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When using the force option to shut down a memory-disk device,

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I/O operations already in its queue were not being properly drained.
The GEOM framework does the queue draining, but the device driver
needs to wait for the draining to happen. The waiting is done by
adding a g_md_providergone() function to wait for the I/O operations
to finish up.

It is likely that every GEOM provider that implements orphaning
attached GEOM consumers needs to use the "providergone" mechanism
for this same reason, but some of them do not do so. Apparently
Kenneth Merry (ken@) added the drain for just such races, but he
missed adding it to some of the device drivers that needed it.

Submitted by: Chuck Silvers
Reviewed by:  imp
Tested by:    Chuck Silvers
MFC after:    1 week
Sponsored by: Netflix
This commit is contained in:
Kirk McKusick 2019-03-31 21:34:58 +00:00
parent fe2825be6f
commit 7e1a6d4777
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=345758
1 changed files with 20 additions and 4 deletions
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24
sys/dev/md/md.c
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@ -110,6 +110,7 @@
#define MD_SHUTDOWN 0x10000 /* Tell worker thread to terminate. */
#define MD_EXITING 0x20000 /* Worker thread is exiting. */
#define MD_PROVIDERGONE 0x40000 /* Safe to free the softc */
#ifndef MD_NSECT
#define MD_NSECT (10000 * 2)
@ -199,6 +200,7 @@ static g_start_t g_md_start;
static g_access_t g_md_access;
static void g_md_dumpconf(struct sbuf *sb, const char *indent,
struct g_geom *gp, struct g_consumer *cp __unused, struct g_provider *pp);
static g_provgone_t g_md_providergone;
static struct cdev *status_dev = NULL;
static struct sx md_sx;
@ -220,6 +222,7 @@ struct g_class g_md_class = {
.start = g_md_start,
.access = g_md_access,
.dumpconf = g_md_dumpconf,
.providergone = g_md_providergone,
};
DECLARE_GEOM_CLASS(g_md_class, g_md);
@ -481,8 +484,8 @@ g_md_start(struct bio *bp)
}
mtx_lock(&sc->queue_mtx);
bioq_disksort(&sc->bio_queue, bp);
mtx_unlock(&sc->queue_mtx);
wakeup(sc);
mtx_unlock(&sc->queue_mtx);
}
#define MD_MALLOC_MOVE_ZERO 1
@ -1496,17 +1499,30 @@ mdcreate_vnode(struct md_s *sc, struct md_req *mdr, struct thread *td)
return (error);
}
static void
g_md_providergone(struct g_provider *pp)
{
struct md_s *sc = pp->geom->softc;
mtx_lock(&sc->queue_mtx);
sc->flags |= MD_PROVIDERGONE;
wakeup(&sc->flags);
mtx_unlock(&sc->queue_mtx);
}
static int
mddestroy(struct md_s *sc, struct thread *td)
{
if (sc->gp) {
sc->gp->softc = NULL;
g_topology_lock();
g_wither_geom(sc->gp, ENXIO);
g_topology_unlock();
sc->gp = NULL;
sc->pp = NULL;
mtx_lock(&sc->queue_mtx);
while (!(sc->flags & MD_PROVIDERGONE))
msleep(&sc->flags, &sc->queue_mtx, PRIBIO, "mddestroy", 0);
mtx_unlock(&sc->queue_mtx);
}
if (sc->devstat) {
devstat_remove_entry(sc->devstat);