e28smtp04.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751917Ab3JYPql (ORCPT ); Fri, 25 Oct 2013 11:46:41 -0400 From: Robert Jennings To: linux-kernel@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Alexander Viro , Rik van Riel , Andrea Arcangeli , Dave Hansen , Robert Jennings , Matt Helsley , Anthony Liguori , Michael Roth , Lei Li , Leonardo Garcia , Simon Jin , Vlastimil Babka Subject: [PATCH v2 1/2] vmsplice: unmap gifted pages for recipient Date: Fri, 25 Oct 2013 10:46:23 -0500 Message-Id: <1382715984-10558-2-git-send-email-rcj@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1382715984-10558-1-git-send-email-rcj@linux.vnet.ibm.com> References: <1382715984-10558-1-git-send-email-rcj@linux.vnet.ibm.com> X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13102515-5564-0000-0000-00000A5E7DD9 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3104 Lines: 106 From: Robert C Jennings Introduce use of the unused SPLICE_F_MOVE flag for vmsplice to zap pages. When vmsplice is called with flags (SPLICE_F_GIFT | SPLICE_F_MOVE) the writer's gift'ed pages would be zapped. This patch supports further work to move vmsplice'd pages rather than copying them. That patch has the restriction that the page must not be mapped by the source for the move, otherwise it will fall back to copying the page. Signed-off-by: Matt Helsley Signed-off-by: Robert C Jennings --- Changes since v1: - Cleanup zap coalescing in splice_to_pipe for readability - Field added to struct partial_page in v1 was unnecessary, using private field instead. --- fs/splice.c | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/fs/splice.c b/fs/splice.c index 3b7ee65..c14be6f 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -188,12 +188,18 @@ ssize_t splice_to_pipe(struct pipe_inode_info *pipe, { unsigned int spd_pages = spd->nr_pages; int ret, do_wakeup, page_nr; + struct vm_area_struct *vma; + unsigned long user_start, user_end, addr; ret = 0; do_wakeup = 0; page_nr = 0; + vma = NULL; + user_start = user_end = 0; pipe_lock(pipe); + /* mmap_sem taken for zap_page_range with SPLICE_F_MOVE */ + down_read(¤t->mm->mmap_sem); for (;;) { if (!pipe->readers) { @@ -215,6 +221,33 @@ ssize_t splice_to_pipe(struct pipe_inode_info *pipe, if (spd->flags & SPLICE_F_GIFT) buf->flags |= PIPE_BUF_FLAG_GIFT; + /* Prepare to move page sized/aligned bufs. + * Gather pages for a single zap_page_range() + * call per VMA. + */ + if (spd->flags & (SPLICE_F_GIFT | SPLICE_F_MOVE) && + !buf->offset && + (buf->len == PAGE_SIZE)) { + addr = buf->private; + + if (vma && (addr == user_end) && + (addr + PAGE_SIZE <= vma->vm_end)) { + /* Same vma, no holes */ + user_end += PAGE_SIZE; + } else { + if (vma) + zap_page_range(vma, user_start, + (user_end - user_start), + NULL); + vma = find_vma(current->mm, addr); + if (!IS_ERR_OR_NULL(vma)) { + user_start = addr; + user_end = (addr + PAGE_SIZE); + } else + vma = NULL; + } + } + pipe->nrbufs++; page_nr++; ret += buf->len; @@ -255,6 +288,10 @@ ssize_t splice_to_pipe(struct pipe_inode_info *pipe, pipe->waiting_writers--; } + if (vma) + zap_page_range(vma, user_start, (user_end - user_start), NULL); + + up_read(¤t->mm->mmap_sem); pipe_unlock(pipe); if (do_wakeup) @@ -1475,6 +1512,7 @@ static int get_iovec_page_array(const struct iovec __user *iov, partial[buffers].offset = off; partial[buffers].len = plen; + partial[buffers].private = (unsigned long)base; off = 0; len -= plen; -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/