btrfs: introduce alloc_chunk_ctl

Introduce "struct alloc_chunk_ctl" to wrap needed parameters for the
chunk allocation.  This will be used to split __btrfs_alloc_chunk() into
smaller functions.

This commit folds a number of local variables in __btrfs_alloc_chunk()
into one "struct alloc_chunk_ctl ctl". There is no functional change.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/volumes.c

@@ -4780,6 +4780,36 @@ static void check_raid1c34_incompat_flag(struct btrfs_fs_info *info, u64 type)
 	btrfs_set_fs_incompat(info, RAID1C34);
 }
 
+/*
+ * Structure used internally for __btrfs_alloc_chunk() function.
+ * Wraps needed parameters.
+ */
+struct alloc_chunk_ctl {
+	u64 start;
+	u64 type;
+	/* Total number of stripes to allocate */
+	int num_stripes;
+	/* sub_stripes info for map */
+	int sub_stripes;
+	/* Stripes per device */
+	int dev_stripes;
+	/* Maximum number of devices to use */
+	int devs_max;
+	/* Minimum number of devices to use */
+	int devs_min;
+	/* ndevs has to be a multiple of this */
+	int devs_increment;
+	/* Number of copies */
+	int ncopies;
+	/* Number of stripes worth of bytes to store parity information */
+	int nparity;
+	u64 max_stripe_size;
+	u64 max_chunk_size;
+	u64 stripe_size;
+	u64 chunk_size;
+	int ndevs;
+};
+
 static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 			       u64 start, u64 type)
 {
@@ -4790,23 +4820,11 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 	struct extent_map_tree *em_tree;
 	struct extent_map *em;
 	struct btrfs_device_info *devices_info = NULL;
+	struct alloc_chunk_ctl ctl;
 	u64 total_avail;
-	int num_stripes;	/* total number of stripes to allocate */
 	int data_stripes;	/* number of stripes that count for
 				   block group size */
-	int sub_stripes;	/* sub_stripes info for map */
-	int dev_stripes;	/* stripes per dev */
-	int devs_max;		/* max devs to use */
-	int devs_min;		/* min devs needed */
-	int devs_increment;	/* ndevs has to be a multiple of this */
-	int ncopies;		/* how many copies to data has */
-	int nparity;		/* number of stripes worth of bytes to
-				   store parity information */
 	int ret;
-	u64 max_stripe_size;
-	u64 max_chunk_size;
-	u64 stripe_size;
-	u64 chunk_size;
 	int ndevs;
 	int i;
 	int j;
@@ -4823,32 +4841,36 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 		return -ENOSPC;
 	}
 
+	ctl.start = start;
+	ctl.type = type;
+
 	index = btrfs_bg_flags_to_raid_index(type);
 
-	sub_stripes = btrfs_raid_array[index].sub_stripes;
-	dev_stripes = btrfs_raid_array[index].dev_stripes;
-	devs_max = btrfs_raid_array[index].devs_max;
-	if (!devs_max)
-		devs_max = BTRFS_MAX_DEVS(info);
-	devs_min = btrfs_raid_array[index].devs_min;
-	devs_increment = btrfs_raid_array[index].devs_increment;
-	ncopies = btrfs_raid_array[index].ncopies;
-	nparity = btrfs_raid_array[index].nparity;
+	ctl.sub_stripes = btrfs_raid_array[index].sub_stripes;
+	ctl.dev_stripes = btrfs_raid_array[index].dev_stripes;
+	ctl.devs_max = btrfs_raid_array[index].devs_max;
+	if (!ctl.devs_max)
+		ctl.devs_max = BTRFS_MAX_DEVS(info);
+	ctl.devs_min = btrfs_raid_array[index].devs_min;
+	ctl.devs_increment = btrfs_raid_array[index].devs_increment;
+	ctl.ncopies = btrfs_raid_array[index].ncopies;
+	ctl.nparity = btrfs_raid_array[index].nparity;
 
