From patchwork Thu Aug 22 19:28:19 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Denis V. Lunev\" via" X-Patchwork-Id: 11110157 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id ABBE013B1 for ; Thu, 22 Aug 2019 22:00:03 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3E4C921655 for ; Thu, 22 Aug 2019 22:00:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=crudebyte.com header.i=@crudebyte.com header.b="eBe97Q0Q" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3E4C921655 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=nongnu.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:48148 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i0v7i-0007cY-7c for patchwork-qemu-devel@patchwork.kernel.org; Thu, 22 Aug 2019 18:00:02 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43204) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from <5415baa3955c354d9f1e6aab39270ab2abca662a@lizzy.crudebyte.com>) id 1i0v6x-0006sf-Db for qemu-devel@nongnu.org; Thu, 22 Aug 2019 17:59:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from <5415baa3955c354d9f1e6aab39270ab2abca662a@lizzy.crudebyte.com>) id 1i0v6v-0006xo-TS for qemu-devel@nongnu.org; Thu, 22 Aug 2019 17:59:15 -0400 Received: from lizzy.crudebyte.com ([91.194.90.13]:46489) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from <5415baa3955c354d9f1e6aab39270ab2abca662a@lizzy.crudebyte.com>) id 1i0v6v-0006ay-Mz for qemu-devel@nongnu.org; Thu, 22 Aug 2019 17:59:13 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=lizzy; h=Subject:Date:Cc:To:From:References:In-Reply-To: Message-Id:Sender:Reply-To:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=ATo9ZxD30LpwfiShVhASAlgxgIkm/nBKSWUfpzx5kYM=; b=eBe97Q0QXsj2cq1LNaAo0KPdh 4rLwOdBM+BK9Ao3ZRYJCQNQUYG7XBo+QmH9nsTH4kKqurHIQ0lTuLqDnLWFng9QjowBsygMoxQPfN YttwewU6jwE10vlyaKWCPW6lNcYU7EzAJUbSW0pa87UnwWoAP1NvEltHlWBwczG9P10g/D3U6zjxs S+i8AeYv50/4C0RIa/MJUc9Q9YQuhw56dmWJXMCjpZWD+Ciu8qwjBqVeKbgVWrlZMAQtdJZXU6Z7U WaYrgyKgCj3Qq9175134gl3DKbOVIiaRvFWiyYwLL0VBv6mkQ1zn7Ok8oLFhnmDZ0J5U2QyXB7k0S Pv0+yeS0Q==; Message-Id: <5415baa3955c354d9f1e6aab39270ab2abca662a.1566503584.git.qemu_oss@crudebyte.com> In-Reply-To: References: To: qemu-devel@nongnu.org Date: Thu, 22 Aug 2019 21:28:19 +0200 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 91.194.90.13 Subject: [Qemu-devel] [PATCH v6 1/4] 9p: Treat multiple devices on one export as an error X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Christian Schoenebeck via Qemu-devel From: "Denis V. Lunev\" via" Reply-To: Christian Schoenebeck Cc: Stefan Hajnoczi , Daniel =?utf-8?b?UC4gQmVycmFuZ8Op?= , Greg Kurz , Antonios Motakis , "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" The QID path should uniquely identify a file. However, the inode of a file is currently used as the QID path, which on its own only uniquely identifies files within a device. Here we track the device hosting the 9pfs share, in order to prevent security issues with QID path collisions from other devices. Signed-off-by: Antonios Motakis [CS: - Assign dev_id to export root's device already in v9fs_device_realize_common(), not postponed in stat_to_qid(). - error_report_once() if more than one device was shared by export. - Return -ENODEV instead of -ENOSYS in stat_to_qid(). - Fixed typo in log comment. ] Signed-off-by: Christian Schoenebeck --- hw/9pfs/9p.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++------------ hw/9pfs/9p.h | 1 + 2 files changed, 56 insertions(+), 14 deletions(-) diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index 586a6dccba..8cc65c2c67 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -572,10 +572,18 @@ static void coroutine_fn virtfs_reset(V9fsPDU *pdu) P9_STAT_MODE_SOCKET) /* This is the algorithm from ufs in spfs */ -static void stat_to_qid(const struct stat *stbuf, V9fsQID *qidp) +static int stat_to_qid(V9fsPDU *pdu, const struct stat *stbuf, V9fsQID *qidp) { size_t size; + if (pdu->s->dev_id != stbuf->st_dev) { + error_report_once( + "9p: Multiple devices detected in same VirtFS export. " + "You must use a separate export for each device." + ); + return -ENODEV; + } + memset(&qidp->path, 0, sizeof(qidp->path)); size = MIN(sizeof(stbuf->st_ino), sizeof(qidp->path)); memcpy(&qidp->path, &stbuf->st_ino, size); @@ -587,6 +595,8 @@ static void stat_to_qid(const struct stat *stbuf, V9fsQID *qidp) if (S_ISLNK(stbuf->st_mode)) { qidp->type |= P9_QID_TYPE_SYMLINK; } + + return 0; } static int coroutine_fn fid_to_qid(V9fsPDU *pdu, V9fsFidState *fidp, @@ -599,7 +609,10 @@ static int coroutine_fn fid_to_qid(V9fsPDU *pdu, V9fsFidState *fidp, if (err < 0) { return err; } - stat_to_qid(&stbuf, qidp); + err = stat_to_qid(pdu, &stbuf, qidp); + if (err < 0) { + return err; + } return 0; } @@ -830,7 +843,10 @@ static int coroutine_fn stat_to_v9stat(V9fsPDU *pdu, V9fsPath *path, memset(v9stat, 0, sizeof(*v9stat)); - stat_to_qid(stbuf, &v9stat->qid); + err = stat_to_qid(pdu, stbuf, &v9stat->qid); + if (err < 0) { + return err; + } v9stat->mode = stat_to_v9mode(stbuf); v9stat->atime = stbuf->st_atime; v9stat->mtime = stbuf->st_mtime; @@ -891,7 +907,7 @@ static int coroutine_fn stat_to_v9stat(V9fsPDU *pdu, V9fsPath *path, #define P9_STATS_ALL 0x00003fffULL /* Mask for All fields above */ -static void stat_to_v9stat_dotl(V9fsState *s, const struct stat *stbuf, +static int stat_to_v9stat_dotl(V9fsPDU *pdu, const struct stat *stbuf, V9fsStatDotl *v9lstat) { memset(v9lstat, 0, sizeof(*v9lstat)); @@ -913,7 +929,7 @@ static void stat_to_v9stat_dotl(V9fsState *s, const struct stat *stbuf, /* Currently we only support BASIC fields in stat */ v9lstat->st_result_mask = P9_STATS_BASIC; - stat_to_qid(stbuf, &v9lstat->qid); + return stat_to_qid(pdu, stbuf, &v9lstat->qid); } static void print_sg(struct iovec *sg, int cnt) @@ -1115,7 +1131,6 @@ static void coroutine_fn v9fs_getattr(void *opaque) uint64_t request_mask; V9fsStatDotl v9stat_dotl; V9fsPDU *pdu = opaque; - V9fsState *s = pdu->s; retval = pdu_unmarshal(pdu, offset, "dq", &fid, &request_mask); if (retval < 0) { @@ -1136,7 +1151,10 @@ static void coroutine_fn v9fs_getattr(void *opaque) if (retval < 0) { goto out; } - stat_to_v9stat_dotl(s, &stbuf, &v9stat_dotl); + retval = stat_to_v9stat_dotl(pdu, &stbuf, &v9stat_dotl); + if (retval < 0) { + goto out; + } /* fill st_gen if requested and supported by underlying fs */ if (request_mask & P9_STATS_GEN) { @@ -1381,7 +1399,10 @@ static void coroutine_fn v9fs_walk(void *opaque) if (err < 0) { goto out; } - stat_to_qid(&stbuf, &qid); + err = stat_to_qid(pdu, &stbuf, &qid); + if (err < 0) { + goto out; + } v9fs_path_copy(&dpath, &path); } memcpy(&qids[name_idx], &qid, sizeof(qid)); @@ -1483,7 +1504,10 @@ static void coroutine_fn v9fs_open(void *opaque) if (err < 0) { goto out; } - stat_to_qid(&stbuf, &qid); + err = stat_to_qid(pdu, &stbuf, &qid); + if (err < 0) { + goto out; + } if (S_ISDIR(stbuf.st_mode)) { err = v9fs_co_opendir(pdu, fidp); if (err < 0) { @@ -1593,7 +1617,10 @@ static void coroutine_fn v9fs_lcreate(void *opaque) fidp->flags |= FID_NON_RECLAIMABLE; } iounit = get_iounit(pdu, &fidp->path); - stat_to_qid(&stbuf, &qid); + err = stat_to_qid(pdu, &stbuf, &qid); + if (err < 0) { + goto out; + } err = pdu_marshal(pdu, offset, "Qd", &qid, iounit); if (err < 0) { goto out; @@ -2327,7 +2354,10 @@ static void coroutine_fn v9fs_create(void *opaque) } } iounit = get_iounit(pdu, &fidp->path); - stat_to_qid(&stbuf, &qid); + err = stat_to_qid(pdu, &stbuf, &qid); + if (err < 0) { + goto out; + } err = pdu_marshal(pdu, offset, "Qd", &qid, iounit); if (err < 0) { goto out; @@ -2384,7 +2414,10 @@ static void coroutine_fn v9fs_symlink(void *opaque) if (err < 0) { goto out; } - stat_to_qid(&stbuf, &qid); + err = stat_to_qid(pdu, &stbuf, &qid); + if (err < 0) { + goto out; + } err = pdu_marshal(pdu, offset, "Q", &qid); if (err < 0) { goto out; @@ -3064,7 +3097,10 @@ static void coroutine_fn v9fs_mknod(void *opaque) if (err < 0) { goto out; } - stat_to_qid(&stbuf, &qid); + err = stat_to_qid(pdu, &stbuf, &qid); + if (err < 0) { + goto out; + } err = pdu_marshal(pdu, offset, "Q", &qid); if (err < 0) { goto out; @@ -3222,7 +3258,10 @@ static void coroutine_fn v9fs_mkdir(void *opaque) if (err < 0) { goto out; } - stat_to_qid(&stbuf, &qid); + err = stat_to_qid(pdu, &stbuf, &qid); + if (err < 0) { + goto out; + } err = pdu_marshal(pdu, offset, "Q", &qid); if (err < 0) { goto out; @@ -3633,6 +3672,8 @@ int v9fs_device_realize_common(V9fsState *s, const V9fsTransport *t, goto out; } + s->dev_id = stat.st_dev; + s->ctx.fst = &fse->fst; fsdev_throttle_init(s->ctx.fst); diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h index 8883761b2c..5e316178d5 100644 --- a/hw/9pfs/9p.h +++ b/hw/9pfs/9p.h @@ -256,6 +256,7 @@ struct V9fsState Error *migration_blocker; V9fsConf fsconf; V9fsQID root_qid; + dev_t dev_id; }; /* 9p2000.L open flags */ From patchwork Thu Aug 22 19:33:37 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Denis V. Lunev\" via" X-Patchwork-Id: 11110151 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 15023184E for ; Thu, 22 Aug 2019 21:58:05 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CF9A020679 for ; Thu, 22 Aug 2019 21:58:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=crudebyte.com header.i=@crudebyte.com header.b="K7rwguaQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CF9A020679 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=nongnu.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:48116 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i0v5n-0005fY-Tg for patchwork-qemu-devel@patchwork.kernel.org; Thu, 22 Aug 2019 17:58:03 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:42870) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from <50fc6fbbfd80c25d2ad1752fb945cdfc7d847f20@lizzy.crudebyte.com>) id 1i0v50-0004JV-Ei for qemu-devel@nongnu.org; Thu, 22 Aug 2019 17:57:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from <50fc6fbbfd80c25d2ad1752fb945cdfc7d847f20@lizzy.crudebyte.com>) id 1i0v4x-0006Hu-Nu for qemu-devel@nongnu.org; Thu, 22 Aug 2019 17:57:14 -0400 Received: from lizzy.crudebyte.com ([91.194.90.13]:33343) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from <50fc6fbbfd80c25d2ad1752fb945cdfc7d847f20@lizzy.crudebyte.com>) id 1i0v4x-000623-7A for qemu-devel@nongnu.org; Thu, 22 Aug 2019 17:57:11 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=lizzy; h=Subject:Date:Cc:To:From:References:In-Reply-To: Message-Id:Sender:Reply-To:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=vnME3I052jcZIHUVQ8d2TkPqHGmKWQEf9VDFkZhhJiE=; b=K7rwguaQbrOA6IwW606m2RoLk CJQEgJj50BX1lhwP1YFQfwvAjK0Xh2vXXEZvYo6qfNAAGiie50bnwA4igzwxHNMcvOh5qmfAyWdD5 lJh4uxVqZfikMgYt22h1fWIWD/igkBgNZ5pzHMlvGB2jA6aptVB5pVlAEjJIKd+walRFYzuF9ATJY Y4Txl61PHjwwWqTv6lwIuZmwwRllThHlIpPDsDvgQXpEzRDs4WPu/izPaB+7AE1SzX6Afi8mjJm+d vHctLi2sGa1xJF89s8vkGZB3wZfJ4bxPVYd1pF09pBJZmEqPe7yjVzz63irLMBSoMDGQ2b+CDu7+R KDj5huBxg==; Message-Id: <50fc6fbbfd80c25d2ad1752fb945cdfc7d847f20.1566503584.git.qemu_oss@crudebyte.com> In-Reply-To: References: To: qemu-devel@nongnu.org Date: Thu, 22 Aug 2019 21:33:37 +0200 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 91.194.90.13 Subject: [Qemu-devel] [PATCH v6 2/4] 9p: Added virtfs option 'multidevs=remap|forbid|warn' X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Christian Schoenebeck via Qemu-devel From: "Denis V. Lunev\" via" Reply-To: Christian Schoenebeck Cc: Stefan Hajnoczi , Daniel =?utf-8?b?UC4gQmVycmFuZ8Op?= , Greg Kurz , Antonios Motakis , "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" 'warn' (default): Only log an error message (once) on host if more than one device is shared by same export, except of that just ignore this config error though. This is the default behaviour for not breaking existing installations implying that they really know what they are doing. 'forbid': Like 'warn', but except of just logging an error this also denies access of guest to additional devices. 'remap': Allows to share more than one device per export by remapping inodes from host to guest appropriately. To support multiple devices on the 9p share, and avoid qid path collisions we take the device id as input to generate a unique QID path. The lowest 48 bits of the path will be set equal to the file inode, and the top bits will be uniquely assigned based on the top 16 bits of the inode and the device id. Signed-off-by: Antonios Motakis [CS: - Rebased to https://github.com/gkurz/qemu/commits/9p-next (SHA1 177fd3b6a8). - Updated hash calls to new xxhash API. - Added virtfs option 'multidevs', original patch simply did the inode remapping without being asked. - Updated docs for new option 'multidevs'. - Capture root_ino in v9fs_device_realize_common() as well, not just the device id. - Fixed v9fs_do_readdir() not having remapped inodes. - Log error message when running out of prefixes in qid_path_prefixmap(). - Fixed definition of QPATH_INO_MASK. - Dropped unnecessary parantheses in qpp_lookup_func(). - Dropped unnecessary g_malloc0() result checks. ] Signed-off-by: Christian Schoenebeck --- fsdev/file-op-9p.h | 5 ++ fsdev/qemu-fsdev-opts.c | 7 +- fsdev/qemu-fsdev.c | 11 +++ hw/9pfs/9p.c | 182 ++++++++++++++++++++++++++++++++++++++++++------ hw/9pfs/9p.h | 13 ++++ qemu-options.hx | 33 +++++++-- vl.c | 6 +- 7 files changed, 229 insertions(+), 28 deletions(-) diff --git a/fsdev/file-op-9p.h b/fsdev/file-op-9p.h index c757c8099f..f2f7772c86 100644 --- a/fsdev/file-op-9p.h +++ b/fsdev/file-op-9p.h @@ -59,6 +59,11 @@ typedef struct ExtendedOps { #define V9FS_RDONLY 0x00000040 #define V9FS_PROXY_SOCK_FD 0x00000080 #define V9FS_PROXY_SOCK_NAME 0x00000100 +/* + * multidevs option (either one of the two applies exclusively) + */ +#define V9FS_REMAP_INODES 0x00000200 +#define V9FS_FORBID_MULTIDEVS 0x00000400 #define V9FS_SEC_MASK 0x0000003C diff --git a/fsdev/qemu-fsdev-opts.c b/fsdev/qemu-fsdev-opts.c index 7c31ffffaf..07a18c6e48 100644 --- a/fsdev/qemu-fsdev-opts.c +++ b/fsdev/qemu-fsdev-opts.c @@ -31,7 +31,9 @@ static QemuOptsList qemu_fsdev_opts = { }, { .name = "readonly", .type = QEMU_OPT_BOOL, - + }, { + .name = "multidevs", + .type = QEMU_OPT_STRING, }, { .name = "socket", .type = QEMU_OPT_STRING, @@ -76,6 +78,9 @@ static QemuOptsList qemu_virtfs_opts = { .name = "readonly", .type = QEMU_OPT_BOOL, }, { + .name = "multidevs", + .type = QEMU_OPT_STRING, + }, { .name = "socket", .type = QEMU_OPT_STRING, }, { diff --git a/fsdev/qemu-fsdev.c b/fsdev/qemu-fsdev.c index 077a8c4e2b..ed03d559a9 100644 --- a/fsdev/qemu-fsdev.c +++ b/fsdev/qemu-fsdev.c @@ -58,6 +58,7 @@ static FsDriverTable FsDrivers[] = { "writeout", "fmode", "dmode", + "multidevs", "throttling.bps-total", "throttling.bps-read", "throttling.bps-write", @@ -121,6 +122,7 @@ int qemu_fsdev_add(QemuOpts *opts, Error **errp) const char *fsdev_id = qemu_opts_id(opts); const char *fsdriver = qemu_opt_get(opts, "fsdriver"); const char *writeout = qemu_opt_get(opts, "writeout"); + const char *multidevs = qemu_opt_get(opts, "multidevs"); bool ro = qemu_opt_get_bool(opts, "readonly", 0); if (!fsdev_id) { @@ -161,6 +163,15 @@ int qemu_fsdev_add(QemuOpts *opts, Error **errp) } else { fsle->fse.export_flags &= ~V9FS_RDONLY; } + if (multidevs) { + if (!strcmp(multidevs, "remap")) { + fsle->fse.export_flags &= ~V9FS_FORBID_MULTIDEVS; + fsle->fse.export_flags |= V9FS_REMAP_INODES; + } else if (!strcmp(multidevs, "forbid")) { + fsle->fse.export_flags &= ~V9FS_REMAP_INODES; + fsle->fse.export_flags |= V9FS_FORBID_MULTIDEVS; + } + } if (fsle->fse.ops->parse_opts) { if (fsle->fse.ops->parse_opts(opts, &fsle->fse, errp)) { diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index 8cc65c2c67..c96ea51116 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -25,6 +25,7 @@ #include "trace.h" #include "migration/blocker.h" #include "sysemu/qtest.h" +#include "qemu/xxhash.h" int open_fd_hw; int total_open_fd; @@ -571,22 +572,109 @@ static void coroutine_fn virtfs_reset(V9fsPDU *pdu) P9_STAT_MODE_NAMED_PIPE | \ P9_STAT_MODE_SOCKET) -/* This is the algorithm from ufs in spfs */ + +/* creative abuse of tb_hash_func7, which is based on xxhash */ +static uint32_t qpp_hash(QppEntry e) +{ + return qemu_xxhash7(e.ino_prefix, e.dev, 0, 0, 0); +} + +static bool qpp_lookup_func(const void *obj, const void *userp) +{ + const QppEntry *e1 = obj, *e2 = userp; + return e1->dev == e2->dev && e1->ino_prefix == e2->ino_prefix; +} + +static void qpp_table_remove(void *p, uint32_t h, void *up) +{ + g_free(p); +} + +static void qpp_table_destroy(struct qht *ht) +{ + qht_iter(ht, qpp_table_remove, NULL); + qht_destroy(ht); +} + +/* stat_to_qid needs to map inode number (64 bits) and device id (32 bits) + * to a unique QID path (64 bits). To avoid having to map and keep track + * of up to 2^64 objects, we map only the 16 highest bits of the inode plus + * the device id to the 16 highest bits of the QID path. The 48 lowest bits + * of the QID path equal to the lowest bits of the inode number. + * + * This takes advantage of the fact that inode number are usually not + * random but allocated sequentially, so we have fewer items to keep + * track of. + */ +static int qid_path_prefixmap(V9fsPDU *pdu, const struct stat *stbuf, + uint64_t *path) +{ + QppEntry lookup = { + .dev = stbuf->st_dev, + .ino_prefix = (uint16_t) (stbuf->st_ino >> 48) + }, *val; + uint32_t hash = qpp_hash(lookup); + + val = qht_lookup(&pdu->s->qpp_table, &lookup, hash); + + if (!val) { + if (pdu->s->qp_prefix_next == 0) { + /* we ran out of prefixes */ + error_report_once( + "9p: No more prefixes available for remapping inodes from " + "host to guest." + ); + return -ENFILE; + } + + val = g_malloc0(sizeof(QppEntry)); + *val = lookup; + + /* new unique inode prefix and device combo */ + val->qp_prefix = pdu->s->qp_prefix_next++; + qht_insert(&pdu->s->qpp_table, val, hash, NULL); + } + + *path = ((uint64_t)val->qp_prefix << 48) | (stbuf->st_ino & QPATH_INO_MASK); + return 0; +} + static int stat_to_qid(V9fsPDU *pdu, const struct stat *stbuf, V9fsQID *qidp) { + int err; size_t size; - if (pdu->s->dev_id != stbuf->st_dev) { - error_report_once( - "9p: Multiple devices detected in same VirtFS export. " - "You must use a separate export for each device." - ); - return -ENODEV; + if (pdu->s->ctx.export_flags & V9FS_REMAP_INODES) { + /* map inode+device to qid path (fast path) */ + err = qid_path_prefixmap(pdu, stbuf, &qidp->path); + if (err) { + return err; + } + } else { + if (pdu->s->dev_id != stbuf->st_dev) { + if (pdu->s->ctx.export_flags & V9FS_FORBID_MULTIDEVS) { + error_report_once( + "9p: Multiple devices detected in same VirtFS export. " + "Access of guest to additional devices is (partly) " + "denied due to virtfs option 'multidevs=forbid' being " + "effective." + ); + return -ENODEV; + } else { + error_report_once( + "9p: Multiple devices detected in same VirtFS export, " + "which might lead to file ID collisions and severe " + "misbehaviours on guest! You should either use a " + "separate export for each device shared from host or " + "use virtfs option 'multidevs=remap'!" + ); + } + } + memset(&qidp->path, 0, sizeof(qidp->path)); + size = MIN(sizeof(stbuf->st_ino), sizeof(qidp->path)); + memcpy(&qidp->path, &stbuf->st_ino, size); } - memset(&qidp->path, 0, sizeof(qidp->path)); - size = MIN(sizeof(stbuf->st_ino), sizeof(qidp->path)); - memcpy(&qidp->path, &stbuf->st_ino, size); qidp->version = stbuf->st_mtime ^ (stbuf->st_size << 8); qidp->type = 0; if (S_ISDIR(stbuf->st_mode)) { @@ -616,6 +704,30 @@ static int coroutine_fn fid_to_qid(V9fsPDU *pdu, V9fsFidState *fidp, return 0; } +static int coroutine_fn dirent_to_qid(V9fsPDU *pdu, V9fsFidState *fidp, + struct dirent *dent, V9fsQID *qidp) +{ + struct stat stbuf; + V9fsPath path; + int err; + + v9fs_path_init(&path); + + err = v9fs_co_name_to_path(pdu, &fidp->path, dent->d_name, &path); + if (err < 0) { + goto out; + } + err = v9fs_co_lstat(pdu, &path, &stbuf); + if (err < 0) { + goto out; + } + err = stat_to_qid(pdu, &stbuf, qidp); + +out: + v9fs_path_free(&path); + return err; +} + V9fsPDU *pdu_alloc(V9fsState *s) { V9fsPDU *pdu = NULL; @@ -1964,16 +2076,39 @@ static int coroutine_fn v9fs_do_readdir(V9fsPDU *pdu, V9fsFidState *fidp, v9fs_string_free(&name); return count; } - /* - * Fill up just the path field of qid because the client uses - * only that. To fill the entire qid structure we will have - * to stat each dirent found, which is expensive - */ - size = MIN(sizeof(dent->d_ino), sizeof(qid.path)); - memcpy(&qid.path, &dent->d_ino, size); - /* Fill the other fields with dummy values */ - qid.type = 0; - qid.version = 0; + + if (pdu->s->ctx.export_flags & V9FS_REMAP_INODES) { + /* + * dirent_to_qid() implies expensive stat call for each entry, + * we must do that here though since inode remapping requires + * the device id, which in turn might be different for + * different entries; we cannot make any assumption to avoid + * that here. + */ + err = dirent_to_qid(pdu, fidp, dent, &qid); + if (err < 0) { + v9fs_readdir_unlock(&fidp->fs.dir); + v9fs_co_seekdir(pdu, fidp, saved_dir_pos); + v9fs_string_free(&name); + return err; + } + } else { + /* + * Fill up just the path field of qid because the client uses + * only that. To fill the entire qid structure we will have + * to stat each dirent found, which is expensive. For the + * latter reason we don't call dirent_to_qid() here. Only drawback + * is that no multi-device export detection of stat_to_qid() + * would be done and provided as error to the user here. But + * user would get that error anyway when accessing those + * files/dirs through other ways. + */ + size = MIN(sizeof(dent->d_ino), sizeof(qid.path)); + memcpy(&qid.path, &dent->d_ino, size); + /* Fill the other fields with dummy values */ + qid.type = 0; + qid.version = 0; + } /* 11 = 7 + 4 (7 = start offset, 4 = space for storing count) */ len = pdu_marshal(pdu, 11 + count, "Qqbs", @@ -3672,8 +3807,13 @@ int v9fs_device_realize_common(V9fsState *s, const V9fsTransport *t, goto out; } + s->root_ino = stat.st_ino; s->dev_id = stat.st_dev; + /* QID path hash table. 