4951 ZFS administrative commands should use reserved space, not fail …

…with ENOSPC (fix call)

Approved by: Christopher Siden <christopher.siden@delphix.com>

usr/src/uts/common/fs/zfs/dsl_pool.c

@@ -612,17 +612,12 @@ dsl_pool_adjustedsize(dsl_pool_t *dp, boolean_t netfree)
 	uint64_t space, resv;
 
 	/*
-	 * Reserve about 1.6% (1/64), or at least 32MB, for allocation
-	 * efficiency.
-	 * XXX The intent log is not accounted for, so it must fit
-	 * within this slop.
-	 *
 	 * If we're trying to assess whether it's OK to do a free,
 	 * cut the reservation in half to allow forward progress
 	 * (e.g. make it possible to rm(1) files from a full pool).
 	 */
 	space = spa_get_dspace(dp->dp_spa);
-	resv = MAX(space >> 6, SPA_MINDEVSIZE >> 1);
+	resv = spa_get_slop_space(dp->dp_spa);
 	if (netfree)
 		resv >>= 1;
 

usr/src/uts/common/fs/zfs/sys/spa.h

@@ -739,6 +739,7 @@ extern spa_load_state_t spa_load_state(spa_t *spa);
 extern uint64_t spa_freeze_txg(spa_t *spa);
 extern uint64_t spa_get_asize(spa_t *spa, uint64_t lsize);
 extern uint64_t spa_get_dspace(spa_t *spa);
+extern uint64_t spa_get_slop_space(spa_t *spa);
 extern void spa_update_dspace(spa_t *spa);
 extern uint64_t spa_version(spa_t *spa);
 extern boolean_t spa_deflate(spa_t *spa);