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Reduce stack usage of dsl_dir_tempreserve_impl 

Buildbots and zfs-tests regularly see 7 kilobytes of stack
usage with this function. Convert self-calls to iterations

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: DHE <git@dehacked.net>
Closes #6219
This commit is contained in:
DeHackEd 2017-06-12 14:41:03 -04:00 committed by Brian Behlendorf
parent 851aa99c89
commit 419c80e6dc
1 changed files with 19 additions and 6 deletions
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25
module/zfs/dsl_dir.c
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@ -1119,11 +1119,16 @@ dsl_dir_tempreserve_impl(dsl_dir_t *dd, uint64_t asize, boolean_t netfree,
boolean_t ignorequota, list_t *tr_list,
dmu_tx_t *tx, boolean_t first)
{
uint64_t txg = tx->tx_txg;
uint64_t txg;
uint64_t quota;
struct tempreserve *tr;
int retval = EDQUOT;
uint64_t ref_rsrv = 0;
int retval;
uint64_t ref_rsrv;
top_of_function:
txg = tx->tx_txg;
retval = EDQUOT;
ref_rsrv = 0;
ASSERT3U(txg, !=, 0);
ASSERT3S(asize, >, 0);
@ -1220,10 +1225,18 @@ dsl_dir_tempreserve_impl(dsl_dir_t *dd, uint64_t asize, boolean_t netfree,
/* see if it's OK with our parent */
if (dd->dd_parent != NULL && parent_rsrv != 0) {
boolean_t ismos = (dsl_dir_phys(dd)->dd_head_dataset_obj == 0);
/*
* Recurse on our parent without recursion. This has been
* observed to be potentially large stack usage even within
* the test suite. Largest seen stack was 7632 bytes on linux.
*/
dd = dd->dd_parent;
asize = parent_rsrv;
ignorequota = (dsl_dir_phys(dd)->dd_head_dataset_obj == 0);
first = B_FALSE;
goto top_of_function;
return (dsl_dir_tempreserve_impl(dd->dd_parent,
parent_rsrv, netfree, ismos, tr_list, tx, B_FALSE));
} else {
return (0);
}