1 entry ought to be enough for anybody ;) */ + qht_init(&s->qpp_table, qpp_lookup_func, 1, QHT_MODE_AUTO_RESIZE); + s->qp_prefix_next = 1; /* reserve 0 to detect overflow */ + s->ctx.fst = &fse->fst; fsdev_throttle_init(s->ctx.fst); @@ -3687,6 +3827,7 @@ out: } g_free(s->tag); g_free(s->ctx.fs_root); + qpp_table_destroy(&s->qpp_table); v9fs_path_free(&path); } return rc; @@ -3699,6 +3840,7 @@ void v9fs_device_unrealize_common(V9fsState *s, Error **errp) } fsdev_throttle_cleanup(s->ctx.fst); g_free(s->tag); + qpp_table_destroy(&s->qpp_table); g_free(s->ctx.fs_root); } diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h index 5e316178d5..a283b0193e 100644 --- a/hw/9pfs/9p.h +++ b/hw/9pfs/9p.h @@ -8,6 +8,7 @@ #include "fsdev/9p-iov-marshal.h" #include "qemu/thread.h" #include "qemu/coroutine.h" +#include "qemu/qht.h" enum { P9_TLERROR = 6, @@ -235,6 +236,15 @@ struct V9fsFidState V9fsFidState *rclm_lst; }; +#define QPATH_INO_MASK ((1ULL << 48) - 1) + +/* QID path prefix entry, see stat_to_qid */ +typedef struct { + dev_t dev; + uint16_t ino_prefix; + uint16_t qp_prefix; +} QppEntry; + struct V9fsState { QLIST_HEAD(, V9fsPDU) free_list; @@ -256,7 +266,10 @@ struct V9fsState Error *migration_blocker; V9fsConf fsconf; V9fsQID root_qid; + ino_t root_ino; dev_t dev_id; + struct qht qpp_table; + uint16_t qp_prefix_next; }; /* 9p2000.L open flags */ diff --git a/qemu-options.hx b/qemu-options.hx index 9621e934c0..603e5e8e15 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -1335,17 +1335,17 @@ ETEXI DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs, "-virtfs local,path=path,mount_tag=tag,security_model=mapped-xattr|mapped-file|passthrough|none\n" - " [,id=id][,writeout=immediate][,readonly][,fmode=fmode][,dmode=dmode]\n" - "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly]\n" - "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly]\n" + " [,id=id][,writeout=immediate][,readonly][,fmode=fmode][,dmode=dmode][,multidevs=remap|forbid|warn]\n" + "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly][,multidevs=remap|forbid|warn]\n" + "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly][,multidevs=remap|forbid|warn]\n" "-virtfs synth,mount_tag=tag[,id=id][,readonly]\n", QEMU_ARCH_ALL) STEXI -@item -virtfs local,path=@var{path},mount_tag=@var{mount_tag} ,security_model=@var{security_model}[,writeout=@var{writeout}][,readonly] [,fmode=@var{fmode}][,dmode=@var{dmode}] -@itemx -virtfs proxy,socket=@var{socket},mount_tag=@var{mount_tag} [,writeout=@var{writeout}][,readonly] -@itemx -virtfs proxy,sock_fd=@var{sock_fd},mount_tag=@var{mount_tag} [,writeout=@var{writeout}][,readonly] +@item -virtfs local,path=@var{path},mount_tag=@var{mount_tag} ,security_model=@var{security_model}[,writeout=@var{writeout}][,readonly] [,fmode=@var{fmode}][,dmode=@var{dmode}][,multidevs=@var{multidevs}] +@itemx -virtfs proxy,socket=@var{socket},mount_tag=@var{mount_tag} [,writeout=@var{writeout}][,readonly][,multidevs=@var{multidevs}] +@itemx -virtfs proxy,sock_fd=@var{sock_fd},mount_tag=@var{mount_tag} [,writeout=@var{writeout}][,readonly][,multidevs=@var{multidevs}] @itemx -virtfs synth,mount_tag=@var{mount_tag} @findex -virtfs @@ -1399,6 +1399,27 @@ Specifies the default mode for newly created directories on the host. Works only with security models "mapped-xattr" and "mapped-file". @item mount_tag=@var{mount_tag} Specifies the tag name to be used by the guest to mount this export point. +@item multidevs=@var{multidevs} +Specifies how to deal with multiple devices being shared with a 9p export. +Supported behaviours are either "remap", "forbid" or "warn". The latter is +the default behaviour on which virtfs 9p expects only one device to be +shared with the same export, and if more than one device is shared and +accessed via the same 9p export then only a warning message is logged +(once) by qemu on host side. In order to avoid file ID collisions on guest +you should either create a separate virtfs export for each device to be +shared with guests (recommended way) or you might use "remap" instead which +allows you to share multiple devices with only one export instead, which is +achieved by remapping the original inode numbers from host to guest in a +way that would prevent such collisions. Remapping inodes in such use cases +is required because the original device IDs from host are never passed and +exposed on guest. Instead all files of an export shared with virtfs always +share the same device id on guest. So two files with identical inode +numbers but from actually different devices on host would otherwise cause a +file ID collision and hence potential misbehaviours on guest. "forbid" on +the other hand assumes like "warn" that only one device is shared by the +same export, however it will not only log a warning message but also +deny access to additional devices on guest. Note though that "forbid" does +currently not block all possible file access operations. @end table ETEXI diff --git a/vl.c b/vl.c index b426b32134..9cb29b483d 100644 --- a/vl.c +++ b/vl.c @@ -3320,7 +3320,7 @@ int main(int argc, char **argv, char **envp) case QEMU_OPTION_virtfs: { QemuOpts *fsdev; QemuOpts *device; - const char *writeout, *sock_fd, *socket, *path, *security_model; + const char *writeout, *sock_fd, *socket, *path, *security_model, *multidevs; olist = qemu_find_opts("virtfs"); if (!olist) { @@ -3380,6 +3380,10 @@ int main(int argc, char **argv, char **envp) qemu_opt_set_bool(fsdev, "readonly", qemu_opt_get_bool(opts, "readonly", 0), &error_abort); + multidevs = qemu_opt_get(opts, "multidevs"); + if (multidevs) { + qemu_opt_set(fsdev, "multidevs", multidevs, &error_abort); + } device = qemu_opts_create(qemu_find_opts("device"), NULL, 0, &error_abort); qemu_opt_set(device, "driver", "virtio-9p-pci", &error_abort); From patchwork Thu Aug 22 19:44:28 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Denis V. Lunev\" via" X-Patchwork-Id: 11110155 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 61E2913A4 for ; Thu, 22 Aug 2019 21:59:05 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 38E7C21655 for ; Thu, 22 Aug 2019 21:59:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=crudebyte.com header.i=@crudebyte.com header.b="bMI2h6a6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 38E7C21655 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=nongnu.