Implemented sharing datasets via NFS using libshare.

[zfs.git] / module / zfs / zio.c

diff --git a/module/zfs/zio.c b/module/zfs/zio.c
index 2c38e10..0fa8236 100644 (file)
--- a/module/zfs/zio.c
+++ b/module/zfs/zio.c
@@ -86,7 +86,7 @@ extern vmem_t *zio_alloc_arena;
  */
 #define        IO_IS_ALLOCATING(zio) ((zio)->io_orig_pipeline & ZIO_STAGE_DVA_ALLOCATE)
 
-boolean_t      zio_requeue_io_start_cut_in_line = B_TRUE;
+int zio_requeue_io_start_cut_in_line = 1;
 
 #ifdef ZFS_DEBUG
 int zio_buf_debug_limit = 16384;
@@ -1150,6 +1150,8 @@ __zio_execute(zio_t *zio)
        while (zio->io_stage < ZIO_STAGE_DONE) {
                enum zio_stage pipeline = zio->io_pipeline;
                enum zio_stage stage = zio->io_stage;
+               dsl_pool_t *dsl;
+               boolean_t cut;
                int rv;
 
                ASSERT(!MUTEX_HELD(&zio->io_lock));
@@ -1162,19 +1164,26 @@ __zio_execute(zio_t *zio)
 
                ASSERT(stage <= ZIO_STAGE_DONE);
 
+               dsl = spa_get_dsl(zio->io_spa);
+               cut = (stage == ZIO_STAGE_VDEV_IO_START) ?
+                   zio_requeue_io_start_cut_in_line : B_FALSE;
+
                /*
                 * If we are in interrupt context and this pipeline stage
                 * will grab a config lock that is held across I/O,
                 * or may wait for an I/O that needs an interrupt thread
                 * to complete, issue async to avoid deadlock.
                 *
+                * If we are in the txg_sync_thread or being called
+                * during pool init issue async to minimize stack depth.
+                * Both of these call paths may be recursively called.
+                *
                 * For VDEV_IO_START, we cut in line so that the io will
                 * be sent to disk promptly.
                 */
-               if ((stage & ZIO_BLOCKING_STAGES) && zio->io_vd == NULL &&
-                   zio_taskq_member(zio, ZIO_TASKQ_INTERRUPT)) {
-                       boolean_t cut = (stage == ZIO_STAGE_VDEV_IO_START) ?
-                           zio_requeue_io_start_cut_in_line : B_FALSE;
+               if (((stage & ZIO_BLOCKING_STAGES) && zio->io_vd == NULL &&
+                   zio_taskq_member(zio, ZIO_TASKQ_INTERRUPT)) ||
+                   (dsl != NULL && dsl_pool_sync_context(dsl))) {
                        zio_taskq_dispatch(zio, ZIO_TASKQ_ISSUE, cut);
                        return;
                }
@@ -3006,5 +3015,8 @@ module_param(zio_bulk_flags, int, 0644);
 MODULE_PARM_DESC(zio_bulk_flags, "Additional flags to pass to bulk buffers");
 
 module_param(zio_delay_max, int, 0644);
-MODULE_PARM_DESC(zio_delay_max, "Max zio delay before posting an event (ms)");
+MODULE_PARM_DESC(zio_delay_max, "Max zio millisec delay before posting event");
+
+module_param(zio_requeue_io_start_cut_in_line, int, 0644);
+MODULE_PARM_DESC(zio_requeue_io_start_cut_in_line, "Prioritize requeued I/O");
 #endif