On Tue, Mar 23, 2010 at 1:04 AM, Luca Berra <bluca@xxxxxxxxxx> wrote:
> The attached patch completely disables bitmap support for arrays with
> externally managed metadata.
It should be possible to use an external bitmap, but that requires
that you have storage separate from the raid array.
# mdadm --grow --bitmap=$(pwd)/test --force /dev/md125
# cat /proc/mdstat
Personalities : [raid1] [raid0]
md125 : active raid1 loop1[1] loop0[0]
100143 blocks super external:/md127/0 [2/2] [UU]
bitmap: 13/13 pages [52KB], 4KB chunk, file: /root/test
md127 : inactive loop1[1](S) loop0[0](S)
418 blocks super external:imsm
unused devices: <none>
> on a style note, i do not like having the struct superswitch, which is a
> collection of function pointers which is then instanced with only some
> of the pointers initialized, it forces having to check at runtime if
> they are or not.
In some cases this is a 'feature' as it is an optional implementation
detail of the metadata format whether it supports, or wants to
override a given operation. See ->default_layout() and
->detail_platform(). Another example is the small collection of
operations that are only applicable for mdmon to use.
I think something like this untested patch would be more appropriate
to fix the issue at hand.
diff --git a/bitmap.c b/bitmap.c
index 088e37d..054a507 100644
--- a/bitmap.c
+++ b/bitmap.c
@@ -227,6 +227,12 @@ bitmap_info_t *bitmap_file_read(char *filename,
int brief, struct supertype **st
if (!st) {
/* just look at device... */
lseek(fd, 0, 0);
+ } else if (!st->ss->locate_bitmap) {
+ fprintf(stderr, Name
+ ": %s-metadata arrays do not support
an internal bitmap\n",
+ st->ss->name);
+ close(fd);
+ return NULL;
} else {
st->ss->locate_bitmap(st, fd);
}
> a possible solution would be to wrap every call of these into a macro
> that check for NULL before, but how do you return the correct return
> type from that?
We need to fix up all the locations that assume md-metadata, once that
is done a macro is not needed.
--
Dan
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