[lvm-devel] LVM2 lib/metadata/metadata-exported.h lib/meta ...
wysochanski at sourceware.org
wysochanski at sourceware.org
Tue Jul 28 13:17:05 UTC 2009
CVSROOT: /cvs/lvm2
Module name: LVM2
Changes by: wysochanski at 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)
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