[PATCH] btrfs: separate superblock items out of fs_info

[David Sterba <dsterba@suse.cz>]

fs_info has now ~9kb, more than fits into one page. This will cause
mount failure when memory is too fragmented. Top space consumers are
super block structures super_copy and super_for_commit, ~2.8kb each.
Allocate them dynamically. fs_info will be ~3.5kb. (measured on x86_64)

Add a wrapper for freeing fs_info.

Signed-off-by: David Sterba <dsterba@suse.cz>
---
 fs/btrfs/compression.c |    2 +-
 fs/btrfs/ctree.h       |   12 ++++++++++--
 fs/btrfs/disk-io.c     |   20 ++++++++++----------
 fs/btrfs/extent-tree.c |   14 +++++++-------
 fs/btrfs/file-item.c   |   12 ++++++------
 fs/btrfs/inode.c       |    2 +-
 fs/btrfs/ioctl.c       |    6 +++---
 fs/btrfs/super.c       |   20 ++++++++++++++------
 fs/btrfs/sysfs.c       |    6 +++---
 fs/btrfs/transaction.c |   10 +++++-----
 fs/btrfs/tree-log.c    |    4 ++--
 fs/btrfs/volumes.c     |   24 ++++++++++++------------
 12 files changed, 74 insertions(+), 58 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 41d1d7c..377d581 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -85,7 +85,7 @@ struct compressed_bio {
 static inline int compressed_bio_size(struct btrfs_root *root,
 				      unsigned long disk_size)
 {
-	u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
+	u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 	return sizeof(struct compressed_bio) +
 		((disk_size + root->sectorsize - 1) / root->sectorsize) *
 		csum_size;
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 3458b57..9d83ee4 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -928,8 +928,8 @@ struct btrfs_fs_info {
 	wait_queue_head_t transaction_blocked_wait;
 	wait_queue_head_t async_submit_wait;
 
-	struct btrfs_super_block super_copy;
-	struct btrfs_super_block super_for_commit;
+	struct btrfs_super_block *super_copy;
+	struct btrfs_super_block *super_for_commit;
 	struct block_device *__bdev;
 	struct super_block *sb;
 	struct inode *btree_inode;
@@ -2333,6 +2333,14 @@ int btrfs_drop_subtree(struct btrfs_trans_handle *trans,
 			struct btrfs_root *root,
 			struct extent_buffer *node,
 			struct extent_buffer *parent);
+
+static inline void free_fs_info(struct btrfs_fs_info *fs_info)
+{
+	kfree(fs_info->super_copy);
+	kfree(fs_info->super_for_commit);
+	kfree(fs_info);
+}
+
 /* root-item.c */
 int btrfs_find_root_ref(struct btrfs_root *tree_root,
 			struct btrfs_path *path,
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 8f1d44b..4fced6b 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -210,7 +210,7 @@ static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
 			   int verify)
 {
 	u16 csum_size =
-		btrfs_super_csum_size(&root->fs_info->super_copy);
+		btrfs_super_csum_size(root->fs_info->super_copy);
 	char *result = NULL;
 	unsigned long len;
 	unsigned long cur_len;
@@ -1763,14 +1763,14 @@ struct btrfs_root *open_ctree(struct super_block *sb,
 		goto fail_iput;
 	}
 
-	memcpy(&fs_info->super_copy, bh->b_data, sizeof(fs_info->super_copy));
-	memcpy(&fs_info->super_for_commit, &fs_info->super_copy,
-	       sizeof(fs_info->super_for_commit));
+	memcpy(fs_info->super_copy, bh->b_data, sizeof(*fs_info->super_copy));
+	memcpy(fs_info->super_for_commit, fs_info->super_copy,
+	       sizeof(*fs_info->super_for_commit));
 	brelse(bh);
 
-	memcpy(fs_info->fsid, fs_info->super_copy.fsid, BTRFS_FSID_SIZE);
+	memcpy(fs_info->fsid, fs_info->super_copy->fsid, BTRFS_FSID_SIZE);
 
-	disk_super = &fs_info->super_copy;
+	disk_super = fs_info->super_copy;
 	if (!btrfs_super_root(disk_super))
 		goto fail_iput;
 
@@ -2151,10 +2151,10 @@ fail_srcu:
 fail:
 	kfree(extent_root);
 	kfree(tree_root);
-	kfree(fs_info);
 	kfree(chunk_root);
 	kfree(dev_root);
 	kfree(csum_root);
+	free_fs_info(fs_info);
 	return ERR_PTR(err);
 }
 