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:48134 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i0v6m-0006gc-BJ for patchwork-qemu-devel@patchwork.kernel.org; Thu, 22 Aug 2019 17:59:04 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43056) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from <2f8ddf611be0b69ce936e4bd1bf3b18156a22995@lizzy.crudebyte.com>) id 1i0v5y-0005rP-7W for qemu-devel@nongnu.org; Thu, 22 Aug 2019 17:58:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from <2f8ddf611be0b69ce936e4bd1bf3b18156a22995@lizzy.crudebyte.com>) id 1i0v5w-0006ar-QY for qemu-devel@nongnu.org; Thu, 22 Aug 2019 17:58:14 -0400 Received: from lizzy.crudebyte.com ([91.194.90.13]:38799) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from <2f8ddf611be0b69ce936e4bd1bf3b18156a22995@lizzy.crudebyte.com>) id 1i0v5w-0006I3-K8 for qemu-devel@nongnu.org; Thu, 22 Aug 2019 17:58:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=lizzy; h=Subject:Date:Cc:To:From:References:In-Reply-To: Message-Id:Sender:Reply-To:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=t+Ow+NmaIpgO7UyfrCCEQHSXZ9UqtAyOsPA67TZO4Rk=; b=bMI2h6a62H01nlUY0OxJkbeJt aP4CnMyDXelbnxpiBXcObWurXAVpLJVT5UTBa9/vpLIgeB32RyGFLI/UiP1cUj0cfX8C4skhZwAv5 MCS2gdHgiY4LhzJCVoXucctW92Z0gmi7kNtIuZbNLYWftw+TjZHCihvcaeBuUWPXQqJ8mn34wTbtM CjN8Th0Rc/18OvIqgViKm8tB6fjN5qSwwUO9V2BHP+kqyi5C90o3dfXtc5lvkQMuawUS9RnUaah6r ClcYyBmqA8JhAGan3hupRyrpmnCfg1QTcIcdX34aJHaO33CL5wGbrIqGMeqg7y3SGzrA1lZHPo2Iw 546ki2kzw==; Message-Id: <2f8ddf611be0b69ce936e4bd1bf3b18156a22995.1566503584.git.qemu_oss@crudebyte.com> In-Reply-To: References: To: qemu-devel@nongnu.org Date: Thu, 22 Aug 2019 21:44:28 +0200 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 91.194.90.13 Subject: [Qemu-devel] [PATCH v6 3/4] 9p: stat_to_qid: implement slow path X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Christian Schoenebeck via Qemu-devel From: "Denis V. Lunev\" via" Reply-To: Christian Schoenebeck Cc: Stefan Hajnoczi , Daniel =?utf-8?b?UC4gQmVycmFuZ8Op?= , Greg Kurz , Antonios Motakis , "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" stat_to_qid attempts via qid_path_prefixmap to map unique files (which are identified by 64 bit inode nr and 32 bit device id) to a 64 QID path value. However this implementation makes some assumptions about inode number generation on the host. If qid_path_prefixmap fails, we still have 48 bits available in the QID path to fall back to a less memory efficient full mapping. Signed-off-by: Antonios Motakis [CS: - Rebased to https://github.com/gkurz/qemu/commits/9p-next (SHA1 177fd3b6a8). - Updated hash calls to new xxhash API. - Removed unnecessary parantheses in qpf_lookup_func(). - Removed unnecessary g_malloc0() result checks. - Log error message when running out of prefixes in qid_path_fullmap(). - Log error message about potential degraded performance in qid_path_prefixmap(). - Fixed typo in comment. ] Signed-off-by: Christian Schoenebeck --- hw/9pfs/9p.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++++------ hw/9pfs/9p.h | 9 ++++++++ 2 files changed, 72 insertions(+), 7 deletions(-) diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index c96ea51116..728641fb7f 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -579,23 +579,73 @@ static uint32_t qpp_hash(QppEntry e) return qemu_xxhash7(e.ino_prefix, e.dev, 0, 0, 0); } +static uint32_t qpf_hash(QpfEntry e) +{ + return qemu_xxhash7(e.ino, e.dev, 0, 0, 0); +} + static bool qpp_lookup_func(const void *obj, const void *userp) { const QppEntry *e1 = obj, *e2 = userp; return e1->dev == e2->dev && e1->ino_prefix == e2->ino_prefix; } -static void qpp_table_remove(void *p, uint32_t h, void *up) +static bool qpf_lookup_func(const void *obj, const void *userp) +{ + const QpfEntry *e1 = obj, *e2 = userp; + return e1->dev == e2->dev && e1->ino == e2->ino; +} + +static void qp_table_remove(void *p, uint32_t h, void *up) { g_free(p); } -static void qpp_table_destroy(struct qht *ht) +static void qp_table_destroy(struct qht *ht) { - qht_iter(ht, qpp_table_remove, NULL); + qht_iter(ht, qp_table_remove, NULL); qht_destroy(ht); } +static int qid_path_fullmap(V9fsPDU *pdu, const struct stat *stbuf, + uint64_t *path) +{ + QpfEntry lookup = { + .dev = stbuf->st_dev, + .ino = stbuf->st_ino + }, *val; + uint32_t hash = qpf_hash(lookup); + + /* most users won't need the fullmap, so init the table lazily */ + if (!pdu->s->qpf_table.map) { + qht_init(&pdu->s->qpf_table, qpf_lookup_func, 1 << 16, QHT_MODE_AUTO_RESIZE); + } + + val = qht_lookup(&pdu->s->qpf_table, &lookup, hash); + + if (!val) { + if (pdu->s->qp_fullpath_next == 0) { + /* no more files can be mapped :'( */ + error_report_once( + "9p: No more prefixes available for remapping inodes from " + "host to guest." + ); + return -ENFILE; + } + + val = g_malloc0(sizeof(QppEntry)); + *val = lookup; + + /* new unique inode and device combo */ + val->path = pdu->s->qp_fullpath_next++; + pdu->s->qp_fullpath_next &= QPATH_INO_MASK; + qht_insert(&pdu->s->qpf_table, val, hash, NULL); + } + + *path = val->path; + return 0; +} + /* stat_to_qid needs to map inode number (64 bits) and device id (32 bits) * to a unique QID path (64 bits). To avoid having to map and keep track * of up to 2^64 objects, we map only the 16 highest bits of the inode plus @@ -621,8 +671,7 @@ static int qid_path_prefixmap(V9fsPDU *pdu, const struct stat *stbuf, if (pdu->s->qp_prefix_next == 0) { /* we ran out of prefixes */ error_report_once( - "9p: No more prefixes available for remapping inodes from " - "host to guest." + "9p: Potential degraded performance of inode remapping" ); return -ENFILE; } @@ -647,6 +696,10 @@ static int stat_to_qid(V9fsPDU *pdu, const struct stat *stbuf, V9fsQID *qidp) if (pdu->s->ctx.export_flags & V9FS_REMAP_INODES) { /* map inode+device to qid path (fast path) */ err = qid_path_prefixmap(pdu, stbuf, &qidp->path); + if (err == -ENFILE) { + /* fast path didn't work, fall back to full map */ + err = qid_path_fullmap(pdu, stbuf, &qidp->path); + } if (err) { return err; } @@ -3813,6 +3866,7 @@ int v9fs_device_realize_common(V9fsState *s, const V9fsTransport *t, /* QID path hash table. 