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Avoid race while synchronizing components. It is very hard to bump into,

Browse Source 
but it is possible:
1. Read data from good component for synchronization.
2. Write data to the same area.
3. Write synchronization data, which are now stale.

Found by:	tegge
This commit is contained in:
Pawel Jakub Dawidek 2004-09-26 20:41:07 +00:00
parent 287e12f172
commit e8adbe4499
1 changed files with 31 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
sys/geom/mirror/g_mirror.c
View File

@ -392,6 +392,7 @@ g_mirror_init_disk(struct g_mirror_softc *sc, struct g_provider *pp,
disk->d_sync.ds_consumer = NULL;
disk->d_sync.ds_offset = md->md_sync_offset;
disk->d_sync.ds_offset_done = md->md_sync_offset;
disk->d_sync.ds_resync = -1;
disk->d_sync.ds_syncid = md->md_syncid;
if (errorp != NULL)
*errorp = 0;
@ -952,6 +953,9 @@ g_mirror_sync_request(struct bio *bp)
return;
}
case BIO_WRITE:
{
struct g_mirror_disk_sync *sync;
if (bp->bio_error != 0) {
G_MIRROR_LOGREQ(0, bp,
"Synchronization request failed (error=%d).",
@ -964,17 +968,20 @@ g_mirror_sync_request(struct bio *bp)
return;
}
G_MIRROR_LOGREQ(3, bp, "Synchronization request finished.");
disk->d_sync.ds_offset_done = bp->bio_offset + bp->bio_length;
sync = &disk->d_sync;
sync->ds_offset_done = bp->bio_offset + bp->bio_length;
g_destroy_bio(bp);
if (disk->d_sync.ds_offset_done == sc->sc_provider->mediasize) {
if (sync->ds_resync != -1)
break;
if (sync->ds_offset_done == sc->sc_provider->mediasize) {
/*
* Disk up-to-date, activate it.
*/
g_mirror_event_send(disk, G_MIRROR_DISK_STATE_ACTIVE,
G_MIRROR_EVENT_DONTWAIT);
return;
} else if ((disk->d_sync.ds_offset_done %
(G_MIRROR_SYNC_BLOCK_SIZE * 100)) == 0) {
} else if (sync->ds_offset_done %
(G_MIRROR_SYNC_BLOCK_SIZE * 100) == 0) {
/*
* Update offset_done on every 100 blocks.
* XXX: This should be configurable.
@ -984,6 +991,7 @@ g_mirror_sync_request(struct bio *bp)
g_topology_unlock();
}
return;
}
default:
KASSERT(1 == 0, ("Invalid command here: %u (device=%s)",
bp->bio_cmd, sc->sc_name));
@ -1205,6 +1213,7 @@ g_mirror_register_request(struct bio *bp)
case BIO_DELETE:
{
struct g_mirror_disk *disk;
struct g_mirror_disk_sync *sync;
struct bio_queue_head queue;
struct g_consumer *cp;
struct bio *cbp;
@ -1215,12 +1224,21 @@ g_mirror_register_request(struct bio *bp)
*/
bioq_init(&queue);
LIST_FOREACH(disk, &sc->sc_disks, d_next) {
sync = &disk->d_sync;
switch (disk->d_state) {
case G_MIRROR_DISK_STATE_ACTIVE:
break;
case G_MIRROR_DISK_STATE_SYNCHRONIZING:
if (bp->bio_offset >= disk->d_sync.ds_offset)
if (bp->bio_offset >= sync->ds_offset)
continue;
else if (bp->bio_offset + bp->bio_length >
sync->ds_offset_done &&
(bp->bio_offset < sync->ds_resync ||
sync->ds_resync != -1)) {
sync->ds_resync = bp->bio_offset -
(bp->bio_offset %
G_MIRROR_SYNC_BLOCK_SIZE);
}
break;
default:
continue;
@ -1330,6 +1348,7 @@ g_mirror_worker(void *arg)
{
struct g_mirror_softc *sc;
struct g_mirror_disk *disk;
struct g_mirror_disk_sync *sync;
struct g_mirror_event *ep;
struct bio *bp;
u_int nreqs;
@ -1411,13 +1430,17 @@ g_mirror_worker(void *arg)
G_MIRROR_DISK_STATE_SYNCHRONIZING) {
continue;
}
if (disk->d_sync.ds_offset >=
sync = &disk->d_sync;
if (sync->ds_offset >=
sc->sc_provider->mediasize) {
continue;
}
if (disk->d_sync.ds_offset >
disk->d_sync.ds_offset_done) {
if (sync->ds_offset > sync->ds_offset_done)
continue;
if (sync->ds_resync != -1) {
sync->ds_offset = sync->ds_resync;
sync->ds_offset_done = sync->ds_resync;
sync->ds_resync = -1;
}
g_mirror_sync_one(disk);
}