Code cleanups

- Allocate ve_search on the stack, so we avoid allocating memory for
  every I/O even if the VDEV cache is disabled.
- Reduce lock scope.
- Avoid locking in vdev_cache_read() when the VDEV cache is disabled.
- Sort file names properly.
- Correct comment.

Reviewed-by: Allan Jude <allan@klarasystems.com>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Pawel Jakub Dawidek <pawel@dawidek.net>
Closes #12749

lib/libzpool/Makefile.am

@@ -58,8 +58,8 @@ KERNEL_C = \
 	bplist.c \
 	bpobj.c \
 	bptree.c \
-	btree.c \
 	bqueue.c \
+	btree.c \
 	cityhash.c \
 	dbuf.c \
 	dbuf_stats.c \
@@ -78,23 +78,23 @@ KERNEL_C = \
 	dnode.c \
 	dnode_sync.c \
 	dsl_bookmark.c \
+	dsl_crypt.c \
 	dsl_dataset.c \
 	dsl_deadlist.c \
 	dsl_deleg.c \
+	dsl_destroy.c \
 	dsl_dir.c \
-	dsl_crypt.c \
 	dsl_pool.c \
 	dsl_prop.c \
 	dsl_scan.c \
 	dsl_synctask.c \
-	dsl_destroy.c \
 	dsl_userhold.c \
 	edonr_zfs.c \
-	hkdf.c \
 	fm.c \
 	gzip.c \
-	lzjb.c \
+	hkdf.c \
 	lz4.c \
+	lzjb.c \
 	metaslab.c \
 	mmp.c \
 	multilist.c \
@@ -117,8 +117,8 @@ KERNEL_C = \
 	spa_stats.c \
 	space_map.c \
 	space_reftree.c \
-	txg.c \
 	trace.c \
+	txg.c \
 	uberblock.c \
 	unique.c \
 	vdev.c \
@@ -126,8 +126,8 @@ KERNEL_C = \
 	vdev_draid.c \
 	vdev_draid_rand.c \
 	vdev_file.c \
-	vdev_indirect_births.c \
 	vdev_indirect.c \
+	vdev_indirect_births.c \
 	vdev_indirect_mapping.c \
 	vdev_initialize.c \
 	vdev_label.c \
@@ -135,16 +135,16 @@ KERNEL_C = \
 	vdev_missing.c \
 	vdev_queue.c \
 	vdev_raidz.c \
+	vdev_raidz_math.c \
 	vdev_raidz_math_aarch64_neon.c \
 	vdev_raidz_math_aarch64_neonx2.c \
 	vdev_raidz_math_avx2.c \
 	vdev_raidz_math_avx512bw.c \
 	vdev_raidz_math_avx512f.c \
-	vdev_raidz_math.c \
+	vdev_raidz_math_powerpc_altivec.c \
 	vdev_raidz_math_scalar.c \
 	vdev_raidz_math_sse2.c \
 	vdev_raidz_math_ssse3.c \
-	vdev_raidz_math_powerpc_altivec.c \
 	vdev_rebuild.c \
 	vdev_removal.c \
 	vdev_root.c \
@@ -165,9 +165,9 @@ KERNEL_C = \
 	zfs_fuid.c \
 	zfs_racct.c \
 	zfs_sa.c \
-	zfs_znode.c \
 	zfs_ratelimit.c \
 	zfs_rlock.c \
+	zfs_znode.c \
 	zil.c \
 	zio.c \
 	zio_checksum.c \

module/Makefile.bsd

@@ -268,12 +268,12 @@ SRCS+=	abd.c \
 	vdev_raidz.c \
 	vdev_raidz_math.c \
 	vdev_raidz_math_scalar.c \
-	vdev_rebuild.c \
 	vdev_raidz_math_avx2.c \
 	vdev_raidz_math_avx512bw.c \
 	vdev_raidz_math_avx512f.c \
 	vdev_raidz_math_sse2.c \
 	vdev_raidz_math_ssse3.c \
+	vdev_rebuild.c \
 	vdev_removal.c \
 	vdev_root.c \
 	vdev_trim.c \

module/zfs/dbuf.c

@@ -1997,8 +1997,8 @@ dbuf_free_range(dnode_t *dn, uint64_t start_blkid, uint64_t end_blkid,
 		mutex_exit(&db->db_mtx);
 	}
 
-	kmem_free(db_search, sizeof (dmu_buf_impl_t));
 	mutex_exit(&dn->dn_dbufs_mtx);
+	kmem_free(db_search, sizeof (dmu_buf_impl_t));
 }
 
 void

module/zfs/vdev_cache.c

@@ -251,13 +251,16 @@ boolean_t
 vdev_cache_read(zio_t *zio)
 {
 	vdev_cache_t *vc = &zio->io_vd->vdev_cache;
-	vdev_cache_entry_t *ve, *ve_search;
+	vdev_cache_entry_t *ve, ve_search;
 	uint64_t cache_offset = P2ALIGN(zio->io_offset, VCBS);
 	zio_t *fio;
 	uint64_t cache_phase __maybe_unused = P2PHASE(zio->io_offset, VCBS);
 
 	ASSERT3U(zio->io_type, ==, ZIO_TYPE_READ);
 
+	if (zfs_vdev_cache_size == 0)
+		return (B_FALSE);
+
 	if (zio->io_flags & ZIO_FLAG_DONT_CACHE)
 		return (B_FALSE);
 
@@ -274,10 +277,8 @@ vdev_cache_read(zio_t *zio)
 
 	mutex_enter(&vc->vc_lock);
 
-	ve_search = kmem_alloc(sizeof (vdev_cache_entry_t), KM_SLEEP);
+	ve_search.ve_offset = cache_offset;
-	ve_search->ve_offset = cache_offset;
+	ve = avl_find(&vc->vc_offset_tree, &ve_search, NULL);
-	ve = avl_find(&vc->vc_offset_tree, ve_search, NULL);
-	kmem_free(ve_search, sizeof (vdev_cache_entry_t));
 
 	if (ve != NULL) {
 		if (ve->ve_missed_update) {

module/zfs/vdev_queue.c

@@ -408,7 +408,7 @@ vdev_queue_class_max_active(spa_t *spa, vdev_queue_t *vq, zio_priority_t p)
 }
 
 /*
- * Return the i/o class to issue from, or ZIO_PRIORITY_MAX_QUEUEABLE if
+ * Return the i/o class to issue from, or ZIO_PRIORITY_NUM_QUEUEABLE if
  * there is no eligible class.
  */
 static zio_priority_t