From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 1472 invoked by alias); 28 Jul 2009 13:17:06 -0000 Received: (qmail 1455 invoked by uid 9657); 28 Jul 2009 13:17:05 -0000 Date: Tue, 28 Jul 2009 13:17:00 -0000 Message-ID: <20090728131705.1453.qmail@sourceware.org> From: wysochanski@sourceware.org To: lvm-devel@redhat.com, lvm2-cvs@sourceware.org Subject: LVM2 lib/metadata/metadata-exported.h lib/meta ... Mailing-List: contact lvm2-cvs-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: lvm2-cvs-owner@sourceware.org X-SW-Source: 2009-07/txt/msg00204.txt.bz2 CVSROOT: /cvs/lvm2 Module name: LVM2 Changes by: wysochanski@sourceware.org 2009-07-28 13:17:04 Modified files: lib/metadata : metadata-exported.h metadata.c liblvm : .exported_symbols lvm.h lvm_vg.c test/api : test.c Log message: Add lvm_vg_get_seqno, updating lvm.h and unit test. Adding the ability to get the seqno is important for an application to determine if something has changed in a VG. Otherwise, the only way to know is to open the VG with write permission and hold the handle. Patches: http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/lib/metadata/metadata-exported.h.diff?cvsroot=lvm2&r1=1.103&r2=1.104 http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/lib/metadata/metadata.c.diff?cvsroot=lvm2&r1=1.270&r2=1.271 http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/liblvm/.exported_symbols.diff?cvsroot=lvm2&r1=1.21&r2=1.22 http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/liblvm/lvm.h.diff?cvsroot=lvm2&r1=1.39&r2=1.40 http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/liblvm/lvm_vg.c.diff?cvsroot=lvm2&r1=1.21&r2=1.22 http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/test/api/test.c.diff?cvsroot=lvm2&r1=1.20&r2=1.21 --- LVM2/lib/metadata/metadata-exported.h 2009/07/27 17:43:40 1.103 +++ LVM2/lib/metadata/metadata-exported.h 2009/07/28 13:17:04 1.104 @@ -705,6 +705,7 @@ uint64_t lv_size(const lv_t *lv); int vg_missing_pv_count(const vg_t *vg); +uint32_t vg_seqno(const vg_t *vg); uint32_t vg_status(const vg_t *vg); uint64_t vg_size(const vg_t *vg); uint64_t vg_free(const vg_t *vg); --- LVM2/lib/metadata/metadata.c 2009/07/27 17:43:40 1.270 +++ LVM2/lib/metadata/metadata.c 2009/07/28 13:17:04 1.271 @@ -3424,6 +3424,11 @@ return info ? dm_list_size(&info->mdas) : UINT64_C(0); } +uint32_t vg_seqno(const vg_t *vg) +{ + return vg->seqno; +} + uint32_t vg_status(const vg_t *vg) { return vg->status; --- LVM2/liblvm/.exported_symbols 2009/07/28 11:03:28 1.21 +++ LVM2/liblvm/.exported_symbols 2009/07/28 13:17:04 1.22 @@ -6,6 +6,7 @@ lvm_pv_get_name lvm_pv_get_uuid lvm_pv_get_mda_count +lvm_vg_get_seqno lvm_vg_get_name lvm_vg_get_uuid lvm_vg_get_size --- LVM2/liblvm/lvm.h 2009/07/28 13:16:40 1.39 +++ LVM2/liblvm/lvm.h 2009/07/28 13:17:04 1.40 @@ -49,6 +49,17 @@ * A volume group handle may be obtained with read or write permission. * Any attempt to change a property of a pv_t, vg_t, or lv_t without * obtaining write permission on the vg_t will fail with EPERM. + * + * An application first opening a VG read-only, then later wanting to change + * a property of an object must first close the VG and re-open with write + * permission. Currently liblvm provides no mechanism to determine whether + * the VG has changed on-disk in between these operations - this is the + * application's responsiblity. One way the application can ensure the VG + * has not changed is to save the "vg_seqno" field after opening the VG with + * READ permission. If the application later needs to modify the VG, it can + * close the VG and re-open with WRITE permission. It should then check + * whether the original "vg_seqno" obtained with READ permission matches + * the new one obtained with WRITE permission. */ /** @@ -470,6 +481,21 @@ int lvm_vg_set_extent_size(vg_t *vg, uint32_t new_size); /** + * Get the current metadata sequence number of a volume group. + * + * The metadata sequence number is incrented for each metadata change. + * Applications may use the sequence number to determine if any LVM objects + * have changed from a prior query. + * + * \param vg + * VG handle obtained from lvm_vg_create or lvm_vg_open. + * + * \return + * Metadata sequence number. + */ +uint64_t lvm_vg_get_seqno(const vg_t *vg); + +/** * Get the current name of a volume group. * * Memory is allocated using dm_malloc() and caller must free the memory --- LVM2/liblvm/lvm_vg.c 2009/07/28 09:56:48 1.21 +++ LVM2/liblvm/lvm_vg.c 2009/07/28 13:17:04 1.22 @@ -223,6 +223,11 @@ return list; } +uint64_t lvm_vg_get_seqno(const vg_t *vg) +{ + return vg_seqno(vg); +} + /* FIXME: invalid handle? return INTMAX? */ uint64_t lvm_vg_get_size(const vg_t *vg) { --- LVM2/test/api/test.c 2009/07/28 11:03:29 1.20 +++ LVM2/test/api/test.c 2009/07/28 13:17:04 1.21 @@ -345,10 +345,11 @@ static void _show_one_vg(vg_t *vg) { - printf("%s (%s): size=%"PRIu64", free=%"PRIu64", #pv=%"PRIu64"\n", + printf("%s (%s): sz=%"PRIu64", free=%"PRIu64", #pv=%"PRIu64 + ", seq#=%"PRIu64"\n", lvm_vg_get_name(vg), lvm_vg_get_uuid(vg), lvm_vg_get_size(vg), lvm_vg_get_free_size(vg), - lvm_vg_get_pv_count(vg)); + lvm_vg_get_pv_count(vg), lvm_vg_get_seqno(vg)); } static void _list_open_vgs(void)