From 49a3c4d9b64d2e5d6fd268d53153945d04cb5559 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Thu, 24 Mar 2016 17:49:22 +0100 Subject: [PATCH] btrfs: use dynamic allocation for root item in create_subvol 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). Reviewed-by: Tsutomu Itoh Signed-off-by: David Sterba --- fs/btrfs/ioctl.c | 65 +++++++++++++++++++++++++++--------------------- 1 file changed, 37 insertions(+), 28 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index cfa7d47b1ba0..798f58e7338e 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; @@ -455,16 +455,22 @@ 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; + goto fail_free; /* * Don't create subvolume whose level is not zero. Or qgroup will be * screwed up since it assume subvolme qgroup's level to be 0. */ - if (btrfs_qgroup_level(objectid)) - return -ENOSPC; + if (btrfs_qgroup_level(objectid)) { + ret = -ENOSPC; + goto fail_free; + } btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP); /* @@ -474,14 +480,14 @@ static noinline int create_subvol(struct inode *dir, ret = btrfs_subvolume_reserve_metadata(root, &block_rsv, 8, &qgroup_reserved, false); if (ret) - return ret; + goto fail_free; trans = btrfs_start_transaction(root, 0); if (IS_ERR(trans)) { ret = PTR_ERR(trans); btrfs_subvolume_release_metadata(root, &block_rsv, qgroup_reserved); - return ret; + goto fail_free; } trans->block_rsv = &block_rsv; trans->bytes_reserved = block_rsv.size; @@ -509,47 +515,45 @@ 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 +605,13 @@ 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); @@ -629,6 +634,10 @@ fail: d_instantiate(dentry, inode); } return ret; + +fail_free: + kfree(root_item); + return ret; } static void btrfs_wait_for_no_snapshoting_writes(struct btrfs_root *root)