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logical: Need to overwrite/clear more than just first 512 bytes

Browse Source 
https://bugzilla.redhat.com/show_bug.cgi?id=1430679

As it turns out some file headers (e.g. ext4) may be larger/longer than
the 512 bytes of zeros being written prior to a pvcreate, so let's write
out 2048 bytes similar to how the pvcreate sources would peek at the first
4 sectors of the device.

Make sure there is at enough bytes on the device to clear before doing
doing the clear - just to be sure.
This commit is contained in:
John Ferlan 2017-03-24 12:25:27 -04:00
parent 2902771fa0
commit 6760cc4bfd
1 changed files with 21 additions and 1 deletions
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22
src/storage/storage_backend_logical.c
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@ -93,7 +93,8 @@ static int
virStorageBackendLogicalInitializeDevice(const char *path)
{
int fd = -1;
char zeros[PV_BLANK_SECTOR_SIZE] = {0};
char zeros[4 * PV_BLANK_SECTOR_SIZE] = {0};
off_t size;
int ret = -1;
virCommandPtr pvcmd = NULL;
@ -107,6 +108,25 @@ virStorageBackendLogicalInitializeDevice(const char *path)
return -1;
}
if ((size = lseek(fd, 0, SEEK_END)) == (off_t)-1) {
virReportSystemError(errno,
_("failed to seek to end of %s"), path);
goto cleanup;
}
if (size < 4 * PV_BLANK_SECTOR_SIZE) {
virReportError(VIR_ERR_OPERATION_UNSUPPORTED,
_("cannot initialize '%s' detected size='%lu' less "
"than minimum required='%d"),
path, size, 4 * PV_BLANK_SECTOR_SIZE);
goto cleanup;
}
if ((size = lseek(fd, 0, SEEK_SET)) == (off_t)-1) {
virReportSystemError(errno,
_("failed to seek to start of %s"), path);
goto cleanup;
}
if (safewrite(fd, zeros, sizeof(zeros)) < 0) {
virReportSystemError(errno, _("cannot clear device header of '%s'"),
path);