diff --git a/include/sys/spa.h b/include/sys/spa.h index 07e09d1ec0..42f7fec0fc 100644 --- a/include/sys/spa.h +++ b/include/sys/spa.h @@ -972,6 +972,8 @@ extern int spa_import_progress_set_state(uint64_t pool_guid, /* Pool configuration locks */ extern int spa_config_tryenter(spa_t *spa, int locks, void *tag, krw_t rw); extern void spa_config_enter(spa_t *spa, int locks, const void *tag, krw_t rw); +extern void spa_config_enter_mmp(spa_t *spa, int locks, const void *tag, + krw_t rw); extern void spa_config_exit(spa_t *spa, int locks, const void *tag); extern int spa_config_held(spa_t *spa, int locks, krw_t rw); diff --git a/module/zfs/mmp.c b/module/zfs/mmp.c index f67a4eb22a..139bb0acd2 100644 --- a/module/zfs/mmp.c +++ b/module/zfs/mmp.c @@ -444,7 +444,7 @@ mmp_write_uberblock(spa_t *spa) uint64_t offset; hrtime_t lock_acquire_time = gethrtime(); - spa_config_enter(spa, SCL_STATE, mmp_tag, RW_READER); + spa_config_enter_mmp(spa, SCL_STATE, mmp_tag, RW_READER); lock_acquire_time = gethrtime() - lock_acquire_time; if (lock_acquire_time > (MSEC2NSEC(MMP_MIN_INTERVAL) / 10)) zfs_dbgmsg("MMP SCL_STATE acquisition pool '%s' took %llu ns " diff --git a/module/zfs/spa_misc.c b/module/zfs/spa_misc.c index 10837241b5..113943026d 100644 --- a/module/zfs/spa_misc.c +++ b/module/zfs/spa_misc.c @@ -494,8 +494,9 @@ spa_config_tryenter(spa_t *spa, int locks, void *tag, krw_t rw) return (1); } -void -spa_config_enter(spa_t *spa, int locks, const void *tag, krw_t rw) +static void +spa_config_enter_impl(spa_t *spa, int locks, const void *tag, krw_t rw, + int mmp_flag) { (void) tag; int wlocks_held = 0; @@ -510,7 +511,8 @@ spa_config_enter(spa_t *spa, int locks, const void *tag, krw_t rw) continue; mutex_enter(&scl->scl_lock); if (rw == RW_READER) { - while (scl->scl_writer || scl->scl_write_wanted) { + while (scl->scl_writer || + (!mmp_flag && scl->scl_write_wanted)) { cv_wait(&scl->scl_cv, &scl->scl_lock); } } else { @@ -528,6 +530,27 @@ spa_config_enter(spa_t *spa, int locks, const void *tag, krw_t rw) ASSERT3U(wlocks_held, <=, locks); } +void +spa_config_enter(spa_t *spa, int locks, const void *tag, krw_t rw) +{ + spa_config_enter_impl(spa, locks, tag, rw, 0); +} + +/* + * The spa_config_enter_mmp() allows the mmp thread to cut in front of + * outstanding write lock requests. This is needed since the mmp updates are + * time sensitive and failure to service them promptly will result in a + * suspended pool. This pool suspension has been seen in practice when there is + * a single disk in a pool that is responding slowly and presumably about to + * fail. + */ + +void +spa_config_enter_mmp(spa_t *spa, int locks, const void *tag, krw_t rw) +{ + spa_config_enter_impl(spa, locks, tag, rw, 1); +} + void spa_config_exit(spa_t *spa, int locks, const void *tag) {