1 entry ought to be enough for anybody ;) */ qht_init(&s->qpp_table, qpp_lookup_func, 1, QHT_MODE_AUTO_RESIZE); s->qp_prefix_next = 1; /* reserve 0 to detect overflow */ + s->qp_fullpath_next = 1; s->ctx.fst = &fse->fst; fsdev_throttle_init(s->ctx.fst); @@ -3827,7 +3881,8 @@ out: } g_free(s->tag); g_free(s->ctx.fs_root); - qpp_table_destroy(&s->qpp_table); + qp_table_destroy(&s->qpp_table); + qp_table_destroy(&s->qpf_table); v9fs_path_free(&path); } return rc; @@ -3840,7 +3895,8 @@ void v9fs_device_unrealize_common(V9fsState *s, Error **errp) } fsdev_throttle_cleanup(s->ctx.fst); g_free(s->tag); - qpp_table_destroy(&s->qpp_table); + qp_table_destroy(&s->qpp_table); + qp_table_destroy(&s->qpf_table); g_free(s->ctx.fs_root); } diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h index a283b0193e..f044a88a41 100644 --- a/hw/9pfs/9p.h +++ b/hw/9pfs/9p.h @@ -245,6 +245,13 @@ typedef struct { uint16_t qp_prefix; } QppEntry; +/* QID path full entry, as above */ +typedef struct { + dev_t dev; + ino_t ino; + uint64_t path; +} QpfEntry; + struct V9fsState { QLIST_HEAD(, V9fsPDU) free_list; @@ -269,7 +276,9 @@ struct V9fsState ino_t root_ino; dev_t dev_id; struct qht qpp_table; + struct qht qpf_table; uint16_t qp_prefix_next; + uint64_t qp_fullpath_next; }; /* 9p2000.L open flags */ From patchwork Thu Aug 22 19:49:06 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Denis V. Lunev\" via" X-Patchwork-Id: 11110173 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 511FD1399 for ; Thu, 22 Aug 2019 22:05:56 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0E3AE21655 for ; Thu, 22 Aug 2019 22:05:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=crudebyte.com header.i=@crudebyte.com header.b="DK3CwnHJ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0E3AE21655 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=nongnu.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:48208 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i0vDP-00037F-6R for patchwork-qemu-devel@patchwork.kernel.org; Thu, 22 Aug 2019 18:05:55 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43612) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i0v9C-0008Q3-8D for qemu-devel@nongnu.org; Thu, 22 Aug 2019 18:01:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i0v99-0007nB-HN for qemu-devel@nongnu.org; Thu, 22 Aug 2019 18:01:34 -0400 Received: from lizzy.crudebyte.com ([91.194.90.13]:44805) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i0v99-0007N0-69 for qemu-devel@nongnu.org; Thu, 22 Aug 2019 18:01:31 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=lizzy; h=Subject:Date:Cc:To:From:References:In-Reply-To: Message-Id:Sender:Reply-To:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=UeGdOkPmrOlIzKTtXzTM2YbBuQv/MFh3vfvx06IAkA4=; b=DK3CwnHJJALy5ebhOL4ESkhx/ fx/0yp0uzbx8W74puB6bfDqySgCOx0Qo0cc5MdnpqGb74MNIehj+hj4tUptEl6MkuBPK04PDpGsHK Q7+qBOgZl/INvm315oYSX/ldkMZHFor0wqQwkOeAdl2M2Rbjz96kZMpcp3FDaLqXLxb32lxIx93Vw 12Ry/XXoc6P7BtbZLh/irGVnyGFuqs+0f3zBEI3iCg+GA8lfrdpySuok6nkL2olOMxU3kOf2E1FHc At6eVx66oaNI9iM86782lqtyi2lzVyY/szJd0+C1YxYc/xVrkFrTqH7YlvbNE6/l66dQaYvR4ItVM kz1brcfQw==; Message-Id: In-Reply-To: References: To: qemu-devel@nongnu.org Date: Thu, 22 Aug 2019 21:49:06 +0200 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 91.194.90.13 Subject: [Qemu-devel] [PATCH v6 4/4] 9p: Use variable length suffixes for inode remapping X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Christian Schoenebeck via Qemu-devel From: "Denis V. Lunev\" via" Reply-To: Christian Schoenebeck Cc: Stefan Hajnoczi , Daniel =?utf-8?b?UC4gQmVycmFuZ8Op?= , Greg Kurz , Antonios Motakis , "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" Use variable length suffixes for inode remapping instead of the fixed 16 bit size prefixes before. With this change the inode numbers on guest will typically be much smaller (e.g. around >2^1 .. >2^7 instead of >2^48 with the previous fixed size inode remapping. Additionally this solution is more efficient, since inode numbers in practice can take almost their entire 64 bit range on guest as well, so there is less likely a need for generating and tracking additional suffixes, which might also be beneficial for nested virtualization where each level of virtualization would shift up the inode bits and increase the chance of expensive remapping actions. The "Exponential Golomb" algorithm is used as basis for generating the variable length suffixes. The algorithm has a parameter k which controls the distribution of bits on increasing indeces (minimum bits at low index vs. maximum bits at high index). With k=0 the generated suffixes look like: Index Dec/Bin -> Generated Suffix Bin 1 [1] -> [1] (1 bits) 2 [10] -> [010] (3 bits) 3 [11] -> [110] (3 bits) 4 [100] -> [00100] (5 bits) 5 [101] -> [10100] (5 bits) 6 [110] -> [01100] (5 bits) 7 [111] -> [11100] (5 bits) 8 [1000] -> [0001000] (7 bits) 9 [1001] -> [1001000] (7 bits) 10 [1010] -> [0101000] (7 bits) 11 [1011] -> [1101000] (7 bits) 12 [1100] -> [0011000] (7 bits) ... 65533 [1111111111111101] -> [1011111111111111000000000000000] (31 bits) 65534 [1111111111111110] -> [0111111111111111000000000000000] (31 bits) 65535 [1111111111111111] -> [1111111111111111000000000000000] (31 bits) Hence minBits=1 maxBits=31 And with k=5 they would look like: Index Dec/Bin -> Generated Suffix Bin 1 [1] -> [000001] (6 bits) 2 [10] -> [100001] (6 bits) 3 [11] -> [010001] (6 bits) 4 [100] -> [110001] (6 bits) 5 [101] -> [001001] (6 bits) 6 [110] -> [101001] (6 bits) 7 [111] -> [011001] (6 bits) 8 [1000] -> [111001] (6 bits) 9 [1001] -> [000101] (6 bits) 10 [1010] -> [100101] (6 bits) 11 [1011] -> [010101] (6 bits) 12 [1100] -> [110101] (6 bits) ... 65533 [1111111111111101] -> [0011100000000000100000000000] (28 bits) 65534 [1111111111111110] -> [1011100000000000100000000000] (28 bits) 65535 [1111111111111111] -> [0111100000000000100000000000] (28 bits) Hence minBits=6 maxBits=28 Signed-off-by: Christian Schoenebeck --- hw/9pfs/9p.c | 247 ++++++++++++++++++++++++++++++++++++++++++++++++++++------- hw/9pfs/9p.h | 34 +++++++- 2 files changed, 251 insertions(+), 30 deletions(-) diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index 728641fb7f..0359469cfa 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -26,6 +26,7 @@ #include "migration/blocker.h" #include "sysemu/qtest.h" #include "qemu/xxhash.h" +#include int open_fd_hw; int total_open_fd; @@ -572,6 +573,107 @@ static void coroutine_fn virtfs_reset(V9fsPDU *pdu) P9_STAT_MODE_NAMED_PIPE | \ P9_STAT_MODE_SOCKET) +/* Mirrors all bits of a byte. So e.g. binary 10100000 would become 00000101. */ +static inline uint8_t mirror8bit(uint8_t byte) +{ + return (byte * 0x0202020202ULL & 0x010884422010ULL) % 1023; +} + +/* Same as mirror8bit() just for a 64 bit data type instead for a byte. */ +static inline uint64_t mirror64bit(uint64_t value) +{ + return ((uint64_t)mirror8bit( value & 0xff) << 56) | + ((uint64_t)mirror8bit((value >> 8) & 0xff) << 48) | + ((uint64_t)mirror8bit((value >> 16) & 0xff) << 40) | + ((uint64_t)mirror8bit((value >> 24) & 0xff) << 32) | + ((uint64_t)mirror8bit((value >> 32) & 0xff) << 24) | + ((uint64_t)mirror8bit((value >> 40) & 0xff) << 16) | + ((uint64_t)mirror8bit((value >> 48) & 0xff) << 8 ) | + ((uint64_t)mirror8bit((value >> 56) & 0xff) ) ; +} + +/** @brief Parameter k for the Exponential Golomb algorihm to be used. + * + * The smaller this value, the smaller the minimum bit count for the Exp. + * Golomb generated affixes will be (at lowest index) however for the + * price of having higher maximum bit count of generated affixes (at highest + * index). Likewise increasing this parameter yields in smaller maximum bit + * count for the price of having higher minimum bit count. + * + * In practice that means: a good value for k depends on the expected amount + * of devices to be exposed by one export. For a small amount of devices k + * should be small, for a large amount of devices k might be increased + * instead. The default of k=0 should be fine