 	if (type & BTRFS_BLOCK_GROUP_DATA) {
-		max_stripe_size = SZ_1G;
-		max_chunk_size = BTRFS_MAX_DATA_CHUNK_SIZE;
+		ctl.max_stripe_size = SZ_1G;
+		ctl.max_chunk_size = BTRFS_MAX_DATA_CHUNK_SIZE;
 	} else if (type & BTRFS_BLOCK_GROUP_METADATA) {
 		/* for larger filesystems, use larger metadata chunks */
 		if (fs_devices->total_rw_bytes > 50ULL * SZ_1G)
-			max_stripe_size = SZ_1G;
+			ctl.max_stripe_size = SZ_1G;
 		else
-			max_stripe_size = SZ_256M;
-		max_chunk_size = max_stripe_size;
+			ctl.max_stripe_size = SZ_256M;
+		ctl.max_chunk_size = ctl.max_stripe_size;
 	} else if (type & BTRFS_BLOCK_GROUP_SYSTEM) {
-		max_stripe_size = SZ_32M;
-		max_chunk_size = 2 * max_stripe_size;
-		devs_max = min_t(int, devs_max, BTRFS_MAX_DEVS_SYS_CHUNK);
+		ctl.max_stripe_size = SZ_32M;
+		ctl.max_chunk_size = 2 * ctl.max_stripe_size;
+		ctl.devs_max = min_t(int, ctl.devs_max,
+				      BTRFS_MAX_DEVS_SYS_CHUNK);
 	} else {
 		btrfs_err(info, "invalid chunk type 0x%llx requested",
 		       type);
@@ -4856,8 +4878,8 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 	}
 
 	/* We don't want a chunk larger than 10% of writable space */
-	max_chunk_size = min(div_factor(fs_devices->total_rw_bytes, 1),
-			     max_chunk_size);
+	ctl.max_chunk_size = min(div_factor(fs_devices->total_rw_bytes, 1),
+				  ctl.max_chunk_size);
 
 	devices_info = kcalloc(fs_devices->rw_devices, sizeof(*devices_info),
 			       GFP_NOFS);
@@ -4893,21 +4915,21 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 		if (total_avail == 0)
 			continue;
 
-		ret = find_free_dev_extent(device,
-					   max_stripe_size * dev_stripes,
-					   &dev_offset, &max_avail);
+		ret = find_free_dev_extent(
+			device, ctl.max_stripe_size * ctl.dev_stripes,
+			&dev_offset, &max_avail);
 		if (ret && ret != -ENOSPC)
 			goto error;
 
 		if (ret == 0)
-			max_avail = max_stripe_size * dev_stripes;
+			max_avail = ctl.max_stripe_size * ctl.dev_stripes;
 
-		if (max_avail < BTRFS_STRIPE_LEN * dev_stripes) {
+		if (max_avail < BTRFS_STRIPE_LEN * ctl.dev_stripes) {
 			if (btrfs_test_opt(info, ENOSPC_DEBUG))
 				btrfs_debug(info,
 			"%s: devid %llu has no free space, have=%llu want=%u",
 					    __func__, device->devid, max_avail,
-					    BTRFS_STRIPE_LEN * dev_stripes);
+					    BTRFS_STRIPE_LEN * ctl.dev_stripes);
 			continue;
 		}
 
@@ -4922,30 +4944,31 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 		devices_info[ndevs].dev = device;
 		++ndevs;
 	}
+	ctl.ndevs = ndevs;
 
 	/*
 	 * now sort the devices by hole size / available space
 	 */
-	sort(devices_info, ndevs, sizeof(struct btrfs_device_info),
+	sort(devices_info, ctl.ndevs, sizeof(struct btrfs_device_info),
 	     btrfs_cmp_device_info, NULL);
 
 	/*
 	 * Round down to number of usable stripes, devs_increment can be any
 	 * number so we can't use round_down()
 	 */
-	ndevs -= ndevs % devs_increment;
+	ctl.ndevs -= ctl.ndevs % ctl.devs_increment;
 
-	if (ndevs < devs_min) {
+	if (ctl.ndevs < ctl.devs_min) {
 		ret = -ENOSPC;
 		if (btrfs_test_opt(info, ENOSPC_DEBUG)) {
 			btrfs_debug(info,
 	"%s: not enough devices with free space: have=%d minimum required=%d",
-				    __func__, ndevs, devs_min);
+				    __func__, ctl.ndevs, ctl.devs_min);
 		}
 		goto error;
 	}
 
-	ndevs = min(ndevs, devs_max);
+	ctl.ndevs = min(ctl.ndevs, ctl.devs_max);
 
 	/*
 	 * The primary goal is to maximize the number of stripes, so use as
@@ -4954,14 +4977,15 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 	 * The DUP profile stores more than one stripe per device, the
 	 * max_avail is the total size so we have to adjust.
 	 */
-	stripe_size = div_u64(devices_info[ndevs - 1].max_avail, dev_stripes);
-	num_stripes = ndevs * dev_stripes;
+	ctl.stripe_size = div_u64(devices_info[ctl.ndevs - 1].max_avail,
+				   ctl.dev_stripes);
+	ctl.num_stripes = ctl.ndevs * ctl.dev_stripes;
 
