The size of root item is more than 400 bytes, which is quite a lot of
stack space. As we do IO from inside the subvolume ioctls, we should
keep the stack usage low in case the filesystem is on top of other
layers (NFS, device mapper, iscsi, etc).
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
---
fs/btrfs/ioctl.c | 49 ++++++++++++++++++++++++++-----------------------
1 file changed, 26 insertions(+), 23 deletions(-)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 053e677839fe..0be13b9c53d9 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -439,7 +439,7 @@ static noinline int create_subvol(struct inode *dir,
{
struct btrfs_trans_handle *trans;
struct btrfs_key key;
- struct btrfs_root_item root_item;
+ struct btrfs_root_item *root_item;
struct btrfs_inode_item *inode_item;
struct extent_buffer *leaf;
struct btrfs_root *root = BTRFS_I(dir)->root;
@@ -455,6 +455,10 @@ static noinline int create_subvol(struct inode *dir,
u64 qgroup_reserved;
uuid_le new_uuid;
+ root_item = kzalloc(sizeof(*root_item), GFP_KERNEL);
+ if (!root_item)
+ return -ENOMEM;
+
ret = btrfs_find_free_objectid(root->fs_info->tree_root, &objectid);
if (ret)
return ret;
@@ -509,47 +513,45 @@ static noinline int create_subvol(struct inode *dir,
BTRFS_UUID_SIZE);
btrfs_mark_buffer_dirty(leaf);
- memset(&root_item, 0, sizeof(root_item));
-
- inode_item = &root_item.inode;
+ inode_item = &root_item->inode;
btrfs_set_stack_inode_generation(inode_item, 1);
btrfs_set_stack_inode_size(inode_item, 3);
btrfs_set_stack_inode_nlink(inode_item, 1);
btrfs_set_stack_inode_nbytes(inode_item, root->nodesize);
btrfs_set_stack_inode_mode(inode_item, S_IFDIR | 0755);
- btrfs_set_root_flags(&root_item, 0);
- btrfs_set_root_limit(&root_item, 0);
+ btrfs_set_root_flags(root_item, 0);
+ btrfs_set_root_limit(root_item, 0);
btrfs_set_stack_inode_flags(inode_item, BTRFS_INODE_ROOT_ITEM_INIT);
- btrfs_set_root_bytenr(&root_item, leaf->start);
- btrfs_set_root_generation(&root_item, trans->transid);
- btrfs_set_root_level(&root_item, 0);
- btrfs_set_root_refs(&root_item, 1);
- btrfs_set_root_used(&root_item, leaf->len);
- btrfs_set_root_last_snapshot(&root_item, 0);
+ btrfs_set_root_bytenr(root_item, leaf->start);
+ btrfs_set_root_generation(root_item, trans->transid);
+ btrfs_set_root_level(root_item, 0);
+ btrfs_set_root_refs(root_item, 1);
+ btrfs_set_root_used(root_item, leaf->len);
+ btrfs_set_root_last_snapshot(root_item, 0);
- btrfs_set_root_generation_v2(&root_item,
- btrfs_root_generation(&root_item));
+ btrfs_set_root_generation_v2(root_item,
+ btrfs_root_generation(root_item));
uuid_le_gen(&new_uuid);
- memcpy(root_item.uuid, new_uuid.b, BTRFS_UUID_SIZE);
- btrfs_set_stack_timespec_sec(&root_item.otime, cur_time.tv_sec);
- btrfs_set_stack_timespec_nsec(&root_item.otime, cur_time.tv_nsec);
- root_item.ctime = root_item.otime;
- btrfs_set_root_ctransid(&root_item, trans->transid);
- btrfs_set_root_otransid(&root_item, trans->transid);
+ memcpy(root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
+ btrfs_set_stack_timespec_sec(&root_item->otime, cur_time.tv_sec);
+ btrfs_set_stack_timespec_nsec(&root_item->otime, cur_time.tv_nsec);
+ root_item->ctime = root_item->otime;
+ btrfs_set_root_ctransid(root_item, trans->transid);
+ btrfs_set_root_otransid(root_item, trans->transid);
btrfs_tree_unlock(leaf);
free_extent_buffer(leaf);
leaf = NULL;
- btrfs_set_root_dirid(&root_item, new_dirid);
+ btrfs_set_root_dirid(root_item, new_dirid);
key.objectid = objectid;
key.offset = 0;
key.type = BTRFS_ROOT_ITEM_KEY;
ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
- &root_item);
+ root_item);
if (ret)
goto fail;
@@ -601,12 +603,13 @@ static noinline int create_subvol(struct inode *dir,
BUG_ON(ret);
ret = btrfs_uuid_tree_add(trans, root->fs_info->uuid_root,
- root_item.uuid, BTRFS_UUID_KEY_SUBVOL,
+ root_item->uuid, BTRFS_UUID_KEY_SUBVOL,
objectid);
if (ret)
btrfs_abort_transaction(trans, root, ret);
fail:
+ kfree(root_item);
trans->block_rsv = NULL;
trans->bytes_reserved = 0;
btrfs_subvolume_release_metadata(root, &block_rsv, qgroup_reserved);
--
2.7.1
--
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