Drop KMC_NOEMERGENCY

This is not implemented. If it were implemented, using it would risk
deadlocks on pre-3.18 kernels. Lets just drop it.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Michael Niewöhner <foss@mniewoehner.de>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Closes openzfs#9119

include/spl/sys/kmem_cache.h

@@ -45,7 +45,6 @@ enum {
 	KMC_BIT_VMEM		= 6,	/* Use vmem cache */
 	KMC_BIT_SLAB		= 7,	/* Use Linux slab cache */
 	KMC_BIT_OFFSLAB		= 8,	/* Objects not on slab */
-	KMC_BIT_NOEMERGENCY	= 9,	/* Disable emergency objects */
 	KMC_BIT_DEADLOCKED	= 14,	/* Deadlock detected */
 	KMC_BIT_GROWING		= 15,	/* Growing in progress */
 	KMC_BIT_REAPING		= 16,	/* Reaping in progress */
@@ -73,7 +72,6 @@ typedef enum kmem_cbrc {
 #define	KMC_VMEM		(1 << KMC_BIT_VMEM)
 #define	KMC_SLAB		(1 << KMC_BIT_SLAB)
 #define	KMC_OFFSLAB		(1 << KMC_BIT_OFFSLAB)
-#define	KMC_NOEMERGENCY		(1 << KMC_BIT_NOEMERGENCY)
 #define	KMC_DEADLOCKED		(1 << KMC_BIT_DEADLOCKED)
 #define	KMC_GROWING		(1 << KMC_BIT_GROWING)
 #define	KMC_REAPING		(1 << KMC_BIT_REAPING)

module/spl/spl-zlib.c

@@ -202,7 +202,7 @@ spl_zlib_init(void)
 	zlib_workspace_cache = kmem_cache_create(
 	    "spl_zlib_workspace_cache",
 	    size, 0, NULL, NULL, NULL, NULL, NULL,
-	    KMC_VMEM | KMC_NOEMERGENCY);
+	    KMC_VMEM);
 	if (!zlib_workspace_cache)
 		return (1);