 	/*
 	 * this will have to be fixed for RAID1 and RAID10 over
 	 * more drives
 	 */
-	data_stripes = (num_stripes - nparity) / ncopies;
+	data_stripes = (ctl.num_stripes - ctl.nparity) / ctl.ncopies;
 
 	/*
 	 * Use the number of data stripes to figure out how big this chunk
@@ -4969,44 +4993,46 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 	 * and compare that answer with the max chunk size. If it's higher,
 	 * we try to reduce stripe_size.
 	 */
-	if (stripe_size * data_stripes > max_chunk_size) {
+	if (ctl.stripe_size * data_stripes > ctl.max_chunk_size) {
 		/*
 		 * Reduce stripe_size, round it up to a 16MB boundary again and
 		 * then use it, unless it ends up being even bigger than the
 		 * previous value we had already.
 		 */
-		stripe_size = min(round_up(div_u64(max_chunk_size,
-						   data_stripes), SZ_16M),
-				  stripe_size);
+		ctl.stripe_size =
+			min(round_up(div_u64(ctl.max_chunk_size, data_stripes),
+				     SZ_16M),
+			    ctl.stripe_size);
 	}
 
 	/* align to BTRFS_STRIPE_LEN */
-	stripe_size = round_down(stripe_size, BTRFS_STRIPE_LEN);
+	ctl.stripe_size = round_down(ctl.stripe_size, BTRFS_STRIPE_LEN);
 
-	map = kmalloc(map_lookup_size(num_stripes), GFP_NOFS);
+	map = kmalloc(map_lookup_size(ctl.num_stripes), GFP_NOFS);
 	if (!map) {
 		ret = -ENOMEM;
 		goto error;
 	}
-	map->num_stripes = num_stripes;
 
-	for (i = 0; i < ndevs; ++i) {
-		for (j = 0; j < dev_stripes; ++j) {
-			int s = i * dev_stripes + j;
+	map->num_stripes = ctl.num_stripes;
+
+	for (i = 0; i < ctl.ndevs; ++i) {
+		for (j = 0; j < ctl.dev_stripes; ++j) {
+			int s = i * ctl.dev_stripes + j;
 			map->stripes[s].dev = devices_info[i].dev;
 			map->stripes[s].physical = devices_info[i].dev_offset +
-						   j * stripe_size;
+						   j * ctl.stripe_size;
 		}
 	}
 	map->stripe_len = BTRFS_STRIPE_LEN;
 	map->io_align = BTRFS_STRIPE_LEN;
 	map->io_width = BTRFS_STRIPE_LEN;
 	map->type = type;
-	map->sub_stripes = sub_stripes;
+	map->sub_stripes = ctl.sub_stripes;
 
-	chunk_size = stripe_size * data_stripes;
+	ctl.chunk_size = ctl.stripe_size * data_stripes;
 
-	trace_btrfs_chunk_alloc(info, map, start, chunk_size);
+	trace_btrfs_chunk_alloc(info, map, start, ctl.chunk_size);
 
 	em = alloc_extent_map();
 	if (!em) {
@@ -5017,10 +5043,10 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 	set_bit(EXTENT_FLAG_FS_MAPPING, &em->flags);
 	em->map_lookup = map;
 	em->start = start;
-	em->len = chunk_size;
+	em->len = ctl.chunk_size;
 	em->block_start = 0;
 	em->block_len = em->len;
-	em->orig_block_len = stripe_size;
+	em->orig_block_len = ctl.stripe_size;
 
 	em_tree = &info->mapping_tree;
 	write_lock(&em_tree->lock);
@@ -5032,20 +5058,22 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 	}
 	write_unlock(&em_tree->lock);
 
-	ret = btrfs_make_block_group(trans, 0, type, start, chunk_size);
+	ret = btrfs_make_block_group(trans, 0, type, start, ctl.chunk_size);
 	if (ret)
 		goto error_del_extent;
 
 	for (i = 0; i < map->num_stripes; i++) {
 		struct btrfs_device *dev = map->stripes[i].dev;
 
-		btrfs_device_set_bytes_used(dev, dev->bytes_used + stripe_size);
+		btrfs_device_set_bytes_used(dev,
+					    dev->bytes_used + ctl.stripe_size);
 		if (list_empty(&dev->post_commit_list))
 			list_add_tail(&dev->post_commit_list,
 				      &trans->transaction->dev_update_list);
 	}
 
-	atomic64_sub(stripe_size * map->num_stripes, &info->free_chunk_space);
+	atomic64_sub(ctl.stripe_size * map->num_stripes,
+		     &info->free_chunk_space);
 
 	free_extent_map(em);
 	check_raid56_incompat_flag(info, type);