[linux-lvm] Scanning MD devices - bug or feature?
Dan Bar Dov
danb at voltaire.com
Tue Jun 15 13:44:21 UTC 2004
I have a problem where LVM fails to create VGs from PVs I make on newly
created MDs.
After looking in the code it looks as if LVM (1.0.8 BTW) is relying on a
device cache, so that newly created devices
are not accessible. It means that to use an MD device bt LVM, I need to
create the MD device and reboot.
Digging in the code I found that lvm_dir_cache is calling _scan_devs
either with TRUE or FALSE, _scan_devs on
false scans only /dev/loop and /dev/nb, it does not re-scan /dev/md. In
addition, lvmdiskscan relies on the cache as well.
My first solution was to remove the if - make it scan all the devices
all the time, but that would exclude /dev/loop and nb from the search.
I'm now thinking to add /dev/md to the _notprocdir table.
Another problem I see but need to further investigate is that my
/dev/partitions is so huge that it gets binary characters in it, and
also the proc implementation is not handling the spill over page size
properly.
Any ideas/comments would be appreciated.
Dan
------------------------------------------------------------------------
----------------------------------
/* devices *not* showing up in /proc/partitions must be scanned anyway
*/
static char *_noprocdir[] = {
LVM_DIR_PREFIX "loop",
LVM_DIR_PREFIX "nb",
NULL
};
int lvm_dir_cache(dir_cache_t **dir_cache_ptr)
{
int ret = 0;
debug_enter("lvm_dir_cache -- CALLED\n");
if (!dir_cache_ptr) {
ret = -LVM_EPARAM;
goto out;
}
if (!_dir_cache) {
_scan_partitions();
if(!_cache_size)
_scan_devs( TRUE);
else
_scan_devs( FALSE);
}
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