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authorBrian Behlendorf <[email protected]>2011-04-26 14:56:04 -0700
committerBrian Behlendorf <[email protected]>2011-04-26 15:48:00 -0700
commit40a39e1103bbbd6908bc1b5cf4af953c7e4706ad (patch)
tree7ce38bb8cf7e9112a93f4a29828bc966f4ed37f8 /module
parentb81c4ac9af4f9e8b8c27d8011e3ce608cd04737b (diff)
Conserve stack in dsl_scan_visit()
The dsl_scan_visit() function is a little heavy weight taking 464 bytes on the stack. This can be easily reduced for little cost by moving zap_cursor_t and zap_attribute_t off the stack and on to the heap. After this change dsl_scan_visit() has been reduced in size by 320 bytes. This change was made to reduce stack usage in the dsl_scan_sync() callpath which is recursive and has been observed to overflow the stack. Issue #174
Diffstat (limited to 'module')
-rw-r--r--module/zfs/dsl_scan.c25
1 files changed, 15 insertions, 10 deletions
diff --git a/module/zfs/dsl_scan.c b/module/zfs/dsl_scan.c
index e3d2492a2..ff36ea96b 100644
--- a/module/zfs/dsl_scan.c
+++ b/module/zfs/dsl_scan.c
@@ -1328,8 +1328,8 @@ static void
dsl_scan_visit(dsl_scan_t *scn, dmu_tx_t *tx)
{
dsl_pool_t *dp = scn->scn_dp;
- zap_cursor_t zc;
- zap_attribute_t za;
+ zap_cursor_t *zc;
+ zap_attribute_t *za;
if (scn->scn_phys.scn_ddt_bookmark.ddb_class <=
scn->scn_phys.scn_ddt_class_max) {
@@ -1377,24 +1377,26 @@ dsl_scan_visit(dsl_scan_t *scn, dmu_tx_t *tx)
* bookmark so we don't think that we're still trying to resume.
*/
bzero(&scn->scn_phys.scn_bookmark, sizeof (zbookmark_t));
+ zc = kmem_alloc(sizeof(zap_cursor_t), KM_SLEEP);
+ za = kmem_alloc(sizeof(zap_attribute_t), KM_SLEEP);
/* keep pulling things out of the zap-object-as-queue */
- while (zap_cursor_init(&zc, dp->dp_meta_objset,
+ while (zap_cursor_init(zc, dp->dp_meta_objset,
scn->scn_phys.scn_queue_obj),
- zap_cursor_retrieve(&zc, &za) == 0) {
+ zap_cursor_retrieve(zc, za) == 0) {
dsl_dataset_t *ds;
uint64_t dsobj;
- dsobj = strtonum(za.za_name, NULL);
+ dsobj = strtonum(za->za_name, NULL);
VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
scn->scn_phys.scn_queue_obj, dsobj, tx));
/* Set up min/max txg */
VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
- if (za.za_first_integer != 0) {
+ if (za->za_first_integer != 0) {
scn->scn_phys.scn_cur_min_txg =
MAX(scn->scn_phys.scn_min_txg,
- za.za_first_integer);
+ za->za_first_integer);
} else {
scn->scn_phys.scn_cur_min_txg =
MAX(scn->scn_phys.scn_min_txg,
@@ -1404,11 +1406,14 @@ dsl_scan_visit(dsl_scan_t *scn, dmu_tx_t *tx)
dsl_dataset_rele(ds, FTAG);
dsl_scan_visitds(scn, dsobj, tx);
- zap_cursor_fini(&zc);
+ zap_cursor_fini(zc);
if (scn->scn_pausing)
- return;
+ goto out;
}
- zap_cursor_fini(&zc);
+ zap_cursor_fini(zc);
+out:
+ kmem_free(za, sizeof(zap_attribute_t));
+ kmem_free(zc, sizeof(zap_cursor_t));
}
static int