@@ -2325,10 +2325,10 @@ int write_all_supers(struct btrfs_root *root, int max_mirrors)
 	int total_errors = 0;
 	u64 flags;
 
-	max_errors = btrfs_super_num_devices(&root->fs_info->super_copy) - 1;
+	max_errors = btrfs_super_num_devices(root->fs_info->super_copy) - 1;
 	do_barriers = !btrfs_test_opt(root, NOBARRIER);
 
-	sb = &root->fs_info->super_for_commit;
+	sb = root->fs_info->super_for_commit;
 	dev_item = &sb->dev_item;
 
 	mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
@@ -2601,7 +2601,7 @@ int close_ctree(struct btrfs_root *root)
 	kfree(fs_info->chunk_root);
 	kfree(fs_info->dev_root);
 	kfree(fs_info->csum_root);
-	kfree(fs_info);
+	free_fs_info(fs_info);
 
 	return 0;
 }
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index f619c3c..eb12ad6 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3258,7 +3258,7 @@ static int should_alloc_chunk(struct btrfs_root *root,
 	    alloc_bytes < div_factor(num_bytes, 8))
 		return 0;
 
-	thresh = btrfs_super_total_bytes(&root->fs_info->super_copy);
+	thresh = btrfs_super_total_bytes(root->fs_info->super_copy);
 	thresh = max_t(u64, 256 * 1024 * 1024, div_factor_fine(thresh, 5));
 
 	if (num_bytes > thresh && sinfo->bytes_used < div_factor(num_bytes, 3))
@@ -3789,7 +3789,7 @@ static u64 calc_global_metadata_size(struct btrfs_fs_info *fs_info)
 	u64 num_bytes;
 	u64 meta_used;
 	u64 data_used;
-	int csum_size = btrfs_super_csum_size(&fs_info->super_copy);
+	int csum_size = btrfs_super_csum_size(fs_info->super_copy);
 #if 0
 	/*
 	 * per tree used space accounting can be inaccuracy, so we
@@ -4109,12 +4109,12 @@ static int update_block_group(struct btrfs_trans_handle *trans,
 
 	/* block accounting for super block */
 	spin_lock(&info->delalloc_lock);
-	old_val = btrfs_super_bytes_used(&info->super_copy);
+	old_val = btrfs_super_bytes_used(info->super_copy);
 	if (alloc)
 		old_val += num_bytes;
 	else
 		old_val -= num_bytes;
-	btrfs_set_super_bytes_used(&info->super_copy, old_val);
+	btrfs_set_super_bytes_used(info->super_copy, old_val);
 	spin_unlock(&info->delalloc_lock);
 
 	while (total) {
@@ -4142,7 +4142,7 @@ static int update_block_group(struct btrfs_trans_handle *trans,
 		spin_lock(&cache->space_info->lock);
 		spin_lock(&cache->lock);
 
-		if (btrfs_super_cache_generation(&info->super_copy) != 0 &&
+		if (btrfs_super_cache_generation(info->super_copy) != 0 &&
 		    cache->disk_cache_state < BTRFS_DC_CLEAR)
 			cache->disk_cache_state = BTRFS_DC_CLEAR;
 
@@ -8458,9 +8458,9 @@ int btrfs_read_block_groups(struct btrfs_root *root)
 	if (!path)
 		return -ENOMEM;
 
-	cache_gen = btrfs_super_cache_generation(&root->fs_info->super_copy);
+	cache_gen = btrfs_super_cache_generation(root->fs_info->super_copy);
 	if (cache_gen != 0 &&
-	    btrfs_super_generation(&root->fs_info->super_copy) != cache_gen)
+	    btrfs_super_generation(root->fs_info->super_copy) != cache_gen)
 		need_clear = 1;
 	if (btrfs_test_opt(root, CLEAR_CACHE))
 		need_clear = 1;
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index a6a9d4e..0ae34c9 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -92,7 +92,7 @@ struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
 	struct extent_buffer *leaf;
 	u64 csum_offset = 0;
 	u16 csum_size =
-		btrfs_super_csum_size(&root->fs_info->super_copy);
+		btrfs_super_csum_size(root->fs_info->super_copy);
 	int csums_in_item;
 
