Fix ENXIO from spa_ld_verify_logs() in ztest

This patch fixes a small issue where the zil_check_log_chain()
code path would hit an EBUSY error. This would occur when
2 threads attempted to call metaslab_activate() at the same time.
In this case, the "loser" would receive an error code which should
have been ignored, but was instead floated to the caller. This
ended up resulting in an ENXIO being returned from from
spa_ld_verify_logs().

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes #8010

diff --git a/module/zfs/metaslab.c b/module/zfs/metaslab.c
index a117dc4460b8fd4d3cc901384515487250ef1cdc..616a89507a7f4adbbefd5e5e645d8f64b8931633 100644 (file)
--- a/module/zfs/metaslab.c
+++ b/module/zfs/metaslab.c
@@ -2049,7 +2049,7 @@ metaslab_activate(metaslab_t *msp, int allocator, uint64_t activation_weight)
                         * The metaslab was activated for another allocator
                         * while we were waiting, we should reselect.
                         */
-                       return (EBUSY);
+                       return (SET_ERROR(EBUSY));
                }
                if ((error = metaslab_activate_allocator(msp->ms_group, msp,
                    allocator, activation_weight)) != 0) {
@@ -3886,15 +3886,21 @@ metaslab_claim_concrete(vdev_t *vd, uint64_t offset, uint64_t size,
        int error = 0;
 
        if (offset >> vd->vdev_ms_shift >= vd->vdev_ms_count)
-               return (ENXIO);
+               return (SET_ERROR(ENXIO));
 
        ASSERT3P(vd->vdev_ms, !=, NULL);
        msp = vd->vdev_ms[offset >> vd->vdev_ms_shift];
 
        mutex_enter(&msp->ms_lock);
 
-       if ((txg != 0 && spa_writeable(spa)) || !msp->ms_loaded)
+       if ((txg != 0 && spa_writeable(spa)) || !msp->ms_loaded) {
                error = metaslab_activate(msp, 0, METASLAB_WEIGHT_CLAIM);
+               if (error == EBUSY) {
+                       ASSERT(msp->ms_loaded);
+                       ASSERT(msp->ms_weight & METASLAB_ACTIVE_MASK);
+                       error = 0;
+               }
+       }
 
        if (error == 0 &&
            !range_tree_contains(msp->ms_allocatable, offset, size))