Fix stack dmu_objset_snapshot()

Reduce stack usage by 276 bytes by moving the snaparg struct from the
stack to the heap.  We have limited stack space we must not waste.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

diff --git a/module/zfs/dmu_objset.c b/module/zfs/dmu_objset.c
index 2d06897..1dcfb02 100644 (file)
--- a/module/zfs/dmu_objset.c
+++ b/module/zfs/dmu_objset.c
@@ -946,16 +946,19 @@ dmu_objset_snapshot(char *fsname, char *snapname, char *tag,
     nvlist_t *props, boolean_t recursive, boolean_t temporary, int cleanup_fd)
 {
        dsl_sync_task_t *dst;
-       struct snaparg sn;
+       struct snaparg *sn;
        spa_t *spa;
        minor_t minor;
        int err;
 
-       (void) strcpy(sn.failed, fsname);
+       sn = kmem_alloc(sizeof (struct snaparg), KM_SLEEP);
+       (void) strcpy(sn->failed, fsname);
 
        err = spa_open(fsname, &spa, FTAG);
-       if (err)
+       if (err) {
+               kmem_free(sn, sizeof (struct snaparg));
                return (err);
+       }
 
        if (temporary) {
                if (cleanup_fd < 0) {
@@ -968,46 +971,47 @@ dmu_objset_snapshot(char *fsname, char *snapname, char *tag,
                }
        }
 
-       sn.dstg = dsl_sync_task_group_create(spa_get_dsl(spa));
-       sn.snapname = snapname;
-       sn.htag = tag;
-       sn.props = props;
-       sn.recursive = recursive;
-       sn.needsuspend = (spa_version(spa) < SPA_VERSION_FAST_SNAP);
-       sn.temporary = temporary;
-       sn.ha = NULL;
-       sn.newds = NULL;
+       sn->dstg = dsl_sync_task_group_create(spa_get_dsl(spa));
+       sn->snapname = snapname;
+       sn->htag = tag;
+       sn->props = props;
+       sn->recursive = recursive;
+       sn->needsuspend = (spa_version(spa) < SPA_VERSION_FAST_SNAP);
+       sn->temporary = temporary;
+       sn->ha = NULL;
+       sn->newds = NULL;
 
        if (recursive) {
                err = dmu_objset_find(fsname,
-                   dmu_objset_snapshot_one, &sn, DS_FIND_CHILDREN);
+                   dmu_objset_snapshot_one, sn, DS_FIND_CHILDREN);
        } else {
-               err = dmu_objset_snapshot_one(fsname, &sn);
+               err = dmu_objset_snapshot_one(fsname, sn);
        }
 
        if (err == 0)
-               err = dsl_sync_task_group_wait(sn.dstg);
+               err = dsl_sync_task_group_wait(sn->dstg);
 
-       for (dst = list_head(&sn.dstg->dstg_tasks); dst;
-           dst = list_next(&sn.dstg->dstg_tasks, dst)) {
+       for (dst = list_head(&sn->dstg->dstg_tasks); dst;
+           dst = list_next(&sn->dstg->dstg_tasks, dst)) {
                objset_t *os = dst->dst_arg1;
                dsl_dataset_t *ds = os->os_dsl_dataset;
                if (dst->dst_err) {
-                       dsl_dataset_name(ds, sn.failed);
+                       dsl_dataset_name(ds, sn->failed);
                } else if (temporary) {
-                       dsl_register_onexit_hold_cleanup(sn.newds, tag, minor);
+                       dsl_register_onexit_hold_cleanup(sn->newds, tag, minor);
                }
-               if (sn.needsuspend)
+               if (sn->needsuspend)
                        zil_resume(dmu_objset_zil(os));
-               dmu_objset_rele(os, &sn);
+               dmu_objset_rele(os, sn);
        }
 
        if (err)
-               (void) strcpy(fsname, sn.failed);
+               (void) strcpy(fsname, sn->failed);
        if (temporary)
                zfs_onexit_fd_rele(cleanup_fd);
-       dsl_sync_task_group_destroy(sn.dstg);
+       dsl_sync_task_group_destroy(sn->dstg);
        spa_close(spa, FTAG);
+       kmem_free(sn, sizeof (struct snaparg));
        return (err);
 }