Bug 277673

Hey All,

While toying with different storage options to use with bhyve, I've run across a few frustrations related to visibility into TRIM operations. Specifically, it's not always easy to tell if trim operations are being processed by a hardware device due to the counters not being updated by the SCSI da device. The counters exported as sysctl values are updated by the SCCI UNMAP method, but not by the TRIM or WD methods. You can see the BIO_DELETE opterations being processed in real time by running the gstatus -d command, but the counters never change from 0. This gives the false illusion that nothing is happening. With the following patch, I'm now able to see the counters reflect trim operations that are processed by da devices ...

mgrooms@mgrooms:~/trim $ cat scsi_da.diff
--- scsi_da.c.orig    2024-03-13 11:32:32.098922000 -0500
+++ scsi_da.c    2024-03-13 11:31:37.255187000 -0500
@@ -4197,6 +4197,9 @@
               da_default_timeout * 1000);
     ccb->ccb_h.ccb_state = DA_CCB_DELETE;
     ccb->ccb_h.flags |= CAM_UNLOCKED;
+    softc->trim_count++;
+    softc->trim_ranges += ranges;
+    softc->trim_lbas += block_count;
     cam_iosched_submit_trim(softc->cam_iosched);
 }
 
@@ -4257,6 +4260,8 @@
             da_default_timeout * 1000);
     ccb->ccb_h.ccb_state = DA_CCB_DELETE;
     ccb->ccb_h.flags |= CAM_UNLOCKED;
+    softc->trim_count++;
+    softc->trim_lbas += count;
     cam_iosched_submit_trim(softc->cam_iosched);
 }

Additionally, while attempting to test geom mirror+stripe to provide software RAID10, the diskinfo utility reports that a mirror supports UNMAP/TRIM when at least one underlying devices supports it, but a stripe does not. I added a small patch that attempts to use the same logic as mirror so that it will report that UNMAP/TRIM is supported when one of the underlying devices does ...

--- g_stripe.c.orig    2024-03-12 18:23:52.960025000 -0500
+++ g_stripe.c    2024-03-12 18:25:01.009378000 -0500
@@ -26,6 +26,7 @@
  * SUCH DAMAGE.
  */
 
+#include <sys/cdefs.h>
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/kernel.h>
@@ -568,7 +569,7 @@
     off_t offset, start, length, nstripe, stripesize;
     struct g_stripe_softc *sc;
     u_int no;
-    int error, fast = 0;
+    int error, fast = 0, val = 0;
 
     sc = bp->bio_to->geom->softc;
     /*
@@ -591,6 +592,12 @@
         g_stripe_pushdown(sc, bp);
         return;
     case BIO_GETATTR:
+        if (!strcmp(bp->bio_attribute, "GEOM::candelete")) {
+            if (sc->sc_flags & G_STRIPE_FLAG_CANDELETE)
+                val = 1;
+            g_handleattr(bp, "GEOM::candelete", &val, sizeof(val));
+            return;
+        }
         /* To which provider it should be delivered? */
     default:
         g_io_deliver(bp, EOPNOTSUPP);
@@ -745,7 +752,7 @@
 {
     struct g_consumer *cp, *fcp;
     struct g_geom *gp;
-    int error;
+    int error, i;
 
     g_topology_assert();
     /* Metadata corrupted? */
@@ -792,8 +799,19 @@
             goto fail;
         }
     }
-
     sc->sc_disks[no] = cp;
+
+    /* cascade candelete */
+    error = g_access(cp, 1, 0, 0);
+    if (error == 0)
+    {
+        error = g_getattr("GEOM::candelete", cp, &i);
+        if (error == 0 && i != 0)
+            sc->sc_flags |= G_STRIPE_FLAG_CANDELETE;
+        G_STRIPE_DEBUG(1, "Provider %s candelete %i.", pp->name, i);
+        g_access(cp, -1, 0, 0);
+    }
+
     G_STRIPE_DEBUG(0, "Disk %s attached to %s.", pp->name, sc->sc_name);
     g_stripe_check_and_run(sc);
 
--- g_stripe.h.orig    2024-03-12 18:24:00.960741000 -0500
+++ g_stripe.h    2024-03-12 12:25:22.842925000 -0500
@@ -47,6 +47,8 @@
 #define    G_STRIPE_TYPE_MANUAL    0
 #define    G_STRIPE_TYPE_AUTOMATIC    1
 
+#define    G_STRIPE_FLAG_CANDELETE        0x00000001UL
+
 #define    G_STRIPE_DEBUG(lvl, ...) \
     _GEOM_DEBUG("GEOM_STRIPE", g_stripe_debug, (lvl), NULL, __VA_ARGS__)
 #define    G_STRIPE_LOGREQ(bp, ...) \
@@ -61,6 +63,7 @@
     uint16_t     sc_ndisks;
     off_t         sc_stripesize;
     uint32_t     sc_stripebits;
+    uint32_t     sc_flags;
     struct mtx     sc_lock;
 };
 #define    sc_name    sc_geom->name