mirror of
git://sourceware.org/git/lvm2.git
synced 2025-10-16 23:33:16 +03:00
899fabb26b
The new label_scan() function reads a large buffer of data from the start of the disk, and saves it so that multiple structs can be read from it. Previously, only the label_header was read from this buffer, and the code which needed data structures that immediately followed the label_header would read those from disk separately. This created a large number of small, unnecessary disk reads. In each place that the two read paths (label_scan and vg_read) need to read data from disk, first check if that data is already available from the label_read_data buffer, and if so just copy it from the buffer instead of reading from disk. Code changes ------------ - passing the label_read_data struct down through both read paths to make it available. - before every disk read, first check if the location and size of the desired piece of data exists fully in the label_read_data buffer, and if so copy it from there. Otherwise, use the existing code to read the data from disk. - adding some log_error messages on existing error paths that were already being updated for the reasons above. - using similar naming for parallel functions on the two parallel read paths that are being updated above. label_scan path calls: read_metadata_location_summary, text_read_metadata_summary vg_read path calls: read_metadata_location_vg, text_read_metadata_file Previously, those functions were named: label_scan path calls: vgname_from_mda, text_vgsummary_import vg_read path calls: _find_vg_rlocn, text_vg_import_fd I/O changes ----------- In the label_scan path, the following data is either copied from label_read_data or read from disk for each PV: - label_header and pv_header - mda_header (in _raw_read_mda_header) - vg metadata name (in read_metadata_location_summary) - vg metadata (in config_file_read_fd) Total of 4 reads per PV in the label_scan path. In the vg_read path, the following data is either copied from label_read_data or read from disk for each PV: - mda_header (in _raw_read_mda_header) - vg metadata name (in read_metadata_location_vg) - vg metadata (in config_file_read_fd) Total of 3 reads per PV in the vg_read path. For a common read/reporting command, each PV will be: - read by the command's initial lvmcache_label_scan() - read by lvmcache_label_rescan_vg() at the start of vg_read() - read by vg_read() Previously, this would cause 11 synchronous disk reads per PV: 4 from lvmcache_label_scan(), 4 from lvmcache_label_rescan_vg() and 3 from vg_read(). With this commit's optimization, there are now 2 async disk reads per PV: 1 from lvmcache_label_scan() and 1 from lvmcache_label_rescan_vg(). When a second mda is used on a PV, it is located at the end of the PV. This second mda and copy of metadata will not be found in the label_read_data buffer, and will always require separate disk reads.
133 lines
3.1 KiB
C
133 lines
3.1 KiB
C
/*
|
|
* Copyright (C) 2002-2004 Sistina Software, Inc. All rights reserved.
|
|
* Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
|
|
*
|
|
* This file is part of LVM2.
|
|
*
|
|
* This copyrighted material is made available to anyone wishing to use,
|
|
* modify, copy, or redistribute it subject to the terms and conditions
|
|
* of the GNU Lesser General Public License v.2.1.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public License
|
|
* along with this program; if not, write to the Free Software Foundation,
|
|
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
|
|
#include "lib.h"
|
|
#include "lvm1-label.h"
|
|
#include "disk-rep.h"
|
|
#include "label.h"
|
|
#include "metadata.h"
|
|
#include "xlate.h"
|
|
#include "format1.h"
|
|
|
|
#include <sys/stat.h>
|
|
#include <fcntl.h>
|
|
|
|
static void _not_supported(const char *op)
|
|
{
|
|
log_error("The '%s' operation is not supported for the lvm1 labeller.",
|
|
op);
|
|
}
|
|
|
|
static int _lvm1_can_handle(struct labeller *l __attribute__((unused)), void *buf, uint64_t sector)
|
|
{
|
|
struct pv_disk *pvd = (struct pv_disk *) buf;
|
|
uint32_t version;
|
|
|
|
/* LVM1 label must always be in first sector */
|
|
if (sector)
|
|
return 0;
|
|
|
|
version = xlate16(pvd->version);
|
|
|
|
if (pvd->id[0] == 'H' && pvd->id[1] == 'M' &&
|
|
(version == 1 || version == 2))
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int _lvm1_write(struct label *label __attribute__((unused)), void *buf __attribute__((unused)))
|
|
{
|
|
_not_supported("write");
|
|
return 0;
|
|
}
|
|
|
|
static int _lvm1_read(struct labeller *l, struct device *dev, void *buf,
|
|
struct label_read_data *ld,
|
|
struct label **label)
|
|
{
|
|
struct pv_disk *pvd = (struct pv_disk *) buf;
|
|
struct vg_disk vgd;
|
|
struct lvmcache_info *info;
|
|
const char *vgid = FMT_LVM1_ORPHAN_VG_NAME;
|
|
const char *vgname = FMT_LVM1_ORPHAN_VG_NAME;
|
|
unsigned exported = 0;
|
|
|
|
munge_pvd(dev, pvd);
|
|
|
|
if (*pvd->vg_name) {
|
|
if (!read_vgd(dev, &vgd, pvd))
|
|
return_0;
|
|
vgid = (char *) vgd.vg_uuid;
|
|
vgname = (char *) pvd->vg_name;
|
|
exported = pvd->pv_status & VG_EXPORTED;
|
|
}
|
|
|
|
if (!(info = lvmcache_add(l, (char *)pvd->pv_uuid, dev, vgname, vgid,
|
|
exported)))
|
|
return_0;
|
|
*label = lvmcache_get_label(info);
|
|
|
|
lvmcache_set_device_size(info, ((uint64_t)xlate32(pvd->pv_size)) << SECTOR_SHIFT);
|
|
lvmcache_set_ext_version(info, 0);
|
|
lvmcache_set_ext_flags(info, 0);
|
|
lvmcache_del_mdas(info);
|
|
lvmcache_del_bas(info);
|
|
lvmcache_make_valid(info);
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int _lvm1_initialise_label(struct labeller *l __attribute__((unused)), struct label *label)
|
|
{
|
|
strcpy(label->type, "LVM1");
|
|
|
|
return 1;
|
|
}
|
|
|
|
static void _lvm1_destroy_label(struct labeller *l __attribute__((unused)), struct label *label __attribute__((unused)))
|
|
{
|
|
}
|
|
|
|
static void _lvm1_destroy(struct labeller *l)
|
|
{
|
|
dm_free(l);
|
|
}
|
|
|
|
struct label_ops _lvm1_ops = {
|
|
.can_handle = _lvm1_can_handle,
|
|
.write = _lvm1_write,
|
|
.read = _lvm1_read,
|
|
.verify = _lvm1_can_handle,
|
|
.initialise_label = _lvm1_initialise_label,
|
|
.destroy_label = _lvm1_destroy_label,
|
|
.destroy = _lvm1_destroy,
|
|
};
|
|
|
|
struct labeller *lvm1_labeller_create(struct format_type *fmt)
|
|
{
|
|
struct labeller *l;
|
|
|
|
if (!(l = dm_malloc(sizeof(*l)))) {
|
|
log_error("Couldn't allocate labeller object.");
|
|
return NULL;
|
|
}
|
|
|
|
l->ops = &_lvm1_ops;
|
|
l->fmt = fmt;
|
|
|
|
return l;
|
|
}
|