 	file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
@@ -163,7 +163,7 @@ static int __btrfs_lookup_bio_sums(struct btrfs_root *root,
 	u64 disk_bytenr;
 	u32 diff;
 	u16 csum_size =
-		btrfs_super_csum_size(&root->fs_info->super_copy);
+		btrfs_super_csum_size(root->fs_info->super_copy);
 	int ret;
 	struct btrfs_path *path;
 	struct btrfs_csum_item *item = NULL;
@@ -278,7 +278,7 @@ int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 	int ret;
 	size_t size;
 	u64 csum_end;
-	u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
+	u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 
 	path = btrfs_alloc_path();
 	BUG_ON(!path);
@@ -474,7 +474,7 @@ static noinline int truncate_one_csum(struct btrfs_trans_handle *trans,
 {
 	struct extent_buffer *leaf;
 	u16 csum_size =
-		btrfs_super_csum_size(&root->fs_info->super_copy);
+		btrfs_super_csum_size(root->fs_info->super_copy);
 	u64 csum_end;
 	u64 end_byte = bytenr + len;
 	u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
@@ -533,7 +533,7 @@ int btrfs_del_csums(struct btrfs_trans_handle *trans,
 	struct extent_buffer *leaf;
 	int ret;
 	u16 csum_size =
-		btrfs_super_csum_size(&root->fs_info->super_copy);
+		btrfs_super_csum_size(root->fs_info->super_copy);
 	int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
 
 	root = root->fs_info->csum_root;
@@ -662,7 +662,7 @@ int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 	unsigned long map_len;
 	unsigned long map_start;
 	u16 csum_size =
-		btrfs_super_csum_size(&root->fs_info->super_copy);
+		btrfs_super_csum_size(root->fs_info->super_copy);
 
 	path = btrfs_alloc_path();
 	BUG_ON(!path);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 5cc64ab..d066401 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -812,7 +812,7 @@ static noinline int cow_file_range(struct inode *inode,
 	}
 
 	BUG_ON(disk_num_bytes >
-	       btrfs_super_total_bytes(&root->fs_info->super_copy));
+	       btrfs_super_total_bytes(root->fs_info->super_copy));
 
 	alloc_hint = get_extent_allocation_hint(inode, start, num_bytes);
 	btrfs_drop_extent_cache(inode, start, start + num_bytes - 1, 0);
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index cfc264f..8c88fa7 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -885,7 +885,7 @@ loop_unlock:
 		mutex_unlock(&inode->i_mutex);
 	}
 
-	disk_super = &root->fs_info->super_copy;
+	disk_super = root->fs_info->super_copy;
 	features = btrfs_super_incompat_flags(disk_super);
 	if (range->compress_type == BTRFS_COMPRESS_LZO) {
 		features |= BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO;
@@ -2238,7 +2238,7 @@ static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp)
 		return PTR_ERR(trans);
 	}
 
-	dir_id = btrfs_super_root_dir(&root->fs_info->super_copy);
+	dir_id = btrfs_super_root_dir(root->fs_info->super_copy);
 	di = btrfs_lookup_dir_item(trans, root->fs_info->tree_root, path,
 				   dir_id, "default", 7, 1);
 	if (IS_ERR_OR_NULL(di)) {
@@ -2254,7 +2254,7 @@ static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp)
 	btrfs_mark_buffer_dirty(path->nodes[0]);
 	btrfs_free_path(path);
 
-	disk_super = &root->fs_info->super_copy;
+	disk_super = root->fs_info->super_copy;
 	features = btrfs_super_incompat_flags(disk_super);
 	if (!(features & BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL)) {
 		features |= BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL;
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 58e7de9..10ff1c7 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -490,7 +490,7 @@ static struct dentry *get_default_root(struct super_block *sb,
 	 * will mount by default if we haven't been given a specific subvolume
 	 * to mount.
 	 */
-	dir_id = btrfs_super_root_dir(&root->fs_info->super_copy);
+	dir_id = btrfs_super_root_dir(root->fs_info->super_copy);
 	di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
 	if (IS_ERR(di))
 		return ERR_CAST(di);
@@ -717,7 +717,6 @@ static int btrfs_set_super(struct super_block *s, void *data)
 	return set_anon_super(s, data);
 }
 
-
 /*
  * Find a superblock for the given device / mount point.
  *
@@ -776,6 +775,15 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
 	fs_info->fs_devices = fs_devices;
 	tree_root->fs_info = fs_info;
 
