[lvm-devel] master - lib: reduce parsing in vgname_from_mda
Zdenek Kabelac
zkabelac at fedoraproject.org
Fri Mar 6 13:31:42 UTC 2015
Gitweb: http://git.fedorahosted.org/git/?p=lvm2.git;a=commitdiff;h=a9b28a4f2105b92fdfc9f3915859e0deec4004a0
Commit: a9b28a4f2105b92fdfc9f3915859e0deec4004a0
Parent: 7e7411966afc4309cdd91bfed4846720b308c84d
Author: Zdenek Kabelac <zkabelac at redhat.com>
AuthorDate: Fri Mar 6 10:24:26 2015 +0100
Committer: Zdenek Kabelac <zkabelac at redhat.com>
CommitterDate: Fri Mar 6 13:53:13 2015 +0100
lib: reduce parsing in vgname_from_mda
Use similar logic as with text_vg_import_fd() and avoid repeated
parsing of same mda and its config tree for vgname_from_mda().
Remember last parsed vgname, vgid and creation_host in labeller
structure and if the metadata have the same size and checksum,
return this stored info.
TODO: The reuse of labeller struct is not ideal, some lvmcache API for
this functionality would be nicer.
---
WHATS_NEW | 1 +
lib/format_text/format-text.c | 23 ++++++++++++++++++-----
lib/format_text/import-export.h | 9 +++++----
lib/format_text/import.c | 13 +++++++++++--
lib/format_text/layout.h | 4 +++-
lib/format_text/text_label.c | 27 ++++++++++++++++-----------
lib/label/label.h | 8 ++++++++
7 files changed, 62 insertions(+), 23 deletions(-)
diff --git a/WHATS_NEW b/WHATS_NEW
index ef5abcd..9bf8699 100644
--- a/WHATS_NEW
+++ b/WHATS_NEW
@@ -1,5 +1,6 @@
Version 2.02.118 -
=================================
+ Reduce number of VG metadata parsing when looking for vgname on a PV.
Avoid reparsing same metadata when reading same metadata from multiple PVs.
Save extra device open/close when scanning device for size.
Fix seg_monitor field to report status also for mirrors and thick snapshots.
diff --git a/lib/format_text/format-text.c b/lib/format_text/format-text.c
index 375a793..d80ebf6 100644
--- a/lib/format_text/format-text.c
+++ b/lib/format_text/format-text.c
@@ -1124,14 +1124,14 @@ static int _scan_file(const struct format_type *fmt, const char *vgname)
}
const char *vgname_from_mda(const struct format_type *fmt,
- struct mda_header *mdah,
- struct device_area *dev_area, struct id *vgid,
+ struct mda_header *mdah, struct device_area *dev_area,
+ uint32_t *mda_checksum, size_t *mda_size,
+ const char *vgname, struct id *vgid,
uint64_t *vgstatus, char **creation_host,
uint64_t *mda_free_sectors)
{
struct raw_locn *rlocn;
uint32_t wrap = 0;
- const char *vgname = NULL;
unsigned int len = 0;
char buf[NAME_LEN + 1] __attribute__((aligned(8)));
char uuid[64] __attribute__((aligned(8)));
@@ -1182,6 +1182,10 @@ const char *vgname_from_mda(const struct format_type *fmt,
return NULL;
}
+ /* Check if it could be the same VG */
+ if ((rlocn->checksum != *mda_checksum) || (rlocn->size != *mda_size))
+ vgname = NULL; /* nope, reset to NULL */
+
/* FIXME 64-bit */
if (!(vgname = text_vgname_import(fmt, dev_area->dev,
(off_t) (dev_area->start +
@@ -1190,6 +1194,7 @@ const char *vgname_from_mda(const struct format_type *fmt,
(off_t) (dev_area->start +
MDA_HEADER_SIZE),
wrap, calc_crc, rlocn->checksum,
+ vgname,
vgid, vgstatus, creation_host)))
return_NULL;
@@ -1217,6 +1222,9 @@ const char *vgname_from_mda(const struct format_type *fmt,
*mda_free_sectors = ((buffer_size - 2 * current_usage) / 2) >> SECTOR_SHIFT;
}
+ *mda_checksum = rlocn->checksum;
+ *mda_size = rlocn->size;
+
return vgname;
}
@@ -1230,6 +1238,8 @@ static int _scan_raw(const struct format_type *fmt, const char *vgname __attribu
struct id vgid;
uint64_t vgstatus;
struct mda_header *mdah;
+ uint32_t mda_checksum = 0;
+ size_t mda_size = 0;
raw_list = &((struct mda_lists *) fmt->private)->raws;
@@ -1249,9 +1259,12 @@ static int _scan_raw(const struct format_type *fmt, const char *vgname __attribu
goto close_dev;
}
+ /* TODO: caching as in vgname_from_mda() (trigger this code?) */
if ((scanned_vgname = vgname_from_mda(fmt, mdah,
- &rl->dev_area, &vgid, &vgstatus,
- NULL, NULL))) {
+ &rl->dev_area,
+ &mda_checksum, &mda_size, NULL,
+ &vgid, &vgstatus,
+ NULL, NULL))) {
vg = _vg_read_raw_area(&fid, scanned_vgname, &rl->dev_area, 0, 0);
if (vg)
lvmcache_update_vg(vg, 0);
diff --git a/lib/format_text/import-export.h b/lib/format_text/import-export.h
index d4e25f0..4b2756d 100644
--- a/lib/format_text/import-export.h
+++ b/lib/format_text/import-export.h
@@ -79,10 +79,11 @@ struct volume_group *text_vg_import_fd(struct format_instance *fid,
time_t *when, char **desc);
const char *text_vgname_import(const struct format_type *fmt,
struct device *dev,
- off_t offset, uint32_t size,
- off_t offset2, uint32_t size2,
- checksum_fn_t checksum_fn, uint32_t checksum,
- struct id *vgid, uint64_t *vgstatus,
+ off_t offset, uint32_t size,
+ off_t offset2, uint32_t size2,
+ checksum_fn_t checksum_fn, uint32_t checksum,
+ const char *vgname,
+ struct id *vgid, uint64_t *vgstatus,
char **creation_host);
#endif
diff --git a/lib/format_text/import.c b/lib/format_text/import.c
index 8a1771a..c8ba5ce 100644
--- a/lib/format_text/import.c
+++ b/lib/format_text/import.c
@@ -32,17 +32,22 @@ static void _init_text_import(void)
_text_import_initialised = 1;
}
+/*
+ * Find out vgname on a given device.
