From nobody Wed Dec 17 05:37:09 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1494514571555881.5027183762137; Thu, 11 May 2017 07:56:11 -0700 (PDT) Received: from localhost ([::1]:48635 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d8pVh-0005bp-W8 for importer@patchew.org; Thu, 11 May 2017 10:56:10 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36608) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d8pAF-0001ya-1m for qemu-devel@nongnu.org; Thu, 11 May 2017 10:34:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d8pAB-00076u-Nt for qemu-devel@nongnu.org; Thu, 11 May 2017 10:33:59 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39620) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1d8pA3-0006yE-S3; Thu, 11 May 2017 10:33:48 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C5533448D8D; Thu, 11 May 2017 14:33:46 +0000 (UTC) Received: from noname.str.redhat.com (dhcp-192-175.str.redhat.com [10.33.192.175]) by smtp.corp.redhat.com (Postfix) with ESMTP id 026C97A407; Thu, 11 May 2017 14:33:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com C5533448D8D Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=kwolf@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com C5533448D8D From: Kevin Wolf To: qemu-block@nongnu.org Date: Thu, 11 May 2017 16:32:24 +0200 Message-Id: <1494513181-7900-22-git-send-email-kwolf@redhat.com> In-Reply-To: <1494513181-7900-1-git-send-email-kwolf@redhat.com> References: <1494513181-7900-1-git-send-email-kwolf@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Thu, 11 May 2017 14:33:46 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 21/58] file-posix: Add image locking to perm operations 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: kwolf@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Fam Zheng This extends the permission bits of op blocker API to external using Linux OFD locks. Each permission in @perm and @shared_perm is represented by a locked byte in the image file. Requesting a permission in @perm is translated to a shared lock of the corresponding byte; rejecting to share the same permission is translated to a shared lock of a separate byte. With that, we use 2x number of bytes of distinct permission types. virtlockd in libvirt locks the first byte, so we do locking from a higher offset. Suggested-by: Kevin Wolf Signed-off-by: Fam Zheng Signed-off-by: Kevin Wolf --- block/file-posix.c | 276 +++++++++++++++++++++++++++++++++++++++++++++++++= +++- 1 file changed, 275 insertions(+), 1 deletion(-) diff --git a/block/file-posix.c b/block/file-posix.c index d13e99c..a09055b 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -129,12 +129,23 @@ do { \ =20 #define MAX_BLOCKSIZE 4096 =20 +/* Posix file locking bytes. Libvirt takes byte 0, we start from higher by= tes, + * leaving a few more bytes for its future use. */ +#define RAW_LOCK_PERM_BASE 100 +#define RAW_LOCK_SHARED_BASE 200 + typedef struct BDRVRawState { int fd; + int lock_fd; + bool use_lock; int type; int open_flags; size_t buf_align; =20 + /* The current permissions. */ + uint64_t perm; + uint64_t shared_perm; + #ifdef CONFIG_XFS bool is_xfs:1; #endif @@ -411,6 +422,7 @@ static int raw_open_common(BlockDriverState *bs, QDict = *options, BlockdevAioOptions aio, aio_default; int fd, ret; struct stat st; + OnOffAuto locking; =20 opts =3D qemu_opts_create(&raw_runtime_opts, NULL, 0, &error_abort); qemu_opts_absorb_qdict(opts, options, &local_err); @@ -440,6 +452,37 @@ static int raw_open_common(BlockDriverState *bs, QDict= *options, } s->use_linux_aio =3D (aio =3D=3D BLOCKDEV_AIO_OPTIONS_NATIVE); =20 + locking =3D qapi_enum_parse(OnOffAuto_lookup, qemu_opt_get(opts, "lock= ing"), + ON_OFF_AUTO__MAX, ON_OFF_AUTO_AUTO, &local_e= rr); + if (local_err) { + error_propagate(errp, local_err); + ret =3D -EINVAL; + goto fail; + } + switch (locking) { + case ON_OFF_AUTO_ON: + s->use_lock =3D true; +#ifndef F_OFD_SETLK + fprintf(stderr, + "File lock requested but OFD locking syscall is unavailabl= e, " + "falling back to POSIX file locks.