+	fs_info->super_copy = kzalloc(sizeof(struct btrfs_super_block),
+			GFP_NOFS);
+	fs_info->super_for_commit = kzalloc(sizeof(struct btrfs_super_block),
+			GFP_NOFS);
+	if (!fs_info->super_copy || !fs_info->super_for_commit) {
+		error = -ENOMEM;
+		goto error_close_devices;
+	}
+
 	bdev = fs_devices->latest_bdev;
 	s = sget(fs_type, btrfs_test_super, btrfs_set_super, tree_root);
 	if (IS_ERR(s))
@@ -789,7 +797,7 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
 		}
 
 		btrfs_close_devices(fs_devices);
-		kfree(fs_info);
+		free_fs_info(fs_info);
 		kfree(tree_root);
 	} else {
 		char b[BDEVNAME_SIZE];
@@ -845,7 +853,7 @@ error_s:
 	error = PTR_ERR(s);
 error_close_devices:
 	btrfs_close_devices(fs_devices);
-	kfree(fs_info);
+	free_fs_info(fs_info);
 	kfree(tree_root);
 error_free_subvol_name:
 	kfree(subvol_name);
@@ -873,7 +881,7 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 		if (root->fs_info->fs_devices->rw_devices == 0)
 			return -EACCES;
 
-		if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
+		if (btrfs_super_log_root(root->fs_info->super_copy) != 0)
 			return -EINVAL;
 
 		ret = btrfs_cleanup_fs_roots(root->fs_info);
@@ -1013,7 +1021,7 @@ static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	struct btrfs_root *root = btrfs_sb(dentry->d_sb);
-	struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
+	struct btrfs_super_block *disk_super = root->fs_info->super_copy;
 	struct list_head *head = &root->fs_info->space_info;
 	struct btrfs_space_info *found;
 	u64 total_used = 0;
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 4ce16ef..0bbb5b3 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -44,19 +44,19 @@ static ssize_t super_blocks_used_show(struct btrfs_fs_info *fs, char *buf)
 {
 
 	return snprintf(buf, PAGE_SIZE, "%llu\n",
-		(unsigned long long)btrfs_super_bytes_used(&fs->super_copy));
+		(unsigned long long)btrfs_super_bytes_used(fs->super_copy));
 }
 
 static ssize_t super_total_blocks_show(struct btrfs_fs_info *fs, char *buf)
 {
 	return snprintf(buf, PAGE_SIZE, "%llu\n",
-		(unsigned long long)btrfs_super_total_bytes(&fs->super_copy));
+		(unsigned long long)btrfs_super_total_bytes(fs->super_copy));
 }
 
 static ssize_t super_blocksize_show(struct btrfs_fs_info *fs, char *buf)
 {
 	return snprintf(buf, PAGE_SIZE, "%llu\n",
-		(unsigned long long)btrfs_super_sectorsize(&fs->super_copy));
+		(unsigned long long)btrfs_super_sectorsize(fs->super_copy));
 }
 
 /* this is for root attrs (subvols/snapshots) */
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 5b158da..e4609d9 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1045,7 +1045,7 @@ static void update_super_roots(struct btrfs_root *root)
 	struct btrfs_root_item *root_item;
 	struct btrfs_super_block *super;
 
-	super = &root->fs_info->super_copy;
+	super = root->fs_info->super_copy;
 
 	root_item = &root->fs_info->chunk_root->root_item;
 	super->chunk_root = root_item->bytenr;
@@ -1362,12 +1362,12 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 	update_super_roots(root);
 
 	if (!root->fs_info->log_root_recovering) {
-		btrfs_set_super_log_root(&root->fs_info->super_copy, 0);
-		btrfs_set_super_log_root_level(&root->fs_info->super_copy, 0);
+		btrfs_set_super_log_root(root->fs_info->super_copy, 0);
+		btrfs_set_super_log_root_level(root->fs_info->super_copy, 0);
 	}
 
-	memcpy(&root->fs_info->super_for_commit, &root->fs_info->super_copy,
-	       sizeof(root->fs_info->super_copy));
+	memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
+	       sizeof(*root->fs_info->super_copy));
 
 	trans->transaction->blocked = 0;
 
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index c50271a..4460ead 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2075,9 +2075,9 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
 	BUG_ON(ret);
 	btrfs_wait_marked_extents(log, &log->dirty_log_pages, mark);
 
-	btrfs_set_super_log_root(&root->fs_info->super_for_commit,
+	btrfs_set_super_log_root(root->fs_info->super_for_commit,
 				log_root_tree->node->start);
-	btrfs_set_super_log_root_level(&root->fs_info->super_for_commit,
+	btrfs_set_super_log_root_level(root->fs_info->super_for_commit,
 				btrfs_header_level(log_root_tree->node));
 
 	log_root_tree->log_batch = 0;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 309a57b..6c11a12 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1318,8 +1318,8 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
 		device->fs_devices->open_devices--;
 	}
 