for most users though. + * + * @b IMPORTANT: In case this ever becomes a runtime parameter; the value of + * k should not change as long as guest is still running! Because that would + * cause completely different inode numbers to be generated on guest. + */ +#define EXP_GOLOMB_K 0 + +/** @brief Exponential Golomb algorithm for arbitrary k (including k=0). + * + * The Exponential Golomb algorithm generates @b prefixes (@b not suffixes!) + * with growing length and with the mathematical property of being + * "prefix-free". The latter means the generated prefixes can be prepended + * in front of arbitrary numbers and the resulting concatenated numbers are + * guaranteed to be always unique. + * + * This is a minor adjustment to the original Exp. Golomb algorithm in the + * sense that lowest allowed index (@param n) starts with 1, not with zero. + * + * @param n - natural number (or index) of the prefix to be generated + * (1, 2, 3, ...) + * @param k - parameter k of Exp. Golomb algorithm to be used + * (see comment on EXP_GOLOMB_K macro for details about k) + */ +static VariLenAffix expGolombEncode(uint64_t n, int k) +{ + const uint64_t value = n + (1 << k) - 1; + const int bits = (int) log2(value) + 1; + return (VariLenAffix) { + .type = AffixType_Prefix, + .value = value, + .bits = bits + MAX((bits - 1 - k), 0) + }; +} + +/** @brief Converts a suffix into a prefix, or a prefix into a suffix. + * + * Simply mirror all bits of the affix value, for the purpose to preserve + * respectively the mathematical "prefix-free" or "suffix-free" property + * after the conversion. + * + * If a passed prefix is suitable to create unique numbers, then the + * returned suffix is suitable to create unique numbers as well (and vice + * versa). + */ +static VariLenAffix invertAffix(const VariLenAffix* affix) +{ + return (VariLenAffix) { + .type = (affix->type == AffixType_Suffix) ? AffixType_Prefix : AffixType_Suffix, + .value = mirror64bit(affix->value) >> ((sizeof(affix->value) * 8) - affix->bits), + .bits = affix->bits + }; +} + +/** @brief Generates suffix numbers with "suffix-free" property. + * + * This is just a wrapper function on top of the Exp. Golomb algorithm. + * + * Since the Exp. Golomb algorithm generates prefixes, but we need suffixes, + * this function converts the Exp. Golomb prefixes into appropriate suffixes + * which are still suitable for generating unique numbers. + * + * @param n - natural number (or index) of the suffix to be generated + * (1, 2, 3, ...) + */ +static VariLenAffix affixForIndex(uint64_t index) +{ + VariLenAffix prefix; + prefix = expGolombEncode(index, EXP_GOLOMB_K); + return invertAffix(&prefix); /* convert prefix to suffix */ +} /* creative abuse of tb_hash_func7, which is based on xxhash */ static uint32_t qpp_hash(QppEntry e) @@ -584,13 +686,19 @@ static uint32_t qpf_hash(QpfEntry e) return qemu_xxhash7(e.ino, e.dev, 0, 0, 0); } -static bool qpp_lookup_func(const void *obj, const void *userp) +static bool qpd_cmp_func(const void *obj, const void *userp) +{ + const QpdEntry *e1 = obj, *e2 = userp; + return e1->dev == e2->dev; +} + +static bool qpp_cmp_func(const void *obj, const void *userp) { const QppEntry *e1 = obj, *e2 = userp; return e1->dev == e2->dev && e1->ino_prefix == e2->ino_prefix; } -static bool qpf_lookup_func(const void *obj, const void *userp) +static bool qpf_cmp_func(const void *obj, const void *userp) { const QpfEntry *e1 = obj, *e2 = userp; return e1->dev == e2->dev && e1->ino == e2->ino; @@ -607,6 +715,54 @@ static void qp_table_destroy(struct qht *ht) qht_destroy(ht); } +/* + * Returns how many (high end) bits of inode numbers of the passed fs + * device shall be used (in combination with the device number) to + * generate hash values for qpp_table entries. + * + * This function is required if variable length suffixes are used for inode + * number mapping on guest level. Since a device may end up having multiple + * entries in qpp_table, each entry most probably with a different suffix + * length, we thus need this function in conjunction with qpd_table to + * "agree" about a fix amount of bits (per device) to be always used for + * generating hash values for the purpose of accessing qpp_table in order + * get consistent behaviour when accessing qpp_table. + */ +static int qid_inode_prefix_hash_bits(V9fsPDU *pdu, dev_t dev) +{ + QpdEntry lookup = { + .dev = dev + }, *val; + uint32_t hash = dev; + VariLenAffix affix; + + val = qht_lookup(&pdu->s->qpd_table, &lookup, hash); + if (!val) { + val = g_malloc0(sizeof(QpdEntry)); + *val = lookup; + affix = affixForIndex(pdu->s->qp_affix_next); + val->prefix_bits = affix.bits; + qht_insert(&pdu->s->qpd_table, val, hash, NULL); + pdu->s->qp_ndevices++; + } + return val->prefix_bits; +} + +/** @brief Slow / full mapping host inode nr -> guest inode nr. + * + * This function performs a slower and much more costly remapping of an + * original file inode number on host to an appropriate different inode + * number on guest. For every (dev, inode) combination on host a new + * sequential number is generated, cached and exposed as inode number on + * guest. + * + * This is just a "last resort" fallback solution if the much faster/cheaper + * qid_path_prefixmap() failed. In practice this slow / full mapping is not + * expected ever to be used at all though. + * + * @see qid_path_prefixmap() for details + * + */ static int qid_path_fullmap(V9fsPDU *pdu, const struct stat *stbuf, uint64_t *path) { @@ -615,11 +771,7 @@ static int qid_path_fullmap(V9fsPDU *pdu, const struct stat *stbuf, .ino = stbuf->st_ino }, *val; uint32_t hash = qpf_hash(lookup); - - /* most users won't need the fullmap, so init the table lazily */ - if (!pdu->s->qpf_table.map) { - qht_init(&pdu->s->qpf_table, qpf_lookup_func, 1 << 16, QHT_MODE_AUTO_RESIZE); - } + VariLenAffix affix; val = qht_lookup(&pdu->s->qpf_table, &lookup, hash); @@ -637,8 +789,11 @@ static int qid_path_fullmap(V9fsPDU *pdu, const struct stat *stbuf, *val = lookup; /* new unique inode and device combo */ - val->path = pdu->s->qp_fullpath_next++; - pdu->s->qp_fullpath_next &= QPATH_INO_MASK; + affix = affixForIndex( + 1ULL << (sizeof(pdu->s->qp_affix_next) * 8) + ); + val->path = (pdu->s->qp_fullpath_next++ << affix.bits) | affix.value; + pdu->s->qp_fullpath_next &= ((1ULL << (64 - affix.bits)) - 1); qht_insert(&pdu->s->qpf_table, val, hash, NULL); } @@ -646,30 +801,59 @@ static int qid_path_fullmap(V9fsPDU *pdu, const struct stat *stbuf, return 0; } -/* stat_to_qid needs to map inode number (64 bits) and device id (32 bits) - * to a unique QID path (64 bits). To avoid having to map and keep track - * of up to 2^64 objects, we map only the 16 highest bits of the inode plus - * the device id to the 16 highest bits of the QID path. The 48 lowest bits - * of the QID path equal to the lowest bits of the inode number. +/** @brief Quick mapping host inode nr -> guest inode nr. * - * This takes advantage of the fact that inode number are usually not - * random but allocated sequentially, so we have fewer items to keep - * track of. + * This function