\n" + "Due to the implementation, locks can be lost unexpectedly= .\n"); +#endif + break; + case ON_OFF_AUTO_OFF: + s->use_lock =3D false; + break; + case ON_OFF_AUTO_AUTO: +#ifdef F_OFD_SETLK + s->use_lock =3D true; +#else + s->use_lock =3D false; +#endif + break; + default: + abort(); + } + s->open_flags =3D open_flags; raw_parse_flags(bdrv_flags, &s->open_flags); =20 @@ -455,6 +498,21 @@ static int raw_open_common(BlockDriverState *bs, QDict= *options, } s->fd =3D fd; =20 + s->lock_fd =3D -1; + if (s->use_lock) { + fd =3D qemu_open(filename, s->open_flags); + if (fd < 0) { + ret =3D -errno; + error_setg_errno(errp, errno, "Could not open '%s' for locking= ", + filename); + qemu_close(s->fd); + goto fail; + } + s->lock_fd =3D fd; + } + s->perm =3D 0; + s->shared_perm =3D BLK_PERM_ALL; + #ifdef CONFIG_LINUX_AIO /* Currently Linux does AIO only for files opened with O_DIRECT */ if (s->use_linux_aio && !(s->open_flags & O_DIRECT)) { @@ -542,6 +600,161 @@ static int raw_open(BlockDriverState *bs, QDict *opti= ons, int flags, return raw_open_common(bs, options, flags, 0, errp); } =20 +typedef enum { + RAW_PL_PREPARE, + RAW_PL_COMMIT, + RAW_PL_ABORT, +} RawPermLockOp; + +#define PERM_FOREACH(i) \ + for ((i) =3D 0; (1ULL << (i)) <=3D BLK_PERM_ALL; i++) + +/* Lock bytes indicated by @perm_lock_bits and @shared_perm_lock_bits in t= he + * file; if @unlock =3D=3D true, also unlock the unneeded bytes. + * @shared_perm_lock_bits is the mask of all permissions that are NOT shar= ed. + */ +static int raw_apply_lock_bytes(BDRVRawState *s, + uint64_t perm_lock_bits, + uint64_t shared_perm_lock_bits, + bool unlock, Error **errp) +{ + int ret; + int i; + + PERM_FOREACH(i) { + int off =3D RAW_LOCK_PERM_BASE + i; + if (perm_lock_bits & (1ULL << i)) { + ret =3D qemu_lock_fd(s->lock_fd, off, 1, false); + if (ret) { + error_setg(errp, "Failed to lock byte %d", off); + return ret; + } + } else if (unlock) { + ret =3D qemu_unlock_fd(s->lock_fd, off, 1); + if (ret) { + error_setg(errp, "Failed to unlock byte %d", off); + return ret; + } + } + } + PERM_FOREACH(i) { + int off =3D RAW_LOCK_SHARED_BASE + i; + if (shared_perm_lock_bits & (1ULL << i)) { + ret =3D qemu_lock_fd(s->lock_fd, off, 1, false); + if (ret) { + error_setg(errp, "Failed to lock byte %d", off); + return ret; + } + } else if (unlock) { + ret =3D qemu_unlock_fd(s->lock_fd, off, 1); + if (ret) { + error_setg(errp, "Failed to unlock byte %d", off); + return ret; + } + } + } + return 0; +} + +/* Check "unshared" bytes implied by @perm and ~@shared_perm in the file. = */ +static int raw_check_lock_bytes(BDRVRawState *s, + uint64_t perm, uint64_t shared_perm, + Error **errp) +{ + int ret; + int i; + + PERM_FOREACH(i) { + int off =3D RAW_LOCK_SHARED_BASE + i; + uint64_t p =3D 1ULL << i; + if (perm & p) { + ret =3D qemu_lock_fd_test(s->lock_fd, off, 1, true); + if (ret) { + char *perm_name =3D bdrv_perm_names(p); + error_setg(errp, + "Failed to get \"%s\" lock", + perm_name); + g_free(perm_name); + error_append_hint(errp, + "Is another process using the image?\n"); + return ret; + } + } + } + PERM_FOREACH(i) { + int off =3D RAW_LOCK_PERM_BASE + i; + uint64_t p =3D 1ULL << i; + if (!(shared_perm & p)) { + ret =3D qemu_lock_fd_test(s->lock_fd, off, 1, true); + if (ret) { + char *perm_name =3D bdrv_perm_names(p); + error_setg(errp, + "Failed to get shared \"%s\" lock", + perm_name); + g_free(perm_name); + error_append_hint(errp, + "Is another process using the image?