[6.12] Track btrfs patches

fs/btrfs/Kconfig

@@ -78,6 +78,15 @@ config BTRFS_ASSERT
 
 	  If unsure, say N.
 
+config BTRFS_EXPERIMENTAL
+	bool "Btrfs experimental features"
+	depends on BTRFS_FS
+	help
+	  Enable experimental features.  These features may not be stable enough
+	  for end users.  This is meant for btrfs developers only.
+
+	  If unsure, say N.
+
 config BTRFS_FS_REF_VERIFY
 	bool "Btrfs with the ref verify tool compiled in"
 	depends on BTRFS_FS

fs/btrfs/backref.c

@@ -1127,6 +1127,7 @@ static int add_inline_refs(struct btrfs_backref_walk_ctx *ctx,
 		if (ret)
 			return ret;
 		ptr += btrfs_extent_inline_ref_size(type);
+		cond_resched();
 	}
 
 	return 0;
@@ -1230,7 +1231,7 @@ static int add_keyed_refs(struct btrfs_backref_walk_ctx *ctx,
 		}
 		if (ret)
 			return ret;
-
+		cond_resched();
 	}
 
 	return ret;

fs/btrfs/bio.c

@@ -450,6 +450,14 @@ static void btrfs_submit_dev_bio(struct btrfs_device *dev, struct bio *bio)
 		(unsigned long)dev->bdev->bd_dev, btrfs_dev_name(dev),
 		dev->devid, bio->bi_iter.bi_size);
 
+	/*
+	 * Track reads if tracking is enabled; ignore I/O operations before
+	 * fully initialized.
+	 */
+	if (dev->fs_devices->fs_stats && bio_op(bio) == REQ_OP_READ && dev->fs_info)
+		percpu_counter_add(&dev->fs_info->stats_read_blocks,
+				   bio->bi_iter.bi_size >> dev->fs_info->sectorsize_bits);
+
 	if (bio->bi_opf & REQ_BTRFS_CGROUP_PUNT)
 		blkcg_punt_bio_submit(bio);
 	else

fs/btrfs/disk-io.c

@@ -1259,6 +1259,7 @@ void btrfs_free_fs_info(struct btrfs_fs_info *fs_info)
 {
 	struct percpu_counter *em_counter = &fs_info->evictable_extent_maps;
 
+	percpu_counter_destroy(&fs_info->stats_read_blocks);
 	percpu_counter_destroy(&fs_info->dirty_metadata_bytes);
 	percpu_counter_destroy(&fs_info->delalloc_bytes);
 	percpu_counter_destroy(&fs_info->ordered_bytes);
@@ -2858,6 +2859,10 @@ static int init_mount_fs_info(struct btrfs_fs_info *fs_info, struct super_block
 	if (ret)
 		return ret;
 
+	ret = percpu_counter_init(&fs_info->stats_read_blocks, 0, GFP_KERNEL);
+	if (ret)
+		return ret;
+
 	fs_info->dirty_metadata_batch = PAGE_SIZE *
 					(1 + ilog2(nr_cpu_ids));
 
@@ -3324,6 +3329,7 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 	fs_info->sectors_per_page = (PAGE_SIZE >> fs_info->sectorsize_bits);
 	fs_info->csums_per_leaf = BTRFS_MAX_ITEM_SIZE(fs_info) / fs_info->csum_size;
 	fs_info->stripesize = stripesize;
+	fs_info->fs_devices->fs_info = fs_info;
 
 	/*
 	 * Handle the space caching options appropriately now that we have the

fs/btrfs/fs.h

@@ -625,6 +625,9 @@ struct btrfs_fs_info {
 	struct kobject *qgroups_kobj;
 	struct kobject *discard_kobj;
 
+	/* Track the number of blocks (sectors) read by the filesystem. */
+	struct percpu_counter stats_read_blocks;
+
 	/* Used to keep from writing metadata until there is a nice batch */
 	struct percpu_counter dirty_metadata_bytes;
 	struct percpu_counter delalloc_bytes;

fs/btrfs/super.c

@@ -2468,6 +2468,9 @@ static __cold void btrfs_interface_exit(void)
 static int __init btrfs_print_mod_info(void)
 {
 	static const char options[] = ""
+#ifdef CONFIG_BTRFS_EXPERIMENTAL
+			", experimental=on"
+#endif
 #ifdef CONFIG_BTRFS_DEBUG
 			", debug=on"
 #endif
@@ -2488,7 +2491,17 @@ static int __init btrfs_print_mod_info(void)
 			", fsverity=no"
 #endif
 			;
+
+#ifdef CONFIG_BTRFS_EXPERIMENTAL
+	if (btrfs_get_mod_read_policy() == NULL)
+		pr_info("Btrfs loaded%s\n", options);
+	else
+		pr_info("Btrfs loaded%s, read_policy=%s\n",
+			 options, btrfs_get_mod_read_policy());
+#else
 	pr_info("Btrfs loaded%s\n", options);
+#endif
+
 	return 0;
 }
 
@@ -2546,6 +2559,11 @@ static const struct init_sequence mod_init_seq[] = {
 	}, {
 		.init_func = extent_map_init,
 		.exit_func = extent_map_exit,
+#ifdef CONFIG_BTRFS_EXPERIMENTAL
+	}, {
+		.init_func = btrfs_read_policy_init,
+		.exit_func = NULL,
+#endif
 	}, {
 		.init_func = ordered_data_init,
 		.exit_func = ordered_data_exit,