+ * If the checksum and metadata size is matching the vgname discovered in last read
+ * (multi PVs VG) could be passed back and it may skip parsing of such metadata.
+ */
const char *text_vgname_import(const struct format_type *fmt,
struct device *dev,
off_t offset, uint32_t size,
off_t offset2, uint32_t size2,
checksum_fn_t checksum_fn, uint32_t checksum,
+ const char *vgname,
struct id *vgid, uint64_t *vgstatus,
char **creation_host)
{
struct dm_config_tree *cft;
struct text_vg_version_ops **vsn;
- const char *vgname = NULL;
_init_text_import();
@@ -51,11 +56,15 @@ const char *text_vgname_import(const struct format_type *fmt,
if ((!dev && !config_file_read(cft)) ||
(dev && !config_file_read_fd(cft, dev, offset, size,
- offset2, size2, checksum_fn, checksum, 0))) {
+ offset2, size2, checksum_fn, checksum,
+ (vgname != NULL)))) {
log_error("Couldn't read volume group metadata.");
goto out;
}
+ if (vgname)
+ goto out; /* Everything is matching from the last call */
+
/*
* Find a set of version functions that can read this file
*/
diff --git a/lib/format_text/layout.h b/lib/format_text/layout.h
index 4753fde..5f6b549 100644
--- a/lib/format_text/layout.h
+++ b/lib/format_text/layout.h
@@ -100,7 +100,9 @@ struct mda_context {
const char *vgname_from_mda(const struct format_type *fmt,
struct mda_header *mdah,
- struct device_area *dev_area, struct id *vgid,
+ struct device_area *dev_area,
+ uint32_t *mda_checksum, size_t *mda_size,
+ const char *vgname, struct id *vgid,
uint64_t *vgstatus, char **creation_host,
uint64_t *mda_free_sectors);
diff --git a/lib/format_text/text_label.c b/lib/format_text/text_label.c
index e451be4..3a4835c 100644
--- a/lib/format_text/text_label.c
+++ b/lib/format_text/text_label.c
@@ -319,10 +319,14 @@ static int _update_mda(struct metadata_area *mda, void *baton)
const struct format_type *fmt = p->label->labeller->fmt;
struct mda_context *mdac = (struct mda_context *) mda->metadata_locn;
struct mda_header *mdah;
- const char *vgname = NULL;
- struct id vgid;
- uint64_t vgstatus;
- char *creation_host;
+ struct labeller *l = p->label->labeller;
+
+ /*
+ * Using the labeller struct to preserve info about
+ * the last parsed vgname, vgid, creation host
+ *
+ * TODO: make lvmcache smarter and move this cache logic there
+ */
if (!dev_open_readonly(mdac->area.dev)) {
mda_set_ignored(mda, 1);
@@ -346,17 +350,18 @@ static int _update_mda(struct metadata_area *mda, void *baton)
return 1;
}
- if ((vgname = vgname_from_mda(fmt, mdah,
- &mdac->area,
- &vgid, &vgstatus, &creation_host,
- &mdac->free_sectors)) &&
- !lvmcache_update_vgname_and_id(p->info, vgname,
- (char *) &vgid, vgstatus,
- creation_host)) {
+ if ((l->vgname = vgname_from_mda(fmt, mdah, &mdac->area,
+ &l->mda_checksum, &l->mda_size, l->vgname,
+ &l->vgid, &l->vgstatus, &l->creation_host,
+ &mdac->free_sectors)) &&
+ !lvmcache_update_vgname_and_id(p->info, l->vgname,
+ (char *) &l->vgid, l->vgstatus,
+ l->creation_host)) {
if (!dev_close(mdac->area.dev))
stack;
return_0;
}
+
close_dev:
if (!dev_close(mdac->area.dev))
stack;
diff --git a/lib/label/label.h b/lib/label/label.h
index 253e1e8..831977f 100644
--- a/lib/label/label.h
+++ b/lib/label/label.h
@@ -89,6 +89,14 @@ struct label_ops {
struct labeller {
struct label_ops *ops;
const struct format_type *fmt;
+
+ /* Caching info */
+ const char *vgname;
+ struct id vgid;
+ uint64_t vgstatus;
+ char *creation_host;
+ uint32_t mda_checksum;
+ size_t mda_size;
};
int label_init(void);
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