\n"); + return ret; + } + } + } + return 0; +} + +static int raw_handle_perm_lock(BlockDriverState *bs, + RawPermLockOp op, + uint64_t new_perm, uint64_t new_shared, + Error **errp) +{ + BDRVRawState *s =3D bs->opaque; + int ret =3D 0; + Error *local_err =3D NULL; + + if (!s->use_lock) { + return 0; + } + + if (bdrv_get_flags(bs) & BDRV_O_INACTIVE) { + return 0; + } + + assert(s->lock_fd > 0); + + switch (op) { + case RAW_PL_PREPARE: + ret =3D raw_apply_lock_bytes(s, s->perm | new_perm, + ~s->shared_perm | ~new_shared, + false, errp); + if (!ret) { + ret =3D raw_check_lock_bytes(s, new_perm, new_shared, errp); + if (!ret) { + return 0; + } + } + op =3D RAW_PL_ABORT; + /* fall through to unlock bytes. */ + case RAW_PL_ABORT: + raw_apply_lock_bytes(s, s->perm, ~s->shared_perm, true, &local_err= ); + if (local_err) { + /* Theoretically the above call only unlocks bytes and it cann= ot + * fail. Something weird happened, report it. + */ + error_report_err(local_err); + } + break; + case RAW_PL_COMMIT: + raw_apply_lock_bytes(s, new_perm, ~new_shared, true, &local_err); + if (local_err) { + /* Theoretically the above call only unlocks bytes and it cann= ot + * fail. Something weird happened, report it. + */ + error_report_err(local_err); + } + break; + } + return ret; +} + static int raw_reopen_prepare(BDRVReopenState *state, BlockReopenQueue *queue, Error **errp) { @@ -1410,6 +1623,10 @@ static void raw_close(BlockDriverState *bs) qemu_close(s->fd); s->fd =3D -1; } + if (s->lock_fd >=3D 0) { + qemu_close(s->lock_fd); + s->lock_fd =3D -1; + } } =20 static int raw_truncate(BlockDriverState *bs, int64_t offset, Error **errp) @@ -1954,6 +2171,54 @@ static QemuOptsList raw_create_opts =3D { } }; =20 +static int raw_check_perm(BlockDriverState *bs, uint64_t perm, uint64_t sh= ared, + Error **errp) +{ + return raw_handle_perm_lock(bs, RAW_PL_PREPARE, perm, shared, errp); +} + +static void raw_set_perm(BlockDriverState *bs, uint64_t perm, uint64_t sha= red) +{ + BDRVRawState *s =3D bs->opaque; + raw_handle_perm_lock(bs, RAW_PL_COMMIT, perm, shared, NULL); + s->perm =3D perm; + s->shared_perm =3D shared; +} + +static void raw_abort_perm_update(BlockDriverState *bs) +{ + raw_handle_perm_lock(bs, RAW_PL_ABORT, 0, 0, NULL); +} + +static int raw_inactivate(BlockDriverState *bs) +{ + int ret; + uint64_t perm =3D 0; + uint64_t shared =3D BLK_PERM_ALL; + + ret =3D raw_handle_perm_lock(bs, RAW_PL_PREPARE, perm, shared, NULL); + if (ret) { + return ret; + } + raw_handle_perm_lock(bs, RAW_PL_COMMIT, perm, shared, NULL); + return 0; +} + + +static void raw_invalidate_cache(BlockDriverState *bs, Error **errp) +{ + BDRVRawState *s =3D bs->opaque; + int ret; + + assert(!(bdrv_get_flags(bs) & BDRV_O_INACTIVE)); + ret =3D raw_handle_perm_lock(bs, RAW_PL_PREPARE, s->perm, s->shared_pe= rm, + errp); + if (ret) { + return; + } + raw_handle_perm_lock(bs, RAW_PL_COMMIT, s->perm, s->shared_perm, NULL); +} + BlockDriver bdrv_file =3D { .format_name =3D "file", .protocol_name =3D "file", @@ -1984,7 +2249,11 @@ BlockDriver bdrv_file =3D { .bdrv_get_info =3D raw_get_info, .bdrv_get_allocated_file_size =3D raw_get_allocated_file_size, - + .bdrv_inactivate =3D raw_inactivate, + .bdrv_invalidate_cache =3D raw_invalidate_cache, + .bdrv_check_perm =3D raw_check_perm, + .bdrv_set_perm =3D raw_set_perm, + .bdrv_abort_perm_update =3D raw_abort_perm_update, .create_opts =3D &raw_create_opts, }; =20 @@ -2443,6 +2712,11 @@ static BlockDriver bdrv_host_device =3D { .bdrv_get_info =3D raw_get_info, .bdrv_get_allocated_file_size =3D raw_get_allocated_file_size, + .bdrv_inactivate =3D raw_inactivate, + .bdrv_invalidate_cache =3D raw_invalidate_cache, + .bdrv_check_perm =3D raw_check_perm, + .bdrv_set_perm =3D raw_set_perm, + .bdrv_abort_perm_update =3D raw_abort_perm_update, .bdrv_probe_blocksizes =3D hdev_probe_blocksizes, .bdrv_probe_geometry =3D hdev_probe_geometry, =20 --=20 1.8.3.1