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Remove some branching from GEOM_DISK hot path.
pp->private just can not be NULL in those places. In g_disk_start() and g_disk_ioctl() both dp != NULL and !dp->d_destroyed should always be true if disk_gone() and disk_destroy() are used properly, since GEOM does not send requests to errored providers. If the protocol is not followed, then no amount of additional checks here give real safety. In g_disk_access() though the checks are useful, since GEOM blocks only new opens for errored providers, but allows closes. It should not happen if disk_gone() and disk_destroy() are used properly, but may otherwise. To improve cases when disk_gone() is not used, call it from disk_destroy(). It does not give full guaranties, but it errors the provider and makes GEOM block unwanted requests at least after some race. MFC after: 2 weeks
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parent
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=355451
@ -108,7 +108,7 @@ g_disk_access(struct g_provider *pp, int r, int w, int e)
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pp->name, r, w, e);
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g_topology_assert();
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sc = pp->private;
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if (sc == NULL || (dp = sc->dp) == NULL || dp->d_destroyed) {
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if ((dp = sc->dp) == NULL || dp->d_destroyed) {
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/*
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* Allow decreasing access count even if disk is not
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* available anymore.
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@ -274,6 +274,8 @@ g_disk_ioctl(struct g_provider *pp, u_long cmd, void * data, int fflag, struct t
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sc = pp->private;
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dp = sc->dp;
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KASSERT(dp != NULL && !dp->d_destroyed,
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("g_disk_ioctl(%lx) on destroyed disk %s", cmd, pp->name));
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if (dp->d_ioctl == NULL)
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return (ENOIOCTL);
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@ -432,10 +434,9 @@ g_disk_start(struct bio *bp)
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biotrack(bp, __func__);
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sc = bp->bio_to->private;
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if (sc == NULL || (dp = sc->dp) == NULL || dp->d_destroyed) {
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g_io_deliver(bp, ENXIO);
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return;
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}
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dp = sc->dp;
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KASSERT(dp != NULL && !dp->d_destroyed,
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("g_disk_start(%p) on destroyed disk %s", bp, bp->bio_to->name));
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error = EJUSTRETURN;
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switch(bp->bio_cmd) {
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case BIO_DELETE:
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@ -896,8 +897,9 @@ void
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disk_destroy(struct disk *dp)
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{
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g_cancel_event(dp);
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disk_gone(dp);
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dp->d_destroyed = 1;
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g_cancel_event(dp);
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if (dp->d_devstat != NULL)
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devstat_remove_entry(dp->d_devstat);
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g_post_event(g_disk_destroy, dp, M_WAITOK, NULL);
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@ -922,6 +924,16 @@ disk_gone(struct disk *dp)
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struct g_provider *pp;
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mtx_pool_lock(mtxpool_sleep, dp);
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/*
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* Second wither call makes no sense, plus we can not access the list
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* of providers without topology lock after calling wither once.
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*/
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if (dp->d_goneflag != 0) {
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mtx_pool_unlock(mtxpool_sleep, dp);
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return;
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}
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dp->d_goneflag = 1;
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/*
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@ -946,13 +958,11 @@ disk_gone(struct disk *dp)
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mtx_pool_unlock(mtxpool_sleep, dp);
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gp = dp->d_geom;
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if (gp != NULL) {
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pp = LIST_FIRST(&gp->provider);
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if (pp != NULL) {
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KASSERT(LIST_NEXT(pp, provider) == NULL,
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("geom %p has more than one provider", gp));
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g_wither_provider(pp, ENXIO);
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}
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pp = LIST_FIRST(&gp->provider);
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if (pp != NULL) {
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KASSERT(LIST_NEXT(pp, provider) == NULL,
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("geom %p has more than one provider", gp));
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g_wither_provider(pp, ENXIO);
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}
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}
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