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Tinker with slop space accounting with dedup 

* Tinker with slop space accounting with dedup

Do not include the deduplicated space usage in the slop space
reservation, it leads to surprising outcomes.

* Update spa_dedup_dspace sometimes

Sometimes, we get into spa_get_slop_space() with
spa_dedup_dspace=~0ULL, AKA "unset", while spa_dspace is correctly set.

So call the code to update it before we use it if we hit that case.

Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Mark Maybee <mark.maybee@delphix.com>
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
Closes #12271
This commit is contained in:
Rich Ercolani 2021-07-13 11:47:57 -04:00 committed by Tony Hutter
parent 45305a067f
commit 960a5a557b
2 changed files with 17 additions and 3 deletions
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2
module/zfs/ddt.c
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@ -503,7 +503,7 @@ ddt_get_dedup_histogram(spa_t *spa, ddt_histogram_t *ddh)
{
for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
ddt_t *ddt = spa->spa_ddt[c];
for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
for (enum ddt_type type = 0; type < DDT_TYPES && ddt; type++) {
for (enum ddt_class class = 0; class < DDT_CLASSES;
class++) {
ddt_histogram_add(ddh,

18
module/zfs/spa_misc.c
View File

@ -1787,8 +1787,22 @@ spa_get_worst_case_asize(spa_t *spa, uint64_t lsize)
uint64_t
spa_get_slop_space(spa_t *spa)
{
uint64_t space = spa_get_dspace(spa);
uint64_t slop = MIN(space >> spa_slop_shift, spa_max_slop);
uint64_t space = 0;
uint64_t slop = 0;
/*
* Make sure spa_dedup_dspace has been set.
*/
if (spa->spa_dedup_dspace == ~0ULL)
spa_update_dspace(spa);
/*
* spa_get_dspace() includes the space only logically "used" by
* deduplicated data, so since it's not useful to reserve more
* space with more deduplicated data, we subtract that out here.
*/
space = spa_get_dspace(spa) - spa->spa_dedup_dspace;
slop = MIN(space >> spa_slop_shift, spa_max_slop);
/*
* Subtract the embedded log space, but no more than half the (3.2%)