From patchwork Sat May 12 09:28:24 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 10395865 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 7AF0C60215 for ; Sat, 12 May 2018 09:40:13 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 66E792901C for ; Sat, 12 May 2018 09:40:13 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 57C492901E; Sat, 12 May 2018 09:40:13 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id B66972901C for ; Sat, 12 May 2018 09:40:12 +0000 (UTC) Received: from localhost ([::1]:60582 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fHR0e-0002X2-07 for patchwork-qemu-devel@patchwork.kernel.org; Sat, 12 May 2018 05:40:12 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34946) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fHQqs-0006Vl-77 for qemu-devel@nongnu.org; Sat, 12 May 2018 05:30:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fHQqq-0000sg-Re for qemu-devel@nongnu.org; Sat, 12 May 2018 05:30:06 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:50326 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fHQqo-0000pu-1c; Sat, 12 May 2018 05:30:02 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id AF7DB7D85E; Sat, 12 May 2018 09:30:01 +0000 (UTC) Received: from localhost (ovpn-116-42.ams2.redhat.com [10.36.116.42]) by smtp.corp.redhat.com (Postfix) with ESMTP id 65ECC215CDA7; Sat, 12 May 2018 09:30:01 +0000 (UTC) From: Stefan Hajnoczi To: Date: Sat, 12 May 2018 10:28:24 +0100 Message-Id: <20180512092824.13848-9-stefanha@redhat.com> In-Reply-To: <20180512092824.13848-1-stefanha@redhat.com> References: <20180512092824.13848-1-stefanha@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Sat, 12 May 2018 09:30:01 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Sat, 12 May 2018 09:30:01 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'stefanha@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PULL 8/8] block/file-posix: add x-check-page-cache=on|off option X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , qemu-block@nongnu.org Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP mincore(2) checks whether pages are resident. Use it to verify that page cache has been dropped. You can trigger a verification failure by mmapping the image file from another process that loads a byte from a page, forcing it to become resident. bdrv_co_invalidate_cache() will fail while that process is alive. Signed-off-by: Stefan Hajnoczi Reviewed-by: Fam Zheng Message-id: 20180427162312.18583-3-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi --- qapi/block-core.json | 7 ++- block/file-posix.c | 100 ++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 104 insertions(+), 3 deletions(-) diff --git a/qapi/block-core.json b/qapi/block-core.json index c50517bff3..21c3470234 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -2530,6 +2530,10 @@ # @locking: whether to enable file locking. If set to 'auto', only enable # when Open File Descriptor (OFD) locking API is available # (default: auto, since 2.10) +# @x-check-cache-dropped: whether to check that page cache was dropped on live +# migration. May cause noticeable delays if the image +# file is large, do not use in production. +# (default: off) (since: 2.13) # # Since: 2.9 ## @@ -2537,7 +2541,8 @@ 'data': { 'filename': 'str', '*pr-manager': 'str', '*locking': 'OnOffAuto', - '*aio': 'BlockdevAioOptions' } } + '*aio': 'BlockdevAioOptions', + '*x-check-cache-dropped': 'bool' } } ## # @BlockdevOptionsNull: diff --git a/block/file-posix.c b/block/file-posix.c index 3707ea2d1c..5a602cfe37 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -161,6 +161,7 @@ typedef struct BDRVRawState { bool page_cache_inconsistent:1; bool has_fallocate; bool needs_alignment; + bool check_cache_dropped; PRManager *pr_mgr; } BDRVRawState; @@ -168,6 +169,7 @@ typedef struct BDRVRawState { typedef struct BDRVRawReopenState { int fd; int open_flags; + bool check_cache_dropped; } BDRVRawReopenState; static int fd_open(BlockDriverState *bs); @@ -415,6 +417,11 @@ static QemuOptsList raw_runtime_opts = { .type = QEMU_OPT_STRING, .help = "id of persistent reservation manager object (default: none)", }, + { + .name = "x-check-cache-dropped", + .type = QEMU_OPT_BOOL, + .help = "check that page cache was dropped on live migration (default: off)" + }, { /* end of list */ } }, }; @@ -500,6 +507,9 @@ static int raw_open_common(BlockDriverState *bs, QDict *options, } } + s->check_cache_dropped = qemu_opt_get_bool(opts, "x-check-cache-dropped", + false); + s->open_flags = open_flags; raw_parse_flags(bdrv_flags, &s->open_flags); @@ -777,6 +787,7 @@ static int raw_reopen_prepare(BDRVReopenState *state, { BDRVRawState *s; BDRVRawReopenState *rs; + QemuOpts *opts; int ret = 0; Error *local_err = NULL; @@ -787,6 +798,19 @@ static int raw_reopen_prepare(BDRVReopenState *state, state->opaque = g_new0(BDRVRawReopenState, 1); rs = state->opaque; + rs->fd = -1; + + /* Handle options changes */ + opts = qemu_opts_create(&raw_runtime_opts, NULL, 0, &error_abort); + qemu_opts_absorb_qdict(opts, state->options, &local_err); + if (local_err) { + error_propagate(errp, local_err); + ret = -EINVAL; + goto out; + } + + rs->check_cache_dropped = qemu_opt_get_bool(opts, "x-check-cache-dropped", + s->check_cache_dropped); if (s->type == FTYPE_CD) { rs->open_flags |= O_NONBLOCK; @@ -794,8 +818,6 @@ static int raw_reopen_prepare(BDRVReopenState *state, raw_parse_flags(state->flags, &rs->open_flags); - rs->fd = -1; - int fcntl_flags = O_APPEND | O_NONBLOCK; #ifdef O_NOATIME fcntl_flags |= O_NOATIME; @@ -850,6 +872,8 @@ static int raw_reopen_prepare(BDRVReopenState *state, } } +out: + qemu_opts_del(opts); return ret; } @@ -858,6 +882,7 @@ static void raw_reopen_commit(BDRVReopenState *state) BDRVRawReopenState *rs = state->opaque; BDRVRawState *s = state->bs->opaque; + s->check_cache_dropped = rs->check_cache_dropped; s->open_flags = rs->open_flags; qemu_close(s->fd); @@ -2236,6 +2261,73 @@ static int coroutine_fn raw_co_block_status(BlockDriverState *bs, return ret | BDRV_BLOCK_OFFSET_VALID; } +#if defined(__linux__) +/* Verify that the file is not in the page cache */ +static void check_cache_dropped(BlockDriverState *bs, Error **errp) +{ + const size_t window_size = 128 * 1024 * 1024; + BDRVRawState *s = bs->opaque; + void *window = NULL; + size_t length = 0; + unsigned char *vec; + size_t page_size; + off_t offset; + off_t end; + + /* mincore(2) page status information requires 1 byte per page */ + page_size = sysconf(_SC_PAGESIZE); + vec = g_malloc(DIV_ROUND_UP(window_size, page_size)); + + end = raw_getlength(bs); + + for (offset = 0; offset < end; offset += window_size) { + void *new_window; + size_t new_length; + size_t vec_end; + size_t i; + int ret; + + /* Unmap previous window if size has changed */ + new_length = MIN(end - offset, window_size); + if (new_length != length) { + munmap(window, length); + window = NULL; + length = 0; + } + + new_window = mmap(window, new_length, PROT_NONE, MAP_PRIVATE, + s->fd, offset); + if (new_window == MAP_FAILED) { + error_setg_errno(errp, errno, "mmap failed"); + break; + } + + window = new_window; + length = new_length; + + ret = mincore(window, length, vec); + if (ret < 0) { + error_setg_errno(errp, errno, "mincore failed"); + break; + } + + vec_end = DIV_ROUND_UP(length, page_size); + for (i = 0; i < vec_end; i++) { + if (vec[i] & 0x1) { + error_setg(errp, "page cache still in use!"); + break; + } + } + } + + if (window) { + munmap(window, length); + } + + g_free(vec); +} +#endif /* __linux__ */ + static void coroutine_fn raw_co_invalidate_cache(BlockDriverState *bs, Error **errp) { @@ -2269,6 +2361,10 @@ static void coroutine_fn raw_co_invalidate_cache(BlockDriverState *bs, error_setg_errno(errp, ret, "fadvise failed"); return; } + + if (s->check_cache_dropped) { + check_cache_dropped(bs, errp); + } #else /* __linux__ */ /* Do nothing. Live migration to a remote host with cache.direct=off is * unsupported on other host operating systems. Cache consistency issues