performs quick remapping of an original file inode number + * on host to an appropriate different inode number on guest. This remapping + * of inodes is required to avoid inode nr collisions on guest which would + * happen if the 9p export contains more than 1 exported file system (or + * more than 1 file system data set), because unlike on host level where the + * files would have different device nrs, all files exported by 9p would + * share the same device nr on guest (the device nr of the virtual 9p device + * that is). + * + * Inode remapping is performed by chopping off high end bits of the original + * inode number from host, shifting the result upwards and then assigning a + * generated suffix number for the low end bits, where the same suffix number + * will be shared by all inodes with the same device id AND the same high end + * bits that have been chopped off. That approach utilizes the fact that inode + * numbers very likely share the same high end bits (i.e. due to their common + * sequential generation by file systems) and hence we only have to generate + * and track a very limited amount of suffixes in practice due to that. + * + * We generate variable size suffixes for that purpose. The 1st generated + * suffix will only have 1 bit and hence we only need to chop off 1 bit from + * the original inode number. The subsequent suffixes being generated will + * grow in (bit) size subsequently, i.e. the 2nd and 3rd suffix being + * generated will have 3 bits and hence we have to chop off 3 bits from their + * original inodes, and so on. That approach of using variable length suffixes + * (i.e. over fixed size ones) utilizes the fact that in practice only a very + * limited amount of devices are shared by the same export (e.g. typically + * less than 2 dozen devices per 9p export), so in practice we need to chop + * off less bits than with fixed size prefixes and yet are flexible to add + * new devices at runtime below host's export directory at any time without + * having to reboot guest nor requiring to reconfigure guest for that. And due + * to the very limited amount of original high end bits that we chop off that + * way, the total amount of suffixes we need to generate is less than by using + * fixed size prefixes and hence it also improves performance of the inode + * remapping algorithm, and finally has the nice side effect that the inode + * numbers on guest will be much smaller & human friendly. ;-) */ static int qid_path_prefixmap(V9fsPDU *pdu, const struct stat *stbuf, uint64_t *path) { + const int ino_hash_bits = qid_inode_prefix_hash_bits(pdu, stbuf->st_dev); QppEntry lookup = { .dev = stbuf->st_dev, - .ino_prefix = (uint16_t) (stbuf->st_ino >> 48) + .ino_prefix = (uint16_t) (stbuf->st_ino >> (64-ino_hash_bits)) }, *val; uint32_t hash = qpp_hash(lookup); val = qht_lookup(&pdu->s->qpp_table, &lookup, hash); if (!val) { - if (pdu->s->qp_prefix_next == 0) { - /* we ran out of prefixes */ + if (pdu->s->qp_affix_next == 0) { + /* we ran out of affixes */ error_report_once( "9p: Potential degraded performance of inode remapping" ); @@ -679,12 +863,13 @@ static int qid_path_prefixmap(V9fsPDU *pdu, const struct stat *stbuf, val = g_malloc0(sizeof(QppEntry)); *val = lookup; - /* new unique inode prefix and device combo */ - val->qp_prefix = pdu->s->qp_prefix_next++; + /* new unique inode affix and device combo */ + val->qp_affix_index = pdu->s->qp_affix_next++; + val->qp_affix = affixForIndex(val->qp_affix_index); qht_insert(&pdu->s->qpp_table, val, hash, NULL); } - - *path = ((uint64_t)val->qp_prefix << 48) | (stbuf->st_ino & QPATH_INO_MASK); + /* assuming generated affix to be suffix type, not prefix */ + *path = (stbuf->st_ino << val->qp_affix.bits) | val->qp_affix.value; return 0; } @@ -3863,9 +4048,15 @@ int v9fs_device_realize_common(V9fsState *s, const V9fsTransport *t, s->root_ino = stat.st_ino; s->dev_id = stat.st_dev; - /* QID path hash table. 1 entry ought to be enough for anybody ;) */ - qht_init(&s->qpp_table, qpp_lookup_func, 1, QHT_MODE_AUTO_RESIZE); - s->qp_prefix_next = 1; /* reserve 0 to detect overflow */ + /* init inode remapping : */ + /* hash table for variable length inode suffixes */ + qht_init(&s->qpd_table, qpd_cmp_func, 1, QHT_MODE_AUTO_RESIZE); + /* hash table for slow/full inode remapping (most users won't need it) */ + qht_init(&s->qpf_table, qpf_cmp_func, 1 << 16, QHT_MODE_AUTO_RESIZE); + /* hash table for quick inode remapping */ + qht_init(&s->qpp_table, qpp_cmp_func, 1, QHT_MODE_AUTO_RESIZE); + s->qp_ndevices = 0; + s->qp_affix_next = 1; /* reserve 0 to detect overflow */ s->qp_fullpath_next = 1; s->ctx.fst = &fse->fst; @@ -3881,6 +4072,7 @@ out: } g_free(s->tag); g_free(s->ctx.fs_root); + qp_table_destroy(&s->qpd_table); qp_table_destroy(&s->qpp_table); qp_table_destroy(&s->qpf_table); v9fs_path_free(&path); @@ -3895,6 +4087,7 @@ void v9fs_device_unrealize_common(V9fsState *s, Error **errp) } fsdev_throttle_cleanup(s->ctx.fst); g_free(s->tag); + qp_table_destroy(&s->qpd_table); qp_table_destroy(&s->qpp_table); qp_table_destroy(&s->qpf_table); g_free(s->ctx.fs_root); diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h index f044a88a41..597b2c7222 100644 --- a/hw/9pfs/9p.h +++ b/hw/9pfs/9p.h @@ -236,13 +236,39 @@ struct V9fsFidState V9fsFidState *rclm_lst; }; -#define QPATH_INO_MASK ((1ULL << 48) - 1) +typedef enum AffixType_t { + AffixType_Prefix, + AffixType_Suffix, /* A.k.a. postfix. */ +} AffixType_t; + +/** @brief Unique affix of variable length. + * + * An affix is (currently) either a suffix or a prefix, which is either + * going to be prepended (prefix) or appended (suffix) with some other + * number for the goal to generate unique numbers. Accordingly the + * suffixes (or prefixes) we generate @b must all have the mathematical + * property of being suffix-free (or prefix-free in case of prefixes) + * so that no matter what number we concatenate the affix with, that we + * always reliably get unique numbers as result after concatenation. + */ +typedef struct VariLenAffix { + AffixType_t type; /* Whether this affix is a suffix or a prefix. */ + uint64_t value; /* Actual numerical value of this affix. */ + int bits; /* Lenght of the affix, that is how many (of the lowest) bits of @c value must be used for appending/prepending this affix to its final resulting, unique number. */ +} VariLenAffix; + +/* See qid_inode_prefix_hash_bits(). */ +typedef struct { + dev_t dev; /* FS device on host. */ + int prefix_bits; /* How many (high) bits of the original inode number shall be used for hashing. */ +} QpdEntry; /* QID path prefix entry, see stat_to_qid */ typedef struct { dev_t dev; uint16_t ino_prefix; - uint16_t qp_prefix; + uint32_t qp_affix_index; + VariLenAffix qp_affix; } QppEntry; /* QID path full entry, as above */ @@ -275,9 +301,11 @@ struct V9fsState V9fsQID root_qid; ino_t root_ino; dev_t dev_id; + struct qht qpd_table; struct qht qpp_table; struct qht qpf_table; - uint16_t qp_prefix_next; + uint64_t qp_ndevices; /* Amount of entries in qpd_table. */ + uint16_t qp_affix_next; uint64_t qp_fullpath_next; };