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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 (for gmirror)
This commit is contained in:
Pawel Jakub Dawidek 2004-09-27 20:32:35 +00:00
parent 52c55a26b1
commit d2fb9c62e2
2 changed files with 37 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

43
sys/geom/raid3/g_raid3.c
View File

@ -465,6 +465,7 @@ g_raid3_init_disk(struct g_raid3_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;
@ -1318,6 +1319,9 @@ g_raid3_sync_request(struct bio *bp)
return;
}
case BIO_WRITE:
{
struct g_raid3_disk_sync *sync;
if (bp->bio_error != 0) {
G_RAID3_LOGREQ(0, bp,
"Synchronization request failed (error=%d).",
@ -1330,9 +1334,12 @@ g_raid3_sync_request(struct bio *bp)
return;
}
G_RAID3_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 ==
if (sync->ds_resync != -1)
return;
if (sync->ds_offset_done ==
sc->sc_mediasize / (sc->sc_ndisks - 1)) {
/*
* Disk up-to-date, activate it.
@ -1340,8 +1347,8 @@ g_raid3_sync_request(struct bio *bp)
g_raid3_event_send(disk, G_RAID3_DISK_STATE_ACTIVE,
G_RAID3_EVENT_DONTWAIT);
return;
} else if ((disk->d_sync.ds_offset_done %
(G_RAID3_MAX_IO_SIZE * 100)) == 0) {
} else if (sync->ds_offset_done %
(G_RAID3_MAX_IO_SIZE * 100) == 0) {
/*
* Update offset_done on every 100 blocks.
* XXX: This should be configurable.
@ -1351,6 +1358,7 @@ g_raid3_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));
@ -1403,8 +1411,23 @@ g_raid3_register_request(struct bio *pbp)
break;
case BIO_WRITE:
case BIO_DELETE:
{
struct g_raid3_disk_sync *sync;
ndisks = sc->sc_ndisks;
if (sc->sc_syncdisk == NULL)
break;
sync = &sc->sc_syncdisk->d_sync;
if (offset >= sync->ds_offset)
break;
if (offset + length <= sync->ds_offset_done)
break;
if (offset >= sync->ds_resync && sync->ds_resync != -1)
break;
sync->ds_resync = offset - (offset % G_RAID3_MAX_IO_SIZE);
break;
}
}
for (n = 0; n < ndisks; n++) {
disk = &sc->sc_disks[n];
@ -1572,6 +1595,7 @@ g_raid3_worker(void *arg)
{
struct g_raid3_softc *sc;
struct g_raid3_disk *disk;
struct g_raid3_disk_sync *sync;
struct g_raid3_event *ep;
struct bio *bp;
u_int nreqs;
@ -1649,10 +1673,15 @@ g_raid3_worker(void *arg)
*/
nreqs = 0;
disk = sc->sc_syncdisk;
if (disk->d_sync.ds_offset <
sync = &disk->d_sync;
if (sync->ds_offset <
sc->sc_mediasize / (sc->sc_ndisks - 1) &&
disk->d_sync.ds_offset ==
disk->d_sync.ds_offset_done) {
sync->ds_offset == sync->ds_offset_done) {
if (sync->ds_resync != -1) {
sync->ds_offset = sync->ds_resync;
sync->ds_offset_done = sync->ds_resync;
sync->ds_resync = -1;
}
g_raid3_sync_one(sc);
}
G_RAID3_DEBUG(5, "%s: I'm here 2.", __func__);

1
sys/geom/raid3/g_raid3.h
View File

@ -112,6 +112,7 @@ struct g_raid3_disk_sync {
off_t ds_offset; /* Offset of next request to send. */
off_t ds_offset_done; /* Offset of already synchronized
region. */
off_t ds_resync; /* Resynchronize from this offset. */
u_int ds_syncid; /* Disk's synchronization ID. */
u_char *ds_data;
};