btrfs: split out CONFIG_BTRFS_EXPERIMENTAL from CONFIG_BTRFS_DEBUG

Currently CONFIG_BTRFS_EXPERIMENTAL is not only for the extra debugging
output, but also for experimental features.

This is not ideal to distinguish planned but not yet stable features
from those purely designed for debugging.

This patch splits the following features into CONFIG_BTRFS_EXPERIMENTAL:

- Extent map shrinker
  This seems to be the first one to exit experimental.

- Extent tree v2
  This seems to be the last one to graduate from experimental.

- Raid stripe tree
- Csum offload mode
- Send protocol v3

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/Kconfig

@@ -78,6 +78,32 @@ config BTRFS_ASSERT
 
 	  If unsure, say N.
 
+config BTRFS_EXPERIMENTAL
+	bool "Btrfs experimental features"
+	depends on BTRFS_FS
+	default n
+	help
+	  Enable experimental features.  These features may not be stable enough
+	  for end users.  This is meant for btrfs developers or users who wish
+	  to test the functionality and report problems.
+
+	  Current list:
+
+	  - extent map shrinker - performance problems with too frequent shrinks
+
+	  - send stream protocol v3 - fs-verity support
+
+	  - checksum offload mode - sysfs knob to affect when checksums are
+	                            calculated (at IO time, or in a thread)
+
+	  - raid-stripe-tree - additional mapping of extents to devices to
+			       support RAID1* profiles on zoned devices,
+			       RAID56 not yet supported
+
+	  - extent tree v2 - complex rework of extent tracking
+
+	  If unsure, say N.
+
 config BTRFS_FS_REF_VERIFY
 	bool "Btrfs with the ref verify tool compiled in"
 	depends on BTRFS_FS

fs/btrfs/bio.c

@@ -587,7 +587,7 @@ static bool should_async_write(struct btrfs_bio *bbio)
 {
 	bool auto_csum_mode = true;
 
-#ifdef CONFIG_BTRFS_DEBUG
+#ifdef CONFIG_BTRFS_EXPERIMENTAL
 	struct btrfs_fs_devices *fs_devices = bbio->fs_info->fs_devices;
 	enum btrfs_offload_csum_mode csum_mode = READ_ONCE(fs_devices->offload_csum_mode);
 

fs/btrfs/fs.h

@@ -263,10 +263,10 @@ enum {
 	 BTRFS_FEATURE_INCOMPAT_ZONED		|	\
 	 BTRFS_FEATURE_INCOMPAT_SIMPLE_QUOTA)
 
-#ifdef CONFIG_BTRFS_DEBUG
+#ifdef CONFIG_BTRFS_EXPERIMENTAL
 	/*
 	 * Features under developmen like Extent tree v2 support is enabled
-	 * only under CONFIG_BTRFS_DEBUG.
+	 * only under CONFIG_BTRFS_EXPERIMENTAL
 	 */
 #define BTRFS_FEATURE_INCOMPAT_SUPP		\
 	(BTRFS_FEATURE_INCOMPAT_SUPP_STABLE |	\

fs/btrfs/send.h

@@ -16,7 +16,7 @@ struct btrfs_ioctl_send_args;
 
 #define BTRFS_SEND_STREAM_MAGIC "btrfs-stream"
 /* Conditional support for the upcoming protocol version. */
-#ifdef CONFIG_BTRFS_DEBUG
+#ifdef CONFIG_BTRFS_EXPERIMENTAL
 #define BTRFS_SEND_STREAM_VERSION 3
 #else
 #define BTRFS_SEND_STREAM_VERSION 2

fs/btrfs/super.c

@@ -2396,10 +2396,10 @@ static long btrfs_nr_cached_objects(struct super_block *sb, struct shrink_contro
 	trace_btrfs_extent_map_shrinker_count(fs_info, nr);
 
 	/*
-	 * Only report the real number for DEBUG builds, as there are reports of
-	 * serious performance degradation caused by too frequent shrinks.
+	 * Only report the real number for EXPERIMENTAL builds, as there are
+	 * reports of serious performance degradation caused by too frequent shrinks.
 	 */
-	if (IS_ENABLED(CONFIG_BTRFS_DEBUG))
+	if (IS_ENABLED(CONFIG_BTRFS_EXPERIMENTAL))
 		return nr;
 	return 0;
 }

fs/btrfs/sysfs.c

@@ -1390,7 +1390,7 @@ static ssize_t btrfs_bg_reclaim_threshold_store(struct kobject *kobj,
 BTRFS_ATTR_RW(, bg_reclaim_threshold, btrfs_bg_reclaim_threshold_show,
 	      btrfs_bg_reclaim_threshold_store);
 
-#ifdef CONFIG_BTRFS_DEBUG
+#ifdef CONFIG_BTRFS_EXPERIMENTAL
 static ssize_t btrfs_offload_csum_show(struct kobject *kobj,
 				       struct kobj_attribute *a, char *buf)
 {
@@ -1450,7 +1450,7 @@ static const struct attribute *btrfs_attrs[] = {
 	BTRFS_ATTR_PTR(, bg_reclaim_threshold),
 	BTRFS_ATTR_PTR(, commit_stats),
 	BTRFS_ATTR_PTR(, temp_fsid),
-#ifdef CONFIG_BTRFS_DEBUG
+#ifdef CONFIG_BTRFS_EXPERIMENTAL
 	BTRFS_ATTR_PTR(, offload_csum),
 #endif
 	NULL,

fs/btrfs/volumes.h

@@ -306,7 +306,7 @@ enum btrfs_read_policy {
 	BTRFS_NR_READ_POLICY,
 };
 
-#ifdef CONFIG_BTRFS_DEBUG
+#ifdef CONFIG_BTRFS_EXPERIMENTAL
 /*
  * Checksum mode - offload it to workqueues or do it synchronously in
  * btrfs_submit_chunk().
@@ -430,7 +430,7 @@ struct btrfs_fs_devices {
 	/* Policy used to read the mirrored stripes. */
 	enum btrfs_read_policy read_policy;
 
-#ifdef CONFIG_BTRFS_DEBUG
+#ifdef CONFIG_BTRFS_EXPERIMENTAL
 	/* Checksum mode - offload it or do it synchronously. */
 	enum btrfs_offload_csum_mode offload_csum_mode;
 #endif