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add label_read_pvid

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To read the lvm headers and set dev->pvid if the
device is a PV.  Difference from label_scan_ functions
is this does not read any vg metadata or add any info
to lvmcache.
This commit is contained in:
David Teigland 2020-10-15 14:05:45 -05:00
parent c7311d4722
commit 677f829e54
2 changed files with 49 additions and 0 deletions
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48
lib/label/label.c
View File

@ -1254,6 +1254,54 @@ int label_scan(struct cmd_context *cmd)
return 1;
}
/*
* Read the header of the disk and if it's a PV
* save the pvid in dev->pvid.
*/
int label_read_pvid(struct device *dev)
{
char buf[4096] __attribute__((aligned(8)));
struct label_header *lh;
struct pv_header *pvh;
memset(buf, 0, sizeof(buf));
if (!label_scan_open(dev))
return_0;
/*
* We could do:
* dev_read_bytes(dev, 512, LABEL_SIZE, buf);
* which works, but there's a bcache issue that
* prevents proper invalidation after that.
*/
if (!dev_read_bytes(dev, 0, 4096, buf)) {
label_scan_invalidate(dev);
return 0;
}
lh = (struct label_header *)(buf + 512);
if (memcmp(lh->id, LABEL_ID, sizeof(lh->id))) {
/* Not an lvm deice */
label_scan_invalidate(dev);
return 0;
}
/*
* wipefs -a just clears the type field, leaving the
* rest of the label_header intact.
*/
if (memcmp(lh->type, LVM2_LABEL, sizeof(lh->type))) {
/* Not an lvm deice */
label_scan_invalidate(dev);
return 0;
}
pvh = (struct pv_header *)(buf + 512 + 32);
memcpy(dev->pvid, pvh->pv_uuid, ID_LEN);
return 1;
}
/*
* Scan and cache lvm data from the listed devices. If a device is already
* scanned and cached, this replaces the previously cached lvm data for the

1
lib/label/label.h
View File

@ -117,6 +117,7 @@ int label_scan_open(struct device *dev);
int label_scan_open_excl(struct device *dev);
int label_scan_open_rw(struct device *dev);
int label_scan_reopen_rw(struct device *dev);
int label_read_pvid(struct device *dev);
int label_scan_for_pvid(struct cmd_context *cmd, char *pvid, struct device **dev_out);