-	num_devices = btrfs_super_num_devices(&root->fs_info->super_copy) - 1;
-	btrfs_set_super_num_devices(&root->fs_info->super_copy, num_devices);
+	num_devices = btrfs_super_num_devices(root->fs_info->super_copy) - 1;
+	btrfs_set_super_num_devices(root->fs_info->super_copy, num_devices);
 
 	if (device->fs_devices->open_devices == 0) {
 		struct btrfs_fs_devices *fs_devices;
@@ -1379,7 +1379,7 @@ static int btrfs_prepare_sprout(struct btrfs_trans_handle *trans,
 	struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
 	struct btrfs_fs_devices *old_devices;
 	struct btrfs_fs_devices *seed_devices;
-	struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
+	struct btrfs_super_block *disk_super = root->fs_info->super_copy;
 	struct btrfs_device *device;
 	u64 super_flags;
 
@@ -1612,12 +1612,12 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 	if (!blk_queue_nonrot(bdev_get_queue(bdev)))
 		root->fs_info->fs_devices->rotating = 1;
 
-	total_bytes = btrfs_super_total_bytes(&root->fs_info->super_copy);
-	btrfs_set_super_total_bytes(&root->fs_info->super_copy,
+	total_bytes = btrfs_super_total_bytes(root->fs_info->super_copy);
+	btrfs_set_super_total_bytes(root->fs_info->super_copy,
 				    total_bytes + device->total_bytes);
 
-	total_bytes = btrfs_super_num_devices(&root->fs_info->super_copy);
-	btrfs_set_super_num_devices(&root->fs_info->super_copy,
+	total_bytes = btrfs_super_num_devices(root->fs_info->super_copy);
+	btrfs_set_super_num_devices(root->fs_info->super_copy,
 				    total_bytes + 1);
 	mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
 
@@ -1708,7 +1708,7 @@ static int __btrfs_grow_device(struct btrfs_trans_handle *trans,
 		      struct btrfs_device *device, u64 new_size)
 {
 	struct btrfs_super_block *super_copy =
-		&device->dev_root->fs_info->super_copy;
+		device->dev_root->fs_info->super_copy;
 	u64 old_total = btrfs_super_total_bytes(super_copy);
 	u64 diff = new_size - device->total_bytes;
 
@@ -1768,7 +1768,7 @@ static int btrfs_free_chunk(struct btrfs_trans_handle *trans,
 static int btrfs_del_sys_chunk(struct btrfs_root *root, u64 chunk_objectid, u64
 			chunk_offset)
 {
-	struct btrfs_super_block *super_copy = &root->fs_info->super_copy;
+	struct btrfs_super_block *super_copy = root->fs_info->super_copy;
 	struct btrfs_disk_key *disk_key;
 	struct btrfs_chunk *chunk;
 	u8 *ptr;
@@ -2091,7 +2091,7 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
 	bool retried = false;
 	struct extent_buffer *l;
 	struct btrfs_key key;
-	struct btrfs_super_block *super_copy = &root->fs_info->super_copy;
+	struct btrfs_super_block *super_copy = root->fs_info->super_copy;
 	u64 old_total = btrfs_super_total_bytes(super_copy);
 	u64 old_size = device->total_bytes;
 	u64 diff = device->total_bytes - new_size;
@@ -2208,7 +2208,7 @@ static int btrfs_add_system_chunk(struct btrfs_trans_handle *trans,
 			   struct btrfs_key *key,
 			   struct btrfs_chunk *chunk, int item_size)
 {
-	struct btrfs_super_block *super_copy = &root->fs_info->super_copy;
+	struct btrfs_super_block *super_copy = root->fs_info->super_copy;
 	struct btrfs_disk_key disk_key;
 	u32 array_size;
 	u8 *ptr;
@@ -3689,7 +3689,7 @@ int btrfs_read_super_device(struct btrfs_root *root, struct extent_buffer *buf)
 
 int btrfs_read_sys_array(struct btrfs_root *root)
 {
-	struct btrfs_super_block *super_copy = &root->fs_info->super_copy;
+	struct btrfs_super_block *super_copy = root->fs_info->super_copy;
 	struct extent_buffer *sb;
 	struct btrfs_disk_key *disk_key;
 	struct btrfs_chunk *chunk;
-- 
1.7.4.1.176.g501cc